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1

Historic and modern abundance of wild lean lake trout in Michigan waters of Lake Superior: Implications for restoration goals  

USGS Publications Warehouse

Populations of lake trout Salvelinus namaycush in Lake Superior collapsed in the late 1950s due to overfishing and predation by sea lampreys Petromyzon marinus. A binational effort to restore the lean morphotype of lake trout began with the stocking of hatchery-reared fish followed by the chemical control of sea lampreys and closure of the commercial fishery. Previous comparisons of the contemporary abundance of wild lean lake trout with that from historic commercial fishery statistics indicate that abundance was higher historically. However, this conclusion may be biased because several factors- the inclusion of siscowet (the 'fat' morphotype of lake trout) in the catch statistics, the soak time of nets, seasonal effects on catch per effort, and the confounding effects of effort targeted at lake whitefish Coregonus clupeaformis- were not accounted for. We developed new indices of historic lean lake trout abundance that correct for these biases and compared them with the assessment data from 1984 to 1998 in Michigan waters of Lake Superior. The modern (1984-1998) abundance of wild lean lake trout is at least as high as that during 1929-1943 in six of eight management areas but lower in one area. Measures to promote and protect naturally reproducing populations have been more successful than previously realized.

Wilberg, Michael J.; Hansen, Michael J.; Bronte, Charles R.

2003-01-01

2

A genetic basis for the phenotypic differentiation between siscowet and lean lake trout (Salvelinus namaycush).  

PubMed

In Lake Superior there are three principal forms of lake trout (Salvelinus namaycush): lean, siscowet and humper. Wild lean and siscowet differ in the shape and relative size of the head, size of the fins, location and size of the eyes, caudal peduncle shape and lipid content of the musculature. To investigate the basis for these phenotypic differences, lean and siscowet lake trout, derived from gametes of wild populations in Lake Superior, were reared communally under identical environmental conditions for 2.5 years. Fish were analysed for growth, morphometry and lipid content, and differences in liver transcriptomics were investigated using Roche 454 GS-FLX pyrosequencing. The results demonstrate that key phenotypic differences between wild lean and siscowet lake trout such as condition factor, morphometry and lipid levels, persist in these two forms when reared in the laboratory under identical environmental conditions. This strongly suggests that these differences are genetic and not a result of environmental plasticity. Transcriptomic analysis involving the comparison of hepatic gene frequencies (RNA-seq) and expression (quantitative reverse transcription-polymerase chain reaction (qPCR)) between the two lake trout forms, indicated two primary gene groups that were differentially expressed; those involving lipid synthesis, metabolism and transport (acyl-CoA desaturase, acyl-CoA binding protein, peroxisome proliferator-activated receptor gamma, and apolipoproteins), and those involved with immunity (complement component C3, proteasome, FK506 binding protein 5 and C1q proteins). The results demonstrate that RNA-seq can be used to identify differentially expressed genes; however, some discrepancies between RNA-seq analysis and qPCR indicate that methods for deep sequencing may need to be refined and/or different RNA-seq platforms utilized. PMID:20331779

Goetz, Frederick; Rosauer, Daniel; Sitar, Shawn; Goetz, Giles; Simchick, Crystal; Roberts, Steven; Johnson, Ronald; Murphy, Cheryl; Bronte, Charles R; Mackenzie, Simon

2010-03-01

3

Growth and Contaminant Dynamics of Lake Superior Lake Trout  

Microsoft Academic Search

Lean lake trout (Salvelinus namaycush) and the endemic siscowet are ecologically distinct phenotypes of char inhabiting Lake Superior. To examine growth and contaminant concentration dynamics of these fishes, and to assess their utility as indicators of environmental contamination, length, weight, estimated age, and muscle tissue lipid and organochlorine (OC) chemical concentration data were analyzed. Lean lake trout grew faster in

Michael A. Miller; Stephen T. Schram

2000-01-01

4

Pesticide residues, PCBs and PAHs in baked, charbroiled, salt boiled and smoked Great Lakes lake trout  

Microsoft Academic Search

Skin-off lean lake trout (Salvelinus namaycush namaycush) from Lakes Huron, Michigan and Ontario as well as siscowets (fat lake trout) (Salvelinus namaycush siscowet) from Lake Superior were cooked by baking and charbroiling to determine the potential of processing\\/cooking on reducing the levels of pesticides and total PCBs in fish at the dinner table. Lake trout from Lakes Michigan and Superior

Mary E Zabik; Al Booren; Matthew J Zabik; Robert Welch; Harold Humphrey

1996-01-01

5

Lake Trout Discovered in Yellowstone Lake Threaten Native Cutthroat Trout  

Microsoft Academic Search

On 30 July 1994, lake trout (Salvelinus namaycush) were discovered in Yellowstone Lake in Yellowstone National Park, Wyoming, the core of the remaining undisturbed natural habitat for native Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri). Data from this and other lake trout subsequently caught by anglers and the U.S. Fish and Wildlife Service suggest lake trout have reproduced in Yellowstone Lake

Lynn R. Kaeding; Glenn D. Boltz; Daniel G. Carty

1996-01-01

6

Diet and Prey Selection by Lake Superior Lake Trout during Spring, 1986–2001  

Microsoft Academic Search

We describe the diet and prey selectivity of lean (Salvelinus namaycush namaycush) and siscowet lake trout (S. n. siscowet) collected during spring (April–June) from Lake Superior during 1986–2001. We estimated prey selectivity by comparing prey numerical abundance estimates from spring bottom trawl surveys and lake trout diet information in similar areas from spring gill net surveys conducted annually in Lake

Bradley A. Ray; Thomas R. Hrabik; Mark P. Ebener; Owen T. Gorman; Donald R. Schreiner; Stephen T. Schram; Shawn P. Sitar; William P. Mattes; Charles R. Bronte

2007-01-01

7

Diet and prey selection by Lake Superior lake trout during springs 1986-2001  

USGS Publications Warehouse

We describe the diet and prey selectivity of lean (Salvelinus namaycush namaycush) and siscowet lake trout (S. n. siscowet) collected during spring (April-June) from Lake Superior during 1986-2001. We estimated prey selectivity by comparing prey numerical abundance estimates from spring bottom trawl surveys and lake trout diet information in similar areas from spring gill net surveys conducted annually in Lake Superior. Rainbow smelt (Osmerus mordax) was the most common prey and was positively selected by both lean and siscowet lake trout throughout the study. Selection by lean lake trout for coregonine (Coregonus spp.) prey increased after 1991 and corresponded with a slight decrease in selection for rainbow smelt. Siscowet positively selected for rainbow smelt after 1998, a change that was coincident with the decrease in selection for this prey item by lean lake trout. However, diet overlap between lean and siscowet lake trout was not strong and did not change significantly over the study period. Rainbow smelt remains an important prey species for lake trout in Lake Superior despite declines in abundance.

Ray, B.A.; Hrabik, T.R.; Ebener, M.P.; Gorman, O.T.; Schreiner, D.R.; Schram, S.T.; Sitar, S.P.; Mattes, W.P.; Bronte, C.R.

2007-01-01

8

Congener specific PCB distribution in lake trout/siscowets and walleye from the Great Lakes  

SciTech Connect

Lean lake trout (Salvelinus namaycush) from Lakes Huron, Michigan and Ontario and siscowets (fat lake trout) from Lake Superior as well as walleye (Stizotedium vitreum vitreum) from Lakes Erie, Huron and Michigan were analyzed for 53 PCB congeners commonly found in Aroclor 1254. The average PCB congener pattern is presented for a minimum of 12 fish from each species from each lake and the distribution of PCB congeners among species and lakes is compared. Greater differences were found for the lake source of the lake trout than for the walleye. Lake trout from Lake Ontario had high levels of congener 198. Lake trout from Lakes Huron and Superior also tended to have higher levels of higher chlorinated congeners while lake trout from Lake Michigan had the highest levels of the lower chlorinated congeners. Fewer lake effect differences were found for distribution of PCB congeners for the walleye. Walleye from Lake Huron had a greater percentage of the total PCB congeners with lower chlorination than did lake trout but the pattern of percent of total for lake trout and walleye from Lake Michigan was quite similar.

Zabik, M.J.; Zabik, M.E.; Booren, A.M.; Daubenmire, S.; Pascall, M.; Dickmann, G.; Khedr, G. [Michigan State Univ., East Lansing, MI (United States)

1995-12-31

9

Food of Lake Trout in Lake Superior  

Microsoft Academic Search

Stomachs were examined from 1,492 lake trout and 83 siscowets collected from Lake Superior. Data are given on the food of lake trout of legal size (17 inches or longer) by year, season, and depth of water, and on the relation between food and size among smaller lake trout.Fish contributed 96.7 to 99.9 per cent of the total volume of

William R. Dryer; Leo F. Erkkila; Clifford L. Tetzloff

1965-01-01

10

Lake Trout Rehabilitation in Lake Huron  

Microsoft Academic Search

Efforts to restore lake trout (Salvelinus namaycush) in Lake Huron after their collapse in the 1940s were underway in the early 1970s with completion of the first round oflampricide applications in tributary streams and the stocking of several genotypes. We assess results of rehabilitation and establish a historical basis for comparison by quantifying the catch of spawning lake trout from

Randy L. Eshenroder; N. Robert Payne; James E. Johnson; Charles Bowen II; Mark P. Ebener

1995-01-01

11

Lake Trout Reproduction in Lake Champlain  

Microsoft Academic Search

Native lake trout Salvelinus namaycush were driven to extirpation in Lake Champlain in the early 1900s. Possible causes include overharvest, predation on adults by sea lamprey Petromyzon marinus, and predation on fry by rainbow smelt Osmerus mordax. Efforts to restore a lake trout fishery began in 1972 when a coordinated stocking program was initiated. Attempts to control sea lamprey populations

Brian J. Ellrott; J. Ellen Marsden

2004-01-01

12

Longevity of Lake Superior lake trout  

USGS Publications Warehouse

The age structure of mature lake trout Salvelinus namaycush from the Wisconsin waters of Lake Superior increased following a population recovery that has taken place since the 1960s. As the population aged, it became apparent that scales were unreliable aging structures. Beginning in 1986, we examined both scale and sagittal otolith ages from tagged fish with a known period at liberty. We found large discrepancies in scale and sagittal otolith ages of mature fish, such that scale ages were biased low. We estimated lake trout living up to 42 years, which is greater than previously reported from Lake Superior. Investigators studying lake trout population dynamics in the Great Lakes should be aware that lake trout can live longer than previously thought.

Schram, Stephen T.; Fabrizio, Mary C.

1998-01-01

13

Lake trout rehabilitation in Lake Huron  

USGS Publications Warehouse

Efforts to restore lake trout (Salvelinus namaycush) in Lake Huron after their collapse in the 1940s were underway in the early 1970s with completion of the first round of lampricide applications in tributary streams and the stocking of several genotypes. We assess results of rehabilitation and establish a historical basis for comparison by quantifying the catch of spawning lake trout from Michigan waters in 1929-1932. Sixty-eight percent of this catch occurred in northern waters (MH-1) and most of the rest (15%) was from remote reefs in the middle of the main basin. Sea lampreys (Petromyzon marinus) increased in the early 1980s in the main basin and depressed spawning populations of lake trout. This increase was especially severe in northern waters and appeared to be associated with untreated populations in the St. Marys River. Excessive commercial fishing stemming from unresolved treaty rights also contributed to loss of spawning fish in northern Michigan waters. Seneca-strain lake trout did not appear to be attacked by sea lampreys until they reached a size > 532 mm. At sizes > 632 mm, Seneca trout were 40-fold more abundant than the Marquette strain in matched-planting experiments. Natural reproduction past the fry stage has occurred in Thunder Bay and South Bay, but prospects for self-sustaining populations of lake trout in the main basin are poor because sea lampreys are too abundant, only one side of the basin is stocked, and stocking is deferred to allow commercial gillnetting in areas where most of the spawning occurred historically. Backcross lake trout, a lake trout x splake (s. Fontinalis x s. Namaycush) hybrid, did not reproduce in Georgian Bay, but this genotype is being replaced with pure-strain lake trout, whose early performance appears promising.

Eshenroder, Randy L.; Payne, N. Robert; Johnson, James E.; Bowen, Charles, II; Ebener, Mark P.

1995-01-01

14

Lake Trout Rehabilitation in Lake Ontario  

Microsoft Academic Search

Attempts to maintain the native lake trout (Salvelinus namaycush) population in Lake Ontario by stocking fry failed and the species was extirpated by the 1950s. Hatchery fish stocked in the 1960s did not live to maturity because of sea lamprey (Petromyzon marinus) predation and incidental commercial harvest. Suppression of sea lampreys began with larvicide treatments of Lake Ontario tributaries in

Joseph H. Elrod; Robert O’Gorman; Clifford P. Schneider; Thomas H. Eckert; Ted Schaner; James N. Bowlby; Larry P. Schleen

1995-01-01

15

Evaluating the growth potential of sea lampreys (Petromyzon marinus) feeding on siscowet lake trout (Salvelinus namaycush) in Lake Superior  

USGS Publications Warehouse

Differences in the preferred thermal habitat of Lake Superior lake trout morphotypes create alternative growth scenarios for parasitic sea lamprey (Petromyzon marinus) attached to lake trout hosts. Siscowet lake trout (Salvelinus namaycush) inhabit deep, consistently cold water (4–6 °C) and are more abundant than lean lake trout (Salvelinus namaycush) which occupy temperatures between 8 and 12 °C during summer thermal stratification. Using bioenergetics models we contrasted the growth potential of sea lampreys attached to siscowet and lean lake trout to determine how host temperature influences the growth and ultimate size of adult sea lamprey. Sea lampreys simulated under the thermal regime of siscowets are capable of reaching sizes within the range of adult sea lamprey sizes observed in Lake Superior tributaries. High lamprey wounding rates on siscowets suggest siscowets are important lamprey hosts. In addition, siscowets have higher survival rates from lamprey attacks than those observed for lean lake trout which raises the prospect that siscowets serve as a buffer to predation on more commercially desirable hosts such as lean lake trout, and could serve to subsidize lamprey growth.

Moody, E.K.; Weidel, B.C.; Ahrenstorff, T.D.; Mattes, W.P.; Kitchell, J.F.

2011-01-01

16

Harvest and Relative Abundance of Siscowet Lake Trout in  

E-print Network

Abstract.—Siscowet, a deepwater morphotype of lake trout Salvelinus namaycush and the top predator in Lake Superior, currently makes up most of the lake trout biomass in this lake. Anecdotal accounts indicate that siscowets made up some portion of the historical lake trout commercial fishery, but estimates of harvest and relative abundance are lacking. By using the location information provided by historical fishers on monthly catch reports and past and contemporary knowledge of the depth distribution of siscowets, we provide the first estimates of historical siscowet commercial harvest, fishing effort, and changes in relative abundance for Michigan waters of Lake Superior from 1929 to 1961. Siscowets made up about 27 % of the historical yield of lake trout in Michigan waters during this period, but the composition varied greatly among management units. The relative abundance of siscowet in its principal habitat (waters deeper than 80 m) generally declined in most management units before the increase in fishing effort in the mid to late 1940s and the invasion of sea lamprey Petromyzon marinus during the 1950s. These factors led to the collapse of nearshore lean lake trout populations by the late 1950s. Modest levels of fishing effort (around 2,000 km annually) before sea lamprey invasion were sufficient to cause declines in siscowet and were probably related to the low production rates associated with the k-selected life history attributes of this deepwater morphotype. Lake Superior had a substantial commercial fishery

Charles R. Bronte; Shawn P. Sitar

17

Lake Trout Rehabilitation in Lake Erie: A Case History  

Microsoft Academic Search

Native lake trout (Salvelinus namaycush) once thrived in the deep waters of eastern Lake Erie. The impact of nearly 70 years of unregulated exploitation and over 100 years of progressively severe cultural eutrophication resulted in the elimination of lake trout stocks by 1950. Early attempts to restore lake trout by stocking were unsuccessful in establishing a self-sustaining population. In the

Floyd C. Cornelius; Kenneth M. Muth; Roger Kenyon

1995-01-01

18

Evidence of offshore lake trout reproduction in Lake Huron  

USGS Publications Warehouse

Six Fathom Bank-Yankee Reef, an offshore reef complex, was an historically important spawning area believed to represent some of the best habitat for the rehabilitation of lake trout Salvelinus namaycush in Lake Huron. Since 1986, lake trout have been stocked on these offshore reefs to reestablish self-sustaining populations. We sampled with beam trawls to determine the abundance of naturally reproduced age-0 lake trout on these offshore reefs during May-July in 1994-1998 and 2000-2002. In total, 123 naturally reproduced lake trout fry were caught at Six Fathom Bank, and 2 naturally reproduced lake trout fry were caught at nearby Yankee Reef. Our findings suggest that this region of Lake Huron contains suitable habitat for lake trout spawning and offers hope that lake trout rehabilitation can be achieved in the main basin of Lake Huron.

DeSorcie, Timothy J.; Bowen, Charles A., II

2003-01-01

19

Suitability of habitat for spawning lake trout  

Microsoft Academic Search

We provide further insight into the reproductive ecology and spawning requirements of lake trout. New comparative information about substrate characteristics, sediment transport, quality of interstitial water at spawning substrates, and the role of temperature in site selection and time of spawning is given for lakes Simcoe and Manitou (Ontario) and Seneca Lake (New York). Spawning lake trout commonly use stable

P. G. Sly; D. O. Evans

1996-01-01

20

Predation on emergent lake trout fry in Lake Champlain  

Microsoft Academic Search

The rehabilitation of extirpated lake trout (Salvelinus namaycush) in the Great Lakes and Lake Champlain has been hindered by various biological and physiological impediments. Efforts to restore a lake trout fishery to Lake Champlain include hatchery stocking and sea lamprey control. Despite these management actions, there is little evidence of recruitment of naturally-produced fish in annual fall assessments. Spawning occurs

Jacob W. Riley; J. Ellen Marsden

2009-01-01

21

Natural Reproduction by Stocked Lake Trout ( Salvelinus namaycush) and Hybrid (Backcross) Lake Trout in South Bay, Lake Huron  

Microsoft Academic Search

In 1977, a study was begun in South Bay, Lake Huron, to assess the fitness of lake trout (Salvelinus namaycush) and lake trout backcrossed to splake (S. namaycush X S. fontinalis) for rehabilitating the lake. Mature lake trout were fivefold more abundant than mature backcross from paired stockings. Wild progeny consisting of 321 fry and 67 age-0 to age-2 juveniles

David M. Anderson; John J. Collins

1995-01-01

22

A blood chemistry profile for lake trout  

USGS Publications Warehouse

A blood chemistry profile for lake trout Salvelinus namaycush was developed by establishing baseline ranges for several clinical chemistry tests (glucose, total protein, amylase, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase, calcium, and magnesium). Measurements were made accurately and rapidly with a Kodak Ektachem DT60 Analyzer and the Ektachem DTSC Module. Blood serum was collected from both laboratory-reared lake trout (1978 and 1986 year-classes) and feral spawning trout from Lake Michigan and then analyzed in the laboratory. No clinically significant differences were found between samples analyzed fresh and those frozen for 1 or 6 weeks. The ranges in chemistry variables for feral lake trout were generally wider than those for laboratory-reared lake trout, and significant differences existed between male and female feral lake trout for several tests. Blood chemistry profiles also varied seasonally on fish sampled repeatedly.

Edsall, Carol Cotant

1999-01-01

23

Demography of lake trout in relation to population suppression in Yellowstone Lake, Yellowstone National Park .  

E-print Network

??Introduced lake trout Salvelinus namaycush threaten to extirpate native Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri in Yellowstone Lake, Yellowstone National Park. Suppression of the lake… (more)

Syslo, John Michael.

2010-01-01

24

Age, growth, maturity, and fecundity of 'humper' lake trout, Isle Royale, Lake Superior  

USGS Publications Warehouse

Humper lake trout are one of the several races or subpopulations of lake trout in Lake Superior. This study is based on 3,705 fish collected on a reef south of Isle Royale near the eastern end. The mean lengths of humper trout from commercial gill nets were smaller than those of lean lake trout. Members of age-groups VII, VIII, and IX represented 81.5 per cent of the commercial humper catch. The body-scale relation was described by two intersecting straight lines. The weight of humper trout increased as the 3.282 power of the length. Growth in length was slow and ranged from 1.6 to 3.5 inches per year. Annual increments were greatest in the first, sixth, and seventh years. Growth in weight was also slow but increased each year. Humper trout became legal (1 1/2 pounds) in the eighth year of life and reached 5 pounds in 11 years. All fish longer than 19.1 inches and older than age-group VIII were mature; the shortest mature fish were: males, 12.7 inches; females, 14.7 inches. At minimum legal size, 98 per cent of the males and 56 per cent of the females were mature. Humper trout produced an average of 1,351 eggs per fish or 516 per pound.

Rahrer, Jerold F.

1965-01-01

25

Reevaluation of lake trout and lake whitefish bioenergetics models  

USGS Publications Warehouse

Using a corrected algorithm for balancing the energy budget, we reevaluated the Wisconsin bioenergetics model for lake trout (Salvelinus namaycush) in the laboratory and for lake whitefish (Coregonus clupeaformis) in the laboratory and in the field. For lake trout, results showed that the bioenergetics model slightly overestimated food consumption by the lake trout when they were fed low and intermediate rations, whereas the model predicted food consumption by lake trout fed ad libitum without any detectable bias. The slight bias in model predictions for lake trout on restricted rations may have been an artifact of the feeding schedule for these fish, and we would therefore recommend application of the Wisconsin lake trout bioenergetics model to lake trout populations in the field without any revisions to the model. Use of the Wisconsin bioenergetics model for coregonids resulted in overestimation of food consumption by lake whitefish both in the laboratory and in the field by between 20 and 30%, on average. This overestimation of food consumption was most likely due to overestimation of respiration rate. We therefore adjusted the respiration component of the bioenergetics model to obtain a good fit to the observed consumption in our laboratory tanks. The adjusted model predicted the consumption in the laboratory and the field without any detectable bias. Until a detailed lake whitefish respiration study can be conducted, we recommend application of our adjusted version of the Wisconsin generalized coregonid bioenergetics model to lake whitefish populations in the field.

Madenjian, Charles P.; Pothoven, Steve A.; Kao, Yu-Chun

2013-01-01

26

Lake trout rehabilitation in Lake Erie: a case history  

USGS Publications Warehouse

Native lake trout (Salvelinus namaycush) once thrived in the deep waters of eastern Lake Erie. The impact of nearly 70 years of unregulated exploitation and over 100 years of progressively severe cultural eutrophication resulted in the elimination of lake trout stocks by 1950. Early attempts to restore lake trout by stocking were unsuccessful in establishing a self-sustaining population. In the early 1980s, New York's Department of Environmental Conservation, Pennsylvania's Fish and Boat Commission, and the U.S. Fish and Wildlife Service entered into a cooperative program to rehabilitate lake trout in the eastern basin of Lake Erie. After 11 years of stocking selected strains of lake trout in U.S. waters, followed by effective sea lamprey control, lake trout appear to be successfully recolonizing their native habitat. Adult stocks have built up significantly and are expanding their range in the lake. Preliminary investigations suggest that lake trout reproductive habitat is still adequate for natural reproduction, but natural recruitment has not been documented. Future assessments will be directed toward evaluation of spawning success and tracking age-class cohorts as they move through the fishery.

Cornelius, Floyd C.; Muth, Kenneth M.; Kenyon, Roger

1995-01-01

27

Gillnet selectivity for lake trout (Salvelinus namaycush) in Lake Superior  

Microsoft Academic Search

Gillnet selectivity for lake trout ( Salvelinus namaycush) was estimated indirectly from catches in nets of 102-, 114-, 127-, 140-, and 152-mm stretch measure. Mesh selectivity was modeled as a nonlinear response surface that describes changes in the mean, standard deviation, and skewness of fish lengths across mesh sizes. Gillnet selectivity for lake trout was described by five parameters that

Michael J. Hansen; Charles P. Madenjian; James H. Selgeby; Thomas E. Helser

1998-01-01

28

Introduced Lake Trout Produced a Four-Level Trophic Cascade in Yellowstone Lake  

E-print Network

82071-3332, USA Abstract.--Introduction of lake trout Salvelinus namaycush into a system can add are present and where lake trout have been introduced. Lake trout Salvelinus namaycush are introduced clarkii henshawi in Lake Tahoe, California, and bull trout Salvelinus confluentus in Lake Mc

Hall Jr., Robert O.

29

Gillnet selectivity for lake trout (Salvelinus namaycush) in Lake Superior  

USGS Publications Warehouse

Gillnet selectivity for lake trout (Salvelinus namaycush) was estimated indirectly from catches in nets of 102-, 114-, 127-, 140-, and 152-mm stretch measure. Mesh selectivity was modeled as a nonlinear response surface that describes changes in the mean, standard deviation, and skewness of fish lengths across mesh sizes. Gillnet selectivity for lake trout was described by five parameters that explained 88% of the variation in wedged and entangled catches, 81% of the variation in wedged catches, and 82% of the variation in entangled catches. Combined catches of wedged and entangled lake trout were therefore described more parsimoniously than separate catches of wedged and entangled lake trout. Peak selectivity of wedged and entangled fish increased from 588 to 663 mm total length as mesh size increased from 102 to 152 mm, and relative selectivity peaked at a total length of 638 mm. The estimated lake trout population size-frequency indicated that gillnet catches were negatively biased toward both small and large lake trout. As a consequence of this bias, survival of Lake Superior lake trout across ages 9-11 was underestimated by about 20% when the catch curve was not adjusted for gillnet selectivity.

Hansen, Michael J.; Madenjian, Charles P.; Selgeby, James H.; Helser, Thomas E.

1997-01-01

30

Evidence of Lake Trout reproduction at Lake Michigan's mid-lake reef complex  

USGS Publications Warehouse

The Mid-Lake Reef Complex (MLRC), a large area of deep (> 40 m) reefs, was a major site where indigenous lake trout (Salvelinus namaycush) in Lake Michigan aggregated during spawning. As part of an effort to restore Lake Michigan's lake trout, which were extirpated in the 1950s, yearling lake trout have been released over the MLRC since the mid-1980s and fall gill net censuses began to show large numbers of lake trout in spawning condition beginning about 1999. We report the first evidence of viable egg deposition and successful lake trout fry production at these deep reefs. Because the area's existing bathymetry and habitat were too poorly known for a priori selection of sampling sites, we used hydroacoustics to locate concentrations of large fish in the fall; fish were congregating around slopes and ridges. Subsequent observations via unmanned submersible confirmed the large, fish to be lake trout. Our technological objectives were driven by biological objectives of locating where lake trout spawn, where lake trout fry were produced, and what fishes ate lake trout eggs and fry. The unmanned submersibles were equipped with a suction sampler and electroshocker to sample eggs deposited on the reef, draw out and occasionally catch emergent fry and collect egg predators (slimy sculpin Cottus cognatus). We observed slimy sculpin to eat unusually high numbers of lake trout eggs. Our qualitative approaches are a first step toward quantitative assessments of the importance of lake trout spawning on the MLRC.

Janssen, J.; Jude, D.J.; Edsall, T.A.; Paddock, R.W.; Wattrus, N.; Toneys, M.; McKee, P.

2006-01-01

31

PCB concentrations in lake trout (Salvelinus namaycush) are correlated to habitat use and lake characteristics.  

PubMed

This study considers the importance of lake trout habitat as a factor determining persistent organochlorine (OC) concentration. Lake trout is a stenothermal, cold water species and sensitive to hypoxia. Thus, factors such as lake depth, thermal stratification, and phosphorus enrichment may determine not only which lakes can support lake trout but may also influence among-lake variability in lake trout population characteristics including bioaccumulation of OCs. A survey of 23 lakes spanning much of the natural latitudinal distribution of lake trout provided a range of lake trout habitat to test the hypothesis that lake trout with greater access to littoral habitat for feeding will have lower concentrations of OCs than lake trout that are more restricted to pelagic habitat. Using the delta13C stable isotope signature in lake trout as an indicator of influence of benthic littoral feeding, we found a negative correlation between lipid-corrected delta13C and sigmaPCB concentrations supporting the hypothesis that increasing accessto littoral habitat results in lower OCs in lake trout. The prominence of mixotrophic phytoplankton in lakes with more contaminated lake trout indicated the pelagic microbial food web may exacerbate the biomagnification of OCs when lake trout are restricted to pelagic feeding. A model that predicted sigmaPCB in lake trout based on lake area and latitude (used as proximate variables for proportion of littoral versus pelagic habitat and accessibility to littoral habitat respectively) explained 73% of the variability in sigmaPCBs in lake trout in the 23 lakes surveyed. PMID:19068800

Guildford, S J; Muir, D C G; Houde, M; Evans, M S; Kidd, K A; Whittle, D M; Drouillard, K; Wang, X; Anderson, M R; Bronte, C R; Devault, D S; Haffner, D; Payne, J; Kling, H J

2008-11-15

32

EFFECTS OF INTRODUCED LAKE TROUT ON NATIVE CUTTHROAT TROUT IN YELLOWSTONE LAKE  

Microsoft Academic Search

The establishment of a reproducing population of nonnative lake trout (Sal- velinus namaycush) poses a serious threat to the integrity of the Yellowstone Lake eco- system, particularly to the indigenous cutthroat trout ( Oncorhynchus clarki bouvieri ). We used standard fisheries techniques to quantify the population-level impact resulting from this introduction, while the U.S. National Park Service (NPS) developed a

James R. Ruzycki; David A. Beauchamp; Daniel L. Yule

2003-01-01

33

Diet Overlap of Top-Level Predators in Recent Sympatry: Bull Trout and Nonnative Lake Trout  

E-print Network

, Montana 59803 Abstract The establishment of nonnative lake trout Salvelinus namaycush in lakes containing trout Salvelinus namaycush (Figure 1) introduc- tions and invasions have been implicated in declines lacustrine­adfluvial bull trout Salvelinus confluentus often results in a precipitous decline in bull trout

McMahon, Thomas E.

34

Diet overlap of top-level predators in recent sympatry: bull trout and nonnative lake trout  

USGS Publications Warehouse

The establishment of nonnative lake trout Salvelinus namaycush in lakes containing lacustrine–adfluvial bull trout Salvelinus confluentus often results in a precipitous decline in bull trout abundance. The exact mechanism for the decline is unknown, but one hypothesis is related to competitive exclusion for prey resources. We had the rare opportunity to study the diets of bull trout and nonnative lake trout in Swan Lake, Montana during a concomitant study. The presence of nonnative lake trout in Swan Lake is relatively recent and the population is experiencing rapid population growth. The objective of this study was to evaluate the diets of bull trout and lake trout during the early expansion of this nonnative predator. Diets were sampled from 142 bull trout and 327 lake trout during the autumn in 2007 and 2008. Bull trout and lake trout had similar diets, both consumed Mysis diluviana as the primary invertebrate, especially at juvenile stages, and kokanee Oncorhynchus nerka as the primary vertebrate prey, as adults. A diet shift from primarily M. diluviana to fish occurred at similar lengths for both species, 506 mm (476–545 mm, 95% CI) for bull trout and 495 mm (470–518 mm CI) for lake trout. These data indicate high diet overlap between these two morphologically similar top-level predators. Competitive exclusion may be a possible mechanism if the observed overlap remains similar at varying prey densities and availability.

Guy, Christopher S.; McMahon, Thomas E.; Fredenberg, Wade A.; Smith, Clinton J.; Garfield, David W.; Cox, Benjamin S.

2011-01-01

35

Fecundity of hatchery lake trout in Lake Ontario  

USGS Publications Warehouse

Fecundity (egg number) was determined from 26 stocked (617-800 mm, total length) lake trout (Salvelinus namaycush) collected in western Lake Ontario during September 1992. Previous to this study, fecundity was evaluated only once in Lake Ontario using native stocks in 1927. The following relationships between fecundity and total length (TL) and weight (W) were obtained. Fecundity = -12,492 + 25.87 TL(mm) and Fecundity = -1,010 + 1,307 W(kg). Relative fecundity (number of eggs per kg of body weight) was unrelated to body weight and averaged 1,592 eggs kg-1. Fecundity of contemporary lake trout based on length was significantly lower than that of historic native stocks, but was similar to contemporary stocked lake trout in Lake Superior.

Fitzsimons, John D.; O'Gorman, Robert

1996-01-01

36

Lake Trout ( Salvelinus namaycush) Populations in Lake Superior and Their Restoration in 1959–1993  

Microsoft Academic Search

Naturally-reproducing populations of lake trout (Salvelinus namaycush) have been reestablished in most of Lake Superior, but have not been restored to 1929-1943 average abundance. Progress toward lake trout restoration in Lake Superior is described, management actions are reviewed, and the effectiveness of those actions is evaluated; especially stocking lake trout as a tool for building spawning stocks, and subsequently, populations

Michael J. Hansen; James W. Peck; Richard G. Schorfhaar; James H. Selgeby; Donald R. Schreiner; Stephen T. Schram; Bruce L. Swanson; Wayne R. MacCallum; Mary K. Burnham-Curtis; Gary L. Curtis; John W. Heinrich; Robert J. Young

1995-01-01

37

Laboratory evaluation of a lake trout bioenergetics model  

USGS Publications Warehouse

Lake trout Salvelinus namaycush, aged 3 and 6 years and with average weights of 700 and 2,000 g, were grown in laboratory tanks for up to 407 d under a thermal regime similar to that experienced by lake trout in nearshore Lake Michigan. Lake trout were fed alewife Alosa pseudoharengus and rainbow smelt Osmerus mordax, prey typical of lake trout in Lake Michigan. Of the 120 lake trout used in the experiment, 40 were fed a low ration (0.25% of their body weight per day), 40 were fed a medium ration (0.5% of their body weight per day), and 40 were fed a high ration (ad libitum). We measured consumption and growth, and we compared observed consumption with that predicted by the Wisconsin bioenergetics model. For lake trout fed the medium ration, model predictions for monthly consumption were unbiased. Moreover, predicted cumulative consumption by medium-ration lake trout for the entire experiment (320 d for smaller lake trout and 407 d for larger lake trout) agreed quite well with observed cumulative consumption; predictions were as close as within 0.1 to 5.2% of observed cumulative consumption. Even so, the model consistently overestimated consumption by low-ration fish and underestimated consumption by high-ration fish. The bias was significant in both cases, but was more severe for the low-ration trout. Because the low-ration and high-ration regimes were probably unrealistic for lake trout residing in Lake Michigan and because the model fit our laboratory data rather well for medium-ration trout, we conclude that applying the Wisconsin bioenergetics model to the Lake Michigan lake trout population in order to estimate the amount of prey fish consumed by lake trout each year is appropriate.

Madenjian, Charles P.; O'Connor, Daniel V.

1999-01-01

38

Brook Trout Removal as a Conservation Tool to Restore Eagle Lake Rainbow Trout  

E-print Network

Brook Trout Removal as a Conservation Tool to Restore Eagle Lake Rainbow Trout GERARD CARMONA Girona, Catalonia, Spain Abstract.--Nonnative brook trout Salvelinus fontinalis are abundant in Pine Spring Creek to determine whether brook trout removal was a feasible restoration tool and to document

García-Berthou, Emili

39

Biology of young lake trout (Salvelinus namaycush) in Lake Michigan  

USGS Publications Warehouse

Experimental fishing with gill nets of 5 mesh sizes (2 3/8 to 3 inches) in Lake Michigan in 1930-32 yielded more than 16,000 young lake trout. Data are presented here on age, growth, length-weight relationship, abundance, geographical and bathymetric distribution, and other details of their biology.

Van Oosten, John; Eschmeyer, Paul H.

1956-01-01

40

Genetic Evaluation of a Great Lakes Lake Trout Hatchery Program  

Microsoft Academic Search

Efforts over several decades to restore lake trout Salvelinus namaycush in U.S. waters of the upper Great Lakes have emphasized the stocking of juveniles from each of six hatchery broodstocks. Retention of genetic diversity across all offspring life history stages throughout the hatchery system has been an important component of the restoration hatchery and stocking program. Different stages of the

Kevin S. Page; Kim T. Scribner; Dale Bast; Mark E. Holey; Mary K. Burnham-Curtis

2005-01-01

41

Nonnative Lake Trout Result in Yellowstone Cutthroat Trout Decline and Impacts to Bears and Anglers  

Microsoft Academic Search

During the Past Decade, Yellowstone cutthroat trout (Oncorhynchus darki bouvierO of Yellowstone Lake and its tributary streams have been affected by the introduction of lake trout (Salvelinus naymaycush), invasion by Myxobolus cerebralis (the cause of whirling disease), and drought conditions. Numbers of upstream migrating cutthroat trout at Clear and Bridge creeks have declined >90% in the past 5 years. Activity

Todd M. Koel; Patricia E. Bigelow; Philip D. Doepke; Brian D. Ertel; Daniel L. Mahony

2005-01-01

42

Lake Trout Rehabilitation in the Great Lakes: an Evolutionary, Ecological, and Ethical Perspective  

Microsoft Academic Search

We reviewed key features of the evolutionary biology of lake trout (Salvelinus namaycush) and their significance for rehabilitation programs in the Great Lakes. Despite repeated transloca-tion by glacial advances during the Ice Age (the Pleistocene) that eliminated most populations, lake trout have genetic diversity comparable with other North American salmonines. Various embryological and adult features suggest lake trout had a

Randy L. Eshenroder; E. J. Crossman; Gary K. Meffe; Charles H. Olver; Edwin P. Pister

1995-01-01

43

Geographical distributions of lake trout strains stocked in Lake Ontario  

USGS Publications Warehouse

Geographical distributions of lake trout (Salvelinus namaycush) stocked at seven locations in U.S. waters and at four locations in Canadian waters of Lake Ontario were determined from fish caught with gill nets in September in 17 areas of U.S. waters and at 10 fixed locations in Canadian waters in 1986-95. For fish of a given strain stocked at a given location, geographical distributions were not different for immature males and immature females or for mature males and mature females. The proportion of total catch at the three locations nearest the stocking location was higher for mature fish than for immature fish in all 24 available comparisons (sexes combined) and was greater for fish stocked as yearlings than for those stocked as fingerlings in all eight comparisons. Mature fish were relatively widely dispersed from stocking locations indicating that their tendency to return to stocking locations for spawning was weak, and there was no appreciable difference in this tendency among strains. Mature lake trout were uniformly distributed among sampling locations, and the strain composition at stocking locations generally reflected the stocking history 5 to 6 years earlier. Few lake trout moved across Lake Ontario between the north and south shores or between the eastern outlet basin and the main lake basin. Limited dispersal from stocking sites supports the concept of stocking different genetic strains in various parts of the lake with the attributes of each strain selected to match environmental conditions in the portion of the lake where it is stocked.

Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.; Schaner, Ted

1996-01-01

44

Relationships between trout stocking and amphibians in British Columbia's Southern Interior lakes.  

E-print Network

??Stocking lakes with non-native trout to encourage recreational fishing causes changes in lake ecosystems that can negatively affect biodiversity. I examined associations between rainbow trout… (more)

Hirner, Joanna Lynne McGarvie

2006-01-01

45

Acoustic estimates of abundance and distribution of spawning lake trout on Sheboygan Reef in Lake Michigan  

USGS Publications Warehouse

Efforts to restore self-sustaining lake trout (Salvelinus namaycush) populations in the Laurentian Great Lakes have had widespread success in Lake Superior; but in other Great Lakes, populations of lake trout are maintained by stocking. Recruitment bottlenecks may be present at a number of stages of the reproduction process. To study eggs and fry, it is necessary to identify spawning locations, which is difficult in deep water. Acoustic sampling can be used to rapidly locate aggregations of fish (like spawning lake trout), describe their distribution, and estimate their abundance. To assess these capabilities for application to lake trout, we conducted an acoustic survey covering 22 km2 at Sheboygan Reef, a deep reef (<40 m summit) in southern Lake Michigan during fall 2005. Data collected with remotely operated vehicles (ROV) confirmed that fish were large lake trout, that lake trout were 1–2 m above bottom, and that spawning took place over specific habitat. Lake trout density exhibited a high degree of spatial structure (autocorrelation) up to a range of ~190 m, and highest lake trout and egg densities occurred over rough substrates (rubble and cobble) at the shallowest depths sampled (36–42 m). Mean lake trout density in the area surveyed (~2190 ha) was 5.8 fish/ha and the area surveyed contained an estimated 9500–16,000 large lake trout. Spatial aggregation in lake trout densities, similarity of depths and substrates at which high lake trout and egg densities occurred, and relatively low uncertainty in the lake trout density estimate indicate that acoustic sampling can be a useful complement to other sampling tools used in lake trout restoration research.

Warner, D.M.; Claramunt, R.M.; Janssen, J.; Jude, D.J.; Wattrus, N.

2009-01-01

46

First evidence of successful natural reproduction by planted lake trout in Lake Huron  

USGS Publications Warehouse

Twenty-two lake trout (Salvelinus namaycush) swim-up fry, 24-27 mm long, were captured with emergent fry traps and a tow net in northwestern Lake Huron on a small nearshore reef off Alpena, Michigan, between May 10 and June 1, 1982. These catches represent the first evidence of successful production of swim-up fry by planted, hatchery-reared lake trout in Lake Huron since the lake trout rehabilitation program began in 1973.

Nester, Robert T.; Poe, Thomas P.

1984-01-01

47

Use of cover habitat by bull trout Salvelinus confluentus and lake trout Salvelinus namaycush in a laboratory environment  

USGS Publications Warehouse

Lacustrine-adfluvial bull trout, Salvelinus confluentus, migrate from spawning and rearing streams to lacustrine environments as early as age 0. Within lacustrine environments, cover habitat pro- vides refuge from potential predators and is a resource that is competed for if limiting. Competitive inter- actions between bull trout and other species could result in bull trout being displaced from cover habitat, and bull trout may lack evolutionary adaptations to compete with introduced species, such as lake trout, Salvelinus namaycush. A laboratory experiment was performed to examine habitat use and interactions for cover by juvenile (i.e., <80 mm total length) bull trout and lake trout. Differences were observed between bull trout and lake trout in the proportion of time using cover (F1,22.6=20.08, P<0.001) and bottom (F1,23.7 = 37.01, P < 0.001) habitat, with bull trout using cover and bottom habitats more than lake trout. Habitat selection ratios indicated that bull trout avoided water column habitat in the presence of lake trout and that lake trout avoided bottom habitat. Intraspecific and interspecific agonistic interactions were infrequent, but approximately 10 times greater for intraspecific inter- actions between lake trout. Results from this study provide little evidence that juvenile bull trout and lake trout compete for cover, and that species-specific differences in habitat use and selection likely result in habitat partitioning between these species.

Meeuwig, Michael H.; Guy, Christopher S.; Fredenberg, Wade A.

2011-01-01

48

A STUDY OF' TWIN LAKES, COLORADO, WITH ESPECIAL CONSIDERATION OF THE FOOD OF THE TROUTS.  

E-print Network

. _ __ ..·. _.. __ . _.... __ ; .. . .. _... _ __ .. Mackinaw trout _.. __ .. _.·....... _ __ . -. . __ .. __ .. Small brook trout _.......· _ __ __ . _ .. _. _. Large brook trout, . _. _ _ _.. _ _. _ .. _ ...........·.. FryA STUDY OF' TWIN LAKES, COLORADO,· WITH ESPECIAL CONSIDERATION OF THE FOOD OF THE TROUTS

49

Environmental contaminants and the reproductive success of lake trout in the great lakes: An epidemiological approach  

Microsoft Academic Search

Epidemiological criteria were used to examine the influence of environmental contamination on reproductive success of lake trout (Salvelinus namaycush,) in the Laurentian Great Lakes. Most of the information was obtained from lake trout eggs collected in southeastern Lake Michigan and reared in the laboratory. Two separate end points that measure reproductive success—egg hatchability and fry survival?were used in the evaluation.

Michael J. Mac; Carol C. Edsall

1991-01-01

50

Lake?shore spawning of rainbow trout at Lake Rotoma, New Zealand  

Microsoft Academic Search

The presence of suitable gravel size alone can stimulate female rainbow trout (Salmo gairdneri) to excavate nests for spawning on the shores of Lake Rotoma. Emergent fry result from lake?shore spawning, and could contribute significantly to the trout fishery in Lake Rotoma. Lake?shore spawning could be enhanced by the use of stable artificial spawning beds that have adequate depth and

B. P. Penlington

1983-01-01

51

A Study of the Lake Trout, Salvelinus Namaycush, in two Algonquin Park, Ontario, Lakes  

Microsoft Academic Search

A study was made of the depth distribution, feeding, and growth of the lake trout, Salvelinus namaycush, in Lake Louisa and Redrock Lake, Ontario, in 1947. In the spring the trout were widely dispersed in Redrock Lake but as surface waters warmed to 14° or 15° C. in mid-June they moved into deeper waters. During the summer months the Redrock

Nigel V. Martin

1952-01-01

52

Evaluation of offshore stocking of Lake Trout in Lake Ontario  

USGS Publications Warehouse

Restoration stocking of hatchery-reared lake trout Salvelinus namaycush has occurred in Lake Ontario since 1973. In U.S. waters, fish stocked through 1990 survived well and built a large adult population. Survival of yearlings stocked from shore declined during 1990–1995, and adult numbers fell during 1998–2005. Offshore stocking of lake trout was initiated in the late 1990s in response to its successful mitigation of predation losses to double-crested cormorants Phalacrocorax auritus and the results of earlier studies that suggested it would enhance survival in some cases. The current study was designed to test the relative effectiveness of three stocking methods at a time when poststocking survival for lake trout was quite low and losses due to fish predators was a suspected factor. The stocking methods tested during 2000–2002 included May offshore, May onshore, and June onshore. Visual observations during nearshore stockings and hydroacoustic observations of offshore stockings indicated that release methods were not a direct cause of fish mortality. Experimental stockings were replicated for 3 years at one site in the southwest and for 2 years at one site in the southeast. Offshore releases used a landing craft to transport hatchery trucks from 3 to 6 km offshore out to 55–60-m-deep water. For the southwest site, offshore stocking significantly enhanced poststocking survival. Among the three methods, survival ratios were 1.74 : 1.00 : 1.02 (May offshore : May onshore : June onshore). Although not statistically significant owing to the small samples, the trends were similar for the southeast site, with survival ratios of 1.67 : 1.00 : 0.72. Consistent trends across years and sites indicated that offshore stocking of yearling lake trout during 2000–2002 provided nearly a twofold enhancement in survival; however, this increase does not appear to be great enough to achieve the 12-fold enhancement necessary to return population abundance to restoration targets.

Lantry, B.F.; O'Gorman, R.; Strang, T.G.; Lantry, J.R.; Connerton, M.J.; Schanger, T.

2011-01-01

53

Lake Trout Status in the Main Basin of Lake Huron, 1973–2010  

Microsoft Academic Search

We developed indices of lake trout Salvelinus namaycush status in the main basin of Lake Huron (1973–2010) to understand increases in the relative abundance of wild year-classes during 1995–2010. Sea lamprey Petromyzon marinus wounds per 100 lake trout declined from 23.63 in 2000 to 5.86–10.64 in 2002–2010. The average age-7 lake trout catch per effort per recruitment (CPE\\/R; fish·305 m

Ji X. He; Mark P. Ebener; Stephen C. Riley; Adam Cottrill; Adam Kowalski; Scott Koproski; Lloyd Mohr; James E. Johnson

2012-01-01

54

Assessment of lake trout spawning habitat quality in central Lake Huron by submarine  

USGS Publications Warehouse

Interstitial water quality was measured using a submersible at seven locations on Six Fathom Bank. Historically, the bank was an important lake trout spawning ground. It is currently the focus of coordinated, interagency efforts to rehabilitate lake trout in Lake Huron. Water quality, evaluated from measurements of biochemical oxygen demand, dissolved oxygen, ammonia, and hydrogen sulfide among the rocks, would not prevent lake trout eggs from hatching successfully on the bank.

Manny, Bruce A.; Edsall, Thomas A.

1989-01-01

55

Contaminant trends in lake trout ( Salvelinus namaycush ) from the Upper Great Lakes  

Microsoft Academic Search

Contaminant body burdens in lake trout (Salvelinus namaycush) from the Upper Great Lakes have been monitored since 1970 on Lake Michigan and since 1977 and 1978 on Lakes Superior and Huron by United States Environmental Protection Agency (USEPA), Great Lakes National Program Office and U.S. Fish and Wildlife Service (USFWS), Great Lakes Fishery Laboratory. Analysis of the Lake Michigan data

David S. DeVault; Wayne A. Willford; Robert J. Hesselberg; David A. Nortrupt; Eric G. S. Rundberg; Alwan K. Alwan; Cecilia Bautista

1986-01-01

56

Morphological variation of siscowet lake trout in Lake Superior  

USGS Publications Warehouse

Historically, Lake Superior has contained many morphologically distinct forms of the lake trout Salvelinus namaycush that have occupied specific depths and locations and spawned at specific times of the year. Today, as was probably the case historically, the siscowet morphotype is the most abundant. Recent interest in harvesting siscowets to extract oil containing omega-3 fatty acids will require additional knowledge of the biology and stock structure of these lightly exploited populations. The objective of this study was to determine whether shape differences exist among siscowet populations across Lake Superior and whether these shape differences can be used to infer stock structure. Morphometric analysis (truss protocol) was used to differentiate among siscowets sampled from 23 locations in Lake Superior. We analyzed 31 distance measurements among 14 anatomical landmarks taken from digital images of fish recorded in the field. Cluster analysis of size-corrected data separated fish into three geographic groups: the Isle Royale, eastern (Michigan), and western regions (Michigan). Finer scales of stock structure were also suggested. Discriminant function analysis demonstrated that head measurements contributed to most of the observed variation. Cross-validation classification rates indicated that 67-71 % of individual fish were correctly classified to their region of capture. This is the first study to present shape differences associated with location within a lake trout morphotype in Lake Superior. ?? Copyright by the American Fisheries Society 2007.

Bronte, C.R.; Moore, S.A.

2007-01-01

57

Diet of lake trout and burbot in northern Lake Michigan during spring: Evidence of ecological interaction  

USGS Publications Warehouse

We used analyses of burbot (Lota lota) and lake trout (Salvelinus namaycush) diets taken during spring gill-net surveys in northern Lake Michigan in 2006-2008 to investigate the potential for competition and predator-prey interactions between these two species. We also compared our results to historical data from 1932. During 2006-2008, lake trout diet consisted mainly of alewives (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax), whereas burbot utilized a much wider prey base including round goby (Neogobius melanostomus), rainbow smelt, alewives, and sculpins. Using the Schoener's diet overlap index, we found a higher potential for interspecific competition in 1932 than in 2006-2008, though diet overlap was not significant in either time period. No evidence of cannibalism by lake trout or lake trout predation on burbot was found in either time period. In 2006-2008, however, lake trout composed 5.4% (by weight) of burbot diet. To determine whether this predation could be having an impact on lake trout rehabilitation efforts in northern Lake Michigan, we developed a bioenergetic-based consumption estimate for burbot on Boulder Reef (a representative reef within the Northern Refuge) and found that burbot alone can consume a considerable proportion of the yearling lake trout stocked annually, depending on burbot density. Overall, we conclude that predation, rather than competition, is the more important ecological interaction between burbot and lake trout, and burbot predation may be contributing to the failed lake trout rehabilitation efforts in Lake Michigan.

Jacobs, Gregory R.; Madenjian, Charles P.; Bunnell, David B.; Holuszko, Jeffrey D.

2010-01-01

58

Limitations to Lake Trout ( Salvelinus namaycush) Rehabilitation in the Great Lakes Imposed by Biotic Interactions Occurring at Early Life Stages  

Microsoft Academic Search

We examine evidence that biotic factors, particularly predation, may be limiting early survival of wild lake trout (Salvelinus namaycush) juveniles in many areas of the Great Lakes. The Great Lakes contain numerous potential predators of lake trout eggs and fry, some of which are recent invaders, and most of which were probably absent when lake trout most recently re-invaded the

Michael L. Jones; Gary W. Eck; David O. Evans; Mary C. Fabrizio; Michael H. Hoff; Patrick L. Hudson; John Janssen; David Jude; Robert O’Gorman; Jacqueline F. Savino

1995-01-01

59

Effects of large lake trout ( Salvelinus namaycush ) on the dietary habits of small lake trout: a comparison of stable isotopes (? 15 N and ? 13 C) and stomach content analyses  

Microsoft Academic Search

We examined the effect of large (potentially piscivorous) lake trout (Salvelinus namaycush) on the dietary habits of small lake trout in an arctic lake. We hypothesized that large lake trout constrain the foraging\\u000a of small lake trout, thus, in the absence of large lake trout, small lake trout will shift their diet from littoral to more\\u000a abundant prey offshore. We

Matthew D. Keyse; Kenneth Fortino; Anne E. Hershey; W. John O’Brien; Philip W. Lienesch; Chris Luecke; Michael E. McDonald

2007-01-01

60

Helminths in an intensively stocked population of lake trout, Salvelinus namaycush, from Lake Huron  

USGS Publications Warehouse

Eighty stocked lake trout Salvelinus namaycush (Salmonidae), collected from 2 locations in Lake Huron in May 1995, were examined for parasites. The parasite fauna of this top predator in Lake Huron was characterized by only 6 helminth species. Echinorhynchus salmonis infected all lake trout with a mean intensity of 163.9. The intensity of this acanthocephalan species significantly increased with host length and weight. Eubothrium salvelini infected 78 lake trout with a maximum number of 81 scoleces counted. Diplostomum sp., Cyathocephalus truncatus, Capillaria salvelini, and Neoechinorhynchus sp. infrequently infected lake trout. The low parasite species richness in these lake trout is believed to be due to their large size at stocking and to the loss of historical enzootic host-parasite relationships that followed the absence of this fish species in Lake Huron for 26 yr.

Muzzall, Patrick M.; Bowen, Charles A., II

2000-01-01

61

Population structure of lake trout (Salvelinus namaycush) in a large glacial-fed lake inferred  

E-print Network

Population structure of lake trout (Salvelinus namaycush) in a large glacial-fed lake inferred from Columbia, Canada, and contains relatively pristine populations of lake trout (Salvelinus namaycush, et il contient des populations de touladis (Salvelinus namaycush) encore relativement dans leur e

Taylor, Eric B. "Rick"

62

Lake trout (Salvelinus namaycush) populations in Lake Superior and their restoration in 1959-1993  

USGS Publications Warehouse

Naturally-reproducing populations of lake trout (Salvelinus namaycush) have been re-established in most of Lake Superior, but have not been restored to 1929-1943 average abundance. Progress toward lake trout restoration in Lake Superior is described, management actions are reviewed, and the effectiveness of those actions is evaluated; especially stocking lake trout as a tool for building spawning stocks, and subsequently, populations of wild recruits. Widespread destruction of lake trout stocks in the 1950s due to an intense fishery and sea lamprey (Petromyzon marinus) predation resulted in lower overall phenotypic diversity than was previously present. Stocking of yearling lake trout, begun in the 1950s, produced high densities of spawners that reproduced wherever inshore spawning habitat was widespread. Sea lampreys were greatly reduced beginning in 1961, using selective chemical toxicants and barrier dams, but continue to exert substantial mortality. Fishery regulation was least effective in Wisconsin, where excessive gillnet effort caused high by catch of lake trout until 1991, and in eastern Michigan, where lake trout restoration was deferred in favor of a tribal fishery for lake whitefish (Coregonus clupeaformis) in 1985. Restoration of stocks was quicker in offshore areas where remnant wild lake trout survived and fishing intensity was low, and was slower in inshore areas where stocked lake trout reproduced successfully and fishing intensity was high. Inshore stocks of wild lake trout are currently about 61% of historic abundance in Michigan and 53% in Wisconsin. Direct comparison of modern and historic abundances of inshore lake trout stocks in Minnesota and Ontario is impossible due to lack of historic stock assessment data. Stocks in Minnesota are less abundant at present than in Michigan or Wisconsin, and stocks in Ontario are similar to those in Michigan. Further progress in stock recovery can only be achieved if sea lampreys are depressed and if fisheries are constrained further than at present.

Hansen, Michael J.; Peck, James W.; Schorfhaar, Richard G.; Selgeby, James H.; Schreiner, Donald R.; Schram, Stephen T.; Swanson, Bruce L.; MacCallum, Wayne R.; Burnham-Curtis, Mary K.; Curtis, Gary L.; Heinrich, John W.; Young, Robert J.

1995-01-01

63

Management Perspectives on Coaster Brook Trout Rehabilitation in the Lake Superior Basin  

Microsoft Academic Search

Coaster brook trout are a migratory form of brook trout Salvelinus fontinalis that spend part of their lives in the Great Lakes. Over the last century the abundance of coaster brook trout in Lake Superior has declined dramatically, and only remnant stocks remain. Recently, the rehabilitation of coaster brook trout in Lake Superior has become a goal of fish management

Donald R. Schreiner; Ken I. Cullis; Michael C. Donofrio; Gregory J. Fischer; Laura Hewitt; Karen G. Mumford; Dennis M. Pratt; Henry R. Quinlan; Steven J. Scott

2008-01-01

64

Brook Trout Removal as a Conservation Tool to Restore Eagle Lake Rainbow Trout  

Microsoft Academic Search

Nonnative brook trout Salvelinus fontinalis are abundant in Pine Creek and its main tributary, Bogard Spring Creek, California. These creeks historically provided the most spawning and rearing habitat for endemic Eagle Lake rainbow trout Oncorhynchus mykiss aquilarum. Three-pass electrofishing removal was conducted in 2007–2009 over the entire 2.8-km length of Bogard Spring Creek to determine whether brook trout removal was

Gerard Carmona-Catot; Peter B. Moyle; Enric Aparicio; Patrick K. Crain; Lisa C. Thompson; Emili García-Berthou

2010-01-01

65

Lake trout in northern Lake Huron spawn on submerged drumlins Stephen C. Riley a,  

E-print Network

Huron Glacial bedforms Recent observations of spawning lake trout Salvelinus namaycush near Drummond Salvelinus namaycush historically were the dominant predator and supported a valuable commercial fishery

Marsden, Ellen

66

Biology, population structure, and estimated forage requirements of lake trout in Lake Michigan  

USGS Publications Warehouse

Data collected during successive years (1971-79) of sampling lake trout (Salvelinus namaycush) in Lake Michigan were used to develop statistics on lake trout growth, maturity, and mortality, and to quantify seasonal lake trout food and food availability. These statistics were then combined with data on lake trout year-class strengths and age-specific food conversion efficiencies to compute production and forage fish consumption by lake trout in Lake Michigan during the 1979 growing season (i.e., 15 May-1 December). An estimated standing stock of 1,486 metric tons (t) at the beginning of the growing season produced an estimated 1,129 t of fish flesh during the period. The lake trout consumed an estimated 3,037 t of forage fish, to which alewives (Alosa pseudoharengus) contributed about 71%, rainbow smelt (Osmerus mordax) 18%, and slimy sculpins (Cottus cognatus) 11%. Seasonal changes in bathymetric distributions of lake trout with respect to those of forage fish of a suitable size for prey were major determinants of the size and species compositions of fish in the seasonal diet of lake trout.

Eck, Gary W.; Wells, LaRue

1983-01-01

67

Response of lake trout ( Salvelinus namaycush ) and brook trout ( S. fontinalis ) to surface water acidification in Ontario  

Microsoft Academic Search

Netting surveys of lakes varying in pH (4.4–7.1) showed that lake trout (Salvelinus namaycush) populations fail to recruit at pH S. fontinalis) were extirpated in lakes with pH -1). Threshold pH levels determined from fisheries assessments were used to estimate that 1% of lake trout and brook trout populations have been lost due to acidification.

Gail L. Beggs; John M. Gunn

1986-01-01

68

Dynamics of Reproduction by Hatchery-Origin Lake Trout ( Salvelinus namaycush) at Stony Island Reef, Lake Ontario  

Microsoft Academic Search

Natural recruitment from hatchery-origin lake trout in the Great Lakes has been minimal, except in Lake Superior and a few limited areas in Lake Huron. Quantitative studies of survival between egg deposition and fry emergence were conducted on a spawning reef in the eastern basin of Lake Ontario to determine variables associated with poor reproduction of hatchery-origin lake trout. Thirty

David L. Perkins; Charles C. Krueger

1995-01-01

69

Influence of egg predation and physical disturbance on lake trout Salvelinus namaycush egg mortality and  

E-print Network

Influence of egg predation and physical disturbance on lake trout Salvelinus namaycush egg and physical disturbance on lake trout Salvelinus namaycush egg mortality was investigated in situ in Lake Society of the British Isles #12;INTRODUCTION Lake trout Salvelinus namaycush (Walbaum) in all

Marsden, Ellen

70

Spatiotemporal Distribution and Population Characteristics of a Nonnative Lake Trout Population, with Implications for Suppression  

Microsoft Academic Search

We evaluated the distribution and population characteristics of nonnative lake trout Salvelinus namaycush in Lake McDonald, Glacier National Park, Montana, to provide biological data in support of a potential suppression program. Using ultrasonic telemetry, we identified spatial and temporal distribution patterns by tracking 36 adult lake trout (1,137 relocations). Lake trout rarely occupied depths greater than 30 m and were

Andrew M. Dux; Christopher S. Guy; Wade A. Fredenberg

2011-01-01

71

Relationship between lake trout spawning, embryonic survival, and currents: A case of bet hedging in the face of environmental stochasticity?  

E-print Network

: Spawning Currents Habitat Reproductive strategy Lake trout, Salvelinus namaycush, spawning in the Great suspected of influencing lake trout, Salvelinus namaycush, spawning habitat selection and embryonic survival

Marsden, Ellen

72

Twelve microsatellite loci for lake trout (Salvelinus namaycush).  

PubMed

We describe 12 microsatellite loci isolated from lake trout (Salvelinus namaycush). The number of alleles at these loci ranged from two to 11 with an average of 5.3 alleles per locus. The expected heterozygosity ranged from 0.29 to 0.76, with an average of 0.68. Accidental (or illegal) introductions of lake trout into watersheds are decimating native trout populations in the northern Rocky Mountains, and these loci will be useful for identifying the source of these introductions and for estimating the number of founding individuals. PMID:21564773

Rollins, Maryclare F; Vu, Ninh V; Spies, Ingrid B; Kalinowski, Steven T

2009-05-01

73

Factors Affecting Survival Rates of a Recovering Lake Trout Population Estimated by MarkRecapture in Lake Superior,  

E-print Network

­recapture study to examine the dynamics of survival in a recovering population of lake trout Salvelinus namaycush the recovery of populations of native lake trout Salvelinus namaycush that had been severely depressed

Newman, Michael C.

74

Genetic and Environmental Influences on Life History Traits in Lake Trout  

Microsoft Academic Search

Lake trout Salvelinus namaycush exhibit substantial life history variation associated with variation in climatic and biotic variables. To assess the environmental and genetic influences on lake trout life history traits, eggs were collected from two lakes in Algonquin Park, Ontario, Lake Opeongo and Louisa Lake, with contrasting ecotypes and forage bases. Eggs from both populations and interpopulation hybrids (Lake Opeongo

Jenni L. McDermid; Peter E. Ihssen; William N. Sloan; Brian J. Shuter

2007-01-01

75

Fertilization of eggs of Lake Michigan lake trout Salvelinus namaycush in lake water: Effect of PCBs (Aroclor 1254)  

USGS Publications Warehouse

Various studies indicate that PCBs appear to have an adverse effect on the viability of fertilized eggs and subsequent early life stages of lake trout and related species. Our tests detected no impairment of fertilization of lake trout eggs in PCB-dosed lake water. The concentration of PCBs in the fertilization medium that we used was more than 20 times as high as estimated ambient levels in southeastern Lake Michigan and it appears unlikley that ambient levels of PCBs in the water at fertilization would contribute significantly to the apparent widespread reproductive failure of lake trout there.

Foster, N.R.; Berlin, W.H.

1997-01-01

76

Phylogeography and postglacial dispersal of lake trout ( Salvelinus namaycush ) in North America  

Microsoft Academic Search

We used restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) diversity to assess the complex postglacial history of lake trout (Salvelinus namaycush) and test existing dispersal hypotheses. A pilot survey with 30 restriction enzymes was carried out on lake trout from 16 geographically representative populations to determine phylogenetically informative characters. Subsequent screening of 1416 lake trout from 93

Christopher C. Wilson; Paul D. N. Hebert

1998-01-01

77

Model of PCB in the Lake Michigan lake trout food chain  

Microsoft Academic Search

An age-dependent food chain model that considers species bioenergetics and toxicant exposure through water and food is developed. The model is successfully calibrated to 1971 PCB concentrations of Lake Michigan alewife and lake trout by using a dissolved PCB concentration in the water of 5-10 ng\\/L. The model indicates that for the top predator lake trout, PCB exposure through the

Robert V. Thomann; John P. Connolly

1984-01-01

78

Dynamics of an Increasing Lake Trout Population in Lake Pend Oreille, Idaho  

Microsoft Academic Search

To quantify movement and abundance of lake trout Salvelinus namaycush in Lake Pend Oreille, Idaho, large trap nets were fished during two periods (30 September 2003–31 March 2004 and 10 September–15 December 2005) and gill nets were fished from 12 February to 6 April 2006. Trap-net catch rates and recapture rates of previously marked lake trout suggested that sampling locations

Michael J. Hansen; Ned J. Horner; Mark Liter; Mike P. Peterson; Melo A. Maiolie

2008-01-01

79

Effects of a Whole-lake, Experimental Fertilization on Lake Trout in a Small Oligotrophic Arctic Lake  

Microsoft Academic Search

We tested whether increased phosphorus and nitrogen concentrations would affect a lake trout (Salvelinus namaycush) population in a small oligotrophic lake with a benthically dominated food web. From 1990 to 1994, nitrogen and phosphorus were added to Lake N1 (4.4 ha) at the arctic Long-Term Ecological Research site in Alaska. We used mark\\/recapture methods to determine the lake trout population size,

Philip W. Lienesch; Michael E. McDonald; Anne E. Hershey; W. John O’Brien; Neil D. Bettez

2005-01-01

80

Increasing thiamine concentrations in lake trout eggs from Lakes Huron and Michigan coincide with low alewife abundance  

USGS Publications Warehouse

Lake trout Salvelinus namaycush in the Laurentian Great Lakes suffer from thiamine deficiency as a result of adult lake trout consuming prey containing thiaminase, a thiamine-degrading enzyme. Sufficiently low egg thiamine concentrations result in direct mortality of or sublethal effects on newly hatched lake trout fry. To determine the prevalence and severity of low thiamine in lake trout eggs, we monitored thiamine concentrations in lake trout eggs from 15 sites in Lakes Huron and Michigan from 2001 to 2009. Lake trout egg thiamine concentrations at most sites in both lakes were initially low and increased over time at 11 of 15 sites, and the proportion of females with egg thiamine concentrations lower than the recommended management objective of 4 nmol/g decreased over time at eight sites. Egg thiamine concentrations at five of six sites in Lakes Huron and Michigan were significantly inversely related to site-specific estimates of mean abundance of alewives Alosa pseudoharengus, and successful natural reproduction of lake trout has been observed in Lake Huron since the alewife population crashed. These results support the hypothesis that low egg thiamine in Great Lakes lake trout is associated with increased alewife abundance and that low alewife abundance may currently be a prerequisite for successful reproduction by lake trout in the Great Lakes.

Riley, Stephen C.; Rinchard, Jacques; Honeyfield, Dale C.; Evans, Allison N.; Begnoche, Linda

2011-01-01

81

A physiologically based toxicokinetic model for lake trout (Salvelinus namaycush).  

PubMed

A physiologically based toxicokinetic (PB-TK) model for fish, incorporating chemical exchange at the gill and accumulation in five tissue compartments, was parameterized and evaluated for lake trout (Salvelinus namaycush). Individual-based model parameterization was used to examine the effect of natural variability in physiological, morphological, and physico-chemical parameters on model predictions. The PB-TK model was used to predict uptake of organic chemicals across the gill and accumulation in blood and tissues in lake trout. To evaluate the accuracy of the model, a total of 13 adult lake trout were exposed to waterborne 1,1,2,2-tetrachloroethane (TCE), pentachloroethane (PCE), and hexachloroethane (HCE), concurrently, for periods of 6, 12, 24 or 48 h. The measured and predicted concentrations of TCE, PCE and HCE in expired water, dorsal aortic blood and tissues were generally within a factor of two, and in most instances much closer. Variability noted in model predictions, based on the individual-based model parameterization used in this study, reproduced variability observed in measured concentrations. The inference is made that parameters influencing variability in measured blood and tissue concentrations of xenobiotics are included and accurately represented in the model. This model contributes to a better understanding of the fundamental processes that regulate the uptake and disposition of xenobiotic chemicals in the lake trout. This information is crucial to developing a better understanding of the dynamic relationships between contaminant exposure and hazard to the lake trout. PMID:11090894

Lien, G J; McKim, J M; Hoffman, A D; Jenson, C T

2001-01-01

82

Side-scan sonar mapping of lake trout spawning habitat in northern Lake Michigan  

USGS Publications Warehouse

Native stocks of lake trout Salvelinus namaycush were virtually or completely extirpated from the lower four Great Lakes by the early 1960s. The failure of early attempts to reestablish self-sustaining populations of lake trout was attributed partly to the practice of stocking hatchery-reared juveniles at locations and over substrates that had not been used in the past for spawning by native fish. Subsequent attempts to improve the selection of stocking locations were impeded by the lack of reliable information on the distribution of substrates on historical spawning grounds. Here we demonstrate the potential of side-scan sonar to substantially expand the data base needed to pinpoint the location of substrates where lake trout eggs, fry or juveniles could be stocked to maximize survival and help ensure that survivors returning to spawn would encounter suitable substrates. We also describe are the substrates and bathymetry of large areas on historical lake trout spawning grounds in the Fox Island Lake Trout Sanctuary in northern Lake Michigan. These areas could be used to support a contemporary self-sustaining lake trout population in the sanctuary and perhaps also in adjacent waters.

Edsall, Thomas A.; Poe, Thomas P.; Nester, Robert T.; Brown, Charles L.

1989-01-01

83

Introduction of Lake Trout ( Salvelinus namaycush) to Inland Lakes of Ontario, Canada: Factors Contributing to Successful Colonization  

Microsoft Academic Search

We evaluated the success of 183 introductions of lake trout (Salvelinus namaycush) in small inland lakes in Ontario, Canada. Our purpose was to identify variables associated with successful versus failed natural recruitment after introductions of hatchery-reared lake trout. Origin of donor stocks, angling regulations, geophysical and water quality characteristics, and fish species presence-absence of the recipient lakes were evaluated as

David O. Evans; Charles H. Olver

1995-01-01

84

In situ determination of the annual thermal habitat use by lake trout (Salvelinus namaycush) in Lake Huron  

USGS Publications Warehouse

Records of the temperatures occupied by 33 lake trout (Salvelinus namaycush) at large in Lake Huron were obtained for up to 14 months per fish, at 75-minute intervals, from surgically implanted archival temperature tags. The dataset covered nearly three years, from October 1998 to June 2001, and included 160,000 observations. The objectives of the tagging were to obtain temperature data to refine bioenergetics models of sea lamprey (Petromyzon marinus) predation on lake trout, and compare the temperatures occupied by strains of lake trout stocked in Lake Huron. The seasonal, thermal-use profiles of lake trout followed the general warming and cooling pattern of Lake Huron. During periods when the zone of surface water mixing extended below the depth range occupied by lake trout, variability among individual fish and strains was low and followed surface temperature. However, during the period of summer stratification, the average temperatures occupied varied substantially among individual fish and strains. Strains originating from the upper Great Lakes (Lake Superior and Lewis Lake, WY) occupied similar temperatures. Between June and mid August, upper Great Lakes lake trout typically occupied water several degrees warmer than that occupied by lake trout of Finger Lakes, New York origin. Most of the lake trout occupied summer temperatures lower than the preferred temperatures suggested by laboratory studies. In October, all strains occupied water as warm or warmer than that occupied in summer, which may partially explain the higher lethality of sea lamprey attacks during October.

Bergstedt, Roger A.; Argyle, Ray L.; Seelye, James G.; Scribner, Kim T.; Curtis, Gary L.

2003-01-01

85

Microsatellite and mtDNA analysis of lake trout, Salvelinus namaycush, from Great Bear Lake, Northwest Territories  

E-print Network

Microsatellite and mtDNA analysis of lake trout, Salvelinus namaycush, from Great Bear Lake genetic variation in lake trout (Salvelinus namaycush) from Great Bear Lake (GBL), NT and one population, Salvelinus. Correspondence Les N. Harris, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB

Taylor, Eric B. "Rick"

86

REDUCING EXPOSURE UNCERTAINTY FOR ASSESSMENT OF DIOXIN TOXICITY RISKS TO LAKE TROUT POPULATIONS IN THE GREAT LAKES  

EPA Science Inventory

During the 20th century, declines of lake trout (Salvelinus namaycush) populations to virtual extinction in all the Great Lakes except Lake Superior were followed by failure of stocked lake trout to achieve recruitment through natural reproduction. Stresses such as excessive harv...

87

Assessing movement of rainbow trout and common smelt between Lake Rotoiti and Lake Rotorua using otolith chemical signatures: a  

E-print Network

Assessing movement of rainbow trout and common smelt between Lake Rotoiti and Lake Rotorua using...................................................................................................................................................12 Summary of rainbow trout and smelt otoliths processed............................................................................................................................................24 #12;3 Tables Table 1. Summary of rainbow trout and smelt otoliths analysed in 2005

Waikato, University of

88

Egg thiamine status of Lake Ontario salmonines 1995-2004 with emphasis on lake trout  

USGS Publications Warehouse

Alewives (Alosa pseudoharengus), the major prey fish for Lake Ontario, contain thiaminase. They are associated with development of a thiamine deficiency in salmonines which greatly increases the potential for developing an early mortality syndrome (EMS). To assess the possible effects of thiamine deficiency on salmonine reproduction we measured egg thiamine concentrations for five species of Lake Ontario salmonines. From this we estimated the proportion of families susceptible to EMS based on whether they were below the ED20, the egg thiamine concentration associated with 20% mortality due to EMS. The ED20s were 1.52, 2.63, and 2.99 nmol/g egg for Chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch), respectively. Based on the proportion of fish having egg thiamine concentrations falling below the ED20, the risk of developing EMS in Lake Ontario was highest for lake trout, followed by coho (O. kisutch), and Chinook salmon, with the least risk for rainbow trout (O. mykiss). For lake trout from western Lake Ontario, mean egg thiamine concentration showed significant annual variability during 1994 to 2003, when the proportion of lake trout at risk of developing EMS based on ED20 ranged between 77 and 100%. Variation in the annual mean egg thiamine concentration for western Lake Ontario lake trout was positively related (p < 0.001, r2 = 0.94) with indices of annual adult alewife biomass. While suggesting the possible involvement of density-dependent changes in alewives, the changes are small relative to egg thiamine concentrations when alewife are not part of the diet and are of insufficient magnitude to allow for natural reproduction by lake trout.

Fitzsimons, J.D.; Williston, B.; Williston, G.; Brown, L.; El-Shaarawi, A.; Vandenbyllaardt, L.; Honeyfeld, D.; Tillitt, D.; Wolgamood, M.; Brown, S.B.

2007-01-01

89

Gill net saturation by lake trout in Michigan waters of Lake Superior  

USGS Publications Warehouse

We conducted experimental fishing for lake trout Salvelinus namaycush in Michigan waters of Lake Superior to determine the importance of soak time on catch per effort (CPE) in numbers per kilometer of standard gill net. We modeled CPE as a nonlinear function of the number of nights between setting and lifting (soak time), in which the nets fill at a certain rate toward some maximum after which the nets cannot hold more fish. We found that lake trout CPE increased with soak time at a rate that varied with lake trout density toward a saturation level that was independent of lake trout density. The CPE values of nets soaked 2-5 nights divided by the CPE of nets soaked 1 night were significantly lower than would be expected had CPE increased as a linear function of the number of nights soaked. We derived a means for correcting gill-net CPE values for differing soak times to a common base of 1 night soaked. We concluded that it is inappropriate to assume lake trout catches in gill nets will increase in direct proportion to the number of nights soaked and recommend that CPE of lake trout in gill nets be corrected for soak time.

Hansen, Michael J.; Schorfhaar, Richard G.; Selgeby, James H.

1998-01-01

90

Use of egg traps to investigate lake trout spawning in the Great Lakes  

USGS Publications Warehouse

Disk-shaped traps were used to examine egg deposition by lake trout (Salvelinus namaycush) at 29 sites in the Great Lakes. The main objectives were to; first, evaluate the disk trap as a device for sampling lake trout eggs in the Great Lakes, and second, summarize what has been learned about lake trout spawning through the use of disk traps. Of the 5,085 traps set, 60% were classified as functional when retrieved. Evidence of lake trout egg deposition was documented in each of the lakes studied at 14 of 29 sites. A total of 1,147 eggs were trapped. The percentage of traps functioning and catch per effort were compared among sites based on depth, timing of egg deposition, distance from shore, size of reef and type of reef (artificial or natural). Most eggs were caught on small, shallow, protected reefs that were close to shore. Use of disk traps on large, shallow, unprotected offshore reefs or along unprotected shorelines was generally unsuccessful due to the effects of heavy wind and wave action. Making multiple lifts at short intervals, and retrieval before and re-deployment after storms are recommended for use in exposed al eas. On large reefs, preliminary surveys to identify preferred lake trout spawning habitat may be required to deploy disk traps most effectively. Egg deposition by hatchery-reared fish was widespread throughout the Great Lakes, and the use of artificial structures by these fish was extensive.

Schreiner, Donald R.; Bronte, Charles R.; Payne, N. Robert; Fitzsimons, John D.; Casselman, John M.

1995-01-01

91

A Comparison of Lake Trout Spawning, Fry Emergence, and Habitat Use in Lakes Michigan, Huron, and Champlain  

Microsoft Academic Search

Restoration of self-sustaining populations of lake trout is underway in all of the Great Lakes and Lake Champlain, but restoration has only been achieved in Lake Superior and in Parry Sound, Lake Huron. We evaluated progress toward restoration by comparing spawning habitat availability, spawner abundance, egg and fry density, and egg survival in Parry Sound in Lake Huron, in Lake

J. Ellen Marsden; Brian J. Ellrott; Randall M. Claramunt; Jory L. Jonas; John D. Fitzsimons

2005-01-01

92

Embryonic developmental progression in lake trout (Salvelinus namaycush) (Walbaum, 1792) and its relation to lake temperature  

USGS Publications Warehouse

Developmental progression of lake trout (Salvelinus namaycush) embryos was examined with light and scanning electron microscopy. From this examination, key developmental stages were described in detail. The key developmental stages were then applied to individual lake trout egg lots incubated in constant temperatures of 2, 4, 6, 8, and 10A?C. We used Belehradek's, Thermodynamic, and Power models, and also developed the Zero model to determine stage specific developmental rates of lake trout eggs for each background temperature. From the models, hatch dates and staging were predicted for temperature regimes from Lake Superior (1990-91) and Lake Huron (1996-97). Based on the existing lake temperature data and the observed spawning dates, the Zero and the Power models predict that post peak spawning may contribute significantly to overall recruitment success for these years.

Allen, Jeffrey D.; Walker, Glenn K.; Adams, Jean V.; Nichols, S. Jerrine; Edsall, Carol C.

2005-01-01

93

Bathythermal habitat use by strains of Great Lakes- and Finger Lakes-origin lake trout in Lake Huron after a change in prey fish abundance and composition  

USGS Publications Warehouse

A study conducted in Lake Huron during October 1998–June 2001 found that strains of Great Lakes-origin (GLO) lake trout Salvelinus namaycush occupied significantly higher temperatures than did Finger Lakes-origin (FLO; New York) lake trout based on data from archival (or data storage) telemetry tags that recorded only temperature. During 2002 and 2003, we implanted archival tags that recorded depth as well as temperature in GLO and FLO lake trout in Lake Huron. Data subsequently recorded by those tags spanned 2002–2005. Based on those data, we examined whether temperatures and depths occupied by GLO and FLO lake trout differed during 2002–2005. Temperatures occupied during those years were also compared with occupied temperatures reported for 1998–2001, before a substantial decline in prey fish biomass. Temperatures occupied by GLO lake trout were again significantly higher than those occupied by FLO lake trout. This result supports the conclusion of the previous study. The GLO lake trout also occupied significantly shallower depths than FLO lake trout. In 2002–2005, both GLO and FLO lake trout occupied significantly lower temperatures than they did in 1998–2001. Aside from the sharp decline in prey fish biomass between study periods, the formerly abundant pelagic alewife Alosa pseudoharengus virtually disappeared and the demersal round goby Neogobius melanostomus invaded the lake and became locally abundant. The lower temperatures occupied by lake trout in Lake Huron during 2002–2005 may be attributable to changes in the composition of the prey fish community, food scarcity (i.e., a retreat to cooler water could increase conversion efficiency), or both.

Bergstedt, Roger A.; Argyle, Ray L.; Krueger, Charles C.; Taylor, William W.

2012-01-01

94

Accumulation of PCBs by lake trout (Salvelinus namaycush): an individual-based model approach  

USGS Publications Warehouse

To explain the variation in growth and in concentration of polychlorinated biphenyls (PCBs) among individual fish, an individual-based model (IBM) was applied to the lake trout (Salvelinus namaycush) population in Lake Michigan. The IBM accurately represented the variation in growth exhibited by the different age classes of lake trout. Uncertainty analysis of the IBM revealed that mean PCB concentration for the lake trout population was most sensitive to PCB concentration in their prey. The variability in PCB concentration among lake trout individuals was not adequately explained by the IBM, unless variation in prey fish PCBs was included in the model. To accomplish this, the simulated lake trout population was divided into subsets subjected to different levels of PCB concentration in the prey fish. Thus, model results indicated that variability in prey fish PCB concentration was an important component of the variation in PCB concnetration observed among individual lake trout comprising the Lake Michigan population.

Madenjian, Charles P.; Carpenter, Stephen R.; Eck, Gary W.; Miller, Michael A.

1993-01-01

95

Use of Antimycin for Removal of Brook Trout from a Tributary of Yellowstone Lake  

Microsoft Academic Search

A major spawning migration of native Yellowstone cutthroat trout Oncorhynchus clarki bouvieri occurs in Arnica Creek, a tributary of Yellowstone Lake. An introduced population of brook trout Salvelinus fontinalis was detected in Arnica Creek in May 1985. Subsequent elec­ trofishing surveys of 40 additional tributaries of Yellowstone Lake revealed that brook trout were restricted to Arnica Creek. Because of undesirable

ROBERT E. GRESSWELL

1991-01-01

96

Q BAND CHROMOSOMAL POLYMORPHISMS IN LAKE TROUT (SALVELINUS NAMAYCUSH)  

Microsoft Academic Search

Q banding of chromosome preparations from lake trout revealed the presence of heteromorphic quinacrine bright bands on several chromosomes. All of the metacentric chromosome pairs can be distinguished on the basis of number, position and intensity of the quinacrine bright bands and chromosome size. These bands appear to represent heterochromatin, since they are darkly staining with the C band technique.

RUTH B. PHILLIPS; KERRY D. ZAJICEK

97

Limitations to lake trout (Salvelinus namaycush) rehabilitation in the Great Lakes imposed by biotic interactions occurring at early life stages  

USGS Publications Warehouse

We examine evidence that biotic factors, particularly predation, may be limiting early survival of wild lake trout (Salvelinus namaycush) juveniles in many areas of the Great Lakes. The Great Lakes contain numerous potential predators of lake trout eggs and fry, some of which are recent invaders, and most of which were probably absent when lake trout most recently re-invaded the Great Lakes after the last ice age. Simple quantitative models of predation suggest that plausible assumptions about prey densities, predator feeding rates, and duration of exposure of predator to prey can lead to very high estimates of predation mortality, in some instances approaching 100%. Indirect evidence from inter-Great Lake comparisons and inland lake examples also suggest that biotic factors may impede successful lake trout colonization. Our synthesis of the evidence leads to recommendations for research to better define field feeding rates of lake trout egg and fry predators and comparative studies of densities of potential egg and fry predators on lake trout spawning reefs. Management options should be designed to provide useful information as well as achieve short-term goals. From a management standpoint we recommend that: newly constructed lake trout reefs should be placed well away from concentrations of potential predators; offshore spawning reefs should be stocked; salmonine stocking, nutrient abatement, and commercial harvest of alewives should all be considered as options to enhance survival of young lake trout; hatchery lake trout should not be stocked at sites where wild lake trout are showing signs of recovery; and exotic species expansions or introductions must be curtailed to maintain or improve on our recent successes in lake trout rehabilitation.

Jones, Michael L.; Eck, Gary W.; Evans, David O.; Fabrizio, Mary C.; Hoff, Michael H.; Hudson, Patrick L.; Janssen, John; Jude, David; O'Gorman, Robert; Savino, Jacqueline F.

1995-01-01

98

Gamete ripening and hormonal correlates in three strains of lake trout  

USGS Publications Warehouse

In our 2-year laboratory study of hatchery-reared adult lake trout Salvelinus namaycush of the Seneca Lake, Marquette (Lake Superior Lean), and Jenny Lake strains, we compared gamete ripening times and changes in plasma concentrations of seven hormones. If interstrain differences in these traits were found, such differences might help explain the apparent failure of stocked fish of these strains to develop large, naturally reproducing populations in the Great Lakes. The complex temporal changes in plasma hormone levels that occur during sexual maturation in lake trout have not been previously described. We detected little evidence of temporal isolation that would prevent interbreeding among the three strains. Strain had no effect on ovulation date (OD) in either year. Strain did not affect spermiation onset date (SOD) in year 1 but did in year 2, when the mean SOD of Jenny Lake males was earlier than that of Seneca Lake males but not different from that of Marquette males. Hormonal data were normalized around ODs for individual females and SODs for individual males. In females, estradiol-17beta (E2) was highest 8 weeks before the OD; the highest testosterone (T) level occurred 6 weeks before the OD, and the next highest level occurred simultaneously with the highest level of 11-ketotestosterone (11-KT) 2 weeks before the OD. Plasma levels of 17alpha-hydroxy-20beta-dihydroprogesterone (DHP) peaked 1 week before the OD, then abruptly declined immediately after. Cortisol (F), triiodothyronine (T3), and thyroxine (T4) were highly variable, but F was the only hormone that showed no trend with week in either year. In males, plasma E2 levels were highest 3 weeks before the SOD, highest levels of T and of 11-KT occurred simultaneously 2 weeks after the SOD, and DHP peaked 5 weeks after the SOD and 3 weeks after the highest levels of T and 11-KT. As in females, plasma levels of F, T3, and T4 were highly variable, and F was the only hormone that showed no trend with week in either year. Strain had no effect on any hormones in females and only on T and F in males. The lack of pronounced interstrain differences in gamete ripening dates and reproductive endocrinology and the similarity of the temporal patterns and relative concentrations of hormones to those reported for other salmonids suggest nothing unusual or dysfunctional about these reproductive traits that would impede lake trout rehabilitation in the Great Lakes.

Foster, N.R.; O'Connor, D.V.; Schreck, C.B.

1993-01-01

99

Temporal trends of organochlorine contaminants in burbot and lake trout from three selected Yukon lakes.  

PubMed

Historical studies have demonstrated that organochlorine (OC) concentrations in top predators can vary considerably from lake to lake within a small geographic region but temporal trends of these contaminants have rarely been monitored in a sub-Arctic area for a long period of time. This study examined OC concentrations, including chlordane (CHL), DDT, hexachlorocyclohexane (HCH), toxaphene (CHB), PCB and chlorinated benzenes (CBz) in lake trout and burbot, from three Yukon lakes (Laberge, Kusawa, Quiet), over a span of 11 years (1992-2003). Temporal and spatial differences continue to exist in the OC concentrations of burbot and lake trout between these lakes. There is strong evidence that these contaminants are declining at various rates in lake trout (Salveninus namaycush) in Laberge, Kusawa and Quiet Lakes. For example, SigmaDDT concentrations have decreased 39%, 85% and 84% in Kusawa, Quiet and Laberge Lakes, respectively. Conversely, no consistent trends were observed in OC concentrations for burbot (Lota lota). For example, there is no evidence of a decline in toxaphene concentrations of Kusawa burbot yet a 58% decrease was observed in Laberge samples. Increases were also observed in the SigmaHCH levels of Kusawa Lake burbot, as well as increases in all OC groups (except SigmaHCH) for the Quiet Lake burbot samples. Decreases in burbot were evident in SigmaHCH and SigmaCHB for Lake Laberge fish and in SigmaCHL for Kusawa Lake samples. Spatial variations in OC levels are quite evident as Lake Laberge trout and burbot continued to maintain the highest levels over the eleven-year period from 1992 to 2003 followed by Kusawa Lake and then Quiet Lake. These differences were related to a variety of factors especially the species morphological characteristics such as log age, log weights and fish lipid content. A decreasing trend in Quiet and Laberge Lake trout lipid content, coupled with fluctuating condition factors and increases in body masses, suggest biotic changes may be occurring within the food webs due to fish population variations related to the cessation of commercial fishing or potentially an increase in lake plankton productivity related to annual climate variation. It is suspected that biotic factors rather than atmospheric inputs are the primary factors affecting the contaminant concentrations in lake trout and burbot in the study lakes. PMID:16140362

Ryan, M J; Stern, G A; Diamond, M; Croft, M V; Roach, P; Kidd, K

2005-12-01

100

Comparative hatching success of lake trout eggs in Lake Michigan water and well water  

USGS Publications Warehouse

A study was undertaken to examine the influence of water from southern Lake Michigan on the survival of lake trout (Salvelinus namaycush) eggs by comparing the hatching success of eggs from the same source incubated in water from Lake Michigan, or from the laboratory well. It is concluded that the observed differences in hatching are probably attributable to chemical constituents of water from the lake (eg, chlorinated hydrocarbons, metals and other industrial and agricultural chemicals).

Edsall, Carol C.; Mac, Michael J.

1982-01-01

101

Sexual difference in PCB concentrations of lake trout (Salvelinus namaycush) from Lake Ontario  

USGS Publications Warehouse

We determined polychlorinated biphenyl (PCB) concentrations in 61 female lake trout (Salvelinus namaycush) and 71 male lake trout from Lake Ontario (Ontario, Canada and New York, United States). To estimate the expected change in PCB concentration due to spawning, PCB concentrations in gonads and in somatic tissue of lake trout were also determined. In addition, bioenergetics modeling was applied to investigate whether gross growth efficiency (GGE) differed between the sexes. Results showed that, on average, males were 22% higher in PCB concentration than females in Lake Ontario. Results from the PCB determinations of the gonads and somatic tissues revealed that shedding of the gametes led to 3% and 14% increases in PCB concentration for males and females, respectively. Therefore, shedding of the gametes could not explain the higher PCB concentration in male lake trout. According to the bioenergetics modeling results, GGE of males was about 2% higher than adult female GGE, on average. Thus, bioenergetics modeling could not explain the higher PCB concentrations exhibited by the males. Nevertheless, a sexual difference in GGE remained a plausible explanation for the sexual difference in PCB concentrations of the lake trout.

Madenjian, Charles P.; Keir, Michael J.; Whittle, D. Michael; Noguchi, George E.

2010-01-01

102

Sexual difference in PCB concentrations of lake trout (Salvelinus namaycush) from Lake Ontario.  

PubMed

We determined polychlorinated biphenyl (PCB) concentrations in 61 female lake trout (Salvelinus namaycush) and 71 male lake trout from Lake Ontario (Ontario, Canada and New York, United States). To estimate the expected change in PCB concentration due to spawning, PCB concentrations in gonads and in somatic tissue of lake trout were also determined. In addition, bioenergetics modeling was applied to investigate whether gross growth efficiency (GGE) differed between the sexes. Results showed that, on average, males were 22% higher in PCB concentration than females in Lake Ontario. Results from the PCB determinations of the gonads and somatic tissues revealed that shedding of the gametes led to 3% and 14% increases in PCB concentration for males and females, respectively. Therefore, shedding of the gametes could not explain the higher PCB concentration in male lake trout. According to the bioenergetics modeling results, GGE of males was about 2% higher than adult female GGE, on average. Thus, bioenergetics modeling could not explain the higher PCB concentrations exhibited by the males. Nevertheless, a sexual difference in GGE remained a plausible explanation for the sexual difference in PCB concentrations of the lake trout. PMID:20067852

Madenjian, Charles P; Keir, Michael J; Whittle, D Michael; Noguchi, George E

2010-03-01

103

Egg fatty acid composition from lake trout fed two Lake Michigan prey fish species.  

PubMed

We previously demonstrated that there were significant differences in the egg thiamine content in lake trout Salvelinus namaycush fed two Lake Michigan prey fish (alewife Alosa pseudoharengus and bloater Coregonus hoyi). Lake trout fed alewives produced eggs low in thiamine, but it was unknown whether the consumption of alewives affected other nutritionally important components. In this study we investigated the fatty acid composition of lake trout eggs when females were fed diets that resulted in different egg thiamine concentrations. For 2 years, adult lake trout were fed diets consisting of four combinations of captured alewives and bloaters (100% alewives; 65% alewives, 35% bloaters; 35% alewives, 65% bloaters; and 100% bloaters). The alewife fatty acid profile had higher concentrations of arachidonic acid and total omega-6 fatty acids than the bloater profile. The concentrations of four fatty acids (cis-13, 16-docosadienoic, eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids) were higher in bloaters than in alewives. Although six fatty acid components were higher in lake trout eggs in 2001 than in 2000 and eight fatty acids were lower, diet had no effect on any fatty acid concentration measured in lake trout eggs in this study. Based on these results, it appears that egg fatty acid concentrations differ between years but that the egg fatty acid profile does not reflect the alewife-bloater mix in the diet of adults. The essential fatty acid content of lake trout eggs from females fed alewives and bloaters appears to be physiologically regulated and adequate to meet the requirements of developing embryos. PMID:20218501

Honeyfield, Dale C; Fitzsimons, John D; Tillitt, Donald E; Brown, Scott B

2009-12-01

104

Recruitment Dynamics of the 1971–1991 Year-Classes of Lake Trout in Michigan Waters of Lake Superior  

Microsoft Academic Search

In the 1950s, populations of lake trout Salvelinus namaycush in Lake Superior collapsed because of excessive exploitation and predation by sea lampreys Petromyzon marinus. Restoration began in the 1950s with the stocking of juvenile, hatchery-reared lake trout and controls on fisheries and sea lampreys. Partial restoration was declared in 1996 because wild fish made up most of the populations in

Jessica M. Richards; Michael J. Hansen; Charles R. Bronte; Shawn P. Sitar

2004-01-01

105

Response of non-native lake trout (Salvelinus namaycush) to 15 years of harvest in Yellowstone Lake, Yellowstone National Park  

USGS Publications Warehouse

Introduced lake trout (Salvelinus namaycush) threaten to extirpate native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) in the 34 000 ha Yellowstone Lake in Yellowstone National Park, USA. Suppression (and eventual eradication) of the lake trout population is deemed necessary for the conservation of Yellowstone cutthroat trout. A US National Park Service gill-netting program removed nearly 450 000 lake trout from Yellowstone Lake from 1995 through 2009. We examined temporal variation in individual growth, body condition, length and age at maturity, fecundity, mortality, and population models to assess the efficacy of the lake trout suppression program. Population metrics did not indicate overharvest despite more than a decade of fish removal. The current rate of population growth is positive; however, it is lower than it would be in the absence of lake trout suppression. Fishing effort needs to increase above observed levels to reduce population growth rate below replacement. Additionally, high sensitivity of population growth rate to reproductive vital rates indicates that increasing fishing mortality for sexually mature lake trout may increase the effectiveness of suppression. Lake trout suppression in Yellowstone Lake illustrates the complexities of trying to remove an apex predator to restore a relatively large remote lentic ecosystem with a simple fish assemblage.

Syslo, J.M.; Guy, C.S.; Bigelow, P.E.; Doepke, P.D.; Ertel, B.D.; Koel, T.M.

2011-01-01

106

Crayfish (Orconectes virilis) feeding on young lake trout (Salvelinus namaycush): effect of rock size  

USGS Publications Warehouse

In laboratory studies, we quantified predation rates of crayfish (Orconectes virilis) on the eggs and sac fry of lake trout (Salvelinus namaycush) and a surrogate species, rainbow trout (Oncorhynchus mykiss), dispersed among different sized substrates (bare bottom, gravel, cobble, large rocks). Predation was most severe when no rocks were present. Feeding rate then decreased as the substrate changed from large rocks to cobble to gravel. Crayfish predation rate did not change with prey type -- rainbow trout and lake trout eggs or sac fry. Crayfish foraging in large tanks containing cobble averaged about two eggs or sac fry per day. In most instances, crayfish would have little impact on lake trout egg survival. Only in lake trout spawning grounds with relatively low egg densities, large crayfish populations, and cobble or large rock substrate, would crayfish be expected to have some impact on lake trout egg survival.

Savino, Jacqueline F.; Miller, John E.

1991-01-01

107

Energy budget for yearling lake trout, Salvelinus namaycush  

USGS Publications Warehouse

Components of the energy budget of yearling lake trout (Salvelinus namaycush) were derived from data gathered in laboratory growth and metabolism studies; values for energy lost as waste were estimated with previously published equations. Because the total caloric value of food consumed by experimental lake trout was significantly different during the two years in which the studies were done, separate annual energy budgets were formulated. The gross conversion efficiency in yearling lake trout fed ad libitum rations of alewives at 10A?C was 26.6% to 41%. The distribution of energy with temperature was similar for each component of the energy budget. Highest conversion efficiencies were observed in fish fed less than ad libitum rations; fish fed an amount of food equivalent to about 4% of their body weight at 10A?C had a conversion efficiency of 33% to 45.1%. Physiologically useful energy was 76.1-80.1% of the total energy consumed. Estimated growth for age-I and -II lake fish was near that observed for laboratory fish held at lake temperatures and fed reduced rations.

Rottiers, Donald V.

1993-01-01

108

Q Band Chromosomal Polymorphisms in Lake Trout (SALVELINUS NAMAYCUSH)  

PubMed Central

Q banding of chromosome preparations from lake trout revealed the presence of heteromorphic quinacrine bright bands on several chromosomes. All of the metacentric chromosome pairs can be distinguished on the basis of number, position and intensity of the quinacrine bright bands and chromosome size. These bands appear to represent heterochromatin, since they are darkly staining with the C band technique. Since all of the fish examined had consistent heteromorphisms at several of the quinacrine bright bands, these chromosome markers should be useful in genetic comparisons between different trout stocks and populations. PMID:7173603

Phillips, Ruth B.; Zajicek, Kerry D.

1982-01-01

109

Evidence of widespread natural reproduction by lake trout Salvelinus namaycush in the Michigan waters of Lake Huron  

USGS Publications Warehouse

Localized natural reproduction of lake trout Salvelinus namaycush in Lake Huron has occurred since the 1980s near Thunder Bay, Michigan. During 2004-2006, USGS spring and fall bottom trawl surveys captured 63 wild juvenile lake trout at depths ranging from 37-73 m at four of five ports in the Michigan waters of the main basin of Lake Huron, more than five times the total number captured in the previous 30-year history of the surveys. Relatively high catches of wild juvenile lake trout in bottom trawls during 2004-2006 suggest that natural reproduction by lake trout has increased and occurred throughout the Michigan waters of the main basin. Increased catches of wild juvenile lake trout in the USGS fall bottom trawl survey were coincident with a drastic decline in alewife abundance, but data were insufficient to determine what mechanism may be responsible for increased natural reproduction by lake trout. We recommend further monitoring of juvenile lake trout abundance and research into early life history of lake trout in Lake Huron.

Riley, S.C.; He, J.X.; Johnson, J.E.; O'Brien, T. P.; Schaeffer, J.S.

2007-01-01

110

CALCULATED CONTRIBUTION OF SURFACE MICROLAYER PCB TO CONTAMINATION OF LAKE MICHIGAN LAKE TROUT  

EPA Science Inventory

The possible significance of PCB concentration in the surface microlayer of Lake Michigan to contamination of lake trout was examined using a modification of a previously developed food chain model. Vertically migrating zooplankton were assumed to spend a fraction of each day exp...

111

Sexual difference in mercury concentrations of lake trout (Salvelinus namaycush) from Lake Ontario.  

PubMed

We determined total mercury (Hg) concentrations in 50 female lake trout (Salvelinus namaycush) and 69 male lake trout from Lake Ontario (Ontario, Canada and New York, United States). Results showed that, on average, males were 8% higher in Hg concentration than females in Lake Ontario. We also used bioenergetics modeling to determine whether a sexual difference in gross growth efficiency (GGE) could explain the observed sexual difference in Hg concentrations. According to the bioenergetics modeling results, male GGE was about 3% higher than female GGE, on average. Although the bioenergetics modeling could not explain the higher Hg concentrations exhibited by the males, a sexual difference in GGE remained a plausible explanation for the sexual difference in Hg concentrations of the lake trout. In an earlier study, male lake trout from Lake Ontario were found to be 22% higher in polychlorinated biphenyl (PCB) concentration than females from Lake Ontario. Thus, although males were higher in both Hg and PCB concentrations, the degree of the sexual difference in concentration varied between the two contaminants. Further research on sexual differences in Hg excretion rates and Hg direct uptake rates may be needed to resolve the disparity in results between the two contaminants. PMID:21429556

Madenjian, Charles P; Keir, Michael J; Whittle, D Michael

2011-05-01

112

Sexual difference in mercury concentrations of lake trout (Salvelinus namaycush) from Lake Ontario  

USGS Publications Warehouse

We determined total mercury (Hg) concentrations in 50 female lake trout (Salvelinus namaycush) and 69 male lake trout from Lake Ontario (Ontario, Canada and New York, United States). Results showed that, on average, males were 8% higher in Hg concentration than females in Lake Ontario. We also used bioenergetics modeling to determine whether a sexual difference in gross growth efficiency (GGE) could explain the observed sexual difference in Hg concentrations. According to the bioenergetics modeling results, male GGE was about 3% higher than female GGE, on average. Although the bioenergetics modeling could not explain the higher Hg concentrations exhibited by the males, a sexual difference in GGE remained a plausible explanation for the sexual difference in Hg concentrations of the lake trout. In an earlier study, male lake trout from Lake Ontario were found to be 22% higher in polychlorinated biphenyl (PCB) concentration than females from Lake Ontario. Thus, although males were higher in both Hg and PCB concentrations, the degree of the sexual difference in concentration varied between the two contaminants. Further research on sexual differences in Hg excretion rates and Hg direct uptake rates may be needed to resolve the disparity in results between the two contaminants.

Madenjian, C.P.; Keir, M.J.; Whittle, D.M.

2011-01-01

113

Contaminant trends in lake trout and walleye from the Laurentian Great Lakes  

USGS Publications Warehouse

Trends in PCBs, DDT, and other contaminants have been monitored in Great Lakes lake trout and walleye since the 1970s using composite samples of whole fish. Dramatic declines have been observed in concentrations of PCB, I#DDT, dieldrin, and oxychlordane, with declines initially following first order loss kinetics. Mean PCB concentrations in Lake Michigan lake trout increased from 13 I?g/g in 1972 to 23 I?g/g in 1974, then declined to 2.6 I?g/g by 1986. Between 1986 and 1992 there was little change in concentration, with 3.5 I?g/g observed in 1992. I#DDT in Lake Michigan trout followed a similar trend, decreasing from 19.2 I?g/g in 1970 to 1.1 I?g/g in 1986, and 1.2 I?g/g in 1992. Similar trends were observed for PCBs and I#DDT in lake trout from Lakes Superior, Huron and Ontario. Concentrations of both PCB and I#DDT in Lake Erie walleye declined between 1977 and 1982, after which concentrations were relatively constant through 1990. When originally implemented it was assumed that trends in the mean contaminant concentrations in open-lake fish would serve as cost effective surrogates to trends in the water column. While water column data are still extremely limited it appears that for PCBs in lakes Michigan and Superior, trends in lake trout do reasonably mimic those in the water column over the long term. Hypotheses to explain the trends in contaminant concentrations are briefly reviewed. The original first order loss kinetics used to describe the initial decline do not explain the more recent leveling of contaminant concentrations. Recent theories have examined the possibilities of multiple contaminant pools. We suggest another hypothesis, that changes in the food web may have resulted in increased bioaccumulation. However, a preliminary exploration of this hypothesis using a change point analysis was inconclusive.

DeVault, David S.; Hesselberg, Robert J.; Rodgers, Paul W.; Feist, Timothy J.

1996-01-01

114

Population biology of lake trout (Salvelinus namaycush) of Lake Superior before 1950  

USGS Publications Warehouse

Scale samples collected in 1948 were used to estimate the instantaneous total mortality rate (0.70) and growth for lake trout (Salvelinus namaycush) in Lake Superior before the population had been significantly reduced by the sea lamprey (Petromyzon marinus). Indirect evidence indicates that the instantaneous natural mortality rate was probably 0.10-0.25. The Ricker model was used to calculate yield per recruitment, which varied with natural mortality and growth. Natural mortality was more critical than growth; yield per recruitment increased 183.3% with a 60% decrease in instantaneous natural mortality (from 0.25 to 0.10). For the prelamprey lake trout population the yield per recruitment was about 12-34 lb; the recruitment of about 3.6-10.1 million lake trout of age 1.5 resulted in an annual commercial production of 4 million lb.

Sakagawa, Gary T.; Pycha, Richard L.

1971-01-01

115

Dynamics of Piscivory by Lake Trout following a Smallmouth Bass Invasion: A Historical Reconstruction  

Microsoft Academic Search

Our objective was to assess the dynamics of piscivory by lake trout Salvelinus namaycush in Lake Opeongo, Ontario, following the introduction of smallmouth bass Micropterus dolomieu early in the 1900s. The effects of this introduction on lake trout were thought to be of slight significance at the time, but they may have been obscured by the introduction of cisco Coregonus

Yolanda E. Morbey; Kris Vascotto; Brian J. Shuter

2007-01-01

116

Low genetic variability in lake populations of brook trout (Salvelinus fontinalis): A consequence of exploitation?  

Microsoft Academic Search

Previous studies have found lower levels of genetic variation in lake than stream populations of brook trout (Salvelinus fontinalis). We test the generality of this observation by examining whether brook trout genetic variation at 10 allozyme loci differed within and among 9 pairs of lake and adjacent stream populations. With one exception, we found that lake populations had lower heterozygosity

Matthew W. Jones; Tara L. McParland; Jeffrey A. Hutchings; Roy G. Danzmann

2001-01-01

117

Predation by Alewives on Lake Trout Fry in Lake Ontario: Role of an Exotic Species in Preventing Restoration of a Native Species  

Microsoft Academic Search

Lake trout (Salvelinus namaycush) restoration efforts in Lake Ontario have resulted in an abundance of spawning fish of hatchery-origin but virtually no detectable natural recruitment. One explanation has been predation by non-native alewives (Alosa pseudoharengus) on lake trout fry. The purpose of this study was to determine if alewives could be important predators on lake trout fry. In the laboratory,

Charles C. Krueger; David L. Perkins; Edward L. Mills; J. Ellen Marsden

1995-01-01

118

Temporal trends and spatial distribution of dioxins and furans in lake trout or lake whitefish from the Canadian Great Lakes.  

PubMed

Concentrations of the seventeen 2,3,7,8-substituted, most toxic congeners of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were measured in lake trout (Salvelinus namaycush) or lake whitefish (Coregonus clupeaformis) collected between 1989 and 2003 from the Canadian Great Lakes as a part of the on-going Sport Fish Contaminant Monitoring Program of the Ontario Ministry of the Environment. These monitoring data were used to assess temporal trends and spatial variations of these compounds in the Canadian Great Lakes. Toxic equivalents (TEQs) were calculated using the measured congener concentrations and toxicity equivalency factors (TEFs) published by the World Health Organization in 1998. Five congeners, namely 2,3,7,8-TCDD, 2,3,7,8-TCDF, 1,2,3,7,8-PeCDD, 1,2,3,7,8-PeCDF, and 2,3,4,7,8-PeCDF, were the most dominant congeners among the 17 congeners analyzed. The highest TEQs were found for Lake Ontario lake trout (22-54 pg g(-1)) while the TEQs for the other Canadian Great Lakes were 60-95% lower. Non-parametric Mann-Kendall and Sen's tests performed on TEQs and PCDD/Fs standardized at a mean lake trout length of 60 cm suggest a linearly decreasing trend for PCDD/Fs in lake trout from Lakes Ontario and Huron. There was no monotonously increasing or decreasing trend found for Lake Superior lake trout. The ratios of 2,3,7,8-TCDD to 2,3,7,8-TCDF concentrations were generally constant during the 1989-2003 period with the values being in the order of Lakes Superior (0.05-0.3) Lakes. PMID:18501406

Bhavsar, Satyendra P; Awad, Emily; Fletcher, Rachael; Hayton, Alan; Somers, Keith M; Kolic, Terry; MacPherson, Karen; Reiner, Eric J

2008-08-01

119

EFFECTS OF SUMMER THERMAL CONDITIONS ON BROOK TROUT (SALVELINUS FONTINALIS) IN AN UNSTRATIFIED ADIRONDACK LAKE .  

E-print Network

??Lake-dwelling populations of brook trout (Salvelinus fontinalis) represent a coldwater fish species potentially susceptible to climatic warming trends. Global climate change and associated warming trends… (more)

Robinson, Jason

2008-01-01

120

Hierarchical Structure and Diversity in a Dendritic Lake Trout (Salvelinus Namaycush) System in Northern Labrador.  

E-print Network

??I examined the relationship between landscape attributes and population differentiation among lake trout (Salvelinus namaycush) populations inhabiting a hierarchically structured dendritic freshwater system in northern… (more)

McCracken, Gregory

2012-01-01

121

The movement of tagged lake trout in Lake Superior, 1950-52  

USGS Publications Warehouse

A total of 733 native lake trout was tagged at two widely separated localities in Lake Superior; subsequent recaptures numbered 155 fish (21.1 percent) during the year following marking. In October 1950, 116 large lake trout (average total length, 27.3 inches) were tagged near Keweenaw Point, Michigan. Fifteen (12.9 percent) were recovered during the first year at points as far west as the Gooseberry River, Minnesota (190 miles), north to the Slate Islands, Ontario (95 miles), and east to Grand Marais, Michigan (100 miles). Nine fish (7.8 percent) were recovered during the second year after marking. Returns from 617 tagged lake trout of smaller size (average length 18.2 inches) released in the Apostle Island region of Wisconsin during the period June 12 to August 6, 1951, numbered 140 (22.7 percent) during the first year. Of these fish, 90 percent were recaptured within a radius of 50 miles of the points of release. Seventy-six percent were caught in Wisconsin, 14 percent in Minnesota, and 9 percent in Michigan waters. The fish retaken in Michigan had moved 120 to 255 miles between the time of release and recapture, traveling as far wast as Grand Marais. Lake trout recaptured at distances of more than 50 miles from the tagging locality were of larger average size than marked fish caught within this radius. The four types of tages used in the marking of lake trout in the Apostle Island region, together with the number tagged and percentage recovered during the first year were as follows: 103 aluminum lower-jaw tags (used only on fish less than 17 inches in length when marked)-10.7 percent; 200 monel upper-jaw tags-14 percent; 162 streamer tags-19.8 percent; and 152 Peterson tags-45.4 percent. Obviously lake trout marked with the Peterson tag, with the discs and ends of the pin projecting from each side near the point of maximum girth, were more vulnerable to the fishery than were fish marked with other tags. The recoveries of marked fish show that Lake Superior lake trout-particularly fish of large size-may move many miles and freely cross political boundaries; and that the rate of harvest is moderately high for a fish with a life history as long as that of the lake trout.

Eschmeyer, Paul H.; Daly, Russell; Erkkila, Leo F.

1953-01-01

122

Predation by sea lamprey (Petromyzon marinus) on lake trout (Salvelinus namaycush) in southern Lake Ontario, 1982-1992  

USGS Publications Warehouse

Dead lake trout (Salvelinus namaycush) killed by sea lamprey (Petromyzon marinus) were collected from the bottom of Lake Ontario using bottom trawls. The number of dead lake trout per hectare could be predicted from the number of type A-1 sea lamprey marks observed on live fish in September gillnet surveys (r2 = 0.60, P P > 0.05) from those of live fish with A-1 marks in 5 of 6 years where comparisons could be made. Compared with Lake Superior strain lake trout, Seneca Lake strain fish were only 0.41 times as likely to be attacked by sea lamprey and were less likely to die from an attack (both differences P < 0.05). Conservative estimates of the numbers of lake trout killed by sea lamprey in southern Lake Ontario from October to mid-November ranged from 17 000 in 1988 to 121 000 in 1984.

Schneider, C.P.; Owens, R.W.; Bergstedt, R.A.; O'Gorman, R.

1996-01-01

123

Short-duration electrical immobilization of lake trout  

USGS Publications Warehouse

Chemical anesthetics induce stress responses, and most leave residues in fish tissues that require a certain withdrawal time before the animal can be released into the environment. Therefore, alternatives are needed in cases when fish must be released immediately, for example, during egg-collecting operations or after implanting elastomer tags. To evaluate pulsed direct current as an alternative method of immobilization, individual lake trout Salvelinus namaycush were electrically immobilized using various pulsed-DC voltage gradients and shock durations. Duration of opercular recovery and narcosis were measured for individual fish. Fish were euthanized 24 h after electrical immobilization and processed for lateral radiograph analysis and assessment of perivertebral hemorrhaging by dissection. Survival of lake trout after electrical immobilization at 0.6 V/cm for 30 or 40 s or 0.8 V/cm for 5 or 15 s was monitored for 81 or 84 d after immobilization. Mean narcosis duration increased with voltage gradient and shock duration. Larger fish had longer periods of narcosis at the same combination of voltage gradient and shock duration. Radiological evaluation indicated that 9 of 28 fish in the oldest age-class tested had detectable injuries of the vertebral column, but all but one were in the lowest injury category. Although vertebral column injuries were observed in most small fish, the majority of vertebral column injuries were minor compressions involving two to seven vertebrae. Of the 82 lake trout electrically immobilized to assess long-term survival, only 5 died (6%). Our data suggest that lake trout could be electrically immobilized for a sufficient period to allow field workers to collect length and weight data and implant visible implant tags or colored elastomer tags. The technique we used, however, is probably not appropriate for procedures that require immobilization for more than 2a??3 min.

Gaikowski, Mark P.; Gingerich, William H.; Gutreuter, Steve

2001-01-01

124

High levels of MHC class II allelic diversity in lake trout from Lake Superior  

USGS Publications Warehouse

Sequence variation in a 216 bp portion of the major histocompatibility complex (MHC) II B1 domain was examined in 74 individual lake trout (Salvelinus namaycush) from different locations in Lake Superior. Forty-three alleles were obtained which encoded 71-72 amino acids of the mature protein. These sequences were compared with previous data obtained from five Pacific salmon species and Atlantic salmon using the same primers. Although all of the lake trout alleles clustered together in the neighbor-joining analysis of amino acid sequences, one amino acid allelic lineage was shared with Atlantic salmon (Salmo salar), a species in another genus which probably diverged from Salvelinus more than 10-20 million years ago. As shown previously in other salmonids, the level of nonsynonymous nucleotide substitution (d(N)) exceeded the level of synonymous substitution (d(S)). The level of nucleotide diversity at the MHC class II B1 locus was considerably higher in lake trout than in the Pacific salmon (genus Oncorhynchus). These results are consistent with the hypothesis that lake trout colonized Lake Superior from more than one refuge following the Wisconsin glaciation. Recent population bottlenecks may have reduced nucleotide diversity in Pacific salmon populations.

Dorschner, M.O.; Duris, T.; Bronte, C.R.; Burnham-Curtis, M. K.; Phillips, R.B.

2000-01-01

125

Contaminant trends in lake trout (Salvelinus namaycush) of the upper Great Lakes  

USGS Publications Warehouse

Contaminant body burdens in lake trout from the Upper Great Lakes have been monitored since 1970 on Lake Michigan and since 1977 and 1978 on Lakes Superior and Huron by USEPA, Great Lakes National Program Office and USFWS, Great Lakes Fishery Laboratory. Analysis of the Lake Michigan data shows that mean PCB concentrations declined from a maximum of 22.91 mg/kg in 1974 to 5.63 in 1982. Mean total DDT concentrations declined from 19.19 mg/kg in 1970 to 2.74 mg/kg in 1982. The decline in both contaminants closely followed first order loss kinetics. If the current decline continues, PCB concentrations will decline to the USFDA tolerance of 2.0 mg/kg in 1988. Mean total DDT concentrations will fall to the IJC objective of 1.0 mg/kg by 1991. Mean dieldrin concentrations increased significantly from 0.20 mg/kg in 1971 to 0.58 mg/kg in 1979 before declining to 0.21 mg/kg in 1982. The decline from 1979-1982 followed first order loss kinetics. As this decline is not reflected in other species (bloater chubs, smelt) it will require additional years of monitoring to determine if the decline in dieldrin concentrations between 1979 and 1982 truly represents a declining trend. Contaminants in lake trout from Lake Superior and Lake Huron generally declined over the study period. The only statistically significant trend other than in Lake Michigan was for total DDT which declined significantly in Lake Superior lake trout. Large data variance and the short time frame covered (1977-1982) interfered with detection of trends on Lakes Superior and Huron.

DeVault, David S.; Willford, Wayne A.; Hesselberg, Robert J.

1985-01-01

126

Yearling Liberations and Change of Food as Effecting Rainbow Trout Yield in Paul Lake, British Columbia  

Microsoft Academic Search

Some effects of the introduction of redside shiner, Richardsonius balteatus (Richardson), on the rainbow trout, Salmo gairdneri Richardson, in Paul Lake from 1952 to 1957 are considered together with results of yearling trout liberations since 1953. Changes in the diet of rainbow trout from invertebrates to redside shiners, already noticeable in 1952, have since intensified. By 1956, shiners comprised over

E. J. Crossman; P. A. Larkin

1959-01-01

127

Lake trout (Salvelinus namaycush) and sea lamprey (Petromyzon marinus) populations in Lake Michigan, 1971-78  

USGS Publications Warehouse

Lake trout (Salvelinus namaycush) was exterminated in Lake Michigan by the mid-1950s as a result of the combined effects of an intensive fishery and predation by the sea lamprey (Petromyzon marinus). The widespread application of lampricide in tributary streams had greatly reduced the abundance of lampreys by the early 1960s, and a program to restore self-sustaining populations of lake trout through stocking of yearlings and fingerlings was initiated in 1965. Although the hatchery-reared fish spawned widely in Lake Michigan each year after 1970, no progeny were observed except in an isolated area in Grand Traverse Bay. During 1971-78, sea lamprey abundance was generally greater in Wisconsin than in other parts of the lake. However, the rate of occurrence of sea lamprey wounds on lake trout dropped dramatically there in 1978 after the Peshtigo River, a tributary to Green Bay, was treated with lampricide. Application of Lake Michigan wounding rates to a regression model relating mortality to lamprey wounding developed from Lake Superior data, yielded lamprey-induced mortality estimates in 1977 of 5% in Michigan plus Indiana (combined) and 31% in Wisconsin; corresponding estimates for 1978 were 5 and 15%.

Wells, LaRue

1980-01-01

128

The response of burbot ( Lota lota ) to change in lake trout ( Salvelinus namaycush ) abundance in Lake Opeongo, Ontario  

Microsoft Academic Search

The purpose of this study was to test the hypothesis that the burbot and lake trout compete with or prey on each other, and that a change in the abundance of lake trout has triggered a response in the burbot population. Burbot growth, length-weight relationship and population size did not change, and it appears that at these population levels, the

Leon M. Carl

1992-01-01

129

Growth and survival of stocked lake trout with nuclear cataracts in Lake Ontario  

USGS Publications Warehouse

Four strains of yearling lake trout Salvelinus namaycush from the 1985 and 1986 year-classes at the Allegheny National Fish Hatchery were evaluated for nuclear cataracts prior to stocking in Lake Ontario in June 1986 and 1987. Lake trout recaptured by bottom trawling from April to August 1987 and 1988 were examined for cataracts. Cataract frequencies in three strains of yearling lake trout at stocking in 1986 and after 14 and 26 months in the lake were: Seneca Lake- 35, 24, and 29%; Lake Ontario- 32, 24, and 42%; and Lake Superior- 7, 4, and 6%. Cataract frequencies for yearlings at stocking in 1987 and after 2 and 14 months were: Seneca Lake- 51, 37, and 51%; Lake Superior- 7, 12, and 12%; and Jenny Lake- 46, 13, and 36%. Cataract frequency was lower (P < 0.05) at capture in three of the six groups recaptured in 1987 and in two of the six groups in 1988. Fish with cataracts in the 1987 recovery had survival ratios of 17-186% after 2 months in the lake and 48-67% after 14 months, compared with normal-eyed fish of the same strain. Nuclear cataract frequency was relatively stable after the first year of lake residency, when equilibrium was achieved between the increased mortality of cataract phenotypes and the rate of cataract development in normal-eyed phenotypes. Within groups, weight and length were not different between healthy fish and fish with cataracts. The absence of growth depression in fish with cataracts and the reduced survival rate suggested that faster growing fish were more susceptible to cataract formation.

Kincaid, Harold L.; Elrod, Joseph H.

1991-01-01

130

Evaluation of coded wire tags for marking lake trout  

USGS Publications Warehouse

Among hatchery-reared lake trout (Salvelinus namaycush) of the 1979-1982 year classes stocked in New York waters of Lake Ontario, more than 3 million fish were marked with a coded wire tag (CWT) plus an adipose fin clip, and 1.5 million with only conventional fin clips. Altogether, 7,640 tags were recovered from fish collected with bottom trawls and gill nets or caught by anglers during 1980-1983. One person was able to extract and decipher 200 or more CWTs per day with about a 1% error rate in reading and recording codes. Presence of the CWT did not affect growth. The adipose fin clip did not regenerate. The occurrence of fish with an adipose fin clip but no CWT resulted primarily from the regeneration of paired fins among fish marked with a combination of the adipose fin and a paired fin. Loss of CWTs between marking and stocking (generally 4-5 months for fish stocked in spring and 1-8 d for fish stocked in fall) declined from nearly 11% for the 1979 year class stocked as fall fingerlings to less than 3% for the 1981 and 1982 year classes - a difference that primarily reflected improvements in instrumentation and tagging technique. The rate of CWT loss after the marked fish were stocked was probably less than 1% per year. The CWT is a reliable method for marking hatchery-reared lake trout. A large number of experimental groups can be uniquely marked, and fish from each group can be accurately identified throughout their life. Use of this technique should greatly facilitate evaluations of genetic strain, hatchery experience, condition at time of stocking, season of stocking, size at stocking, method of stocking and other factors that affect poststocking survival and performance of lake trout stocked in the Great Lakes.

Elrod, Joseph H.; Schneider, Clifford P.

1986-01-01

131

Movement of tagged lake trout in Lake Superior, 1950-1952  

USGS Publications Warehouse

A total of 733 native lake trout was tagged at two widely separated localities in Lake Superior; subsequent recaptures numbered 155 fish (21.1 percent) during the year following marking. In October 1950, 116 large lake trout (average total length, 27.3 inches) were tagged near Keweenaw Point, Michigan. Fifteen (12.9 percent) were recovered during the first year at points as far west as the Gooseberry River, Minnesota (190 miles), north to the Slate Islands, Ontario (95 miles), and east to Grand Marais, Michigan (100 miles). Nine fish (7.8 percent) were recovered during the second year after marking. Returns from 617 tagged lake trout of smaller size released in the Apostle Island region of Wisconsin during the period June 12 to August 6, 1951, numbered 140 (22.7 percent) during the first year. Of these fish, 90 percent were recaptured within a radius of 50 miles of the point of release. Seventy-six percent were caught in Wisconsin, 14 percent in Minnesota, and 9 percent in Michigan waters. The fish retaken in Michigan had moved 120 to 255 miles between the time of release and recapture, traveling as far east as Grand Marais. Lake trout recaptured at distances of more than 50 miles from the tagging locality were of larger average size than marked fish caught within this radius.

Eschmeyer, Paul H.; Daly, Russell; Erkkila, Leo F.

1953-01-01

132

Use of a Seismic Air Gun to Reduce Survival of Nonnative Lake Trout Embryos: A Tool for Conservation?  

Microsoft Academic Search

The detrimental impacts of nonnative lake trout Salvelinus namaycush in the western USA have prompted natural resource management agencies in several states to implement lake trout suppression programs. Currently, these programs rely on mechanical removal methods (i.e., gill nets, trap nets, and angling) to capture subadult and adult lake trout. We conducted a study to explore the potential for using

Benjamin S. Cox; Andrew M. Dux; Michael C. Quist; Christopher S. Guy

2012-01-01

133

Lake trout spawning habitat in the Great Lakes u a review of current knowledge  

USGS Publications Warehouse

We review existing information on lake trout spawning habitat, which might indicate whether habitat is now a limiting factor in lake trout reproductive success. Lake trout spawning habitat quality is defined by the presence or absence of olfactory cues for homing, reef location with respect to the shoreline, water depth, proximity to nursery areas, reef size, contour, substrate size and shape, depth of interstitial spaces, water temperature at spawning time, water quality in interstitial spaces, and the presence of egg and fry predators. Data on factors which attracted native spawners to spawning reefs are lacking, due to the absence of historic data on egg deposition. No direct evidence of egg deposition has been collected from sites deeper than 18 m. Interstitial space and, therefore, substrate size and shape, appear to be critical for both site selection by adults and protection of eggs and fry. Water quality is clearly important for egg incubation, but the critical parameters which define water quality have not yet been well determined in the field. Exposure to wave energy, dictated in part by reef location, may maintain high water quality but may also damage or dislodge eggs. The importance of olfactory cues, water temperature, and proximity to nursery habitat to spawning trout is unclear. Limited data suggest that egg and fry predators, particularly exotic species, may critically affect fry production and survival. Although availability of physical spawning habitat is probably not limiting lake trout reproduction, changes in water quality and species composition may negatively affect early life stages. This review of habitat factors that affect early life stages of lake trout suggests several priorities for research and management.

Marsden, J. Ellen; Casselman, John M.; Edsall, Thomas A.; Elliott, Robert F.; Fitzsimons, John D.; Horns, William H.; Manny, Bruce A.; McAughey, Scott C.; Sly, Peter G.; Swanson, Bruce L.

1995-01-01

134

Do toxic substances pose a threat to rehabilitation of lake trout in the Great Lakes? A review of the literature  

USGS Publications Warehouse

Toxic substances have been suspected of being one of the causes of Great Lakes lake trout reproductive failure. Because toxic substances are present in the Great Lakes basin, managers should be aware of the role of contaminants in preventing lake trout rehabilitation. This paper summarizes studies which have sought to establish a relation between toxic substances and lake trout mortality or morbidity, and offers recommendations for future research and management. The review suggests that exposure to toxic substances has the possibility of affecting the species' rehabilitation. A variety of toxic substances, specifically organochlorine compounds, concentrated in lake trout eggs, fry, and the environment, have affected the hatching success of lake trout in the laboratory, but the strength of the relation between toxic substances and lake trout mortality and morbidity in the field remains unclear. In order to clarify this relation, more information is needed on lake trout physiology, biochemistry, behavior, and genetics. An interdisciplinary workshop should be convened to evaluate existing evidence by epidemiological methods, to set priorities for further research, and to develop management strategies.

Zint, Michaela T.; Taylor, William W.; Carl, Leon; Edsall, Carol C.; Heinrich, John; Sippel, Al; Lavis, Dennis; Schaner, Ted

1995-01-01

135

New insight into the spawning behavior of lake trout, Salvelinus namaycush, from a recovering population in the Laurentian Great Lakes  

USGS Publications Warehouse

Spawning behavior of lake trout, Salvelinus namaycush, is poorly understood, relative to stream-dwelling salmonines. Underwater video records of spawning in a recovering population from the Drummond Island Refuge (Lake Huron) represent the first reported direct observations of lake trout spawning in the Laurentian Great Lakes. These observations provide new insight into lake trout spawning behavior and expand the current conceptual model. Lake trout spawning consisted of at least four distinct behaviors: hovering, traveling, sinking, and gamete release. Hovering is a new courtship behavior that has not been previously described. The apparent concentration of hovering near the margin of the spawning grounds suggests that courtship and mate selection might be isolated from the spawning act (i.e., traveling, sinking, and gamete release). Moreover, we interpret jockeying for position displayed by males during traveling as a unique form of male-male competition that likely evolved in concert with the switch from redd-building to itinerant spawning in lake trout. Unlike previous models, which suggested that intra-sexual competition and mate selection do not occur in lake trout, our model includes both and is therefore consistent with evolutionary theory, given that the sex ratio on spawning grounds is skewed heavily towards males. The model presented in this paper is intended as a working hypothesis, and further revision may become necessary as we gain a more complete understanding of lake trout spawning behavior.

Binder, Thomas R.; Thompson, Henry T.; Muir, Andrew M.; Riley, Stephen C.; Marsden, J. Ellen; Bronte, Charles R.; Krueger, Charles C.

2014-01-01

136

Historical evidence for discrete stocks of lake trout (Salvelinus namaycush) in Lake Michigan  

USGS Publications Warehouse

Although few biological data exist on the now extinct native lake trout, Salvelinus namaycush, of Lake Michigan, historical records and interviews with former commercial fishermen strongly suggest that this once widespread resource was composed of a number of discrete spawning populations or stocks. A natural division of the resource into distinct stocks is consistent with the size of Lake Michigan and its varied physiography. The native trout may have undergone subtle genetic changes over the millennia, although we cannot determine whether the physical and behavioral differences represented different genotypes or only temporary effects of the local environment. Because of physiographic similarities among the upper Great Lakes and probable interchanges of lake trout during the last glacial period, we recommend that progeny of extant wild stocks, particularly from Lake Superior, are genetically most suitable for recolonizing Lake Michigan. Moreover, the hatchery-held parents of such fish should be infused periodically with genes of the wild or feral donor populations. Despite the sound historical basis for these recommendations, we also recognize that sufficiently high stocking rates coupled with a reduction of heavy exploitation may be even more important than heritability in obtaining self-sustaining populations.

Brown, Edward H., Jr.; Eck, G.W.; Foster, N.R.; Horrall, R.M.; Coberly, C.E.

1981-01-01

137

Estimates of Predator Consumption of Yellowstone Cutthroat Trout (Oncorhynchus clarki bouvieri) in Yellowstone Lake  

Microsoft Academic Search

We estimated consumption of Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) by resident terrestrial predators and human anglers to place into context the potential predatory impact of exotic lake trout (Salvelinus namaycush) in Yellowstone Lake, Yellowstone National Park, Wyoming, USA. Estimates of consumption rates of piscivorous birds and mammals from the literature were combined with recent estimates of abundance of these

Paul Stapp; Gregory D. Hayward

2002-01-01

138

Rates of Intraperitoneal Temperature Change in Lake Trout Implanted with Archival Tags  

Microsoft Academic Search

The rates of change in the intraperitoneal temperature of lake trout Salvelinus namaycush weighing between 817 g and 2,230 g were examined in the laboratory. Nine lake trout implanted with archival tags were moved between three tanks containing different water temperatures. The intraperitoneal temperatures recorded by the archival tags lagged behind the external temperatures when these thermal changes were encountered,

Mary T. Negus; Roger A. Bergstedt

2012-01-01

139

Influence of food web structure on the growth and bioenergetics of lake trout (Salvelinus namaycush)  

E-print Network

Influence of food web structure on the growth and bioenergetics of lake trout (Salvelinus namaycush energy budgets of lake trout (Salvelinus namaycush) populations in contrasting food webs. Nonpiscivorous des populations de touladis (Salvelinus namaycush) dans divers réseaux trophiques. Les populations de

Rasmussen, Joseph

140

Effects of crystal structure on the uptake of metals by lake trout (Salvelinus namaycush)  

E-print Network

Effects of crystal structure on the uptake of metals by lake trout (Salvelinus namaycush) otoliths structure of sagittal otoliths from lake trout (Salvelinus namaycush) were studied using laser ablation- tales de truites (Salvelinus namaycush) par ablation laser couplée avec un spectromètre de masse

141

Response by trout populations in alpine lakes to an experimental halt to stocking  

Microsoft Academic Search

Trout are often stocked into alpine lakes based on the generally untested assumption that resident popula- tions would go extinct without stocking. The objectives of our study were to estimate the proportion of currently or formerly stocked alpine lakes in the Sierra Nevada, California, containing naturally reproducing trout populations (Oncorhynchus mykiss, Oncorhynchus mykiss aguabonita, Oncorhynchus clarki henshawi), identify characteristics of

Trip W. Armstrong; Roland A. Knapp

2004-01-01

142

Visual observations of historical lake trout spawning grounds in western Lake Huron  

USGS Publications Warehouse

Direct underwater video observations were made of the bottom substrates at 12 spawning grounds formerly used by lake trout Salvelinus namaycush in western Lake Huron to evaluate their present suitability for successful reproduction by lake trout. Nine locations examined north of Saginaw Bay in the northwestern end of the lake are thought to provide the best spawning habitat. The substrate at these sites consisted of angular rough cobble and rubble with relatively deep interstitial spaces (a?Y 0.5 m), small amounts of fine sediments, and little or no periphytic growth. Conditions at the three other sampling locations south of Saginaw Bay seemed much less suitable for successful reproduction based on the reduced area of high-quality substrate, shallow interstitial spaces, high infiltration of fine sediments, and greater periphytic growth.

Nester, Robert T.; Poe, Thomas P.

1987-01-01

143

Environmental contaminants and the reproductive success of lake trout in the Great Lakes: an epidemiological approach  

USGS Publications Warehouse

Epidemiological criteria were used to examine the influence of environmental contamination on reproductive success of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes. Most of the information was obtained from lake trout eggs collected in southeastern Lake Michigan and reared in the laboratory. Two separate end points that measure reproductive success - egg hatchability and fry survival - were used in the evaluation. Strong evidence for maternally derived polychlorinated biphenyls causing reduced egg hatchability were observed for the time order, strength of association, and coherence criteria. Equally strong evidence for organic environmental contaminants, also of maternal origin, causing a swim-up fry mortality syndrome were presented for the strength of association, specificity, replication, and coherence criteria. The epidemiological approach for demonstrating cause-and-effect relations was useful because of the difficulty in demonstrating definite proof of causality between specific environmental contaminants and reproductive dysfunction in feral fish.

Mac, Michael J.; Edsall, Carol C.

1991-01-01

144

Effect of stocking season and technique on survival of lake trout in Lake Ontario  

USGS Publications Warehouse

To identify the stocking season and technique that resulted in maximum contribution of hatchery-reared lake trout (Salvelinus namaycush) to the population in Lake Ontario, paired lots of yearlings were stocked near shore in March, near shore in May, and offshore by helicopter in May. All mortality associated with stocking season and technique apparently had occurred by age 2. Therefore, survival comparisons were based on combined recoveries of age-2 and older fish. We found statistically significant differences in survival ratios for 19 of 30 comparisons among individual paired lots, but results were not consistent. Variables other than stocking date and technique apparently had a major influence on survival of lake trout following stocking in Lake Ontario. Predation by large salmonids may have been the the dominant mechanism affecting survival.

Elrod, Joseph H.; Schneider, Clifford P.

1992-01-01

145

Environmental contaminants and the reproductive success of lake trout in the Great Lakes: An epidemiological approach  

SciTech Connect

Epidemiological criteria were used to examine the influence of environmental contamination on reproductive success of lake trout (Salvelinus namaycush) in the Laurentian Great Lakes. Most of the information was obtained from lake trout eggs collected in southeastern Lake Michigan and reared in the laboratory. Two separate end points that measure reproductive success--egg hatchability and fry survival--were used in the evaluation. Strong evidence for maternally derived polychlorinated biphenyls causing reduced egg hatchability were observed for the time order, strength of association, and coherence criteria. Equally strong evidence for organic environmental contaminants, also of maternal origin, causing a swim-up fry mortality syndrome were presented for the strength of association, specificity, replication, and coherence criteria. The epidemiological approach for demonstrating cause-and-effect relations was useful because of the difficulty in demonstrating definite proof of causality between specific environmental contaminants and reproductive dysfunction in feral fish.

Mac, M.J.; Edsall, C.C. (U.S. Fish and Wildlife Service, National Fisheries Research Center-Great Lakes, Ann Arbor, MI (USA))

1991-08-01

146

Investigations into the effects of PCB congeners on reproduction in lake trout from the Great Lakes  

USGS Publications Warehouse

Eggs of feral lake trout collected in Lake Michigan were reared under laboratory conditions and monitored for egg hatchability, physical abnormalities, and survival of fry. Subsamples of eggs were also analyzed for PCB congeners. A negative correlation was found between egg hatchability and total PCBs but expressing PCB dose as dioxin equivalents did not produce as strong a correlation. No other measure of reproductive success correlated significantly with PCB concentration in the egg.

Mac, Michael J.; Schwartz, T.R.

1992-01-01

147

Population Dynamics of Lake Ontario Lake Trout during 1985–2007  

Microsoft Academic Search

Lake trout Salvelinus namaycush were extirpated from Lake Ontario circa 1950 owing to commercial and recreational fishing, predation by sea lampreys Petromyzon marinus, and habitat degradation. Since the 1970s, substantial efforts have been devoted to reestablishing a self-sustaining population through stocking, sea lamprey control, and harvest reduction. Although a stocking-supported population has been established, only limited natural reproduction has been

Travis O. Brenden; James R. Bence; Brian F. Lantry; Jana R. Lantry; Ted Schaner

2011-01-01

148

Relative contributions of climate variation, lake trout predation, and other factors to the decline of Yellowstone Lake cutthroat trout during the three recent decades .  

E-print Network

??The relative contributions of climate variation, lake trout Salvelinus namaycush predation, and other factors to the recent, three-decade decline of the lacustrine-adfluvial (i.e., a life-history… (more)

Kaeding, Lynn Robert.

2010-01-01

149

Seasonal habitat selection by lake trout (Salvelinus namaycush) in a small Canadian shield lake: Constraints imposed by winter conditions  

USGS Publications Warehouse

The need for cold, well-oxygenated waters significantly reduces the habitat available for lake trout (Salvelinus namaycush) during stratification of small temperate lakes. We examined the spatial and pelagic distribution of lake trout over two consecutive summers and winters and tested whether winter increased habitat availability and access to littoral regions in a boreal shield lake in which pelagic prey fish are absent. In winter, lake trout had a narrowly defined pelagic distribution that was skewed to the upper 3 m of the water column and spatially situated in the central region of the lake. Individual core areas of use (50% Kernel utilization distributions) in winter were much reduced (75%) and spatially non-overlapping compared to summer areas, but activity levels were similar between seasons. Winter habitat selection is in contrast to observations from the stratified season, when lake trout were consistently located in much deeper waters (>6 m) and widely distributed throughout the lake. Winter distribution of lake trout appeared to be strongly influenced by ambient light levels; snow depth and day length accounted for up to 69% of the variation in daily median fish depth. More restricted habitat use during winter than summer was in contrast to our original prediction and illustrates that a different suite of factors influence lake trout distribution between these seasons. ?? Springer Science+Business Media B.V. 2009.

Blanchfield, P.J.; Tate, L.S.; Plumb, J.M.; Acolas, M.-L.; Beaty, K.G.

2009-01-01

150

Spatiotemporal distribution and population characteristicsof a nonnative lake trout population, with implications for suppression  

USGS Publications Warehouse

We evaluated the distribution and population characteristics of nonnative lake trout Salvelinus namaycush in Lake McDonald,Glacier National Park,Montana, to provide biological data in support of a potential suppression program. Using ultrasonic telemetry, we identified spatial and temporal distribution patterns by tracking 36 adult lake trout (1,137 relocations). Lake trout rarely occupied depths greater than 30 m and were commonly located in the upper hypolimnion directly below the metalimnion during thermal stratification. After breakdown of themetalimnion in the fall, lake trout primarily aggregated at two spawning sites. Lake trout population characteristics were similar to those of populations within the species' native range. However, lake trout in Lake McDonald exhibited lower total annual mortality (13.2%), latermaturity (age 12 formales, age 15 for females), lower body condition, and slower growth than are typically observed in the southern extent of their range. These results will be useful in determining where to target suppression activities (e.g., gillnetting, trap-netting, or electrofishing) and in evaluating responses to suppression efforts. Similar evaluations of lake trout distribution patterns and population characteristics are recommended to increase the likelihood that suppression programs will succeed. ?? American Fisheries Society 2011.

Dux, A.M.; Guy, C.S.; Fredenberg, W.A.

2011-01-01

151

Biotic and abiotic factors that affect contaminant concentrations in Lake Trout from Rocky Mountain lakes  

SciTech Connect

Lake trout were collected from 14 lakes in the Canadian Rocky Mountains in 1991 and 1992. Fish fillets were analyzed for organochlorines using GC-ECD and quantified using internal and external standards. Concentrations of these contaminants ranged considerably between lakes. Mean {Sigma}DDT, {Sigma}PCB and {Sigma}CHB (toxaphene) concentrations ranged from 4 to 92, < 4 to 119, and < 4 to 73 ng g{sup {minus}1} wet weight respectively. Regression analyses indicated that the concentrations of organochlorines were significantly related to drainage area of the lake and log mean weight of the fish. Contaminant levels were not related to mean age of the fish or percent lipid in the muscle tissue. An index was used to determine if length of the food web explained the between-lake variability in organochlorine concentrations. Contaminant concentrations were not significantly related to the presence/absence of mysis or forage fishes, or lake class. The authors are currently the using stable isotope ratios of carbon and nitrogen to determine trophic status of the lake trout from these mountain lakes, and to interpret the variability in contaminant concentrations between and within lakes.

Donal, D.B. [Inland Waters Directorate, Regina, Saskatchewan (Canada); Kidd, K.A. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Zoology

1994-12-31

152

Changes in the lake trout population of southern Lake Superior in relation to the fishery, the sea lamprey, and stocking, 1950-70  

USGS Publications Warehouse

Reduction of sea lamprey abundance resulted in an immediate increase in survival and abundance of lake trout, especially of the larger sizes. As abundance of lake trout progressively increased in 1962-70, survival of the smaller legal-size lake trout increased, probably due to reduction of the predator-prey ratio and an increase in availability of larger lake trout preferred by sea lampreys. Abundance of spawning-size lake trout was limited by high natural mortality in 1965-70. Circumstantial evidence suggested that sea lamprey predation contributed a major part of the high natural mortality.

Pycha, Richard L.; King, George R.

1975-01-01

153

Seasonal habitat use of brook trout and juvenile Atlantic Salmon in a Tributary of Lake Ontario  

USGS Publications Warehouse

The seasonal habitat use of Salvelinus fontinalis (Brook Trout) and subyearling Salmo salar (Atlantic Salmon) was examined in Hart Brook, a tributary of Lake Ontario. Fish habitat use and available habitat were examined during summer and autumn. Interspecific differences in habitat use occurred as well as intraspecific seasonal differences. Overyearling Brook Trout were more selective in their habitat preferences than subyearling Brook Trout or juvenile Atlantic Salmon. Depth and the amount of cover were significantly different among the three fish groups. Salmon occupied faster and shallower water than either age group of trout. Atlantic Salmon were also associated with larger-sized substrate materials than either trout age group, and salmon occurred in habitats with less cover than trout. Overyearling Brook Trout occupied deeper water with more cover than subyearling trout. All three salmonid groups occupied areas with more cover in autumn compared to summer. In autumn, subyearling Brook Trout used deeper areas than they had in the summer. In Hart Brook, the habitat of subyearling Atlantic Salmon can be generally characterized as riffles, the habitat of overyearling Brook Trout was deep pools with extensive cover (35%), and that of subyearling trout was any area with moderate flow and at least 20% cover. As efforts proceed to reintroduce Atlantic Salmon in Lake Ontario, further research is needed to ensure the conservation of Brook Trout populations.

Johnson, J.H.

2008-01-01

154

Successional change in the Lake Superior fish community: population trends in ciscoes, rainbow smelt, and lake trout, 1958-2008  

USGS Publications Warehouse

The Lake Superior fish community underwent massive changes in the second half of the 20th century. Those changes are largely reflected in changes in abundance of the adults of principal prey species, the ciscoes (Coregonus spp.), the invasive rainbow smelt (Osmerus mordax), and the principal predator, lake trout (Salvelinus namaycush). To better understand changes in species abundances, a comprehensive series of gillnet and bottom trawl data collected from 1958 to 2008 were examined. In the late 1950s/early 1960s, smelt abundance was at its maximum, wild lake trout was at its minimum, and an abundance of hatchery lake trout was increasing rapidly. The bloater (Coregonus hoyi) was the prevalent cisco in the lake; abundance was more than 300% greater than the next most abundant cisco, shortjaw cisco (C. zenithicus), followed by kiyi (C. kiyi) and lake cisco (C. artedi). By the mid-1960s, abundance of hatchery lake trout was nearing maximum, smelt abundance was beginning to decline, and abundances of all ciscoes declined, but especially that of shortjaw cisco and kiyi. By the late 1970s, recovery of wild lake trout stocks was well underway and abundances of hatchery lake trout and smelt were declining and the ciscoes were reaching their nadir. During 1980–1990, the fish community underwent a dramatic shift in organization and structure. The rapid increase in abundance of wild lake trout, concurrent with a rapid decline in hatchery lake trout, signaled the impending recovery. Rainbow smelt abundance dropped precipitously and within four years, lake cisco and bloater populations rebounded on the heels of a series of strong recruitment events. Kiyi populations showed signs of recovery by 1989, and shortjaw by 2000, though well below historic maximum abundances. High abundance of adult smelt prior to 1980 appears to be the only factor linked to recruitment failure in the ciscoes. Life history traits of the cisco species were examined to better understand their different responses to conditions of low and high predator levels, i.e., late 1950s–early 1960s vs. post 1980. Bloaters are most likely to become the predominant cisco in the absence of strong predation and the least abundant under prolonged predation; smelt share this pattern. Conversely, the lake cisco and shortjaw cisco fare better when predator abundance is high. The recovery of lake trout in Lake Superior reestablished a strong top-down influence on the fish community and its present structure and organization appears to be approaching an equilibrium that reflects a more natural state. If lake trout recovery is sustained, shortjaw cisco abundance is expected to increase and join lake cisco and kiyi as dominant cisco species, and bloater and smelt will oscillate at lower abundances.

Gorman, Owen T.

2012-01-01

155

Dispersal of three strains of hatchery-reared lake trout in Lake Ontario  

USGS Publications Warehouse

Rates of dispersal and resultant geographical distributions were determined for three strains of hatchery-reared lake trout (Salvelinus namaycush) stocked at six sites in U.S. waters of Lake Ontario. The strains were Lake Superior (SUP); Clearwater Lake, Manitoba (CWL); and Seneca Lake, New York (SEN). The fish were recovered with bottom trawls fished during July and August 1980-1985 at 16 locations, extending from Toronto southward and eastward along the south shore to Dablon Point at the east end of the lake. For SUP fish stocked as spring yearlings, the mean distances from stocking site to capture location 2, 14, and 26 months after stocking were 12, 57, and 62 km, respectively, for fish released at four south-shore sites and 5, 34, and 38 km for fish released at two eastern outlet basin sites. Rates of dispersal for the CWL fish were similar to those of the SUP strain for fish stocked at the four south-shore sites, but were considerably less for fish stocked in the eastern outlet basin. The SEN strain was stocked only in the eastern outlet basin; their dispersal was similar to that of the SUP strain. For fish of the same age, SUP fish stocked as fall fingerlings became more widely dispersed than those stocked as spring yearlings. Movement of lake trout between the eastern outlet basin and the lake proper was limited. Large numbers of fish were captured on the Niagara Bar, but few moved past there into the west end of the lake. Movements of lake trout from stocking sites were generally with the prevailing currents. Differences between geographical distributions of the SUP and CWL strains were probably due to the influence of different current regimes at the depths they occupied. These results will be useful in selecting the best genetic strains of lake trout for rehabilitating the species in Lake Ontario, as well as for identifying the best stocking sizes and maximizing post-stocking survival of hatchery-reared fish.

Elrod, Joseph H.

1987-01-01

156

Xenobiotics in gametes of Lake Michigan lake trout (Salvelinus namaycush) induce hepatic monooxygenase activity in their offspring  

SciTech Connect

Eggs spawned from Lake Michigan lake trout contain a number of xenobiotic compounds, including polychlorinated biphenyls (PCBs). To assess whether this contamination is sufficient to induce hepatic cytochrome P-450-dependent monooxygenase (MO) activity during early development, the hepatic MO systems of laboratory-cultured offspring of Lake Michigan, Green Bay, and Marquette Hatchery lake trout were compared. Additionally, the induction of hepatic cytochrome P-450 systems in developing lake trout by the commercial PCB mixture, Aroclor 1254 (A1254), was characterized. During late embryonic development and at the swim-up stage, the hepatic MO systems of the feral lake trout offspring appeared induced, based on levels of aryl hydrocarbon hydroxylase (AHH) activity that were 3.5- to 8.6-fold higher than the hatchery control levels. Furthermore, at the swim-up stage the feral trout offspring resembled A1254-treated hatchery fry with regard to the degree of inhibition of hepatic AHH activity by alpha-naphthoflavone, and the presence of an inducible Mr . 58,000 polypeptide in hepatic microsomes. The levels of aminopyrine N-demethylase activity, which was relatively unresponsive to inducers, were moderately lower in the Lake Michigan and Green Bay swim-up fry compared to the hatchery control levels. After 7 months of posthatching laboratory culture, when residues of xenobiotics present at fertilization were greatly diluted by growth, the hepatic MO systems of the Lake Michigan and hatchery trout offspring appeared essentially indistinguishable with regard to a number of parameters.

Binder, R.L.; Lech, J.J.

1984-12-01

157

Net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake trout (Salvelinus namaycush) from its prey  

USGS Publications Warehouse

Lake trout (Salvelinus namaycush) were fed bloater (Coregonus hoyi) in eight laboratory tanks over a 135-d experiment. At the start of the experiment, four to nine fish in each tank were sacrificed, and the concentrations of 75 polychlorinated biphenyl (PCB) congeners within these fish were determined. Polychlorinated biphenyl congener concentrations were also determined in the 10 lake trout remaining in each of the eight tanks at the end of the experiment as well as in the bloater fed to the lake trout. Each lake trout was weighed at the start and the end of the experiment, and the amount of food eaten by the lake trout was recorded. Using these measurements, net trophic transfer efficiency (?) from the bloater to the lake trout in each of the eight tanks was calculated for each of the 75 congeners. Results showed that ? did not vary significantly with the degree of chlorination of the PCB congeners, and ? averaged 0.66 across all congeners. However,? did show a slight, but significant, decrease as logKOW increased from 6.0 to 8.2. Activity level of the lake trout did not have a significant effect on ?.

Madenjian, Charles P.; David, Solomon R.; Rediske, Richard R.; O’Keefe, James P.

2012-01-01

158

Net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake trout (Salvelinus namaycush) from its prey.  

PubMed

Lake trout (Salvelinus namaycush) were fed bloater (Coregonus hoyi) in eight laboratory tanks over a 135-d experiment. At the start of the experiment, four to nine fish in each tank were sacrificed, and the concentrations of 75 polychlorinated biphenyl (PCB) congeners within these fish were determined. Polychlorinated biphenyl congener concentrations were also determined in the 10 lake trout remaining in each of the eight tanks at the end of the experiment as well as in the bloater fed to the lake trout. Each lake trout was weighed at the start and the end of the experiment, and the amount of food eaten by the lake trout was recorded. Using these measurements, net trophic transfer efficiency (?) from the bloater to the lake trout in each of the eight tanks was calculated for each of the 75 congeners. Results showed that ? did not vary significantly with the degree of chlorination of the PCB congeners, and ? averaged 0.66 across all congeners. However, ? did show a slight, but significant, decrease as log K(OW) increased from 6.0 to 8.2. Activity level of the lake trout did not have a significant effect on ?. PMID:22927164

Madenjian, Charles P; David, Solomon R; Rediske, Richard R; O'Keefe, James P

2012-12-01

159

Thiamine deficiency effects on the vision and foraging ability of lake trout fry.  

PubMed

The exact causes of the historical recruitment failures of Great Lakes lake trout Salvelinus namaycush are unknown. Thiamine deficiency has been associated with neurological abnormalities in lake trout that lead to early mortality syndrome (EMS) in salmonine swim-up fry, and EMS-related mortality at the swim-up stage is a factor that contributes to the reproductive failure of lake trout populations in the Great Lakes. The potential for adverse effects of thiamine deficiency beyond the swim-up stage is unknown. We investigated the effects of low egg thiamine on behavioral functions in young, post-swim-up lake trout fry. The behavioral endpoints included visual acuity and prey capture rates in the same groups of lake trout fry from each family. Low-thiamine eggs were produced by feeding lake trout broodstock diets entailing thiaminase activity. The thiamine content of the spawned eggs ranged from 0.3 to 26.1 nmol/g. Both visual acuity and prey capture rates were affected by the thiamine content of the eggs. The visual acuity of lake trout was severely affected by low egg thiamine, mainly at thiamine concentrations below the threshold of 0.8 nmol/g but also at higher concentrations in field-collected eggs. Feeding was also reduced with low egg thiamine content. The reduction of prey capture rates was dramatic below 0.8 nmol/g and less dramatic, but still significant, in a portion of the families with egg thiamine concentrations of less than 5.0 nmol/g from both laboratory and field samples. Approximately one-third of the latter families had reduced feeding rates. Deficits in visual acuity may be part of the mechanism leading to decreased feeding rates in these fry. The effects of low egg thiamine on both of the behavioral endpoints studied increase the risk of low recruitment rates in Great Lakes lake trout populations. PMID:20218505

Carvalho, Paulo S M; Tillitt, Donald E; Zajicek, James L; Claunch, Rachel A; Honeyfield, Dale C; Fitzsimons, John D; Brown, Scott B

2009-12-01

160

Recovery of an offshore lake trout (Salvelinus namaycush) population in eastern Lake Superior  

USGS Publications Warehouse

The lake trout (Salvelinus namaucush) population at Stannard Rock, Michigan, an isolated offshore reef in eastern Lake Superior, was monitored each spring from 1959-79 using a permit assessment gill net fishery. This population, like nearly all of those in inshore waters, declined to low levels during the years of intense predation by the sea lamprey (Petromyzon marinus) in the late 1950's and early 1960's. After sea lamprey control began in 1961, the abundance of native lake trout at Stannard Rock began to increase slowly in the 1960's and was limited to recruitment into the fishable stock of native fish that were juveniles during the years of high sea lamprey activity. By the early 1970's lake trout abundance increased sharply and remained at a high level. This rapid recovery resulted from several strong year classes produced by the small spawning aggregations that reached maturity in the 1960's. Reproduction occurred in all years during and after the peak of sea lamprey activity in 1959. The strengths of year classes produced in 1963-1968 were related to the relative abundance of spawners the previous fall.

Curtis, Gary L.

1990-01-01

161

Comparison of catch and lake trout bycatch in commercial trap nets and gill nets targeting lake whitefish in northern Lake Huron  

USGS Publications Warehouse

We compared seasonal lake whitefish catch rates, lake trout bycatch, and gearinduced lake trout mortality between commercial trap nets and gill nets in north-central Lake Huron. Onboard monitors recorded catches from 260 gill net and 96 trap net lifts from October 1998 through December 1999. Catch rates for lake whitefish were highest in fall for both gear types, reflecting proximity of spawning sites to the study area. Lake whitefish catch rates were also relatively high in spring but low in both gear types in summer. Lake trout were the principal bycatch species in both gears. The lake trout bycatch was lowest in both gear types in fall, highest in gill nets in spring, and highest in trap nets in summer. The ratio of lake trout to legal whitefish (the target species) was highest in summer and lowest in fall in both gear types. The high lake trout ratio in summer was due principally to low catch rates of lake whitefish. All but 3 of 186 live lake trout removed from trap net pots survived for at least two days of observation in laboratory tanks. Therefore, we estimated that post-release survival of trap netted lake trout that had not been entangled in the mesh was 98.4%. In addition, we accounted for stress-induced mortality for lake trout that were live at capture but entangled in the mesh of either gear type. Resulting estimates of lake trout survival were higher in trap nets (87.8%) than in gill nets (39.6%). The number of lake trout killed per lift was highest during summer in trap nets and during spring in gill nets. In trap nets, 85% of dead lake trout were observed to be entangled in the mesh of the pot or tunnels. Survival rates of lake trout in gill nets were higher in our study than reported by others, probably because our nets were hand lifted in a small boat. Our trap net-induced mortality estimates on lake trout were higher than those reported by others because we adjusted our estimates to account for post-release mortality caused by handling and injury. Studies such as ours should prove useful to managers developing harvest allocation options that are consistent with the need to protect nontarget populations. For example, applying our seasonal lake trout-whitefish catch ratios to a hypothetical small-boat gill net fishery, the lake trout bycatch from harvest of 100,000 kg of whitefish would equal the estimated lake trout production available for harvest in the study area for year 2002. The two trap net fisheries may have incidentally killed half this number of lake trout annually from 1995-99. Bycatch estimates are also important inputs to catch-at-age decision models used in developing rehabilitation and harvest strategies for target and bycatch species.

Johnson, James E.; Ebener, Mark P.; Gebhardt, Kenneth; Bergstedt, Roger

2004-01-01

162

Interactions between introduced trout and larval salamanders (Ambystoma macrodactylum) in high-elevation lakes  

USGS Publications Warehouse

The larval stage of the long-toed salamander (Ambystoma macrodactylum) is the top vertebrate predator in high-elevation fishless lakes in the North Cascades National Park Service Complex, Washington (U.S.A.). Although most of these high-elevation lakes were naturally fishless, trout have been stocked in many of them. We sought to determine the effects of physicochemical factors and introduced trout on abundance and behavior of A. macrodactylum larvae. Larval salamander densities were estimated by snorkeling. Snorkelers carefully searched through substrate materials within 2 m of the shoreline and recorded the number of larvae observed and if larvae were hidden in benthic substrates. Physicochemical factors were measured in each lake on the same day that snorkel surveys were conducted. In fishless lakes, larval salamander densities were positively related to total Kjeldahl-N concentration and negatively related to lake elevation. Crustacean zooplankton, especially cladocerans, were important food resources for larval A. macrodactylum. Crustacean zooplankton and cladoceran densities were positively related to total Kjeldahl-N, suggesting that increased food resources contributed to increased densities of larval A. macrodactylum. Differences in larval salamander densities between fish and fishless lakes were related to total Kjeldahl-N concentrations and the reproductive status of trout. Mean larval salamander densities for fishless lakes with total Kjeldahl-N < 0.045 mg/L were not significantly different from mean larval densities in lakes with reproducing trout or in lakes with nonreproducing trout. In fishless lakes with total Kjeldahl-N a?Y 0.045 mg/L, however, mean larval densities were significantly higher than in lakes with reproducing trout where fish reached high densities. In fishless lakes with total Kjeldahl-N a?Y 0.095 mg/L, mean larval densities were significantly higher than in lakes with nonreproducing trout where trout fry were stocked at low densities. Reduced larval salamander densities in lakes with trout likely resulted from trout predation. There were no significant differences in the percentage of larvae hidden in benthic substrates between fishless lakes and lakes with fish. Our results imply that assessment of the effects of fish on amphibians requires an understanding of natural abiotic and biotic factors and processes influencing amphibian distribution and abundance.

Tyler, T.; Liss, W.J.; Ganio, L.; Larson, Gary L.; Hoffman, Robert L.; Deimling, E.; Lomnicky, G.A.

1998-01-01

163

Hydroxylated PCBs and other chlorinated phenolic compounds in lake trout (Salvelinus namaycush) blood plasma from the Great Lakes region.  

PubMed

Recently, there has been an increase in studies focusing on an emerging class of organic contaminants, hydroxylated PCBs (OH-PCBs) and chlorinated phenolic compounds (CPCs) in the environment, particularly in northern regions of Europe and Canada. Since information for fish from the Great Lakes are scarce, we determined the blood plasma concentrations of OH-PCB congeners, pentachlorophenol (PCP), 2,3,4,5-tetrachlorophenol (TCP), and 4-hydroxyheptachlorostyrene (4-OH-HpCS) for lake trout (Savelinus namaycush) collected from two of the Great Lakes, Lake Ontario and Lake Superior, and two regional lakes, Lake Champlain and Lake Opeongo. PCP was the dominant CPC in lake trout (105-658 pg/g of plasma). Detectable concentrations of 2,3,4,5-TCP and 4-OH-HpCS were found in all lake trout (2.6-101 and 0.4-27 pg/g, respectively). Highest concentrations were found in trout from Lake Ontario and Lake Superior. Sixteen OH-PCBs were quantified, with 4-OH-CB187 having the highest concentration in all samples (10-173 pg/g of plasma). Unexpectedly, highly chlorinated OH-PCBs such as 4'-OH-CB199 (mean 21.4 and 74.4 pg/g), 4,4'-diOH-CB202 (18.3 and 27.7 pg/g), and 4'-OH-CB208 (24.5 and 34.7 pg/g) were found in lake trout from Lake Ontario and Lake Superior, respectively. Future studies to delineate the sources and impacts of CPCs in the Great Lakes catchment are needed. PMID:12775040

Campbell, Linda M; Muir, Derek C G; Whittle, D Mike; Backus, Sean; Norstrom, Ross J; Fisk, Aaron T

2003-05-01

164

Simulation of the effects of time and size at stocking on PCB accumulation in Lake Trout  

SciTech Connect

Manipulations of size at stocking and timing of stocking have already been used to improve survival of stocked salmonines in the Great Lakes. It should be possible to stock salmonines into the Great Lakes in a way that reduces the rate of polychlorinated biphenyl (PCB) accumulation in these fishes. An individual-based model (IBM) was used to investigate the effects of size at stocking and timing of stocking on PCB accumulation by lake trout Salvelinus namaycush in Lake Michigan. The individual-based feature of the model allowed lake trout individuals to encounter prey fish individuals and then consume sufficiently small prey fish. The IBM accurately accounted for the variation in PCB concentrations observed within the Lake Michigan lake trout population. Results of the IBM simulations revealed that increasing the average size at stocking from 110 to 160 mm total length led to an increase in the average PCB concentration in the stocked cohort at age 5, after the fish had spent 4 years in the lake, from 2.33 to 2.65 mg/kg; the percentage of lake trout in the cohort at the end of the simulated time period with PCB concentration of 2 mg/kg or more increased from 62% to 79%. Thus, PCB contamination was reduced when the simulated size at stocking was smallest. An overall stocking strategy for lake trout into Lake Michigan should weight this advantage regarding PCB contamination against the poor survival of lake trout that may occur if the trout are stocked at too small a size. 28 refs., 5 figs., 1 tab.

Madenjian, C.P. (National Fisheries Research Center-Great Lakes, Sandusky Biological Station, Sandusky, OH (United States))

1993-05-01

165

Comparative susceptibility of Atlantic salmon, lake trout and rainbow trout to Myxobolus cerebralis in controlled laboratory exposures  

USGS Publications Warehouse

The susceptibility of lake trout Salvelinus namaycush, rainbow trout Oncorhynchus mykiss and Atlantic salmon Salmo salar to Myxobolus cerebralis, the causative agent of whirling disease, was compared in controlled laboratory exposures. A total of 450 (225 for each dose) fry for each species were exposed to a low (200 spores per fish) or high (2000 spores per fish) dose of the infective triactinomyxon. At 22 wk post-exposure, 60 fish from each group, as well as controls for each species, were examined for clinical signs (whirling behavior, blacktail, deformed heads and skeletal deformities), microscopic lesions, and presence of spores. Rainbow trout were highly susceptible to infection, with 100% being positive for spores and with microscopic pathological changes in both exposure groups. Rainbow trout were the only species to show whirling behavior and blacktail. Atlantic salmon were less susceptible, with only 44 and 61% being positive for spores, respectively, in the low and high dose groups, while 68 and 75%, respectively, had microscopic pathology associated with cartilage damage. Rainbow trout heads contained mean spore concentrations of 2.2 (low dose) or 4.0 (high dose) ?? 106 spores g tissue-1. The means for positive Atlantic salmon (not including zero values) were 1.7 (low) and 7.4 (high) ?? 104 spores g tissue-1. Lake trout showed no clinical signs of infection, were negative for spores in both groups and showed no histopathological signs of M. cerebralis infection.

Blazer, V.S.; Densmore, C.L.; Schill, W.B.; Cartwright, D.D.; Page, S.J.

2004-01-01

166

Comparative susceptibility of Atlantic salmon, lake trout and rainbow trout to Myxobolus cerebralis in controlled laboratory exposures.  

PubMed

The susceptibility of lake trout Salvelinus namaycush, rainbow trout Oncorhynchus mykiss and Atlantic salmon Salmo salar to Myxobolus cerebralis, the causative agent of whirling disease, was compared in controlled laboratory exposures. A total of 450 (225 for each dose) fry for each species were exposed to a low (200 spores per fish) or high (2000 spores per fish) dose of the infective triactinomyxon. At 22 wk post-exposure, 60 fish from each group, as well as controls for each species, were examined for clinical signs (whirling behavior, blacktail, deformed heads and skeletal deformities), microscopic lesions, and presence of spores. Rainbow trout were highly susceptible to infection, with 100% being positive for spores and with microscopic pathological changes in both exposure groups. Rainbow trout were the only species to show whirling behavior and blacktail. Atlantic salmon were less susceptible, with only 44 and 61% being positive for spores, respectively, in the low and high dose groups, while 68 and 75%, respectively, had microscopic pathology associated with cartilage damage. Rainbow trout heads contained mean spore concentrations of 2.2 (low dose) or 4.0 (high dose) x 10(6) spores g tissue(-1). The means for positive Atlantic salmon (not including zero values) were 1.7 (low) and 7.4 (high) x 10(4) spores g tissue(-1). Lake trout showed no clinical signs of infection, were negative for spores in both groups and showed no histopathological signs of M. cerebralis infection. PMID:15038448

Blazer, V S; Densmore, C L; Schill, W B; Cartwright, D D; Page, S J

2004-01-28

167

Development of Two New Sampling Techniques for Assessing Lake Trout Reproduction in Deep Water  

Microsoft Academic Search

Efforts to restore lake trout Salvelinus namaycush at shallow sites have yielded minimal success in the lower four Great Lakes, and management agencies are examining offshore deepwater reefs as possible sites for restoration efforts. Previous techniques developed for assessing egg deposition and fry relative abundance in shallow waters are not viable for use on deep offshore reefs. To assess lake

Jacob W. Riley; Neil F. Thompson; J. Ellen Marsden; John Janssen

2010-01-01

168

Natural chemical markers identify source and date of introduction of an exotic species: lake trout  

E-print Network

(Salvelinus namaycush) in Yellowstone Lake Andrew R. Munro, Thomas E. McMahon, and James R. Ruzycki Abstract of introduction of exotic lake trout (Salvelinus namaycush) into Yellowstone Lake, Wyoming, USA. Otolith Sr identifier la source probable et la date d'introduction des touladis (Salvelinus namaycush) exoti- ques du

McMahon, Thomas E.

169

Thiamine Status of Cayuga Lake Rainbow Trout and Its Influence on Spawning Migration  

Microsoft Academic Search

Rainbow trout Oncorhynchus mykiss in Cayuga Lake, New York, appear to be suffering from a thiamine deficiency because their progeny develop general weakness, loss of equilibrium, and increased mortality, which are prevented by treatment with thiamine. Thiamine status and its effect on adults are unknown. In 2000 and 2002, we captured, tagged, and released 64 and 189 prespawning rainbow trout,

H. George Ketola; Thomas L. Chiotti; Robert S. Rathman; John D. Fitzsimons; Dale C. Honeyfield; Peter J. Van Dusen; Graham E. Lewis

2005-01-01

170

Crayfish (Orconectes virilis) Feeding on Young Lake Trout (Salvelinus namaycush): Effect of Rock Size  

Microsoft Academic Search

In laboratory studies, we quantified predation rates of crayfish (Orconectes virilis) on the eggs and sac fry of lake trout (Salvelinus namaycush) and a surrogate species, rainbow trout (Oncorhynchus mvkiss), dispersed among different sized substrates (bare bottom, gravel, cobble, large rocks). Predation was most severe when no rocks were present. Feeding rate then decreased as the substrate changed from large

Jacqueline F. Savino; John E. Miller

1991-01-01

171

Evaluating the Reintroduction Potential of Lahontan Cutthroat Trout in Fallen Leaf Lake, California  

Microsoft Academic Search

We evaluated the potential for reintroducing Lahontan cutthroat trout Oncorhynchus clarkii henshawi, a species listed under the Endangered Species Act, into a lacustrine system where the biotic community has changed dramatically since the species' extirpation there. Since 2002, 76,547 Lahontan cutthroat trout have been reintroduced into Fallen Leaf Lake, California; we used creel surveys, diet data, mark–recapture methods, bioenergetics modeling,

Robert Al-Chokhachy; Mary Peacock; Lisa G. Heki; Gary Thiede

2009-01-01

172

Trophic transfer efficiency of DDT to lake trout (Salvelinus namaycush) from their prey  

USGS Publications Warehouse

The objective of our study was to determine the efficiency with which lake trout retain DDT from their natural food. Our estimate of DDT assimilation efficiency would represent the most realistic estimate, to date, for use in risk assessment models.

Madenjian, C.P.; O'Connor, D.V.

2004-01-01

173

Increase in lake trout reproduction in lake huron following the collapse of alewife: Relief from thiamine deficiency or larval predation?  

USGS Publications Warehouse

In the Great Lakes there is still uncertainty as to the population level effects of a thiamine deficiency on salmonines caused by high consumption of alewives Alosa pseudoharengus. A resurgence of lake trout Salvelinus namaycush reproduction in Lake Huron following the crash of alewife stocks between 2002 and 2004 provided an opportunity to evaluate the relative effects of this crash on reproduction through relief from either alewife mediated thiamine deficiency or alewife predation on larval lake trout relative to possible changes in the size of the lake trout spawning stock. Changes in mean lake trout egg thiamine concentration post crash at one spawning reef in Parry Sound, wheremean thiamine concentration increased by almost two fold, were consistent with diet switching from alewives to rainbow smelt Osmerus mordax, the next most abundant prey fish in Lake Huron. Although thiamine levels for lake trout collected at a second reef in Parry Sound did not change post-crash, levels both pre- and post-crash were consistent with a rainbow smelt diet. A reef specific fry emergence index was found to be positively related to reef specific egg thiamine concentration but negatively related to reef specific occurrence of EMS, a thiamine deficiency related mortality syndrome. We found little evidence for overlap between the timing of spring shoreward migration of alewives and lake trout emergence, suggesting that relief from alewife predation effects had relatively little effect on the observed increase in lake trout recruitment. Numbers of spawners in the north, north-central, and southern zones of the lake increased from 2000 onwards. Overall the abundance post-2003 was higher than from pre-2004, suggesting that spawner abundance may also have contributed to increased lake trout reproduction. However, predicted numbers of spawners and measured abundance of wild recruits in assessment gear were poorly correlated suggesting that the increase in reproduction was not totally spawner dependent and hence relief from thiamine deficiency was also likely involved. We conclude from this that eliminating the effects of an alewife diet mediated thiamine deficiency can have positive effects on lake trout reproduction but more research is required to understand the effect of spawner number and the role of spawning habitat availability. ?? 2010 AEHMS.

Fitzsimons, J.D.; Brown, S.; Brown, L.; Honeyfield, D.; He, J.; Johnson, J.E.

2010-01-01

174

Performance of temperature and dissolved oxygen criteria to predict habitat use by lake trout (Salvelinus namaycush)  

USGS Publications Warehouse

We compared theoretical habitat volumes, determined from traditional combinations of temperature and dissolved oxygen concentration (DO) boundaries, with in situ habitat use by acoustically tagged lake trout (Salvelinus namaycush). The widely used criteria of 8-12 ??C underestimated lake trout habitat use by 68%-80%. Instead, combined temperature (<12 or 15 ??C) and DO (>4 or 6 mg??L-1) criteria most closely matched lake trout habitat use, had a similar seasonal trend as the tagged fish, suggested modest reductions (5% of total lake volume) in habitat during a warmer year, and performed best when the constraints of temperature and DO were most limiting. All data were collected in a small boreal shield lake (27 ha, zmax = 21 m) at the Experimental Lakes Area in northwestern Ontario, Canada, during two contrasting periods of thermal stratification (2003: warmer and longer; 2004: cooler and shorter), providing an assessment of observed and theoretical habitat volumes over current environmental extremes.

Plumb, J.M.; Blanchfield, P.J.

2009-01-01

175

Molecular characterization and cytogenetic analysis of highly repeated DNAs of lake trout, Salvelinus namaycush  

Microsoft Academic Search

The chromosomes of lake trout ( Salvelinus namaycush) contain a considerable amount of heterochromatin located at the centromeres and\\/or telomeres of several chromosomes, including a sex-specific block located distally on the X chromosome. In order to investigate further the repetitive DNAs of lake trout, genomic DNA from a female was size fractionated (AluI and fragments were cloned into the bacteriophage

Kent M. Reed; Ruth B. Phillips

1995-01-01

176

Spatial distribution of perfluoroalkyl contaminants in lake trout from the Great Lakes.  

PubMed

Individual whole body homogenates of 4 year old lake trout (Salvelinus namaycush) samples collected in 2001 from each of the Great Lakes were extracted using a novel fluorophilicity cleanup step and analyzed for perfluoroalkyl compounds (PFCs). Standard addition and internal standardization were used for quantification. Results were reported (+/- SE) for perfluorinated carboxylates (PFCAs), perfluorinated sulfonates (PFSAs), and unsaturated fluorotelomer carboxylates (8:2 and 10:2 FTUCA). The lowest average concentration of sigmaPFC was found in samples from Lake Superior (13+/-1 ng g(-1)), while the highest average concentration was found in samples from Lake Erie (152+/-14 ng g(-1)). Samples from Lake Ontario (60+/-5 ng g(-1)) and Lake Huron (58 +/-10 ng g(-1)) showed similar average sigmaPFC concentrations, although the perfluorinated sulfonate/carboxylate ratios were different. The major perfluoroalkyl contaminant observed was perfluorooctane sulfonate (PFOS) with the highest concentration found in samples from Lake Erie (121+/-14 ng g(-1)), followed by samples from Lake Ontario (46+/-5 ng g(-1)), Lake Huron (39 +/-10 ng g(-1)), Lake Michigan (16+/-3 ng g(-1)), and Lake Superior (5+/-1 ng g(-1)). Perfluorodecane sulfonate (PFDS) was detected in 89% of the samples, with the highest concentration in Lake Erie samples (9.8+/-1.6 ng g(-1)), and lowest concentration in samples from Lake Superior (0.7 +/- 0.1 ng g(-1)). Statistically significant correlations were observed between PFOS and PFDS concentrations, and PFOS concentration and body weight, respectively. The PFCAs were detected in all samples, with the highest total average concentration in samples from Lake Erie (19 ng g(-1)), followed by samples from Lake Huron (16 ng g(-1)), Lake Ontario (10 ng g(-1)), Lake Michigan (9 ng g(-1)) and Lake Superior (7 ng g(-1)). The compounds with significant contributions to the sigmaPFCA concentrations were PFOA and C9-C13-PFCAs. The 8:2 FTUCA was detected at concentrations ranging between 0.1 and 0.2 ng g-1, with the highest level in samples showing also elevated concentrations of PFOA (4.4 ng g(-1) for Lake Michigan vs 1.5 ng g(-1) for all other samples). The 10:2 FTUCA was detected only in 9% of all samples (nd, 45 pg g(-1)). For those PFCs where we determined lake water concentrations, the highest log BAFs were calculated for PFOS (4.1), PFDA (3.9), and PFOSA (3.8). PMID:17396640

Furdui, Vasile I; Stock, Naomi L; Ellis, David A; Butt, Craig M; Whittle, D Michael; Crozier, Patrick W; Reiner, Eric J; Muir, Derek C G; Mabury, Scott A

2007-03-01

177

Laboratory estimation of net trophic transfer efficiencies of PCB Congeners to lake trout (Salvelinus namaycush) from its prey.  

PubMed

A technique for laboratory estimation of net trophic transfer efficiency (?) of polychlorinated biphenyl (PCB) congeners to piscivorous fish from their prey is described herein. During a 135-day laboratory experiment, we fed bloater (Coregonus hoyi) that had been caught in Lake Michigan to lake trout (Salvelinus namaycush) kept in eight laboratory tanks. Bloater is a natural prey for lake trout. In four of the tanks, a relatively high flow rate was used to ensure relatively high activity by the lake trout, whereas a low flow rate was used in the other four tanks, allowing for low lake trout activity. On a tank-by-tank basis, the amount of food eaten by the lake trout on each day of the experiment was recorded. Each lake trout was weighed at the start and end of the experiment. Four to nine lake trout from each of the eight tanks were sacrificed at the start of the experiment, and all 10 lake trout remaining in each of the tanks were euthanized at the end of the experiment. We determined concentrations of 75 PCB congeners in the lake trout at the start of the experiment, in the lake trout at the end of the experiment, and in bloaters fed to the lake trout during the experiment. Based on these measurements, ? was calculated for each of 75 PCB congeners in each of the eight tanks. Mean ? was calculated for each of the 75 PCB congeners for both active and inactive lake trout. Because the experiment was replicated in eight tanks, the standard error about mean ? could be estimated. Results from this type of experiment are useful in risk assessment models to predict future risk to humans and wildlife eating contaminated fish under various scenarios of environmental contamination. PMID:25226430

Madenjian, Charles P; Rediske, Richard R; O'Keefe, James P; David, Solomon R

2014-01-01

178

Laboratory estimation of net trophic transfer efficiencies of PCB congeners to lake trout (Salvelinus namaycush) from its prey  

USGS Publications Warehouse

A technique for laboratory estimation of net trophic transfer efficiency (?) of polychlorinated biphenyl (PCB) congeners to piscivorous fish from their prey is described herein. During a 135-day laboratory experiment, we fed bloater (Coregonus hoyi) that had been caught in Lake Michigan to lake trout (Salvelinus namaycush) kept in eight laboratory tanks. Bloater is a natural prey for lake trout. In four of the tanks, a relatively high flow rate was used to ensure relatively high activity by the lake trout, whereas a low flow rate was used in the other four tanks, allowing for low lake trout activity. On a tank-by-tank basis, the amount of food eaten by the lake trout on each day of the experiment was recorded. Each lake trout was weighed at the start and end of the experiment. Four to nine lake trout from each of the eight tanks were sacrificed at the start of the experiment, and all 10 lake trout remaining in each of the tanks were euthanized at the end of the experiment. We determined concentrations of 75 PCB congeners in the lake trout at the start of the experiment, in the lake trout at the end of the experiment, and in bloaters fed to the lake trout during the experiment. Based on these measurements, ? was calculated for each of 75 PCB congeners in each of the eight tanks. Mean ? was calculated for each of the 75 PCB congeners for both active and inactive lake trout. Because the experiment was replicated in eight tanks, the standard error about mean ? could be estimated. Results from this type of experiment are useful in risk assessment models to predict future risk to humans and wildlife eating contaminated fish under various scenarios of environmental contamination.

Madenjian, Charles P.; Rediske, Richard R.; O'Keefe, James P.; David, Solomon R.

2014-01-01

179

Lactate dehydrogenase ontogeny, paternal gene activation, and tetramer assembly in embryos of brook trout, lake trout, and their hybrids  

Microsoft Academic Search

Measurement of lactate dehydrogenase in reciprocal hybrids of trout during development revealed that a maternal effect was involved in the regulation of enzyme levels until resorption of the yolk sac was completed. Malate dehydrogenase specific activities were the same in these embryos and larvae. The more negatively charged B subunits of LDH predominated during early stages of embryogenesis in lake

Erwin Goldberg; J. P. Cuerrier; J. C. Ward

1969-01-01

180

Some Effects of Introduction of the Redside Shiner on the Kamloops Trout in Paul Lake, British Columbia  

Microsoft Academic Search

The redside shiner (Richardsonius balteatus) was introduced into Paul Lake, British Columbia about 1945 and by 1952 was abundant in the lake. Some effects of this introduction on Kamloops trout (Salmo gairdneri kamloops), previously the only other species of fish in the lake, are described. The summer diet of trout underwent marked changes and in 1952 shiners constituted a main

P. A. Larkin; S. B. Smith

1954-01-01

181

Ovarian fluid influences sperm performance in lake trout, Salvelinus namaycush.  

PubMed

The objectives of this study were to determine whether (i) the presence and concentration of ovarian fluid (OF) affects sperm performance traits, and (ii) variation in sperm performance traits is due to male identity, female identity, and/or male×female interactions in lake trout, Salvelinus namaycush. Spermatozoa from four males were activated in river water and OF from four females at two concentrations (10 and 15%). Presence of ovarian fluid influenced sperm traits; no differences were detected between 10 and 15% OF. Sperm traits varied depending on parental identity, such that sperm of some males perform better in the OF of all females and that in OF of some females sperm traits are higher for all males. PMID:23719125

Galvano, Patrick M; Johnson, Katelynn; Wilson, Chris C; Pitcher, Trevor E; Butts, Ian A E

2013-06-01

182

Osteological evidence of genetic divergence of lake trout (Salvelinus namaycush) in Lake Superior  

USGS Publications Warehouse

Three phenotypes of Salvelinus namaycush in Lake Superior, the lean, siscowet, and bumper, are traditionally identified primarily by fat content and body shape. Their taxonomic status is in question because of intermediates as well as the possibility that the diagnostic characters are ecophenotypic. Two osteological characters, the dorsal opercular notch (first recorded by Agassiz in his description of the siscowet) and radii on the anterodorsal part of the supraethmoid, differ between most leans and siscowets. The notch in the opercle near its articulation with the hyomandibular bone is present in humpers, usually present in siscowets, and usually absent in leans. Radii on the anterodorsal surface of the supraethmoid bone usually are found in siscowets and humpers but usually are absent in leans. The correlations among these characters and other features of the phenotype indicate a significant level of differentiation between the three phenotypes. Available evidence suggests that the differentiation is genetic. The frequency of mixed phenotypes is evidence of limited gene flow among the phenotypes. The siscowet and humper phenotypes apparently originated in Lake Superior in postglacial time.

Burnham-Curtis, Mary K.; Smith, Gerald R.

1994-01-01

183

DECLINE AND EXTINCTION OF LAKE TROUT IN THE GREAT LAKES: CAN BIOLOGICAL INDICATORS HELP DIAGNOSE CAUSES, IDENTIFY REMEDIAL ACTIONS, AND PREDICT FUTURE CONDITIONS?  

EPA Science Inventory

The lake trout, Salvelinus namaycush, is the predominant top predator native fish species of the Great Lakes. Lake trout are valued for commercial and recreational use in addition to their ecological importance. In the last half of the 20th century, population declines lead to vi...

184

Colonization of high-elevation lakes by long-toed salamanders ( Ambystoma macrodactylum ) after the extinction of introduced trout populations  

Microsoft Academic Search

Abstract: We surveyed,high-elevation lakes for long-toed salamander,(Ambystoma,macrodactylum,) larvae and trout in the northern Bitterroot Mountains of Montana, U.S.A., in 1978, 1997, and 1998. Our objectives were to (i) test whether,trout exclude salamander,populations; (ii) determine,whether,lakes in which trout have gone,extinct have since been colonized by salamanders; and (iii) estimate the rates of population extinction and colonization in lakes never stocked with

W. Chris Funk; William W. Dunlap

1999-01-01

185

Linking egg thiamine and fatty acid concentrations of Lake Michigan lake trout with early life stage mortality.  

PubMed

The natural reproduction of lake trout Salvelinus namaycush in Lake Michigan is thought to be compromised by nutritional deficiency associated with inadequate levels of thiamine (vitamin B1) in their eggs. However, mortality driven by thiamine deficiency (commonly referred to as early mortality syndrome [EMS]) is not the only significant cause of low lake trout survival at early life stages. In this study, we sought to better understand the combined effects of variable levels of thiamine and fatty acids in lake trout eggs on prehatch, posthatch, and swim-up-stage mortality. We sampled the eggs of 29 lake trout females from southwestern Lake Michigan. The concentrations of free thiamine and its vitamers (e.g., thiamine monophosphate [TMP] and thiamine pyrophosphate [TPP]) as well as fatty acid profiles were determined in sampled eggs. Fertilized eggs and embryos were monitored through the advanced swim-up stage (1,000 degree-days). Three distinct periods of mortality were identified: prehatch (0-400 degree-days), immediately posthatch (401-600 degree-days), and swim-up (601-1,000 degree-days). Stepwise multiple regression analysis revealed (1) that cis-7-hexadecenoic acid in both neutral lipids (NL) and phospholipids (PL) correlated with prehatch mortality, (2) that docosapentaenoic acid in PL and docosahexaenoic acid in NL correlated with posthatch mortality, and (3) that total lipids, TPP, and palmitoleic acid in NL, linoleic acid, and palmitic acid in PL correlated with the frequency of EMS. These results indicate the complexity of early life stage mortality in lake trout and suggest that inadequate levels of key fatty acids in eggs, along with variable thiamine content, contribute to the low survival of lake trout progeny in Lake Michigan. PMID:20218500

Czesny, Sergiusz; Dettmers, John M; Rinchard, Jacques; Dabrowski, Konrad

2009-12-01

186

Evaluation of angler effort and harvest of rainbow trout (Oncorhynchus mykiss), Lake Scanewa, Washington, 2010  

USGS Publications Warehouse

A creel evaluation was conducted in Lake Scanewa, a reservoir on the Cowlitz River, to monitor catch rates of rainbow trout (Oncorhynchus mykiss) and determine if the trout fishery was having negative impacts on juvenile anadromous salmon (Oncorhynchus spp.) in the system. The trout fishery, which is supported by releases of 20,000 fish (2 fish per pound) per year from June to August, was developed to mitigate for the construction of the Cowlitz Falls Dam in 1994. The trout fishery has a target catch rate of at least 0.50 fish per hour. Interviews with 1,214 anglers during the creel evaluation found that most anglers targeted rainbow trout (52 percent) or Chinook and coho salmon (48 percent). The interviewed anglers caught a total of 1,866 fish, most of which were rainbow trout (1,213 fish; 78 percent) or coho salmon (311 fish; 20 percent). We estimated that anglers spent 17,365 hours fishing in Lake Scanewa from June to November 2010. Catch rates for boat anglers (1.39 fish per hour) exceeded the 0.50 fish per hour target, whereas catch rates for shore anglers (0.35 fish per hour) fell short of the goal. The combined catch rates for all trout anglers in the reservoir were 0.96 fish per hour. We estimated that anglers harvested 7,584 (95 percent confidence interval = 2,795-12,372 fish) rainbow trout during the study period and boat anglers caught more fish than shore anglers (5,975 and 1,609 fish, respectively). This estimate suggests that more than 12,000 of the 20,000 rainbow trout released into Lake Scanewa during 2010 were not harvested, and could negatively impact juvenile salmon in the reservoir through predation or competition. We examined 1,236 stomach samples from rainbow trout and found that 2.1 percent (26 fish) of these samples contained juvenile fish. Large trout (greater than 300 millimeters) had a higher incidence of predation than small trout (less than 300 millimeters; 8.50 and 0.06 percent, respectively). A total of 39 fish were found in rainbow trout stomachs and 13 (33 percent) of these were juvenile salmon. These data and uncertainties associated with movement patterns and survival rates of rainbow trout in Lake Scanewa suggest that future evaluations would be helpful to better understand the potential effects of the mitigation trout fishery on juvenile salmon in the reservoir.

Liedtke, Theresa L.; Kock, Tobias J.; Ekstrom, Brian K.; Tomka, Ryan G.; Rondorf, Dennis W.

2011-01-01

187

Food of young-of-the-year lake trout (Salvelinus namaycush) in Presque Isle Harbor, Lake Superior  

USGS Publications Warehouse

The food habits of young lake trout (Salvelinus namaycush) were studied by examining the digestive tracts of 293 young-of-the-year collected in Presque Isle Harbor, Lake Superior. Lake trout in the 25 to 27-mm length range started to eat food organisms before all of their yolk material was absorbed. Organisms consumed by the 25 to 27-mm young-of-the-year included Chironomidae, Copepoda (Harpacticoida, Calanoida, Cyclopoida), and Cladocerea (Daphnia spp., Bosmina sp., Chydorus sp.). Chironomid pupae and chironomid larvae accounted for 74% and 5%, respectively, of the total volume of food eaten by the young lake trout in Presque Isle Harbor. Although copepods, cladocerans, and mysids were present in many stomachs, their contribution to the total volume of food was only 15%. Some lake trout in the 32 to 54-mm length range had consumed fry of sculpin (Cottus spp.) or rainbow smelt (Osmerus mordax), but the overall contribution of fish fry to the total volume of food was only 4% (frequency of occurrence, 10%). The lake trout in Presque Isle Harbor fed heavily on planktonic organisms, sparingly on benthic organisms, and were opportunistic feeders that appeared to prey on whatever forage organisms were available in the shallow nearshore waters.

Swedberg, Donald V.; Peck, James W.

1984-01-01

188

Genetic variation over space and time: Analyses of extinct and remnant lake trout populations in the Upper Great Lakes  

USGS Publications Warehouse

Lake trout (Salvelinus namaycush) in the upper Laurentian Great Lakes of North America experienced striking reductions in abundance and distribution during the mid-twentieth century. Complete collapse of populations was documented for Lake Michigan, and a few remnant populations remained only in lakes Huron and Superior. Using DNA obtained from historical scale collections, we analysed patterns of genetic diversity at five microsatellite loci from archived historical samples representing 15 populations (range 1940-1959) and from three contemporary remnant populations across lakes Huron and Superior (total n = 893). Demographic declines in abundance and the extirpation of native lake trout populations during the past 40 years have resulted in the loss of genetic diversity between lakes owing to extirpation of Lake Michigan populations and a temporal trend for reduction in allelic richness in the populations of lakes Superior and Huron. Naturally reproducing populations in Lake Superior, which had been considered to be remnants of historical populations, and which were believed to be responsible for the resurgence of lake trout numbers and distribution, have probably been affected by hatchery supplementation.

Guinand, B.; Scribner, K.T.; Page, K.S.; Burnham-Curtis, M. K.

2003-01-01

189

Genetic variation over space and time: analyses of extinct and remnant lake trout populations in the Upper Great Lakes.  

PubMed

Lake trout (Salvelinus namaycush) in the upper Laurentian Great Lakes of North America experienced striking reductions in abundance and distribution during the mid-twentieth century. Complete collapse of populations was documented for Lake Michigan, and a few remnant populations remained only in lakes Huron and Superior. Using DNA obtained from historical scale collections, we analysed patterns of genetic diversity at five microsatellite loci from archived historical samples representing 15 populations (range 1940-1959) and from three contemporary remnant populations across lakes Huron and Superior (total n = 893). Demographic declines in abundance and the extirpation of native lake trout populations during the past 40 years have resulted in the loss of genetic diversity between lakes owing to extirpation of Lake Michigan populations and a temporal trend for reduction in allelic richness in the populations of lakes Superior and Huron. Naturally reproducing populations in Lake Superior, which had been considered to be remnants of historical populations, and which were believed to be responsible for the resurgence of lake trout numbers and distribution, have probably been affected by hatchery supplementation. PMID:12639323

Guinand, B; Scribner, K T; Page, K S; Burnham-Curtis, M K

2003-02-22

190

Genetic variation over space and time: analyses of extinct and remnant lake trout populations in the Upper Great Lakes.  

PubMed Central

Lake trout (Salvelinus namaycush) in the upper Laurentian Great Lakes of North America experienced striking reductions in abundance and distribution during the mid-twentieth century. Complete collapse of populations was documented for Lake Michigan, and a few remnant populations remained only in lakes Huron and Superior. Using DNA obtained from historical scale collections, we analysed patterns of genetic diversity at five microsatellite loci from archived historical samples representing 15 populations (range 1940-1959) and from three contemporary remnant populations across lakes Huron and Superior (total n = 893). Demographic declines in abundance and the extirpation of native lake trout populations during the past 40 years have resulted in the loss of genetic diversity between lakes owing to extirpation of Lake Michigan populations and a temporal trend for reduction in allelic richness in the populations of lakes Superior and Huron. Naturally reproducing populations in Lake Superior, which had been considered to be remnants of historical populations, and which were believed to be responsible for the resurgence of lake trout numbers and distribution, have probably been affected by hatchery supplementation. PMID:12639323

Guinand, B; Scribner, K T; Page, K S; Burnham-Curtis, M K

2003-01-01

191

Influence of PCBs in water on uptake and elimination of DDT and DDE by lake trout  

USGS Publications Warehouse

Researchers predicted that several hundred years would be required before DDT (1,1,1 trichloro-2,2-bis [P-chlorophyl] ethane) and its metabolites were likely to decrease to nondetectable levels in Lake Michigan. But following the ban on DDT in 1970, residues of total DDT in Lake Michigan lake trout (Salvelinus namaycush) declined rapidly from 10.5 I?g/g in 1970 to 5.7 I?g/g in 1976. During this period, polychlorinated biphenyls (PCBs) were being detected in lake trout tissues at about 20 I?g/g. It was hypothesized that the high level of PCBs being accumulated by fish may have influenced uptake and elimination of DDT and DDE (1,1-dichloro-2,2-bis [p-chlorophenyl] ethylene) by fish. To test this hypothesis, fingerling lake trout were exposed to various combinations of DDT, DDE (100 ng/liter), and PCBs (100 and 500 ng/liter) in water for 12 weeks. After DDT and DDE exposures were completed, exposure to PCBs was continued for an additional 16 weeks to measure any effect PCBs may have on the elimination of DDT and DDE by fish. Accumulation and elimination rates of DDT and DDE were compared. It was found that PCBs did not influence the accumulation or elimination rates of DDT or DDE in lake trout and therefore should not have had a major influence on the decline of DDT in lake trout.

Hesselberg, Robert J.; Nicholson, Lawrence W.

1981-01-01

192

Natural chemical markers identify source and date of introduction of an exotic species: lake trout ( Salvelinus namaycush ) in Yellowstone Lake  

Microsoft Academic Search

Exotic species invasions pose a pervasive threat to aquatic ecosystems worldwide, yet fundamental questions about the geographic origin and timing of invasions or introductions are frequently difficult to answer. We used natural chemical markers (Sr:Ca ratios) in otoliths to identify probable source and date of introduction of exotic lake trout (Salvelinus namaycush) into Yellowstone Lake, Wyoming, USA. Otolith Sr:Ca ratios

Andrew R. Munro; Thomas E. McMahon; James R. Ruzycki

2005-01-01

193

The accumulation, distribution, and toxicological effects of dietary arsenic exposure in lake whitefish ( Coregonus clupeaformis) and lake trout ( Salvelinus namaycush)  

Microsoft Academic Search

A 20-day experiment was conducted to compare the accumulation, distribution, and toxicological effects of dietary As, as arsenate, in lake whitefish (LWF, Coregonusclupeaformis) and lake trout (LT, Salvelinus namaycush). Results of this experiment were used to design an experiment of longer duration in which one of the fish species was selected and exposed three times per week to lower dietary

R. M Pedlar; M. D Ptashynski; K. G Wautier; R. E Evans; C. L Baron; J. F Klaverkamp

2002-01-01

194

Accumulation, distribution and toxicology of dietary nickel in lake whitefish ( Coregonus clupeaformis) and lake trout ( Salvelinus namaycush)  

Microsoft Academic Search

An 18-day experiment was conducted to investigate the uptake and sublethal toxicity of dietary Ni in adult lake whitefish (LWF, Coregonusclupeaformis) and lake trout (LT, Salvelinus namaycush) fed diets containing 0, 1000 and 10000 ?g Ni\\/g, prepared with and without brine shrimp. The results of this experiment were used to design an experiment of longer duration in which one of

M. D Ptashynski; R. M Pedlar; R. E Evans; K. G Wautier; C. L Baron; J. F Klaverkamp

2001-01-01

195

Genetic Structure and Diversity among Brook Trout from Isle Royale, Lake Nipigon, and Three Minnesota Tributaries of Lake Superior  

Microsoft Academic Search

Brook trout Salvelinus fontinalis from Isle Royale, Michigan, three Minnesota tributaries of Lake Superior, and Lake Nipigon in Ontario were analyzed for genetic variation at 12 microsatellite DNA loci. Analysis of molecular variance, genetic distance measures, and cluster analysis were used to examine the diversity, gene flow, and relatedness among the samples. The diversity estimates for the samples from Isle

Wendylee Stott; Henry R. Quinlan; Owen T. Gorman; Timothy L. King

2010-01-01

196

Cross-basin comparison of mercury bioaccumulation in lake Huron lake trout emphasizes ecological characteristics.  

PubMed

Understanding factors influencing mercury (Hg) bioaccumulation in fish is important for examining both ecosystem and human health. However, little is known of how differing ecosystem and biological characteristics can drive Hg bioaccumulation in top predators. This study compared and contrasted Hg bioaccumulation in multiple age classes of lake trout (Salvelinus namaycush) collected from each of Lake Huron's Georgian Bay, North Channel and Main Basin regions. Hg concentrations exhibited a basin specific pattern with Main Basin fish having the highest average concentration (0.19 ± 0.01 mg/kg) followed by Georgian Bay (0.15 ± 0.02 mg/kg) and North Channel (0.07 ± <0.01 mg/kg) fish. Age-related increases in Hg concentrations were observed across the three basins with North Channel fish exhibiting the slowest rate of Hg bioaccumulation. No significant difference was determined between the relationships describing Hg concentration and age between Main Basin and Georgian Bay fish (p <0.05). Hg biomagnification factors (BMF) determined between lake trout and rainbow smelt, their primary prey, were significantly correlated with fish age and differed across the three basins (p <0.05). Specifically, Georgian Bay fish exhibited the greatest age related increase in Hg BMF followed by Main Basin and North Channel fish and these differences could not be attributed to trophic level (?(15) N) effects or lake trout growth rates. A highly significant negative relationship was determined between Hg BMFs and basin specific prey fish densities indicating that ecological factors associated with food acquisition and foraging efficiencies play an important role in Hg bioaccumulation in feral fish communities. This article is protected by copyright. All rights reserved. PMID:25402744

Abma, Rachel A; Paterson, Gordon; McLeod, Anne; Haffner, G Doug

2014-11-17

197

Influence of lake characteristics on the biomagnification of persistent organic pollutants in lake trout food webs.  

PubMed

The biomagnification of polychlorinated biphenyls (PCBs) and major organochlorine pesticides (OCPs) was studied using lake trout (Salvelinus namaycush) and other food web organisms collected from 17 lakes in Canada and the northeastern United States between 1998 and 2001. Whole lake trout (n = 357) concentrations of the sum (Sigma) of 57 PCB congeners ranged between 1.67 and 2,890 ng/g wet weight (median 61.5 ng/g wet wt). Slimy sculpin had the highest mean concentrations of SigmaPCB of all forage fish (32-73 ng/g wet wt). Positive relationships between log (lipid wt) concentrations of PCB congener 153, PCB congener 52, p,p'-dichlorodiphenyldichloroethylene, hexachlorobenzene, cis-chlordane, trans-nonachlor, or dieldrin and trophic level (determined using stable nitrogen isotope ratios) were found for most of the 17 food webs, indicating biomagnification of these PCBs and OCPs. The p,p'-dichlorodiphenyldichloroethylene had the highest trophic magnification factors (TMFs) of the 14 individual compounds studied, averaging 4.0 +/- 1.8 across the 17 lakes, followed by trans-nonachlor (3.6 +/- 1.5) and PCB congener 153 (3.4 +/- 1.2). Average TMFs for 14 individual PCBs or OCPs were significantly correlated with log octanol-water partition coefficient, implying that the rate of accumulation along the food web is dependent on hydrophobicity and recalcitrance. Significant correlations (p < 0.05) were found between TMFs of SigmaPCBs, hexachlorobenzene, alpha-hexachlorocyclohexane, and lindane and lake area, latitude, and longitude, but not for 11 other PCBs or OCPs. Overall, the results of the present study show that biomagnification of PCBs and most OCPs, as measured by TMFs, is only weakly influenced by such factors as latitude and longitude. Exceptions are hexachlorocyclohexane isomers and hexachlorobenzene, which had generally greater TMFs in northern lakes, possibly due to lower rates of elimination and biotransformation in the food web. PMID:18444699

Houde, Magali; Muir, Derek C G; Kidd, Karen A; Guildford, Stephanie; Drouillard, Ken; Evans, Marlene S; Wang, Xiaowa; Whittle, D Michael; Haffner, Doug; Kling, Hedy

2008-10-01

198

Dynamics of individual growth in a recovering population of lake trout (Salvelinus namaycush  

E-print Network

In 1976 the Wisconsin Department of Natural Resources established a refuge for a nearly depleted population of lake trout (Salvelinus namaycush) at Gull Island Shoal,Lake Superior. The refuge was intended to reduce fishing mortality by protecting adult lake trout. We examined the growth dynamics of these lake trout during the period of recovery by comparing estimates of individual growth before and after the refuge was established. Our estimates are based on an annual mark-recapture survey conducted at the Gull Island Shoal spawning area since 1969. We developed a model that allowed mean growth rates to differ among individuals of different sizes and that accommodated variation in growth rates of individuals of the same size. Likelihood-ratio tests were used to determine if the mean growth increments of lake trout changed after the refuge was established. Our results suggest that growth of mature lake trout (particularly wild fish) decreased significantly in the post-refuge period. This decreased growth may have been associated with a reduction in food availability. We also observed reductions in growth as wild fish grew older and larger,which suggests that the growth of these fish may be adequately approximated by a von Bertalanffy growth model if it becomes possible to obtain accurate ages.

Mary C. Fabrizio; U. S. Geological Survey; Robert M. Dorazio; U. S. Geological Survey; Stephen T. Schram

2001-01-01

199

Dynamics of individual growth in a recovering population of lake trout (Salvelinus namaycush)  

USGS Publications Warehouse

In 1976, the Wisconsin Department of Natural Resources established a refuge for a nearly depleted population of lake trout (Salvelinus namaycush) at Gull Island Shoal, Lake Superior. The refuge was intended to reduce fishing mortality by protecting adult lake trout. We examined the growth dynamics of these lake trout during the period of recovery by comparing estimates of ndividual growth before and after the refuge was established. Our estimates are based on an annual mark-recapture survey conducted at the spawning area since 1969. We developed a model that allowed mean growth rates to differ among individuals of different sizes and that accommodated variation in growth rates of individuals of the same size. Likelihood ratio tests were used to determine if the mean growth increments of lake trout changed ater the refuge was established. Our results suggest that growth of mature lake trout (particularly wild fish) decreased significantly in the postrefuge period. This decreased growth may have been associated with a reduction in food availability. We also observed reductions in growth as wild fish grew older and larger, which suggests that the growth of these fish may be adequately approximated by a von Bertalanffy growth model if it becomes possible to obtain accurate ages.

Fabrizio, Mary C.; Dorazio, Robert M.; Schram, Stephen T.

2001-01-01

200

In Situ Swimming Behavior of Lake Trout Observed Using Integrated Multibeam Acoustics and Biotelemetry  

Microsoft Academic Search

Multibeam echo sounder systems allow the in situ observation of swimming and foraging behavior and give insights into the ecology of fish at the individual level. In Lake Opeongo, Ontario, 16 adult lake trout Salvelinus namaycush were surgically implanted with ultrasonic tags, released, and studied by means of mobile fisheries acoustics. The transmitted pulses from the ultrasonic tags could be

Erin S. Dunlop; Scott W. Milne; Mark S. Ridgway; Jeff Condiotty; Ian Higginbottom

2010-01-01

201

Use of Outlet Barriers to Prevent Fall Emigration of Brook Trout Stocked in Adirondack Lakes  

Microsoft Academic Search

Outlet barriers in stocked lakes of the Adirondack Mountains were used to test the hypothesis that preventing fall emigration by adult brook trout Salvelinus fontinalis would increase trap-net and angling catch rates as well as the number of large trophy fish. Outlet barriers were maintained during the fall spawning season for 6 years on one lake and 10 years on

Daniel C. Josephson; Charles C. Krueger; Patrick J. Sullivan

2001-01-01

202

Linking the occurrence of brook trout with isolation and extinction in small Boreal Shield lakes  

Microsoft Academic Search

SUMMARY 1. We surveyed 62 Canadian Shield lakes (<50 ha) to determine the relationship between factors related to isolation and extinction and the occurrence of brook trout (BT) (Salvelinus fontinalis), for which local extinctions have been documented over the last century in half of the lakes. 2. Logistic regression and information-theoretic model selection were used to determine the importance for

ANDREA B ERTOLO; P IERRE M A GNAN; M ICHEL P LANTE

2008-01-01

203

Spatial distribution of polybrominated diphenyl ethers and polybrominated biphenyls in lake trout from the Laurentian Great Lakes  

Microsoft Academic Search

Concentrations of two types of brominated flame-retardants (BFRs); polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) were determined in a single age class of lake trout (Salvelinus namaycush) collected from the Laurentian Great Lakes in 1997. Mean concentrations of total PBDE were highest in samples from Lake Ontario at 95±22ng\\/g wet weight (ww) or 434±100ng\\/g lipid weight (lw) while the

Jennifer M Luross; Mehran Alaee; David B Sergeant; Christina M Cannon; D Michael Whittle; Keith R Solomon; Derek C. G Muir

2002-01-01

204

Effect of rearing density on poststocking survival of lake trout in Lake Ontario  

USGS Publications Warehouse

Six paired lots of yearling lake trout (Salvelinus namaycush) reared at densities of 41,000 and 51,000 fish per raceway during their last 9 months in the hatchery were stocked in Lake Ontario. Poststocking survival of the high-density (HD) and low-density (LD) fish was not different for the 1982 year-class. However, for the 1983 year-class, mean survival was significantly different between HD and LD fish (P < 0.01). Mean survival of HD fish was only 76% that of LD fish (P < 0.01), and most of the mortality attributable to rearing conditions had apparently occurred within 2 months after stocking. Mean size at stocking was not different for HD and LD fish of the 1982 year-class, but for the 1983 year-class, the LD fish were 6% longer and 22% heavier than the HD fish. Mean lengths and weights of LD and HD fish were not different in samples collected in Lake Ontario at age 2 and older. Size at stocking was not likely the factor that caused the difference in survival. Rather, the rearing conditions (probably water exchange rate in relation to number of fish in the raceway) that resulted in slower growth of the HD fish of the 1983 year-class also caused them to be poorer physiologically than the LD fish. The number of yearling lake trout per rearing unit that will result in maximum contribution to populations in the Great Lakes after stocking may be lower than the rearing densities customarily used at some hatcheries.

Elrod, Joseph H.; Ostergaard, David E.; Schneider, Clifford P.

1989-01-01

205

Diet of juvenile lake trout in southern Lake Ontario in relation to abundance and size of prey fishes, 1979-1987  

USGS Publications Warehouse

We examined the diet of juvenile lake trout Salvelinus namaycush (<450 mm, total length) in Lake Ontario during four sampling periods (April-May, June, July-August, and October 1979-1987) in relation to changes in prey fish abundance in the depth zone where we caught the lake trout. Over all years combined, slimy sculpins Cottus cognatus contributed the most (39-52%) by wet weight to the diet, followed by alewives Alosa pseudoharengus (3-38%), rainbow smelt Osmerus mordax (17-43%), and johnny darters Etheostoma nigrum (2-10%). Over 90% of alewives eaten during April-May and June were age 1, and 98% of those eaten during October were age 0 (few alewives were eaten in July-August). Mean lengths of rainbow smelt and slimy sculpins in stomachs increased with size of lake trout. Juvenile lake trout generally fed opportunistically - seasonal and annual changes in diet usually reflected seasonal and annual changes in abundance of prey fishes near bottom where we captured the lake trout. Furthermore, diet within a given season varied with depth of capture of lake trout, and changes with depth in proportions of prey species in lake trout stomachs mirrored changes in proportions of the prey species in trawl catches at the same depth. Alewives (ages 0 and 1) were the only prey fish eaten in substantial quantities by both juvenile lake trout and other salmonines, and thus are a potential focus of competition between these predators.

Elrod, Joseph H.; O'Gorman, Robert

1991-01-01

206

Residues of DDT in lake trout (Salvelinus namaycush) and coho salmon (Oncorhynchus kisutch) from the Great Lakes  

USGS Publications Warehouse

Concentrations of DDT residues were higher in lake trout (Salvelinus namaycush) from southern Lake Michigan in 1966-70 (average 18.1 ppm in fish 558-684 mm long) than in lake trout of the same size-class from Lake Superior in 1968-69 (4.4 ppm), and higher in adult coho salmon (Oncorhynchus kisutch) from Lake Michigan in 1968-71 (averages for different year-classes, 9.9 to 14.0 ppm) than in those from Lake Erie in 1969 (2.2 ppm). Residues were significantly higher in lake trout from southern Lake Michigan than in those from the northern part of the lake. In lakes Michigan and Superior, the levels increased with length of fish and percentage oil. In Lake Michigan coho salmon, the residues remained nearly stable (2-4 ppm) from September of the 1st yr of lake residence through May or early June of the 2nd yr, but increased three to four times in the next 3 mo. Residues in Lake Erie coho salmon did not increase during this period, which preceded the spawning season. Although the concentrations of total residues in whole, maturing Lake Michigan coho salmon remained unchanged from August 1968 until near the end of the spawning season in January 1969, the residues were redistributed in the tissues of the spawning-run fish; concentrations in the loin and brain were markedly higher in January than in August. This relocation of DDT residues accompanied a marked decrease in the percentage of oil in the fish, from 13.2 in August to 2.8 in January. Concentrations of residues were relatively high in eggs of both lake trout (4.6 ppm) and coho salmon (7.4-10.2 ppm) from Lake Michigan. The percentage composition of the residues (p,p'DDE, o,p'DDT, p,p'DDD, and p,p'DDT) did not differ significantly with life stage, size, age, or locality, or date of collection of lake trout or coho salmon.

Reinert, Robert E.; Bergman, Harold L.

1974-01-01

207

New estimates of lethality of sea lamprey (Petromyzon marinus) attacks on lake trout (Salvelinus namaycush): Implications for fisheries management  

USGS Publications Warehouse

Sea lamprey (Petromyzon marinus) control in North America costs millions of dollars each year, and control measures are guided by assessment of lamprey-induced damage to fisheries. The favored prey of sea lamprey in freshwater ecosystems has been lake trout (Salvelinus namaycush). A key parameter in assessing sea lamprey damage, as well as managing lake trout fisheries, is the probability of an adult lake trout surviving a lamprey attack. The conventional value for this parameter has been 0.55, based on laboratory experiments. In contrast, based on catch curve analysis, mark-recapture techniques, and observed wounding rates, we estimated that adult lake trout in Lake Champlain have a 0.74 probability of surviving a lamprey attack. Although sea lamprey growth in Lake Champlain was lower than that observed in Lake Huron, application of an individual-based model to both lakes indicated that the probability of surviving an attack in Lake Champlain was only 1.1 times higher than that in Lake Huron. Thus, we estimated that lake trout survive a lamprey attack in Lake Huron with a probability of 0.66. Therefore, our results suggested that lethality of a sea lamprey attack on lake trout has been overestimated in previous model applications used in fisheries management. ?? 2008 NRC.

Madenjian, C.P.; Chipman, B.D.; Marsden, J.E.

2008-01-01

208

Nearshore habitat and fish community associations of coaster brook trout in Isle Royale, Lake Superior  

USGS Publications Warehouse

We characterized the nearshore habitat and fish community composition of approximately 300 km of shoreline within and adjacent to the major embayments of Isle Royale, Lake Superior. Sampling yielded 17 species, of which 12 were widespread and represented a common element of the Lake Superior fish community, including cisco Coregonus artedi, lake whitefish C. clupeaformis, round whitefish Prosopium cylindraceum, lake trout Salvelinus namaycush, rainbow smelt Osmerus mordax, lake chub Couesius plumbeus, longnose sucker Catostomus catostomus, white sucker C. commersonii, trout-perch Percopsis omiscomaycus, ninespine stickleback Pungitius pungitius, burbot Lota lota, and slimy sculpin Cottus cognatus. The presence of brook trout S. fontinalis in an embayment was associated with the common species of the Isle Royale nearshore fish community, particularly cisco, longnose sucker, and round whitefish. However, brook trout were present in only five embayments and were common only in Tobin Harbor. Most Isle Royale embayments had broadly overlapping ranges of nearshore habitats. Within embayments, fish were distributed along a habitat gradient from less-protected rocky habitat near the mouth to highly protected habitat with mixed and finer substrates at the head. Embayments with brook trout had greater mean protection from the open lake, greater variation in depth, greater mean cover, and higher mean frequencies of large substrates (cobble, boulder, and bedrock). Within those embayments, brook trout were associated with habitat patches with higher mean frequencies of small substrates (particularly sand and coarse gravel). Within Tobin Harbor, brook trout were associated with midembayment habitat and species assemblages, especially those locations with a mixture of sand, gravel, and cobble substrates, an absence of bedrock, and the presence of round whitefish, white sucker, and trout-perch. Comparison of embayments with the model, Tobin Harbor, showed that six embayments without brook trout had very similar arrays of habitat. However, four embayments with brook trout had relatively different arrays of habitat from Tobin Harbor. These results suggest that there is potential for further recovery of brook trout populations across Isle Royale nearshore habitats. ?? Copyright by the American Fisheries Society 2008.

Gorman, O.T.; Moore, S.A.; Carlson, A.J.; Quinlan, H.R.

2008-01-01

209

Genetic structure and diversity among brook trout from Isle Royale, Lake Nipigon, and three Minnesota tributaries of Lake Superior  

USGS Publications Warehouse

Brook trout Salvelinus fontinalis from Isle Royale, Michigan, three Minnesota tributaries of Lake Superior, and Lake Nipigon in Ontario were analyzed for genetic variation at 12 microsatellite DNA loci. Analysis of molecular variance, genetic distance measures, and cluster analysis were used to examine the diversity, gene flow, and relatedness among the samples. The diversity estimates for the samples from Isle Royale were similar to those for the samples collected from Minnesota tributaries of Lake Superior, and all estimates were lower than those reported in other studies of brook trout from eastern North America. Genetic differences were detected among the brook trout at Isle Royale, Lake Nipigon, and the Minnesota tributaries of Lake Superior. Further, the population in Tobin Harbor at the eastern end of Isle Royale was distinct from the populations from tributaries at the southwestern end of the island. The Minnesota tributary population formed a group that was genetically distinct from those from Isle Royale and Lake Nipigon. The Isle Royale population should be managed to preserve the genetic and phenotypic variation that distinguishes it from the other brook trout populations analyzed to date.

Stott, Wendylee; Quinlan, Henry R.; Gorman, Owen T.; King, Timothy L.

2010-01-01

210

Trophic transfer efficiency of methylmercury and inorganic mercury to lake trout Salvelinus namaycush from its prey  

USGS Publications Warehouse

Based on a laboratory experiment, we estimated the net trophic transfer efficiency of methylmercury to lake trout Salvelinus namaycush from its prey to be equal to 76.6 %. Under the assumption that gross trophic transfer efficiency of methylmercury to lake trout from its prey was equal to 80 %, we estimated that the rate at which lake trout eliminated methylmercury was 0.000244 day?1. Our laboratory estimate of methylmercury elimination rate was 5.5 times lower than the value predicted by a published regression equation developed from estimates of methylmercury elimination rates for fish available from the literature. Thus, our results, in conjunction with other recent findings, suggested that methylmercury elimination rates for fish have been overestimated in previous studies. In addition, based on our laboratory experiment, we estimated that the net trophic transfer efficiency of inorganic mercury to lake trout from its prey was 63.5 %. The lower net trophic transfer efficiency for inorganic mercury compared with that for methylmercury was partly attributable to the greater elimination rate for inorganic mercury. We also found that the efficiency with which lake trout retained either methylmercury or inorganic mercury from their food did not appear to be significantly affected by the degree of their swimming activity.

Madenijian, C.P.; David, S.R.; Krabbenhoft, D.P.

2012-01-01

211

Trophic transfer efficiency of methylmercury and inorganic mercury to lake trout Salvelinus namaycush from its prey.  

PubMed

Based on a laboratory experiment, we estimated the net trophic transfer efficiency of methylmercury to lake trout Salvelinus namaycush from its prey to be equal to 76.6 %. Under the assumption that gross trophic transfer efficiency of methylmercury to lake trout from its prey was equal to 80 %, we estimated that the rate at which lake trout eliminated methylmercury was 0.000244 day(-1). Our laboratory estimate of methylmercury elimination rate was 5.5 times lower than the value predicted by a published regression equation developed from estimates of methylmercury elimination rates for fish available from the literature. Thus, our results, in conjunction with other recent findings, suggested that methylmercury elimination rates for fish have been overestimated in previous studies. In addition, based on our laboratory experiment, we estimated that the net trophic transfer efficiency of inorganic mercury to lake trout from its prey was 63.5 %. The lower net trophic transfer efficiency for inorganic mercury compared with that for methylmercury was partly attributable to the greater elimination rate for inorganic mercury. We also found that the efficiency with which lake trout retained either methylmercury or inorganic mercury from their food did not appear to be significantly affected by the degree of their swimming activity. PMID:22552852

Madenjian, C P; David, S R; Krabbenhoft, D P

2012-08-01

212

Size-specific mortality in fry of lake trout (Salvelinus namaycush) from Lake Michigan  

SciTech Connect

A study to test the presence and magnitude of size-specific mortality in fry from Lake Michigan lake trout and fry of hatchery origin during exposure to PCBs is presented. Fry from both sources were exposed to 50 ng/l PCBs for about 50 days after hatching and fry from both sources were reared in water to which no PCBs were added. The average lengths of fry from all four groups were significantly less than fry from Lake Michigan. Size-specific mortality observed in fry of Lake Michigan origin could be the result of a number of factors, including origin and condition of parents and environmental stresses, including organic contaminants. Higher mortality of the smaller fry might be considered to have a positive effect on long-term fish production in the larger fish are being selected for, however, decreasing genetic variability in the fish population can result in lower production. Considering the similarity between the physiochemical properties of PCBs and DDT, the substantial concentrations of PCBs in the fry of lake origin may be an important factor in explaining the size-specific mortality observed.

Seelye, J.G.; Mac, M.J.

1981-09-01

213

Development of Thiamine Deficiencies and Early Mortality Syndrome in Lake Trout by Feeding Experimental and Feral Fish Diets Containing Thiaminase  

Microsoft Academic Search

We conducted a laboratory investigation on the consequences of feeding predatory salmonids either experimental diets low in thiamine or diets containing alewife Alosa pseudoharengus. In experiment 1, adult lake trout Salvelinus namaycush were fed experimental diets containing bacterial thiaminase. In experiment 2, adult lake trout were fed natural prey species, alewives, and bloaters Coregonus hoyi. The diets consisted of four

Dale C. Honeyfield; Joy P. Hinterkopf; John D. Fitzsimons; Donald E. Tillitt; James L. Zajicek; Scott B. Brown

2005-01-01

214

Evolution and origin of sympatric shallow-water morphotypes of Lake Trout, Salvelinus namaycush, in Canada's Great Bear Lake.  

PubMed

Range expansion in north-temperate fishes subsequent to the retreat of the Wisconsinan glaciers has resulted in the rapid colonization of previously unexploited, heterogeneous habitats and, in many situations, secondary contact among conspecific lineages that were once previously isolated. Such ecological opportunity coupled with reduced competition likely promoted morphological and genetic differentiation within and among post-glacial fish populations. Discrete morphological forms existing in sympatry, for example, have now been described in many species, yet few studies have directly assessed the association between morphological and genetic variation. Morphotypes of Lake Trout, Salvelinus namaycush, are found in several large-lake systems including Great Bear Lake (GBL), Northwest Territories, Canada, where several shallow-water forms are known. Here, we assess microsatellite and mitochondrial DNA variation among four morphotypes of Lake Trout from the five distinct arms of GBL, and also from locations outside of this system to evaluate several hypotheses concerning the evolution of morphological variation in this species. Our data indicate that morphotypes of Lake Trout from GBL are genetically differentiated from one another, yet the morphotypes are still genetically more similar to one another compared with populations from outside of this system. Furthermore, our data suggest that Lake Trout colonized GBL following dispersal from a single glacial refugium (the Mississippian) and support an intra-lake model of divergence. Overall, our study provides insights into the origins of morphological and genetic variation in post-glacial populations of fishes and provides benchmarks important for monitoring Lake Trout biodiversity in a region thought to be disproportionately susceptible to impacts from climate change. PMID:25204304

Harris, L N; Chavarie, L; Bajno, R; Howland, K L; Wiley, S H; Tonn, W M; Taylor, E B

2015-01-01

215

A review of lake trout (Salvelinus namaycush) restoration in Lake Ontario from an early life history perspective  

USGS Publications Warehouse

The authors conclude that small numbers of lake trout spawned successfully each year during 1992-97 in Lake Ontario, although this has yet to result in a trend of increasing natural reproduction. Juxtaposed with the high abundance of mature fish (Selgeby et al., 1995), the situation in Lake Ontario suggests a reduction in reproductive efficiency. This could result from mortality factors that may to a certain extent be density independent because recruitment has remained flat in the face of increasing spawner abundance. According to RESTORE, such factors are likely acting during the first year of life. Accordingly, the authors herin review the evidence that former barriers to lake trout reproduction in Lake Ontario that act as early-life-stage bottlenecks have been removed. In addition, the authors review other potential new barriers for which there has only recently been enough information to judge their relative importance.

Fitzsimons, John; Lantry, Brian F.; O'Gorman, Robert

2003-01-01

216

Trends of Chlorinated Organic Contaminants in Great Lakes Trout and Walleye from 1970 to 1998  

Microsoft Academic Search

Levels of chlorinated organic contaminants in predator fish have been monitored annually in each of the Great Lakes since\\u000a the 1970s. This article updates earlier reports with data from 1991 to 1998 for lake trout (Salvelinus namaycush) and (Lake Erie only) walleye (Sander vitreus) to provide a record that now extends nearly 30 years. Whole fish were analyzed for a

J. P. Hickey; S. A. Batterman; S. M. Chernyak

2006-01-01

217

Lake trout consumption and recent changes in the fish assemblage of Flaming Gorge Reservoir  

SciTech Connect

Bioenergetics modeling was used to quantify the consumption dynamics of lake trout Salvelinus namaycush in Flaming Gorge Reservoir, Utah-Wyoming. Analysis of diet and population estimates of different size-classes of lake trout indicated that kokanees Oncorhynchus nerka made up the greatest proportion of prey biomass. Examination of growth rates of forage fish and predator-prey size ratios indicated that Utah chub Gila atraria were more vulnerable than kokanees to lake trout predation. Utah chub grow slower than kokanees and thus were susceptible to piscivores over a longer age span. The authors conclude the kokanees will make up an even large proportion of the pelagic fish assemblage of Flaming Gorge Reservoir in future years. 44 refs., 5 figs., 4 tabs.

Yule, D.L. (Wyoming Game and Fish Department, Casper, WY (United States)); Luecke, C. (Utah State Univ., Logan, UT (United States))

1993-11-01

218

PAHs, NITRO-PAHs, HOPANES, AND STERANES IN LAKE TROUT FROM LAKE MICHIGAN  

PubMed Central

The present study examines concentrations and risks of polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), steranes, and hopanes in lake trout collected in Lake Michigan. A total of 74 fish were collected in 2 seasons at 3 offshore sites. The total PAH concentration (?9PAH) in whole fish ranged from 223 pg/g to 1704 pg/g wet weight, and PAH concentrations and profiles were similar across season, site, and sex. The total NPAH (?9NPAH) concentrations ranged from 0.2 pg/g to 31 pg/g wet weight, and carcinogenic compounds, including 1-nitropyrene and 6-nitrochrysene, were detected. In the fall, NPAH concentrations were low at the Illinois site (0.2–0.5 pg/g wet wt), and site profiles differed considerably; in the spring, concentrations and profiles were similar across sites, possibly reflecting changes in fish behavior. In the fall, the total sterane (?5Sterane) and total hopane (?2Hopane) levels reached 808 pg/g and 141 pg/g wet weight, respectively, but concentrations in the spring were 10 times lower. Concentrations in eggs (fall only) were on the same order of magnitude as those in whole fish. These results demonstrate the presence of target semivolatile organic compounds in a top predator fish, and are consistent with PAH biodilution observed previously. Using the available toxicity information for PAHs and NPAHs, the expected cancer risk from consumption of lake trout sampled are low. However, NPAHs contributed a significant portion of the toxic equivalencies in some samples. The present study provides the first measurements of NPAHs in freshwater fish, and results suggest that additional assessment is warranted. PMID:24764175

Huang, Lei; Chernyak, Sergei M.; Batterman, Stuart A.

2015-01-01

219

Movements of lake trout in Twin Lakes, Colorado, in relation to the Mt. Elbert pumped-storage powerplant  

SciTech Connect

Mean movement rates of 34 lake trout (Salvelinus namaycush) tagged with ultrasonic transmitters in Twin Lakes, Colorado, ranged from 1.1 m/min in the fall to 1.6 m/min in the summer. Movement rates between 0830 and 1130 were significantly higher than between 2230 and 0500 during spring, summer, and fall. During the fall, afternoon movements were significantly greater than night movements. It is likely that the lake trout of Twin Lakes will be least vulnerable to entrainment by pumping operations between 2230 and 0500 and most vulnerable between 0830 and 1130 during spring, summer, and fall. Seasonally, they will be least vulnerable in the winter and most vulnerable in the spring.

Walch, L.A.

1980-07-01

220

Biochemistry and metabolism of lake trout: laboratory and field studies on the effects of contaminants  

USGS Publications Warehouse

To evaluate the effects of ambient and higher concentrations of PCB's (Aroclor 1254) and DDE in food and water on fry of lake trout (Salvelinus namaycush) from Lake Michigan, I measured several biochemical indicators of stress in exposed and unexposed (control) fry. No differences between treatments were observed in oxygen consumption rates or lactate concentrations of unexercised fry, but apparent differences in specific swimming speed and lactate response in fry that swam to exhaustion suggested that exposed fry had lower stamina. Observed differences between biochemical profiles of 1-day-old sac fry reared from eggs originating from lake trout collected off Saugatuck and those originating from eggs of brood stock at the Marquette (Michigan) hatchery may have been caused by organochlorine contamination or by genetic and dietary differences between the parental stocks. Activity of the enzyme allantoinase was measured in juvenile and adult lake trout as an indicator of sublethal effects of Great Lakes contaminants. The 50% inhibition of allantoinase in vitro occurred at 6.0 mg/L Cu++, 6.7 mg/L Cd++, 34 mg/L Hg++, and 52 mg/L Pb++. Allantoinase was not affected by in vitro exposure to PCB's up to 7 ?g/g, or DDE or DDT up to 10 ?g/g; however, in vivo exposure resulting in 2.6 ?g/g PCB's in the whole fish activated allantoinase slightly (10% significance level). Allantoinase activity was negatively correlated with total length for fish from Lake Michigan but not for fish from Lake Superior or from laboratory stocks. Mercury, PCB's, and DDT, possibly acting in combination with each other and with additional contaminants, may be the cause of the negative correlation of allantoinase activity with size in Lake Michigan lake trout.

Passino, Dora R. May

1981-01-01

221

Effects of water temperature on survival of eggs and fry of lake trout. [Salvelinus namaycush  

SciTech Connect

Eggs of lake trout (Salvelinus namaycush) were incubated during 1984-1985 and 1985-1986 in chilled, water that decreased in temperature from 41.5/sup 0/F in November to 38.7/sup 0/F in January and then increased to 45.9/sup 0/F in February. Ambient water temperatures varied from 51/sup 0/F in November to 47/sup 0/F in February. The mean survival (range in parentheses) from fertilization through hatching to a size of 2500 fish/lb was 54% (49-59%) in chilled water and 18% (12-21%) in ambient-temperature water. Chilled water enhanced the survival of lake trout of both the Lake Ontario and the Seneca Lake strains.

Ostergaard, D.E.

1987-04-01

222

Use of a seismic air gun to reduce survival of nonnative lake trout embryos: A tool for conservation?  

USGS Publications Warehouse

The detrimental impacts of nonnative lake trout Salvelinus namaycush in the western USA have prompted natural resource management agencies in several states to implement lake trout suppression programs. Currently, these programs rely on mechanical removal methods (i.e., gill nets, trap nets, and angling) to capture subadult and adult lake trout. We conducted a study to explore the potential for using high-intensity sound from a relatively small (655.5 cm3 [40 in3]) seismic air gun to reduce survival of lake trout embryos. Lake trout embryos at multiple stages of development were exposed to a single discharge of the seismic air gun at two depths (5 and 15 m) and at two distances from the air gun (0.1 and 2.7 m). Control groups for each developmental stage, distance, and depth were treated identically except that the air gun was not discharged. Mortality in lake trout embryos treated at 0.1 m from the air gun was 100% at 74 daily temperature units in degrees Celsius (TU°C) at both depths. Median mortality in lake trout embryos treated at 0.1 m from the air gun at 207 TU°C (93%) and 267 °C (78%) appeared to be higher than that of controls (49% and 48%, respectively) at 15-m depth. Among the four lake trout developmental stages, exposure to the air gun at 0.1 m resulted in acute mortality up to 60% greater than that of controls. Mortality at a distance of 2.7 m did not appear to differ from that of controls at any developmental stage or at either depth. Our results indicate that seismic air guns have potential as an alternative tool for controlling nonnative lake trout, but further investigation is warranted.

Cox, B.S.; Dux, A.M.; Quist, M.C.; Guy, C.S.

2012-01-01

223

Comparison of prehatch C-start responses in rainbow trout and lake trout embryos by means of a tactile stimulus test  

USGS Publications Warehouse

The C-start in teleost fishes, a type of startle response, mediates the ability to respond to abrupt, unexpected stimuli and is characterized by a short-latency, C-type fast start acceleration. In prehatch fish embryos, the C-start appears necessary for mechanical breakdown of the egg chorion and successful hatching by way of increased embryo movement and distribution of the hatching enzymes. In later stages, the C-start plays an important role in predator avoidance. Using tactile stimulation, we evaluated the C-start response in rainbow trout Oncorhynchus mykiss at 170 degree-days, when 6.6% of embryos exhibited C-starts, and lake trout Salvelinus namaycush embryos at 320 degree-days, when 23% of embryos exhibited C-starts. Triplicate groups of embryos were later tested at three developmental stages: early (220 and 360 degree-days for rainbow trout and lake trout, respectively), middle (260 and 480 degree-days, respectively), and late (320 and 560 degree-days, respectively). The proportion of trout embryos exhibiting C-start increased through time, such that 100% had responded by the late stage, just prior to hatching. C-starts could be obtained by repeated stimulation, and the relative activity of the embryos (based on the number of flexures per stimulus) also increased over time. Rainbow trout and lake trout showed very similar C-start responses at parallel developmental stages, and these patterns of response were similar to those reported in other fish species.

Wright, P.J.; Noltie, D.B.; Tillitt, D.E.

2003-01-01

224

Effects of Reservoir Operations on Hatchery Coastal Rainbow Trout in Lake Roosevelt, Washington  

Microsoft Academic Search

It is suspected that reservoir operations limit the mitigation fishery for coastal rainbow trout Oncorhynchus mykiss irideus in Lake Roosevelt, Washington. Entrainment through Grand Coulee Dam has been suggested as the primary impact of reservoir operations. However, the causal mechanisms and effects of entrainment have been difficult to quantify. A logistic regression model was used to examine the effect of

Holly J. McLellan; Stephen G. Hayes; Allan T. Scholz

2008-01-01

225

Effects of nonlethal sea lamprey attack on the blood chemistry of lake trout  

USGS Publications Warehouse

A laboratory study examined changes in the blood chemistry of field-caught and hatchery-reared lake trout Salvelinus namaycush subjected to a nonlethal attack by sea lampreys Petromyzon marinus. We measured glucose, total protein, amylase, alkaline phosphatase (ALKP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase, calcium, magnesium, triglycerides, sodium, and potassium with a Kodak Ektachem DT60 Analyzer, Ektachem DTSC Module, and the DTE Module. Mean levels of total protein, AST, ALKP, hematocrit, calcium, magnesium, and sodium decreased significantly (Pa?? 0.05), and mean levels of ALT and potassium increased significantly (Pa?? 0.05) after sea lamprey feeding. Lake trout condition (K) and hematocrit levels also decreased significantly (Pa?? 0.05) after the sea lamprey attack. Frequency distributions of eight lake trout blood chemistry variables and the hematocrit were significantly different before and after a sea lamprey attack. A second study that used hatchery lake trout broodstock measured changes in hematocrit before and after a sea lamprey attack.

Edsall, Carol Cotant; Swink, William D.

2001-01-01

226

Introduction of the Lake Trout (Salvelinus namaycush) in Areas Outside its Native Distribution: A Review  

Microsoft Academic Search

A survey revealed that there have been introductions of the lake trout in 15 countries around the world. Most of these were in Canada and the United States. Of those off the North American continent, three have failed, four have established reproducing populations, and six require regular stocking. Outside the indigenous distribution in North America, four provinces and 15 states

E. J. Crossman

1995-01-01

227

RESPIRATORY-CARDIOVASCULAR PHYSIOLOGY AND XENOBIOTIC GILL FLUX IN THE LAKE TROUT (SALVELINUS NAMAYCUSH)  

EPA Science Inventory

An in vivo respirometer-metabolism chamber was used to obtain respiratory-cardiovascular physiology under normoxic and hypoxic conditions, and xenobiotic gill absorption (flux) data on adult lake trout (Salvelinus namaycush) over a 48-h exposure period at 11? 1?C....

228

Dechlorane plus monoadducts in a Lake Ontario (Canada) food web and biotransformation by lake trout (Salvelinus namaycush) liver microsomes.  

PubMed

Compounds related to the high-production-volume flame retardant Dechlorane Plus (DP) were measured in a Lake Ontario food web located downstream of a DP manufacturing plant. These compounds, 1,3- and 1,5-DP-monoadducts (DPMA), are positional isomers and are thought to arise from the incomplete reaction of DP or impurities in the DP starting material during its manufacture. The 1,3-DPMA isomer was measured (0.12-199?ng?g(-1) lipid wt) in all trophic levels, whereas 1,5-DPMA was measured only sporadically in the food web and was not detectable in the apex predator, lake trout (Salvelinus namaycush). Concentrations of DPMA isomers when detected in Lake Ontario biota were greater than that of total DP for all trophic levels. The prevalence of 1,3-DPMA in the food web, and especially in lake trout, may be due to obstruction of the existing carbon double bond to enzyme attack, rendering it less readily metabolized. To examine this hypothesis, biotransformation kinetic experiments using in vitro lake trout liver microsomal exposures were performed. Zero-order depletion rate constants for 1,3- and 1,5-DPMA were 92.2 and 134.6 pmole h(-1) , respectively, with corresponding half-lives of 2.03?±?0.14?h (1,3-DPMA) and 1.39?±?0.09?h (1,5-DPMA). Furthermore, the 1,5-isomer was depleted to a greater extent than 1,3-DPMA. Specific biotransformation products were not identified. These data support the hypothesis that 1,5-DPMA is more readily metabolized than 1,3-DPMA by lake trout. The present study also shows that the concentrations of these isomers, which the authors speculate might be unintended impurities or byproducts in some technical DP formulations, exceed that of the intended product in biota. PMID:23427074

Tomy, Gregg T; Sverko, Ed; Palace, Vince; Rosenberg, Bruno; McCrindle, Robert; McAlees, Alan; Smith, Lindsay A P; Byer, Jonathan; Pacepavicius, Grazina; Alaee, Mehran; McCarry, Brian E

2013-06-01

229

Depth distribution, diet, and overwinter growth of lake trout (Salvelinus namaycush) in southeastern Lake Michigan sampled in December 1981 and March 1982  

USGS Publications Warehouse

Lake trout were collected in graded-mesh gill nets and forage fishes were collected in trawls in mid December 1981 and late March 1982. The length ranges of 317 lake trout caught in December and 138 in March were 280-767 and 286-857 mm, and the age ranges I-XI and II-XIV, respectively. Three year classes (1977-79) made up almost 80% of the catches of lake trout in both sampling periods. Lake trout were most abundant at depth of 18 to 37 m in December (water temperatures, 5.5-6.8A?C) and at 2864 m in March (water temperatures, 1.0-1.3A?C). Fish of the 1977-79 year classes completed 9 to 24% of their annual growth in length, and 14 to 39% of their growth in weight, between mid December and late March. Lake trout ate mainly alewives (Alosa pseudoharengus), especially young-of-the-year, in December, but primarily slimy sculpins (Cottus cognatus) in March, when alewives were mainly at depths of greater than those occupied by most lake trout. Other important food items were rainbow smelt (Osmerus mordax) and, in deeper water, deepwater sculpins (Myoxocephalus thompsoni). Bloaters (Coregonus hoyi) were eaten only sparingly, although they were abundantly available in both sampling periods. Perhaps this species, which coevolved with the lake trout in Lake Michigan and was important in the native trout's diet, is better able to avoid capture by the trout than are the exotic alewife and rainbow smelt. It may not again become a major forage species unless the other food sources become scarce.

Eck, Gary W.; Wells, LaRue

1986-01-01

230

Physiological correlates of seasonal growth patterns in lake trout Salvelinus namaycush.  

PubMed

Physiological correlates of seasonal growth patterns were measured in lake trout Salvelinus namaycush from two populations with contrasting diets (zooplankton-dominated diet in Louisa Lake; fish-dominated diet in Opeongo Lake). Fish in Opeongo Lake grew faster and were in better condition than fish in Louisa Lake. The most prominent biochemical difference between populations was higher citrate synthase (CS) and cytochrome c oxidase activity in the white muscle of fish from Opeongo Lake, indicating greater sustained swimming activity in this lake. In contrast, lactate dehydrogenase (LDH) activity in white muscle, an indicator of capacity for burst swimming, was similar between lakes. Nucleoside diphosphate kinase (NDPK) activity in white muscle, an indicator of protein synthesis, was higher in Opeongo Lake than in Louisa Lake but only in the autumn. In both lakes, protein concentration and therefore nutritional status increased as the growing season progressed from spring to summer to autumn. Biochemical indicators of growth and activity showed similar seasonal patterns in the two lakes with the spring characterized by high NDPK, high CS and high LDH activities (i.e. high levels of protein synthesis in association with high aerobic and anaerobic activities). These results suggest high foraging effort and allocation to growth early in the growing season in both lakes. PMID:21155784

Morbey, Y E; Couture, P; Busby, P; Shuter, B J

2010-12-01

231

Epizootic neoplasia of the lateral line system of lake trout (Salvelinus namaycush) in New York's Finger Lakes.  

PubMed

This article documents an epizootic of inflammation and neoplasia selectively affecting the lateral line system of lake trout (Salvelinus namaycush) in 4 Finger Lakes in New York from 1985 to 1994. We studied more than 100 cases of this disease. Tumors occurred in 8% (5/64) of mature and 21% (3/14) of immature lake trout in the most severely affected lake. Lesions consisted of 1 or more neoplasm(s) in association with lymphocytic inflammation, multifocal erosions, and ulcerations of the epidermis along the lateral line. Lesions progressed from inflammatory to neoplastic, with 2-year-old lake trout showing locally extensive, intense lymphocytic infiltrates; 2- to 3-year-old fish having multiple, variably sized white masses up to 3 mm in diameter; and fish over 5 years old exhibiting 1 or more white, cerebriform masses greater than 1 cm in diameter. Histologic diagnoses of the tumors were predominantly spindle cell sarcomas or benign or malignant peripheral nerve sheath neoplasms, with fewer epitheliomas and carcinomas. Prevalence estimates did not vary significantly between sexes or season. The cause of this epizootic remains unclear. Tumor transmission trials, virus isolation procedures, and ultrastructural study of lesions failed to reveal evidence of a viral etiology. The Finger Lakes in which the disease occurred did not receive substantially more chemical pollution than unaffected lakes in the same chain during the epizootic, making an environmental carcinogen an unlikely primary cause of the epizootic. A hereditary component, however, may have contributed to this syndrome since only fish of the Seneca Lake strain were affected. PMID:23528941

Spitsbergen, J M; Frattini, S A; Bowser, P R; Getchell, R G; Coffee, L L; Wolfe, M J; Fisher, J P; Marinovic, S J; Harr, K E

2013-05-01

232

Conservation genetics of Lake Superior brook trout: Issues, questions, and directions  

USGS Publications Warehouse

Parallel efforts by several genetic research groups have tackled common themes relating to management concerns about and recent rehabilitation opportunities for coaster brook trout Salvelinus fontinalis in Lake Superior. The questions that have been addressed include the evolutionary and genetic status of coaster brook trout, the degree of relatedness among coaster populations and their relationship to riverine tributary brook trout populations, and the role and effectiveness of stocking in maintaining and restoring coasters to Lake Superior. Congruent genetic results indicate that coasters are an ecotype (life history variant) rather than an evolutionarily significant unit or genetically distinct strain. Regional structure exists among brook trout stocks, coasters being produced from local populations. Introgression of hatchery genes into wild populations appears to vary regionally and may relate to local population size, habitat integrity, and anthropogenic pressures. Tracking the genetic diversity and integrity associated with captive breeding programs is helping to ensure that the fish used for stocking are representative of their source populations and appropriate for rehabilitation efforts. Comparative analysis of shared samples among collaborating laboratories is enabling standardization of genotype scoring and interpretation as well as the development of a common toolkit for assessing genetic structure and diversity. Incorporation of genetic data into rehabilitation projects will facilitate monitoring efforts and subsequent adaptive management. Together, these multifaceted efforts provide comprehensive insights into the biology of coaster brook trout and enhance restoration options. ?? Copyright by the American Fisheries Society 2008.

Wilson, C.C.; Stott, W.; Miller, L.; D'Amelio, S.; Jennings, M.J.; Cooper, A.M.

2008-01-01

233

The use of thiamine and thiamine antagonists to investigate the etiology of early mortality syndrome in lake trout ( Salvelinus namaycush)  

Microsoft Academic Search

Early mortality syndrome (EMS) is a non-infectious disease affecting lake trout and other salmonids in the Great Lakes and in inland lakes. It is characterised by loss of equilibrium, hyperexcitability, anorexia, and eventually death. EMS is associated with low thiamine and treatment of eggs or fry with thiamine-HCl eliminates symptoms and mortality. To verify the role of the active form

John D Fitzsimons; Lenore Vandenbyllaardt; Scott B Brown

2001-01-01

234

Development of thiamine deficiencies and early mortality syndrome in lake trout by feeding experimental and feral fish diets containing thiaminase  

USGS Publications Warehouse

We conducted a laboratory investigation on the consequences of feeding predatory saimonids either experimental diets low in thiamine or diets containing alewife Alosa pseudoharengus. In experiment 1, adult lake trout Salvelinus namaycush were fed experimental diets containing bacterial thiaminase. In experiment 2, adult lake trout were fed natural prey species, alewives, and bloaters Coregonus hoyi. The diets consisted of four combinations of alewives and bloaters from Lake Michigan (100% alewives, 65% alewives-35% bloaters, 35% alewives-65% bloaters, and 100% bloaters), alewives from Cayuga Lake, a casein bacterial thiaminase, and a commercial trout diet. We assessed the effects of each diet on egg thiamine concentration and incidence of an embryonic early mortality syndrome (EMS). In experiment 1, incidence of EMS ranged from 0% to 100%. Significant relationships were found between the incidence of EMS and thiamine. In experiment 2, adult lake trout fed 100% alewives from either Lake Michigan or Cayuga Lake or fish fed the casein bacterial thiaminase diet produced eggs with low thiamine and swim-up fry with EMS. At either 35% or 65% alewives in the diet, egg thiamine was significantly lowered. The number of females that produced offspring that died from EMS were low but demonstrated the negative potential if feral lake trout foraged on either 35% or 65% alewives. Depleted egg thiamine and the onset of EMS required diets containing thiaminase for a minimum of 2 years in lake trout initially fully thiamine replete. We conclude that EMS can be caused by extensive feeding on 100% alewives and dietary levels of 35% or greater may prove detrimental to sustainable reproduction of salmonids in the Great Lakes. The data are consistent with that observed in feral lake trout, and it is concluded that EMS is the result of a thiamine deficiency. ?? Copyright by the American Fisheries Society 2005.

Honeyfield, D.C.; Hinterkopf, J.P.; Fitzsimons, J.D.; Tillitt, D.E.; Zajicek, J.L.; Brown, S.B.

2005-01-01

235

Chronic bioassays of rainbow trout fry with compounds representative of contaminants in Great Lakes fish  

USGS Publications Warehouse

To evaluate the hazard of organic compounds detected in Great Lakes fish by gas chromatography/mass spectrometry, we tested compounds representative of heterocyclic nitrogen compounds, polycyclic aromatic hydrocarbons, and cyclic alkanes and alkenes. Sixty-day bioassays on the effects of nicotine, phenanthrene, pinane, and pinene on the behavior, growth, and survival of rainbow trout fry, Oncorhynchus mykiss, were conducted in a large, constant-flow, temperature-controlled water system. The following 60-day LC50's were determined (mg/L): nicotine 5.0, phenanthrene 0.2, pinane 0.8, and pinene 1.2. Values of lowest observed effects level (LOEL) and no observed effects level (NOEL) showed that growth was generally as sensitive an endpoint as behavior and was more sensitive than time of swim-up. The 60-day LC50 values for rainbow trout were compared with earlier acute bioassays with Daphnia pulex and rainbow trout and chronic bioassays with D.pulex conducted at the Great Lakes Science Center. Rainbow trout fry were less sensitive than daphnids in all tests, indicating that toxicity tests with daphnids should be protective of salmonid fry for these types of compounds. The results for representative compounds indicate that these classes of compounds should be included in aquatic risk assessments at sites in the Great Lakes.

Passino-Reader, Dora R.; Berlin, William H.; Hickey, James P.

1995-01-01

236

Effects of vitamin B1 (thiamine) deficiency in lake trout (Salvelinus namaycush) alevins at hatching stage.  

PubMed

The objectives of this study were to examine the relationship between thiamine concentrations in unfertilized eggs and yolksac individuals of lake trout (Salvelinus namaycush), along with any associated histopathological changes in the tissues of alevins at the hatching stage. We address these questions in a lake trout population from different spawning grounds of Lake Michigan (North and South), known for compromised survival due to early mortality syndrome (EMS). However, a dichotomous forage base of lake trout spawning stocks, with a dietary thiaminase-rich alewife in the North, and dietary low-thiaminase round goby in the South, provides the basis for the assumption that different diets may lead to differences in severity of EMS between different stocks. Lake trout eggs of 18 females were collected and fertilized individually with the sperm of several males. The eggs, eyed embryos and newly-hatched alevins were sampled to examine thiamine utilization during embryogenesis. Progenies of females with low (< 0.73 nmol/g) and high (> 0.85 nmol/g) levels of thiamine were chosen for histological studies. The obtained results showed that total thiamine levels in the body and yolk of eyed embryos and alevins at hatching were influenced by thiamine levels of unfertilized eggs and it decreased during embryogenesis (to 51% in eyed embryos and 28% in newly-hatched alevins in comparison to unfertilized eggs). The survival of lake trout until hatching stage does not correlate with the thiamine level, however it was affected by collection site and was significantly higher in fish from the South site (Julian's Reef). At the hatching stage, no pathological changes were observed in the brain, olfactory lobe, retina or liver in embryos regardless of thiamine concentrations in unfertilized eggs. It has been concluded that an enhanced thiamine requirement for the fast muscle mass growth near the swim-up stage is responsible for overt and histopathological signs of EMS. Current study confirms earlier findings that lake trout suffering from EMS can be successfully treated by immersion in thiamine solution as late as at the swim-up stage. PMID:19576291

Jaroszewska, Marta; Lee, Bong-Joo; Dabrowski, Konrad; Czesny, Sergiusz; Rinchard, Jacques; Trzeciak, Paulina; Wilczy?ska, Bogdana

2009-10-01

237

Myxobolus cerebralis in native cutthroat trout of the Yellowstone Lake ecosystem  

USGS Publications Warehouse

The exotic parasite Myxobolus cerebralis was first detected in native adult Yellowstone cutthroat trout Oncorhynchus clarkii bouvierii from Yellowstone Lake in 1998, seriously threatening the ecological integrity of this pristine, naturally functioning ecosystem. We immediately began to assess the prevalence and spatial extent of M. cerebralis infection in Yellowstone cutthroat trout within Yellowstone Lake and to determine the infection risk of age-0 Yellowstone cutthroat trout, the relative abundance and actinospore production of lubificid worms, and the basic environmental characteristics of tributaries. During 1999-2001, juvenile and adult Yellowstone cutthroat trout were infected throughout Yellowstone Lake; the highest prevalence (15.3-16.4%) occurred in the northern and central regions. Exposure studies in 13 streams indicated that Pelican and Clear creeks and the Yellowstone River were positive for M. cerebralis; the highest prevalence (100%) and severity was found in Pelican Creek during mid-July. Sexually mature individuals of the oligochaete Tubifex tubifex were most abundant in early summer, were genetically homogenous, and were members of a lineage known to produce moderate to high levels of M. cerebralis triactinomyxons. Only 20 of the 3,037 sampled tubificids produced actinospores after 7 d in culture, and none of the actinospores were M. cerebralis. However, one non-actinospore-producing T. tubifex from Pelican Creek tested positive for M. cerebralis by polymerase chain reaction. Stream temperatures at Pelican Creek, a fourth-order, low-gradient stream, were over 20??C during the first exposure period, suggesting that T. tubifex were capable of producing triactinomyxons at elevated temperatures in the wild. Although the infection of otherwise healthy adult Yellowstone cutthroat trout within Yellowstone Lake suggests some resistance, our sentinel cage exposures indicated that this subspecies may be more susceptible to whirling disease than previous laboratory challenges have indicated, and M. cerebralis may be contributing to a significant recent decline in this population. ?? Copyright by the American Fisheries Society 2006.

Koel, T.M.; Mahony, D.L.; Kinnan, K.L.; Rasmussen, C.; Hudson, C.J.; Murcia, S.; Kerans, B.L.

2006-01-01

238

Metabolism and Fatty Acid Profile in Fat and Lean Rainbow Trout Lines Fed with Vegetable Oil: Effect of Carbohydrates  

PubMed Central

The present study investigated the effect of dietary carbohydrates on metabolism, with special focus on fatty acid bioconversion and flesh lipid composition in two rainbow trout lines divergently selected for muscle lipid content and fed with vegetable oils. These lines were chosen based on previously demonstrated potential differences in LC-PUFA synthesis and carbohydrate utilization. Applying a factorial study design, juvenile trout from the lean (L) and the fat (F) line were fed vegetable oil based diets with or without gelatinised starch (17.1%) for 12 weeks. Blood, liver, muscle, intestine and adipose tissue were sampled after the last meal. Feed intake and growth was higher in the L line than the F line, irrespective of the diet. Moderate postprandial hyperglycemia, strong induction of hepatic glucokinase and repressed glucose-6-phosphatase transcripts confirmed the metabolic response of both lines to carbohydrate intake. Further at the transcriptional level, dietary carbohydrate in the presence of n-3 LC-PUFA deficient vegetable oils enhanced intestinal chylomicron assembly, disturbed hepatic lipid metabolism and importantly elicited a higher response of key desaturase and elongase enzymes in the liver and intestine that endorsed our hypothesis. PPAR? was identified as the factor mediating this dietary regulation of fatty acid bioconversion enzymes in the liver. However, these molecular changes were not sufficient to modify the fatty acid composition of muscle or liver. Concerning the genotype effect, there was no evidence of substantial genotypic difference in lipid metabolism, LC-PUFA synthesis and flesh fatty acid profile when fed with vegetable oils. The minor reduction in plasma glucose and triglyceride levels in the F line was linked to potentially higher glucose and lipid uptake in the muscle. Overall, these data emphasize the importance of dietary macro-nutrient interface in evolving fish nutrition strategies. PMID:24124573

Kamalam, Biju Sam; Médale, Françoise; Larroquet, Laurence; Corraze, Geneviève; Panserat, Stephane

2013-01-01

239

Biomagnification of mercury through lake trout (Salvelinus namaycush) food webs of lakes with different physical, chemical and biological characteristics.  

PubMed

Mercury (Hg) biomagnification in aquatic ecosystems remains a concern because this pollutant is known to affect the health of fish-eating wildlife and humans, and the fish themselves. The "rate" of mercury biomagnification is being assessed more frequently using stable nitrogen isotope ratios (?(15)N), a measure of relative trophic position of biota within a food web. Within food webs and across diverse systems, log-transformed Hg concentrations are significantly and positively related to ?(15)N and the slopes of these models vary from one study to another for reasons that are not yet understood. Here we compared the rates of Hg biomagnification in 14 lake trout lakes from three provinces in Canada to understand whether any characteristics of the ecosystems explained this among-system variability. Several fish species, zooplankton and benthic invertebrates were collected from these lakes and analyzed for total Hg (fish only), methyl Hg (invertebrates) and stable isotopes (?(15)N; ?(13)C to assess energy sources). Mercury biomagnification rates varied significantly across systems and were higher for food webs of larger (surface area), higher nutrient lakes. However, the slopes were not predictive of among-lake differences in Hg in the lake trout. Results indicate that among-system differences in the rates of Hg biomagnification seen in the literature may be due, in part, to differences in ecosystem characteristics although the mechanisms for this variability are not yet understood. PMID:22982939

Kidd, Karen A; Muir, Derek C G; Evans, Marlene S; Wang, Xioawa; Whittle, Mike; Swanson, Heidi K; Johnston, Tom; Guildford, Stephanie

2012-11-01

240

Identification of sex chromosomes in lake trout (Salvelinus namaycush)  

Microsoft Academic Search

In the male trout there is a difference in the quinacrine banding and C-banding patterns between the two homologs of the second largest chromosome pair. This chromosome is the only large submetacentric in the karyotype, making it easy to identify and suggesting that the sex chromosomes have become differentiated since the time of tetraploidization. In males one homolog has a

R. B. Phillips; P. E. Ihssen

1985-01-01

241

PCR assay for improved diagnostics of epitheliotropic disease virus (EEDV) in lake trout Salvelinus namaycush.  

PubMed

Epizootic epitheliotropic disease virus (EEDV) has caused catastrophic losses among hatchery-reared juvenile lake trout Salvelinus namaycush since the early 1980s and remains a major impediment to lake trout restoration in the Great Lakes basin of the USA. Although EEDV has been tentatively designated as a herpesvirus based upon morphological criteria, further characterization of the virus and development of improved detection methods have been hampered by the inability to propagate the virus in cell culture. Recently obtained sequence data for a region of the putative terminase gene from EEDV as well as the related Salmonid herpesvirus 1 and 2 have permitted the development of a polymerase chain reaction (PCR) assay for specific detection of EEDV. The new EEDV PCR demonstrated both an excellent analytic sensitivity and specificity and detected viral DNA as present in the skin of lake trout during periods of active viral outbreaks. In addition, EEDV DNA was detected among healthy appearing juveniles and in the ovarian fluids of spawning adults. Here we describe the development and initial validation steps of the EEDV PCR as a replacement for current diagnostic methods that require virus extraction from the skin, partial purification by isopycnic centrifugation, and visualization of negatively-stained virions by electron microscopy. PMID:19419003

Kurobe, T; Marcquenski, S; Hedrick, R P

2009-03-01

242

Effect of water temperature on sea lamprey growth and lake trout survival  

SciTech Connect

Percent mortality of lake trout Salvelinus namaycush subjected to single sea lamprey Petromyzon marinus attacks did not differ significantly between lower-temperature (mortality = 54%; temperature [le] 10[degrees]C; N = 33) and higher-temperature (mortality = 69%; temperature = 12.8-14.4[degrees]C; N = 45) laboratory studies conducted from 1 June to 28 November 1989. However, sea lampreys fed longer and killed fewer fish in colder water (mean attachment 467.0 h; 18 fish killed) than in warmer water (mean attachment 161.7 h; 31 fish killed), probably because food consumption was lower in colder water. These results indicate that the number of fish killed by sea lampreys could be much greater in warmer water and that temperature must be considered when fish losses from sea lamprey attacks are estimated. Previous studies (Swink and Hanson 1989; Swink 1990) of the effects of single sea lamprey Petromyzon marinus attacks on lake trout Salvelinus namaycush showed significantly less lake trout mortality at temperatures of 10[degrees]C and lower than at higher temperatures. The reduced host mortality, however, could not be attributed solely to lower temperature because warmwater and coldwater attacks occurred during different seasons. In those studies, the author was unable to hold water temperature at 10[degrees]C or less in late summer and early fall, when most fish are killed by sea lampreys in the Great Lakes (Christie and Kolenosky 1980; Bergstedt and Schneider 1988). Modifications to the fish holding facilities at the Hammond Bay Biological Station in 1988 allowed maintenance of a limited amount of water at 10[degrees]C or less throughout the year. Hence, the objective of this study was to compare sea lamprey-induced mortality of lake trout at 10[degrees]C or less with that at 12.8-14.4[degrees]C during the normal feeding season (June through November). 15 refs., 1 fig., 1 tab.

Swink, W.D. (Hammond Bay Biological Station, Millersburg, MI (United States))

1993-11-01

243

Comparison of hatchery-reared lake trout stocked as fall fingerlings and as spring yearlings in Lake Ontario  

USGS Publications Warehouse

We made 16 paired releases of lake trout Salvelinus namaycush of four year classes (1979-1982) at five locations to compare survival and growth of hatchery-reared fish stocked as fall fingerlings (FF) and as spring yearlings (SY). Comparisons were based on fish at ages 2-8 recovered with bottom trawls, with gill nets, and from anglers' catches. Mean lengths and weights were greater for SY than for FF at all ages, and SY attained sexual maturity at an earlier age than FF. The survival of FF may have been affected by average size at stocking and by the severity of the weather during the first winter after stocking. Survival ratios of SY to FF lake trout from stocking to age 2 ranged from 1.32:1 to 6.80:1, and a ratio of 2.41:1 was considered to be typical. Stocking cost per 1,000 fish was US$21.76 for FF and $35.45 for SY. Under the most cost-effective hatchery regime for producing lake trout (the maximum number of SY plus some FF to fully utililize hatchery space and personnel year round), rearing cost per 1,000 fish was estimated to be $235.41 for SY and $38.75 for FF.

Elrod, Joseph H.; Ostergaard, David E.; Schneider, Clifford P.

1988-01-01

244

Ecological effects of a single intraperitoneal injection of [{sup 14}C]-2,3,4,7,8-pentachlorodibenzofuran on feral populations of lake trout and white suckers  

SciTech Connect

In 1989 a total of 24 lake trout and 35 white suckers from a small lake located in the Experimental Lakes Area (ELA) in northwestern Ontario were each targeted with an I.P. injection of [{sup 14}C]-s,3,4,7,8-pentachlorodibenzofuran in corn oil, to a dose of 1 ng{center_dot}g{sup {minus}1}. Fish were tagged, returned to the lake and recaptured during spawning runs in 1990, 1991 and 1992. Sub-samples of treated and control fish were sacrificed each year for residue and biochemical analyses. Treated females were spawned in 1990 and 1991. Analysis of tag-recapture data showed lower survival of treated lake trout over four years. Growth was significantly lower in white suckers in all years but unaffected in lake trout. Fertilization rate of eggs was lower in eggs from treated female white suckers, but not in lake trout. However, only 1 of 4 treated female lake trout recaptured had undergone oogenesis in the last two years of recaptures. Measurements of EROD showed sustained induction in both lake trout and white suckers. Hepatic levels of retinoids were significantly decreased in lake trout but not in white suckers. Calculated half-lives of P{sub 5}CDF were 9.6 years for lake trout and 4.3 years for white suckers. It appears that long term ecological performance was impaired in both species.

Delorme, P.D. [Univ. of Manitoba, Winnipeg (Canada); Lockhart, W.L.; Muir, D.C.G.; Mills, K.H.; Brown, S.B. [Dept. of Fisheries and Oceans, Winnipeg, Manitoba (Canada). Freshwater Inst.

1994-12-31

245

Paenibacillus thiaminolyticus is not the cause of thiamine deficiency impeding lake trout (Salvelinus namaycush) recruitment in the Great Lakes  

USGS Publications Warehouse

Thiamine (vitamin B1) deficiency is a global concern affecting wildlife, livestock, and humans. In Great Lakes salmonines, thiamine deficiency causes embryo mortality and is an impediment to restoration of native lake trout (Salvelinus namaycush) stocks. Thiamine deficiency in fish may result from a diet of prey with high levels of thiaminase I. The discoveries that the bacterial species Paenibacillus thiaminolyticus produces thiaminase I, is found in viscera of thiaminase-containing prey fish, and causes mortality when fed to lake trout in the laboratory provided circumstantial evidence implicating P. thiaminolyticus. This study quantified the contribution of P. thiaminolyticus to the total thiaminase I activity in multiple trophic levels of Great Lakes food webs. Unexpectedly, no relationship between thiaminase activity and either the amount of P. thiaminolyticus thiaminase I protein or the abundance of P. thiaminolyticus cells was found. These results demonstrate that P. thiaminolyticus is not the primary source of thiaminase activity affecting Great Lakes salmonines and calls into question the long-standing assumption that P. thiaminolyticus is the source of thiaminase in other wild and domestic animals.

Richter, Catherine A.; Evans, Allison N.; Wright-Osment, Maureen K.; Zajicek, James L.; Heppell, Scott A.; Riley, Stephen C.; Krueger, Charles C.; Tillitt, Donald E.

2012-01-01

246

Thiamine status of Cayuga Lake rainbow trout and its influence on spawning migration  

USGS Publications Warehouse

Rainbow trout Oncorhynchus mykiss in Cayuga Lake, New York, appear to be suffering from a thiamine deficiency because their progeny develop general weakness, loss of equilibrium, and increased mortality, which are prevented by treatment with thiamine. Thiamine status and its effect on adults are unknown. In 2000 and 2002, we captured, tagged, and released 64 and 189 prespawning rainbow trout, respectively, in Cayuga Inlet at a collection weir to evaluate their thiamine status and the effect of thiamine injection (150 nmol/g) on instream migration. Half of the rainbow trout in each year (32 in 2000 and 95 in 2002) were injected with thiamine and half were uninjected; all rainbow trout were released above the weir to continue their upstream migration. By means of electrofishing in 2000, we recaptured significantly more thiamine-injected (N = 7) than uninjected (N = 0) rainbow trout approximately 7.0-9.3 river kilometers upstream from the weir. In 2002, the concentration of thiamine in the muscle of rainbow trout collected above a 1.8-m cascade was significantly higher (mean A? SD = 5.47 A? 5.04 nmol/g; range = 1.0- 13.8 nmol/g; N = 8) than that of rainbow trout collected either above a 1.0-m cascade (1.36 A? 0.71 nmol/g; range = 0.6-3.3 nmol/g; N = 16) or below the cascades (1.20 A? 0.46 nmol/g; range = 0.7-1.9 nmol/g; N = 5). The lowest concentration of thiamine observed in the muscle of rainbow trout collected upstream of the 1.8-m cascade was 1.0 nmol/g, suggesting that the threshold concentration required for rainbow trout to ascend the cascade was no more than that. Analyses of thiamine in the muscle of 26 untagged rainbow trout captured in Cayuga Inlet in 2002 showed that 16 fish (62%) had at least 1.0 nmol/g, which was apparently sufficient to support vigorous migration.

Ketola, H. George; Chiotti, Thomas L.; Rathman, Robert S.; Fitzsimons, John D.; Honeyfield, Dale C.; Van Dusen, Peter J.; Lewis, Graham E.

2005-01-01

247

Within and among-population variation in the trophic position of a pelagic predator, lake trout ( Salvelinus namaycush )  

Microsoft Academic Search

Many aquatic consumers have flexible feeding habits, and the diet and trophic position of a species can be expected to vary both within and among populations. In this study, we quantify the importance of both within- and among-population trophic variation for lake trout (Salvelinus namaycush) using stable isotope designations of trophic position from 13 Ontario and Quebec lakes. Lake-to-lake differences

M. Jake Vander Zanden; Brian J. Shuter; Nigel P. Lester; Joseph B. Rasmussen

2000-01-01

248

Phylogeographic origins of lake trout ( Salvelinus namaycush ) in eastern North America  

Microsoft Academic Search

Abstract: There is little consensus regarding either the number,or relative importance of Pleistocene glacial refugia occupied by lake trout (Salvelinus namaycush). Mitochondrial DNA restriction fragment length polymorphisms,were analyzed to test existing hypotheses concerning the postglacial origins and dispersal of Salvelinus namaycush,in eastern North America. Analysis of fish from geographically widespread populations with 20 restriction enzymes,revealed three distinct mitochondrial lineages. These

Chris C. Wilson; Paul D. n. Hebert

1996-01-01

249

Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.  

PubMed

A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ? Erie > Huron > Superior ? Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid. PMID:22722738

Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

2012-11-01

250

Review of potential interactions between stocked rainbow trout and listed Snake River sockeye salmon in Pettit Lake Idaho  

SciTech Connect

The objective of this study was to determine if hatchery rainbow trout compete with or prey on juvenile Snake River sockeye salmon Oncorhynchus nerka in Pettit Lake, Idaho. In 1995, a total of 8,570 age-0 sockeye and 4,000 hatchery rainbow trout were released in Pettit Lake. After releasing the fish, gillnets were set in the pelagic and littoral zones to collected diet and spatial distribution data. Interactions were assessed monthly from June 1995 through March 1996. Competition for food was discounted based on extremely low diet overlap results observed throughout the sample period. Conversely, predation interactions were more significant. A total of 119 rainbow trout stomachs were analyzed, two contained O. nerka. The predation was limited to one sample period, but when extrapolated to the whole rainbow trout populations results in significant losses. Total consumption of O. nerka by rainbow trout ranged from an estimated 10 to 23% of initial stocking numbers. Predation results contradict earlier findings that stocked rainbow trout do not prey on wild kokanee or sockeye in the Sawtooth Lakes. The contradiction may be explained by a combination of poorly adapted hatchery sockeye and a littoral release site that forced spatial overlap that was not occurring in the wild populations. Releasing sockeye in the pelagic zone may have reduced or eliminated predation losses to rainbow trout.

Teuscher, D.

1996-05-01

251

Limnology of nine small lakes, Matanuska-Susitna Borough, Alaska, and the survival and growth rates of rainbow trout  

USGS Publications Warehouse

The survival and growth rates of rainbow trout (Salmo gairdnieri) were concurrently measured with selected limnological characteristics in nine small (surface area < 25 sq hectometers) lakes in the Matanuska-Susitna Borough. The project goal was to develop empirical models for predicting rainbow trout growth rates from the following variables: total phosphorus concentration, chlorophyll a concentration, Secchi disc transparency, or the morphoedaphic index--a means of characterizing potential biological productivity. No suitable model could be developed from the data collected during 1982 and 1983. The lack of significant correlation was attributed in part to the wide variation in survival of rainbow trout. Winterkills, caused by severe depletion of dissolved oxygen, were suspected in four of the lakes. Varied levels of fishing pressure and competition with threespine stickleback (Gasterosteus aculeatus) also influenced survival of rainbow trout but their effects were overshadowed by winterkill. Predictive capability was also reduced because of inconsistencies in rankings generated by each of the four limnological variables chosen as indicators of potential biological productivity. A lake ranked low in productivity by one variable was commonly ranked high in productivity by another variable. The survivability of rainbow trout stocked in lakes such as these nine may be a more important indicator of potential biomass production than are indicators of lake fertility. Assessments of a lake 's susceptibility to winterkill and the degree of competition with threespine stickleback are suggested as important topics for additional research. (Author 's abstract)

Woods, P.F.

1985-01-01

252

Acute and chronic toxicity of nitrate to early life stages of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis).  

PubMed

The acute and chronic toxicity of the nitrate ion (NO3-) to the embryos, alevins, and swim-up fry of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) were tested in laboratory aquaria. The acute (96-h) median lethal concentration (LC50) for swim-up fry was 1,121 mg NO3-N/L for lake trout and 1,903 mg NO3-N/L for lake whitefish. The chronic (approximately 130-150-d) LC50s for embryos to swim-up fry were 190 and 64 mg NO3-N/L, respectively. Sublethal effects on developmental timing and fry body size were observed at concentrations of 6.25 and 25 mg NO3-N/L, respectively, in the chronic tests. These results confirm that the Canadian nitrate water-quality guideline of 2.9 mg NO3-N/L, which was derived from chronic tests on a temperate-zone amphibian, is applicable to the early life stages of two species of Arctic fish. However, it does not support use of the guideline for acute exposures during early life stages of salmonid fish or for acute or chronic exposures to adult fish, which are relatively insensitive to nitrate. PMID:16916038

McGurk, Michael D; Landry, François; Tang, Armando; Hanks, Chris C

2006-08-01

253

Acute toxicities to larval rainbow trout of representative compounds detected in Great Lakes fish  

USGS Publications Warehouse

In recent years the National Fisheries Research Center-Great Lakes has ranked the potential hazard to fish and invertebrates of various chemical compounds detected in two Great Lakes fishes-- lake trout, Salvelinus namaycush, and walleye, Stizostedion vitreum vitreum (Hesselberg and Seelye 1982). This hazard assessment has included the identification of the potential sources of the compounds, determination of the occurrence and abundance of the compounds in Great Lakes fish, and the determination of acute toxicities of representative compounds of 19 chemical classes (Passino and Smith 1987a). In further studies Smith et al. (1988) focused on 6 of the 19 classes of compounds using the zooplankter Daphnia pulex as the test organism. They ranked the six classes as follows (in decreasing order of toxicity): polycyclic aromatic hydrocarbons (PAHs), alkyl halides, nitrogen-containing compounds, cyclic alkanes, heterocyclic nitrogen compounds, and silicon-containing compounds.

Edsall, Carol Cotant

1991-01-01

254

Assessment of sea lamprey (Petromyzon marinus) predation by recovery of dead lake trout (Salvelinus namaycush) from Lake Ontario, 1982-85  

USGS Publications Warehouse

During 1982-85, 89 dead lake trout (Salvelinus namaycush) were recovered with bottom trawls in U.S. waters of Lake Ontario: 28 incidentally during four annual fish-stock assessment surveys and 61 during fall surveys for dead fish. During the assessment surveys, no dead lake trout were recovered in April-June, one was recovered in August, and 27 were recovered in October or November, implying that most mortality from causes other than fishing occurred in the fall. The estimated numbers of dead lake trout between the 30- and 100-m depth contours in U.S. waters ranged from 16 000 (0.08 carcass/ha) in 1983 to 94 000 (0.46 carcass/ha) in 1982. Of 76 carcasses fresh enough to enable recognition of sea lamprey (Petromyzon marinus) wounds, 75 bore fresh wounds. Assuming that sea lamprey wounding rates on dead fish were the same as on live ones of the same length range (430-740 mm), the probability of 75 of the 76 dead lake trout bearing sea lamprey wounds was 3.5 x 10-63 if death was independent of sea lamprey attack, thus strongly implicating sea lampreys as the primary cause of death of fish in the sample. The recovery of only one unwounded dead lake trout also suggested that natural mortality from causes other than sea lamprey attactks is negligible.

Bergstedt, Roger A.; Schneider, Clifford P.

1988-01-01

255

Influence of basin-scale physical variables on life history characteristics of cutthroat trout in Yellowstone Lake  

USGS Publications Warehouse

Individual spawning populations of Yellowstone cutthroat trout Oncorhynchus clarki bouvieri differ in life history characteristics associated with broad spatial and temporal environmental patterns, but relationships between specific life history characteristics of Yellowstone cutthroat trout and physical aspects of the environment are poorly understood. We examined basin-scale physical characteristics of tributary drainages and subbasins of Yellowstone Lake in relation to timing (peak and duration) of lacustrinea??adfluvial Yellowstone cutthroat trout spawning migrations and mean length of cutthroat trout spawners in 27 tributaries to the lake. Stream drainages varied along gradients that can be described by mean aspect, mean elevation, and drainage and stream size. Approximately two-thirds of the variation in the timing of the peak of the annual cutthroat trout spawning migrations and average length of spawners was explained by third-order polynomial regressions with mean aspect and basin area as predictor variables. Because most cutthroat trout ascend tributaries soon after peak runoff, it appears that the influence of basin-scale physical variables on the date of the migration peak is manifested by the pattern of stream discharge. Spawner length does not seem to be a direct function of stream size in the Yellowstone Lake watershed, and aspect of the tributary basin seems to have a greater influence on the body length of cutthroat trout spawners than does stream size. Mechanisms that explain how the interaction of basin-scale physical variables influence spawner length were not investigated directly; however, we found evidence of distinct aggregations of cutthroat trout that are related to physical and limnological characteristics of the lake subbasins, and there is some indication that lake residence may be related to tributary location.

Gresswell, Robert E.; Liss, W.J.; Larson, Gary L.; Bartlein, P.J.

1997-01-01

256

Temporal and Age-Related Trends in Levels of Polychlorinated Biphenyl Congeners and Organochlorine Contaminants in Lake Ontario Lake Trout ( Salvelinus namaycush)  

Microsoft Academic Search

Concentrations of 21 organochlorine contaminants (OCs) and 61 polychlorinated biphenyl (PCB) congeners were determined in archived samples of whole lake trout (Salvelinus namaycush), age 4 years, collected yearly from eastern Lake Ontario between 1977 and 1993. Temporal trend data show decreases in all parameters analyzed in samples collected from 1977 to 1993. OC levels declined between 60 and 90% from

Susan Y. Huestis; Mark R. Servos; D. Michael Whittle; D. George Dixon

1996-01-01

257

Quantifying the potential effects of climate change and the invasion of smallmouth bass on native lake trout populations across Canadian lakes  

Microsoft Academic Search

Climate change and invasive species are two stressors that should have large impacts on native species in aquatic and terrestrial ecosystems. We quantify and integrate the effects of climate change and the establishment of an invasive species (smallmouth bass Micropterus dolomieu) on native lake trout Salvelinus namaycush populations. We assembled a dataset of almost 22 000 Canadian lakes that contained

Sapna Sharma; Donald A. Jackson; Charles K. Minns

2009-01-01

258

Maternal characteristics versus egg size and energy density: do stocked lake trout in Lake Ontario experience premature reproductive senescence?  

USGS Publications Warehouse

Observations from September 1994 and 1997 collections of hatchery-origin, mature female lake trout (Salvelinus namaycush) from Lake Ontario indicated that egg mass decreased with age, fueling the notion that stocked fish experienced premature reproductive senescence. Supplemental collections during September 2002 and November 2002-2004 were combined with the 1994 and 1997 samples to examine whether sample date or maternal age, body mass, condition (K), egg count, or strain were related to egg mass or energy content (percentage dry mass [%DM]). Body mass was correlated with egg mass for age ? 8 lake trout sampled in September, and egg count was correlated with egg mass for September age-6 lake trout only. Within each month, egg mass was not related to K or egg %DM, however, egg %DM was 1.52% greater (P ? 0.0247) in November than in September which is equivalent to a 110 cal/g difference. Samples were grouped for the three most abundant strains (Seneca, Superior, and Ontario) after finding no strain or year effects from our 1994 and 1997 samples and based on life history data from the literature and our assessment sampling. Further analysis indicated that September egg masses were greater for fish ages ? 6 than for fish ages ? 8. The age effect disappeared in November when mean egg mass across all ages (0.078 g) was greater than September means (P < 0.0005) for ages -5 (0.054 g), -6 (0.057 g) and ? 8 (0.041 g). Our results indicate that the decrease in egg mass with female age in September was not due to senescence, but to oogenesis being closer to completion in young age-5 and -6 fish than in older individuals.

Lantry, B.F.; O'Gorman, R.; Machut, L.S.

2008-01-01

259

Lake Roosevelt Rainbow Trout : Habitat/Passage Improvement Project Annual Report 2000.  

SciTech Connect

Lake Franklin D. Roosevelt was created with the completion of the Grand Coulee Dam in 1942. The lake stretches 151 miles up-stream to the International border between the United States and Canada at the 49th parallel. Increased recreational use, subsistence and sport fishing has resulted in intense interest and possible exploitation of the resources within the lake. Previous studies of the lake and its fishery have been limited. Early studies indicate that natural reproduction within the lake and tributaries are not sufficient to support a rainbow trout (Onchoryhnchus mykiss) fishery (Scholz et. al., 1988). These studies indicate that the rainbow trout population may be limited by lack of suitable habitat for spawning and rearing (Scholz et. al., 1988). The initial phase of this project (Phase I, baseline data collection- 1990-91) was directed at the assessment of limiting factors such as quality and quantity of available spawning gravel, identification of passage barriers, and assessment of other limiting factors. Population estimates were conducted using the Seber/LeCren removal/depletion method. After the initial assessment of stream parameters, several streams were selected for habitat/passage improvement projects (Phase II, implementation-1992-96). At the completion of project habitat improvements, the final phase (Phase III, monitoring) began. This phase will assess changes and gauge the success achieved through the improvements. The objective of the project is to correct passage barriers and improve habitat conditions of selected tributaries to Lake Roosevelt for adfluvial rainbow trout that utilize tributary streams for spawning and rearing. Streams with restorable habitats were selected for improvements. Completion of improvement efforts should increase the adfluvial rainbow trout contribution to the resident fishery in Lake Roosevelt. Three co-operating agencies, the Confederated Tribes of the Colville Reservation (CCT), the Spokane Tribe of Indians (STI) and the Washington Department of Fish and Wildlife initiated the project fieldwork in 1990. Phase II included only the Confederated Tribes of the Colville Reservation and the Spokane Tribe of Indians. Phase III is being completed by the Confederated Tribes of the Colville Reservation.

Sear, Sheri

2001-02-01

260

Lake Roosevelt Rainbow Trout : Habitat/Passage Improvement Project : Annual Report 1998.  

SciTech Connect

Lake Franklin D. Roosevelt was created with the completion of the Grand Coulee Dam in 1942. The lake stretches 151 miles up-stream to the International border between the United States and Canada at the 49th parallel. Increased recreational use, subsistence and sport fishing has resulted in intense interest and possible exploitation of the resources within the lake. Previous studies of the lake and its fishery have been limited. Early studies indicate that natural reproduction within the lake and tributaries are not sufficient to support a rainbow trout (Onchoryhnchus mykiss) fishery (Scholz et. al., 1988). These studies indicate that the rainbow trout population may be limited by lack of suitable habitat for spawning and rearing (Scholz et. al., 1988). The initial phase of this project (Phase I, baseline data collection) was directed at the assessment of limiting factors such as quality and quantity of available spawning gravel, identification of passage barriers, and assessment of other limiting factors. Population estimates were conducted using the Seber/LeCren removal/depletion method. After the initial assessment of stream parameters, several streams were selected for habitat/passage improvement projects (Phase II, implementation). At the completion of project habitat improvements, the final phase (Phase III, monitoring) began. This phase will assess changes and gauge the success achieved through the improvements. The objective of the project is to correct passage barriers and improve habitat conditions of selected tributaries to Lake Roosevelt for adfluvial rainbow trout that utilize tributary streams for spawning and rearing. Streams with restorable habitats were selected for improvements. Completion of improvement efforts should increase the adfluvial rainbow trout contribution to the resident fishery in Lake Roosevelt. Personnel of three co-operating agencies, the Confederated Tribes of the Colville Reservation (CCT), the Spokane Tribe of Indians (STI) and the Washington Department of Fish and Wildlife initiated the project fieldwork in 1990. Phase II included only the Confederated Tribes of the Colville Reservation and the Spokane Tribe of Indians. Phase III is being done by the Confederated Tribes of the Colville Reservation.

Jones, Charles D.

1999-02-01

261

Lake Roosevelt Rainbow Trout : Habitat/Passage Improvement Project Annual Report 1999.  

SciTech Connect

Lake Franklin D. Roosevelt was created with the completion of the Grand Coulee Dam in 1942. The lake stretches 151 miles up-stream to the International border between the United States and Canada at the 49th parallel. Increased recreational use, subsistence and sport fishing has resulted in intense interest and possible exploitation of the resources within the lake. Previous studies of the lake and its fishery have been limited. Early studies indicate that natural reproduction within the lake and tributaries are not sufficient to support a rainbow trout (Onchoryhnchus mykiss) fishery (Scholz et. al., 1988). These studies indicate that the rainbow trout population may be limited by lack of suitable habitat for spawning and rearing (Scholz et. al., 1988). The initial phase of this project (Phase I, baseline data collection- 1990-91) was directed at the assessment of limiting factors such as quality and quantity of available spawning gravel, identification of passage barriers, and assessment of other limiting factors. Population estimates were conducted using the Seber/LeCren removal/depletion method. After the initial assessment of stream parameters, several streams were selected for habitat/passage improvement projects (Phase II, implementation-1992-96). At the completion of project habitat improvements, the final phase (Phase III, monitoring) began. This phase will assess changes and gauge the success achieved through the improvements. The objective of the project is to correct passage barriers and improve habitat conditions of selected tributaries to Lake Roosevelt for adfluvial rainbow trout that utilize tributary streams for spawning and rearing. Streams with restorable habitats were selected for improvements. Completion of improvement efforts should increase the adfluvial rainbow trout contribution to the resident fishery in Lake Roosevelt. Three co-operating agencies, the Confederated Tribes of the Colville Reservation (CCT), the Spokane Tribe of Indians (STI) and the Washington Department of Fish and Wildlife initiated the project fieldwork in 1990. Phase II included only the Confederated Tribes of the Colville Reservation and the Spokane Tribe of Indians. Phase III is being completed by the Confederated Tribes of the Colville Reservation.

Jones, Charles D.

2000-02-01

262

Ecology of the Cutthroat Trout in Henrys Lake, Idaho  

Microsoft Academic Search

Henrys Lake, a 6,500-acre reservoir at the elevation of 6,472 feet in eastern Idaho, has a maximum depth of 21 feet and an average depth of 12 feet. Seasonal variation of weather and shallow, fertile waters are the major environmental factors that influence the Henrys Lake biotic community. Phytoplankton is abundant and composed primarily of blue-green algae and cladocerans and

Robert B. Irving

1955-01-01

263

Life-history organization of Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) in Yellowstone Lake  

USGS Publications Warehouse

Life-history organization of the cutthroat trout (Oncorhynchus clarki) may be viewed at various levels, including species, subspecies, metapopulation, population, or individual. Each level varies in spatial scale and temporal persistence, and components at each level continually change with changes in environment. Cutthroat trout are widely distributed throughout the western United States, occurring in such diverse environments as coastal rivers of the Pacific Northwest and interior streams of the Great Basin. During its evolution the species has organized into 14 subspecies with many different life-history characteristics and habitat requirements. Within subspecies, organization is equally complex. For example, life-history traits, such as average size and age, migration strategy, and migration timing, vary among individual spawning populations of Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) in tributary streams of Yellowstone Lake. Understanding the effects of human perturbations on life-history organization is critical for management of the cutthroat trout and other polytypic salmonid species. Loss of diversity at any hierarchical level jeopardizes the long-term ability of the species to adapt to changing environments, and it may also lead to increased fluctuations in abundance and yield and increase the risk of extinction.

Gresswell, Robert E.; Liss, W.J.; Larson, Gary L.

1994-01-01

264

Juvenile rainbow trout production in New York tributaries of Lake Ontario: implications for Atlantic salmon restoration  

USGS Publications Warehouse

Three Pacific salmonid species Onchorynchus spp. have replaced the extirpated Atlantic salmon Salmo salar as the main migratory salmonid in the Lake Ontario drainage. One of those species, the nonnative rainbow trout O. mykiss, has become widely distributed within the historical Atlantic salmon habitat, occupying an ecological niche similar to that of juvenile Atlantic salmon. Consequently, both a tributary's carrying capacity for Atlantic salmon and competition from established nonnative species are important when considering the feasibility of Atlantic salmon restoration. Estimation of juvenile rainbow trout production will help evaluate the capacity of tributaries to produce salmonids that occupy similar niches. Geostatistical methods were applied to standardized and efficiency-corrected electrofishing data from three of New York's best salmonid-producing streams to precisely estimate juvenile rainbow trout populations. Results indicated that each study stream could produce 20,000-40,000 age-0 and 4,000-10,000 age-1 and older rainbow trout per year. Statistical interpolation indicated areas of significantly different production potential and points of significant changes in productivity. Closer examination of the niche similarity and competitive potential of these two species is needed to properly interpret these estimates with regard to Atlantic salmon restoration.

McKenna, James E., Jr.; Johnson, James H.

2005-01-01

265

Acute toxicities to larval rainbow trout of representative compounds detected in Great Lakes fish  

SciTech Connect

In recent years the National Fisheries Research Center-Great Lakes has ranked the potential hazard to fish and invertebrates of various chemical compounds detected in two Great Lakes fishes - lake trout, Salvelinus namaycush, and walleye. Stizostedion vitreum vitreum. This hazard assessment has included the identification of the potential sources of the compound, determination of the occurrence and abundance of the compounds in Great Lakes fish, and the determination of acute toxicities of representative compounds of 19 chemical classes. The author focuses on four of the classes. The PAHs are products of fuel combustion and components of fossil fuels. The other three classes principally originate from industrial applications (alkyl halides), as fossil fuels, insecticides, solvents, and in perfumes (cyclic alkanes); and as herbicides and insecticides (heterocyclic nitrogen compounds). The authors purpose is to report results of static acute toxicity tests in which larval rainbow trout (Oncorhynchus mykiss) were used as the test fish and to compare results of acute toxicity tests with previous studies.

Edsall, C.C. (National Fisheries Research Center-Great Lakes, Ann Arbor, MI (United States))

1991-02-01

266

Factors affecting the foods and feeding patterns of lake?dwelling rainbow trout (Salmo gairdnerii) in the North Island of New Zealand  

Microsoft Academic Search

Differences in feeding between age classes, males and females, and hatchery reared and wild rainbow trout (Salmo gairdnerii) in Lake Rotoma are described. Analysis of results, in conjunction with other published data on trout foods and feeding, showed that there was a summer increase in epibenthic feeding which, in Lake Rotoma, was most apparent in the species of forage fish

D. K. Rowe

1984-01-01

267

Influence of thiamine deficiency on lake trout larval growth, foraging, and predator avoidance.  

PubMed

Diet-related thiamine deficiency increases the acute mortality, known as early mortality syndrome, of salmonines from some of the Great Lakes. The consequences of thiamine deficiency as measured at the egg stage for other important early life stage processes like growth, foraging efficiency, and predator avoidance that may also result in mortality, are unknown. Accordingly, we investigated the impacts of low thiamine on the specific growth rate (SGR) of first-feeding fry, the ability of first-feeding fry to capture Daphnia, fry emergence in the presence of a potential predator (round goby Apollina [formerly Neogobius] melanostomus), and predation by slimy sculpin Cottus cognatus. We used a combination of thiamine-deficient and thiamine-replete wild stocks of lake trout Salvelinus namaycush for this purpose. From these investigations we developed predictive relationships. Specific growth rate was related to egg thiamine concentration. From the exponential relationship, it was predicted that the threshold egg thiamine concentrations associated with 20% and 50% reductions in SGR are 8.1 and 5.1 nmol/g, respectively. The foraging rate on Daphnia was also related to egg thiamine concentration by an exponential relationship. It was predicted that the threshold concentrations associated with 20% and 50% reductions in this rate are 6.9 and 2.9 nmol/g, respectively. The presence of a round goby significantly reduced emergence success, but the level of goby predation was unrelated to egg thiamine concentration. Sculpin predation was related, although weakly, to the initial egg thiamine concentration. This research found that thiamine deficiency affected growth, foraging, and predator avoidance in lake trout fry. Growth effects resulting from thiamine deficiency may represent the most sensitive means of monitoring the impact of the secondary consequences of thiamine deficiency. Mortality associated with the combined effects of reduced growth and foraging has the potential to seriously impair lake trout recruitment. PMID:20218504

Fitzsimons, John D; Brown, Scott B; Williston, Bill; Williston, Georgina; Brown, Lisa R; Moore, Kristin; Honeyfield, Dale C; Tillitt, Donald E

2009-12-01

268

Effects of vitamin B1 (thiamine) deficiency in lake trout alevins and preventive treatments.  

PubMed

The objectives of this study were to examine the effect of thiamine immersion of fish from a population known for compromised survival as a result of early mortality syndrome (EMS) and to investigate the cause-response relationship between thiamine concentration and lesions in tissues in swim-up-stage lake trout Salvelinus namaycush alevins. Lake trout eggs from 14 fish from Lake Michigan were artificially fertilized and the progeny divided into two groups based on the thiamine concentration (low [< 0.73 nmol/g] or high [> 0.85 nmol/g]) in the unfertilized eggs. Progeny were treated or not with a thiamine solution (2,000 mg/L for 2 h) at hatching or the swim-up stage. The survival of progeny in control groups at the swim-up stage correlated with thiamine concentration. The low thiamine-treated groups had significantly higher survival between the swim-up stage (812.0 degree-days) and 16 d after swim-up (963.3 degree-days) than the control groups; the survival of the high thiamine-treated groups did not differ between treated and control fish, regardless of the treatment at hatching and the swim-up stage. Control alevins that had low thiamine levels showed EMS, which resulted in 94.9-100% mortality 16 d after the swim-up stage. No pathological changes were observed in the brain, olfactory lobe, eye, liver, or muscle in alevins of high thiamine-treated group. Glycogen deposits in the liver of alevins from the low control group were variable, no glycogen being observed in the hepatocytes of 7 of the 24 fish. We demonstrate that thiamine treatment at swim-up enhances the survival of EMS-affected lake trout relative to treatment at hatching. PMID:20218503

Lee, Bong-Joo; Jaroszewska, Marta; Dabrowski, Konrad; Czesny, Sergiusz; Rinchard, Jacques

2009-12-01

269

Comparison of three nonlinear models to describe long-term tag shedding by lake trout  

USGS Publications Warehouse

We estimated long-term tag-shedding rates for lake trout Salvelinus namaycush using two existing models and a model we developed to account for the observed permanence of some tags. Because tag design changed over the course of the study, we examined the tag-shedding rates for three types of numbered anchor tags (Floy tags FD-67, FD-67C, and FD-68BC) and an unprinted anchor tag (FD-67F). Lake trout from the Gull Island Shoal region, Lake Superior, were double-tagged and subsequent recaptures were monitored in annual surveys conducted from 1974 to 1992. We modeled tag-shedding rates, using time at liberty and probabilities of tag shedding estimated from fish released in 1974 and 1978-1983 and later recaptured. Long-term shedding of numbered anchor tags in lake trout was best described by a nonlinear model with two parameters: an instantaneous tag-shedding rate and a constant representing the proportion of tags that were never shed. Although our estimates of annual shedding rates varied with tag type (0.300 for FD-67, 0.441 for FD-67C, and 0.656 for FD-68BC), differences were not significant. About 36% of tags remained permanently affixed to the fish. Of the numbered tags that were shed (about 64%), two mechanisms contributed to tag loss: disintegration and dislodgment. Tags from about 11% of recaptured fish had disintegrated, but most tags were dislodged. Unprinted tags were shed at a significant but low rate immediately after release, but the long-term annual shedding rate of these tags was only 0.013. Compared with unprinted tags, numbered tags dislodged at higher annual rates; we hypothesized that this was due to the greater frictional drag associated with the larger cross-sectional area of numbered tags.

Fabrizio, Mary C.; Swanson, Bruce L.; Schram, Stephen T.; Hoff, Michael H.

1996-01-01

270

A dynamic-bioenergetics model to assess depth selection and reproductive growth by lake trout (Salvelinus namaycush).  

PubMed

We coupled dynamic optimization and bioenergetics models to assess the assumption that lake trout (Salvelinus namaycush) depth distribution is structured by temperature, food availability, and predation risk to maximize reproductive mass by autumn spawning. Because the model uses empirical daily thermal-depth profiles recorded in a small boreal shield lake (lake 373 at the Experimental Lakes Area, northwestern Ontario) during 2 years of contrasting thermal stratification patterns, we also assessed how climate-mediated changes in lakes may affect the vertical distribution, growth, and fitness of lake trout, a cold-water top predator. The depths of acoustic-tagged lake trout were recorded concurrently with thermal-depth profiles and were compared to model output, enabling an assessment of model performance in relation to the observed fish behavior and contrasting thermal conditions. The depths and temperatures occupied by simulated fish most closely resembled those of the tagged fish when risk of predation was included in the model, indicating the model may incorporate the most important underlying mechanisms that determine lake trout depth. Annual differences suggest less use of shallow (warm), productive habitats, resulting in markedly less reproductive mass, during the year with the warm stratification pattern. Mass for reproduction may be lower in warmer conditions because of reduced reproductive investment, yet survival may be inadvertently higher because risky surface waters may be avoided more often in warmer, shallower, and metabolically costly conditions. At a minimum our study suggests that lake trout reproductive mass and fitness may be expected to change under the anticipated longer and warmer stratification patterns. PMID:24682254

Plumb, John M; Blanchfield, Paul J; Abrahams, Mark V

2014-06-01

271

Biological consequences of the coaster brook trout restoration stocking program in Lake Superior tributaries with Pictured Rocks National Lakeshore  

USGS Publications Warehouse

The coaster Brook Trout Salvelinus fontinalis is a Lake Superior ecotype representing intraspecific variation that has been impacted by habitat loss and overfishing. Hatchery strains of Brook Trout derived from populations in Lake Superior were stocked into streams within Pictured Rocks National Lakeshore, Michigan, as part of an effort to rehabilitate adfluvial coaster Brook Trout. Wild and hatchery Brook Trout from three streams (Mosquito River, Hurricane River, and Sevenmile Creek) were examined for movement behavior, size, physiology, and reproductive success. Behavior and size of the stocked fish were similar to those of wild fish, and less than 15% of the stocked, tagged Brook Trout emigrated from the river into which they were stocked. There was little evidence of successful reproduction by stocked Brook Trout. Similar to the results of other studies, our findings suggest that the stocking of nonlocal Brook Trout strains where a local population already exists results in limited natural reproduction and should be avoided, particularly if the mechanisms governing the ecotype of interest are poorly understood.

Leonard, Jill B.K.; Stott, Wendylee; Loope, Delora M.; Kusnierz, Paul C.; Sreenivasan, Ashwin

2013-01-01

272

Use of cover habitat by bull trout, Salvelinus confluentus , and lake trout, Salvelinus namaycush , in a laboratory environment  

Microsoft Academic Search

Lacustrine-adfluvial bull trout, Salvelinus confluentus, migrate from spawning and rearing streams to lacustrine environments as early as age 0. Within lacustrine environments,\\u000a cover habitat provides refuge from potential predators and is a resource that is competed for if limiting. Competitive interactions\\u000a between bull trout and other species could result in bull trout being displaced from cover habitat, and bull trout

Michael H. Meeuwig; Christopher S. Guy; Wade A. Fredenberg

2011-01-01

273

Lake Michigan's capacity to support lake trout (Salvelinus namaycush) and other salmonines: an estimate based on the status of prey populations in the 1970s  

USGS Publications Warehouse

We used a mass balance equation relating total mortality of age II and older alewives (Alosa pseudoharengus) to their removals by predatory fish and other sources of mortality as the basis for estimating that the forage base in Lake Michigan could support an additional 13,000 to 21,000 t of lake trout (Salvelinus namaycush) or a total lake trout biomass between 15,000 and 23,000 t. This biomass estimate is projected with biomasses of other trout and salmon held at 1979 levels. Major premises of this approach are that (1) the sustained availability of age II and older alewives to salmonines will ultimately limit the expansion of salmonine stocks, (2) the alewife population was oscillating without trend during 197380, and (3) additional limited predation on alewives would be compensated by a reduction in natural mortality caused by physiological stress and disease.

Eck, Gary W.; Brown, Edward H.

1985-01-01

274

Content and chemical form of mercury and selenium in Lake Ontario salmon and trout  

SciTech Connect

The content and chemical form of mercury and selenium were determined in the edible tissue of salmon (coho, chinook) and trout (lake, brown) taken offshore from Lake Ontario near Rochester, New York. For all species, total mercury content ranged from 0.3 to 0.8 micro g/g (fresh-weight), which is similar to concentrations commonly found in canned tuna. Most of the total mercury (63 to 79%) was present as methylmercury, the remainder being divalent inorganic mercury. For all species, 6 to 45% of the total selenium content was present as selenate (SeVI), the remainder being selenite (SeIV) and selenide (SEII). On a molar basis, total selenium content usually exceeded that of total mercury. Samples of smoked and unsmoked brown trout fillets were also examined. Based on the results of this study there is no immediate human health hazard from mercury and selenium. However, there is a need to report specific forms of these metals in Lake Ontario salmonid fish so that elevated concentrations can be better evaluated. 42 references, 1 figure, 4 tables.

Cappon, C.J.

1984-01-01

275

Chemosensory cues attract lake trout Salvelinus namaycush and an egg predator to the spawning substratum.  

PubMed

A field experiment was conducted to determine whether chemosensory cues emanating from lake trout Salvelinus namaycush spawning substratum attract breeding S. namaycush. Substrata from either a spawning site or a control site were randomly placed in trap nets around an isolated spawning shoal; those containing spawning substratum caught significantly more S. namaycush, as well as a greater proportion in breeding condition. White sucker Catostomus commersoni were a major predator of S. namaycush eggs and were also captured in greater numbers in nets with spawning substratum. PMID:23557313

Wasylenko, B A; Blanchfield, P J; Pyle, G G

2013-04-01

276

Effects of selected polybrominated diphenyl ether flame retardants on lake trout (Salvelinus namaycush).  

PubMed

Polybrominated diphenyl ether (PBDE) flame-retardants have been identified as an emergent contaminants issue in many parts of the world. In vitro analyses were conducted to test the hypothesis that selected PBDEs congeners affect viability, apoptosis, and necrosis of thymocytes from laboratory-reared lake trout (Salvelinus namaycush). At current environmental levels (< 1 mg/L), effects of the tested PBDEs on thymocytes were negligible. However, at 100 mg/L, major effects were seen for congener brominated diphenyl ether 47 (BDE-47) and minor effects were seen for congener BDE-99. PMID:16117131

Birchmeier, Kelly L; Smith, Kimberly A; Passino-Reader, Dora R; Sweet, Leonard I; Chernyak, Sergei M; Adams, Jean V; Omann, Geneva M

2005-06-01

277

Effects of tebufenozide on some aspects of lake trout (Salvelinus namaycush) immune response.  

PubMed

Tebufenozide is a nonsteroid ecdysone agonist that causes premature and incomplete molting in Lepidoptera and is used on crops and in forest spray programs. Lake trout (Salvelinus namaycush) were exposed to one pulse of 0.25 ppm tebufenozide every 3 days (12 pulses in total). Cell ratios and respiratory burst responses of circulating white blood cells (WBCs) as well as head-kidney (HK) WBCs were investigated by using cell observation, Nitro-Blue Tetrazolium tests, and flow cytometry. Endpoints studied suggest a difference in sensitivity between HK and circulating blood cells to tebufenozide and show a stimulation of fish cell function and changes in percentages of cell types. Responses are not associated with a strong stress response as highlighted by the absence of effect on cortisol and blood protein levels. These results and tebufenozide persistence in water warrant further studies on pesticide impact on fish immunity when used on crops or in forest spray programs near lakes and streams. PMID:17537512

Hamoutene, D; Payne, J F; Volkoff, H

2008-02-01

278

Sublethal toxicity of two wastewater treatment polymers to lake trout fry (Salvelinus namaycush).  

PubMed

Lake trout fry (Salvelinus namaycush) were exposed in laboratory experiments to two wastewater treatment polymers, one anionic (MagnaFloc 156) and one cationic (MagnaFloc 368; Ciba Speciality Chemical), to determine if these chemicals which are used and discharged by mining operations in Canada's North pose a significant hazard to juvenile fishes. The cationic polymer was substantially more toxic to lake trout fry than the anionic polymer, with 96-h LC50 estimates of 2.08 and >600 mg/l, respectively. Separate 30-d exposure experiments yielded no observed and lowest observed effect concentrations, respectively, of 0.25 and 0.5mg/l for MagnaFloc 368, and 75 and 150 mg/l for MagnaFloc 156. In both cases, behavioural responses, especially startle response, were the most sensitive test endpoints. Histopathological assessment revealed that gill pathology appeared within a few days of exposure to both polymers, apparently as a result of localized hypoxia. Acute (4 d) effects included cloudy swelling of epithelial cells, increased gill vascularization, and thickening and shortening of the gill lamella. Chronic (30 d) polymer exposure produced only slightly greater pathological effects than acute exposure, with comparable responses observed only at >1.0mg/l MagnaFloc 368 and 150 mg/l MagnaFloc 156, suggesting that the fish displayed some level of both behavioural and physiological adaptation to the respiratory stress imposed by the two polymers. PMID:16263382

Liber, K; Weber, L; Lévesque, C

2005-12-01

279

In vitro immune functions in thiamine-replete and -depleted lake trout (Salvelinus namaycush).  

PubMed

In this study we examined the impacts of in vivo thiamine deficiency on lake trout leukocyte function measured in vitro. When compared outside the context of individual-specific thiamine concentrations no significant differences were observed in leukocyte bactericidal activity or in concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) stimulated leukocyte proliferation. Placing immune functions into context with the ratio of in vivo liver thiamine monophosphate (TMP--biologically inactive form) to thiamine pyrophosphate (TPP--biologically active form) proved to be the best indicator of thiamine depletion impacts as determined using regression modeling. These observed relationships indicated differential effects on the immune measures with bactericidal activity exhibiting an inverse relationship with TMP to TPP ratios, Con A stimulated mitogenesis exhibiting a positive relationship with TMP to TPP ratios and PHA-P stimulated mitogenesis exhibiting no significant relationships. In addition, these relationships showed considerable complexity which included the consistent observation of a thiamine-replete subgroup with characteristics similar to those seen in the leukocytes from thiamine-depleted fish. When considered together, our observations indicate that lake trout leukocytes experience cell-type specific impacts as well as an altered physiologic environment when confronted with a thiamine-limited state. PMID:24680830

Ottinger, Christopher A; Honeyfield, Dale C; Densmore, Christine L; Iwanowicz, Luke R

2014-05-01

280

In vitro immune functions in thiamine-replete and -depleted lake trout (Salvelinus namaycush)  

USGS Publications Warehouse

In this study we examined the impacts of in vivo thiamine deficiency on lake trout leukocyte function measured in vitro. When compared outside the context of individual-specific thiamine concentrations no significant differences were observed in leukocyte bactericidal activity or in concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) stimulated leukocyte proliferation. Placing immune functions into context with the ratio of in vivo liver thiamine monophosphate (TMP – biologically inactive form) to thiamine pyrophosphate (TPP – biologically active form) proved to be the best indicator of thiamine depletion impacts as determined using regression modeling. These observed relationships indicated differential effects on the immune measures with bactericidal activity exhibiting an inverse relationship with TMP to TPP ratios, Con A stimulated mitogenesis exhibiting a positive relationship with TMP to TPP ratios and PHA-P stimulated mitogenesis exhibiting no significant relationships. In addition, these relationships showed considerable complexity which included the consistent observation of a thiamine-replete subgroup with characteristics similar to those seen in the leukocytes from thiamine-depleted fish. When considered together, our observations indicate that lake trout leukocytes experience cell-type specific impacts as well as an altered physiologic environment when confronted with a thiamine-limited state.

Ottinger, Christopher A.; Honeyfield, Dale C.; Densmore, Christine L.; Iwanowicz, Luke R.

2014-01-01

281

Long-term captive breeding does not necessarily prevent reestablishment: lessons learned from Eagle Lake rainbow trout  

Microsoft Academic Search

Captive breeding of animals is often cited as an important tool in conservation, especially for fishes, but there are few\\u000a reports of long-term (<50 years) success of captive breeding programs, even in salmonid fishes. Here we describe the captive\\u000a breeding program for Eagle Lake rainbow trout, Oncorhynchus mykiss aquilarum, which is endemic to the Eagle Lake watershed of northeastern California. The

Gerard Carmona-CatotPeter; Peter B. Moyle; Rachel E. Simmons

282

Estimation of waste outputs by a rainbow trout cage farm using a nutritional approach and monitoring of lake water quality  

Microsoft Academic Search

Nutrients released by cage fish farms to the aquatic environment are an issue of concern since these can result in deleterious environmental changes. In the present study, a mass balance model was used to calculate nutrient loadings from an experimental rainbow trout cage farm located in a freshwater, oligotrophic lake. Detection of these nutrient loadings using water quality monitoring was

P. A. Azevedo; C. L. Podemski; R. H. Hesslein; S. E. M. Kasian; D. L. Findlay; D. P. Bureau

2011-01-01

283

Within-and among-population variation in the trophic position of a pelagic predator, lake trout  

E-print Network

(Salvelinus namaycush) M. Jake Vander Zanden, Brian J. Shuter, Nigel P. Lester, and Joseph B. Rasmussen the importance of both within- and among-population trophic variation for lake trout (Salvelinus namaycush) using (Salvelinus namaycush) provenant de 13 lacs de l'Ontario et du Québec, ce qui per- mettait de quantifier l

Vander Zanden, Jake

284

EFFECTS OF ARYL HYDROCARBON RECEPTOR MEDIATED EARLY LIFE STAGE TOXICITY ON LAKE TROUT POPULATIONS IN LAKE ONTARIO DURING THE 20TH CENTURY  

EPA Science Inventory

Lake trout embryos and sac fry are very sensitive to toxicity associated with maternal exposures to 2,3,7,8-tetrachlorodibenza-p-dioxin (TCDD) and structurally related chemicals that act through a common aryl hydrocarbon receptor (AHR)- mediated mechanism of action. The presence ...

285

Distinguishing wild vs. stocked lake trout (Salvelinus namaycush) in Lake Ontario: Evidence from carbon and oxygen stable isotope values of otoliths  

USGS Publications Warehouse

We investigated the potential for using carbon and oxygen isotope values of otolith carbonate as a method to distinguish naturally produced (wild) lake trout (Salvelinus namaycush) from hatchery-reared lake trout in Lake Ontario. We determined ??13C(CaCO3) and ?? 18O(CaCO3) values of otoliths from juvenile fish taken from two hatcheries, and of otoliths from wild yearlings. Clear differences in isotope values were observed between the three groups. Subsequently we examined otoliths from large marked and unmarked fish captured in the lake, determining isotope values for regions of the otolith corresponding to the first year of life. Marked (i.e., stocked) fish showed isotope ratios similar to one of the hatchery groups, whereas unmarked fish, (wild fish or stocked fish that lost the mark) showed isotope ratios similar either to one of the hatchery groups or to the wild group. We interpret these data to suggest that carbon and oxygen isotope values can be used to determine the origin of lake trout in Lake Ontario, if a catalogue of characteristic isotope values from all candidate years and hatcheries is compiled.

Schaner, T.; Patterson, W.P.; Lantry, B.F.; O'Gorman, R.

2007-01-01

286

Impact of thiamine deficiency on T-cell dependent and T-cell independent antibody production in lake trout.  

PubMed

Lake trout Salvelinus namaycush on thiamine-replete and thiamine-depleted diets were evaluated for the effects of thiamine status on in vivo responses to the T-dependent antigen trinitophenol (TNP)-keyhole limpet hemocyanin (TNP-KLH), the T-independent antigen trinitrophenol-lipolysaccaharide (TNP-LPS), or Dulbecco's phosphate-buffered saline (DPBS; negative control fish). Plasma antibody concentrations were evaluated for possible differences in total anti-TNP activity as well as differences in response kinetics. Associations between anti-TNP activity and muscle and liver thiamine concentrations as well as ratios of muscle-to-liver thiamine to anti-TNP activity were also examined. Thiamine-depleted lake trout that were injected with TNP-LPS exhibited significantly more anti-TNP activity than thiamine-replete fish. The depleted fish injected with TNP-LPS also exhibited significantly different response kinetics relative to thiamine-replete lake trout. No differences in activity or kinetics were observed between the thiamine-replete and -depleted fish injected with TNP-KLH or in the DPBS negative controls. Anti-TNP activity in thiamine-depleted lake trout injected with TNP-KLH was positively associated with muscle thiamine pyrophosphate (thiamine diphosphate; TPP) concentration. A negative association was observed between the ratio of muscle-to-liver TPP and T-independent responses. No significant associations between anti-TNP activity and tissue thiamine concentration were observed in the thiamine-replete fish. We demonstrated that thiamine deficiency leads to alterations in both T-dependent and T-independent immune responses in lake trout. PMID:23134222

Ottinger, Christopher A; Honeyfield, Dale C; Densmore, Christine L; Iwanowicz, Luke R

2012-12-01

287

Impact of thiamine deficiency on T-cell dependent and T-cell independent antibody production in lake trout  

USGS Publications Warehouse

Lake trout Salvelinus namaycush on thiamine-replete and thiamine-depleted diets were evaluated for the effects of thiamine status on in vivo responses to the T-dependent antigen trinitophenol (TNP)-keyhole limpet hemocyanin (TNP-KLH), the T-independent antigen trinitrophenol-lipolysaccaharide (TNP-LPS), or Dulbecco's phosphate-buffered saline (DPBS; negative control fish). Plasma antibody concentrations were evaluated for possible differences in total anti-TNP activity as well as differences in response kinetics. Associations between anti-TNP activity and muscle and liver thiamine concentrations as well as ratios of muscle-to-liver thiamine to anti-TNP activity were also examined. Thiamine-depleted lake trout that were injected with TNP-LPS exhibited significantly more anti-TNP activity than thiamine-replete fish. The depleted fish injected with TNP-LPS also exhibited significantly different response kinetics relative to thiamine-replete lake trout. No differences in activity or kinetics were observed between the thiamine-replete and -depleted fish injected with TNP-KLH or in the DPBS negative controls. Anti-TNP activity in thiamine-depleted lake trout injected with TNP-KLH was positively associated with muscle thiamine pyrophosphate (thiamine diphosphate; TPP) concentration. A negative association was observed between the ratio of muscle-to-liver TPP and T-independent responses. No significant associations between anti-TNP activity and tissue thiamine concentration were observed in the thiamine-replete fish. We demonstrated that thiamine deficiency leads to alterations in both T-dependent and T-independent immune responses in lake trout.

Ottinger, Christopher A.; Honeyfield, Dale C.; Densmore, Christine L.; Iwanowicz, Luke R.

2012-01-01

288

Ecology of lacustrine-adfluvial bull trout populations in an interconnected system of natural lakes .  

E-print Network

??Loss of connectivity among populations and interactions with nonnative species can negatively influence abundance of bull trout Salvelinus confluentus. Connectivity among bull trout populations and… (more)

Meeuwig, Michael Hendrik.

2008-01-01

289

Growth and mortality of fry of Lake Michigan lake trout during chronic exposure to PCB's and DDE  

USGS Publications Warehouse

Fry hatched from eggs of Lake Michigan lake trout (Salvelinus namaycush) were exposed (beginning about 1 week after hatching) to contaminant concentrations of PCB's and DDE similar to those in water and plankton in southeastern Lake Michigan (1X level), and to concentrations about 5 (5X) and 25 (25X) times greater. Body concentrations of contaminants in fry (I?g/g) decreased at 1X levels of PCB's and at 1X and 5X levels of DDE, but generally increased at all other contaminant exposure levels. Uptake of PCB's and DDE was evident from increases in body burden (I?g/fish) of the contaminants at all exposure levels and the controls. Growth was not significantly affected by any of the contaminant exposures. Mortalities of fry exposed to the lower concentrations (1X and 5X) were significantly less than those of control fry before day 56; however, between days 57 and 136, mortality rates increased dramatically and were significantly higher in all nine exposed groups than in the control group. For the last 40-day period (days 137-176), mortality was low and leveled off, but continued to be significantly higher in all exposed fry (except those in 1X and 5X PCB's) than in control fry. By the end of the 176-day study, the total cumulative mortality ranged from 30.5 to 46.5% in the exposed groups and was 21.7% in the control group.

Berlin, William H.; Hesselberg, Robert J.; Mac, Michael J.

1981-01-01

290

Trends of chlorinated organic contaminants in great lakes trout and walleye from 1970 to 1998.  

PubMed

Levels of chlorinated organic contaminants in predator fish have been monitored annually in each of the Great Lakes since the 1970s. This article updates earlier reports with data from 1991 to 1998 for lake trout (Salvelinus namaycush) and (Lake Erie only) walleye (Sander vitreus) to provide a record that now extends nearly 30 years. Whole fish were analyzed for a number of industrial contaminants and pesticides, including polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethane (DDT), dieldrin, toxaphene, and mirex, and contaminant trends were quantified using multicompartment models. As in the past, fish from Lakes Michigan, Ontario, and Huron have the highest levels of PCBs, DDT, and dieldrin; Superior has the highest levels of toxaphene; and Ontario has the highest levels of mirex. In the period after curtailment of chemical use, concentrations rapidly decreased, represented by relatively short half-lives from approximately 1 to 9 years. Although trends depend on both the contaminant and the lake, in many cases the rate of decline has been decreasing, and concentrations are gradually approaching an irreducible concentration. For dioxin-like PCBs, levels have not been decreasing during the most recent 5-year period (1994 to 1998). In some cases, the year-to-year variation in contaminant levels is large, mainly because of food-web dynamics. Although this variation sometimes obscures long-term trends, the general pattern of a rapid decrease followed by slowing or leveling-off of the downward trend seems consistent across the Great Lakes, and future improvements of the magnitude seen in the 1970s and early 1980s likely will take much longer. PMID:16328618

Hickey, J P; Batterman, S A; Chernyak, S M

2006-01-01

291

Effects of oxygen, temperature and light gradients on the vertical distribution of rainbow trout, Oncorhynchus mykiss, in two North Island, New Zealand, lakes differing in trophic status  

Microsoft Academic Search

Vertical distributions of adult rainbow trout (> 25 cm fork length, FL) were determined with a SIMRAD ES470 split?beam echosounder in two 80–90 m deep lakes differing in water quality. Between November 1993 and February 1994, most trout (> 80%) were between 10 and 40 m, within or close to the thermocline. However, a small group of fish occupied colder

D. K. Rowe; B. L. Chisnall

1995-01-01

292

Effects of xenobiotics and steroids on renal and hepatic estrogen metabolism in lake trout.  

PubMed

Experiments were conducted to (1) elucidate the biochemical pathways of E2 metabolism in the lake trout (Salvelinus namaycush) kidney and liver, and (2) test the hypothesis that specific xenobiotics and endogenous steroids inhibit E2 metabolism by these tissues. Kidney and liver tissue fragments from immature lake trout were incubated in vitro in the presence of radiolabelled E2 plus various xenobiotics or steroids. E2 metabolites were identified by liquid chromatography/mass spectroscopy, and quantified by liquid scintillation spectroscopy. A major metabolite produced by both tissues was an unidentified hydroxylated estrogen metabolite (E2-OH) with a molecular mass of 288 that was not estriol (16-OH-E2), but possibly 7alpha-OH-E2 or 2-OH-E2 (catecholestrogen). Both tissues also produced estradiol-17-glucuronide (E2-17-G), estradiol-17-sulfate (E2-17-S), and estradiol-3-glucuronide (E2-3-G). Compared to the kidney, the liver produced half the amount of conjugated metabolites, but twofold more E2-OH. The following xenobiotics (at a concentration of 100 microM) inhibited the production of water-soluble (i.e., conjugated) E2 metabolites by both the kidney and liver: 4,4'-(OH)2-3,3',5,5'- tetrachlorobiphenyl (4,4'-OH-TCB), bisphenol A (BPA), tetrabromobisphenol A (TB-BPA), tetrachlorobisphenol A (TC-BPA), tribromophenol (TBP), trichlorophenol (TCP), and pentachlorophenol (PCP). The alkylphenols, 4-n-nonylphenol (NP), and 4-octylphenol (OP), and 2,2',4,4'-tetrabromodiphenyl ether (TBDE) had no significant effect on E2 metabolism by either tissue. Testosterone and 17alpha,20beta-dihydroxy-4-pregnen-3-one inhibited the production of conjugated E2 metabolites by both the kidney and liver. Cortisol and 11-ketotestosterone inhibited E2 metabolism by the liver only. The median inhibitory concentrations (IC50) for 4,4'-OH-TCB ranged from 7-32 microM in the kidney and 0.6-1.6 microM in the liver. For BPA, IC50's ranged from 40-108 microM in the kidney and 11-18 microM in the liver. Low doses (0.1 microM) of 4,4'-OH-TCB and BPA significantly increased estrogen metabolism in the kidney. The results suggest that certain estrogenic xenobiotics and endogenous steroids may inhibit the phase II conjugation of E2 by the kidney and liver of lake trout, and some of the known biological effects of these compounds are likely mediated, at least partially, by this mechanism of action. PMID:16677648

Jurgella, Gail F; Marwah, Ashok; Malison, Jeffrey A; Peterson, Richard; Barry, Terence P

2006-09-01

293

Bathythermal distribution, maturity, and growth of lake trout strains stocked in U.S. waters of Lake Ontario, 1978-1993  

USGS Publications Warehouse

Bathythermal distributions, sexual maturity, and growth of lake trout (Salvelinus namaycush) strains stocked in Lake Ontario were determined for fish collected with trawls and gill nets in 1978-93. The purpose was to augment the basis for deciding which strains to continue stocking in an effort to reestablish a self-sustaining population. The Clearwater Lake (CWL) strain was found in shallower, warmer water than all other strains; the Seneca Lake (SEN) strain was usually shallower than the Jenny Lake (JEN) and Lake Superior (SUP) strains at ages 1 and 2 but was usually deeper at age 3 and older. Depth distribution of the 'Ontario strain'--from gametes of several strains that survived to maturity in Lake Ontario-- was similar to that of the SEN and SUP strains. About half the males matured at age 4 and half the females at age 5; males < 500 mm and females < 600 mm long were rarely mature. Least-sqaures mean lengths and weights of the CWL strain were greater than those of all other strains through age 4. At age 7 and older, CWL and JEN fish were generally smaller than all other strains. Means lengths and weights of males and females of the same age and strain frequently differed at age 4 and older. Growth in weight at age 4 and older was not associated with biomass indices of prey fishes. Differences in growth rates among strains were associated with bathythermal distribution which is a heritable trait. Weight-length regressions differed by year, sex, and stage of maturity but were rarely different among strains. Competition for space appeared to affect condition of large lake trout. Growth rates and maturity schedules provide little basis for recommending stocking one strain in preference to another. Depth ranges of strains overlapped widely, but lake trout occupied only about one-fourth of available bottom habitat. Stocking several strains should be continued to maximize use of sustainable habitat.

Elrod, Joseph H.; O'Gorman, Robert; Schneider, Clifford P.

1996-01-01

294

Dynamic micro-geographic and temporal genetic diversity in vertebrates: the case of lake-spawning populations of brown trout (Salmo trutta).  

PubMed

Conservation of species should be based on knowledge of effective population sizes and understanding of how breeding tactics and selection of recruitment habitats lead to genetic structuring. In the stream-spawning and genetically diverse brown trout, spawning and rearing areas may be restricted source habitats. Spatio-temporal genetic variability patterns were studied in brown trout occupying three lakes characterized by restricted stream habitat but high recruitment levels. This suggested non-typical lake-spawning, potentially representing additional spatio-temporal genetic variation in continuous habitats. Three years of sampling documented presence of young-of-the-year cohorts in littoral lake areas with groundwater inflow, confirming lake-spawning trout in all three lakes. Nine microsatellite markers assayed across 901 young-of-the-year individuals indicated overall substantial genetic differentiation in space and time. Nested gene diversity analyses revealed highly significant (< or =P = 0.002) differentiation on all hierarchical levels, represented by regional lakes (F(LT) = 0.281), stream vs. lake habitat within regional lakes (F(HL) = 0.045), sample site within habitats (F(SH) = 0.010), and cohorts within sample sites (F(CS) = 0.016). Genetic structuring was, however, different among lakes. It was more pronounced in a natural lake, which exhibited temporally stable structuring both between two lake-spawning populations and between lake- and stream spawners. Hence, it is demonstrated that lake-spawning brown trout form genetically distinct populations and may significantly contribute to genetic diversity. In another lake, differentiation was substantial between stream- and lake-spawning populations but not within habitat. In the third lake, there was less apparent spatial or temporal genetic structuring. Calculation of effective population sizes suggested small spawning populations in general, both within streams and lakes, and indicates that the presence of lake-spawning populations tended to reduce genetic drift in the total (meta-) population of the lake. PMID:19243511

Heggenes, Jan; Røed, Knut H; Jorde, Per Erik; Brabrand, Age

2009-03-01

295

Embryotoxicity of extracts from Lake Ontario rainbow trout (Oncorhynchus mykiss) to Japanese medaka (Oryzias latipes)  

SciTech Connect

Various preparative techniques were used to extract nonpolar organic compounds from the muscle tissue of Lake Ontario rainbow trout (Oncorhynchus mykiss). In this extract, PCBs and organochlorine compounds were detected in nanogram-per-milliliter quantities, and polychlorinated dibenzo-p-dioxins and dibenzofurans were detected in picogram-per-milliliter quantities. The extract and various subfractions of the extract were tested for embryotoxicity in a bioassay with embryos of Japanese medaka (Oryzias latipes). The whole extract was embryotoxic to medaka, as were an extract fraction containing PCBs (fraction A) and extract fractions containing nonpolar organochlorine compounds (fractions B and C). When subfractions prepared from fraction A were tested for embryotoxicity, a subfraction containing non-ortho-substituted PCB congeners was embryo-toxic, whereas subfractions containing mono-ortho- and di-ortho-substituted PCB congeners were relatively nontoxic. Pathological lesions characteristic of exposure to planar halogenated aromatic hydrocarbons were observed only in embryos exposed to the non-ortho-PCB subfraction. The non-ortho-PCB subfraction of fraction A was more toxic than the original fraction A, which indicates that nontoxic PCBs reduce the toxicity of the non-ortho-PCBs through some unknown mechanism. This study indicates that organochlorine compounds and non-ortho-substituted PCBs have the potential to be embryotoxic to early life stages of Great lakes fish, but nontoxic contaminants can modify this toxic response. These data are relevant to the interpretation of correlations between embryo mortalities and concentrations of persistent organic contaminants in Great Lakes salmonids.

Harris, G.E.; Metcalfe, T.L.; Metcalfe, C.D. (Trent Univ., Peterborough, Ontario (Canada). Environmental and Resources Studies Program); Huestis, S.Y. (Canada Centre for Inland Waters, Burlington, Ontario (Canada))

1994-09-01

296

Ovarian fluid enhances sperm velocity based on relatedness in lake trout, Salvelinus namaycush.  

PubMed

Studying mate choice at the gamete level can provide valuable insights into proximate mechanisms that underlie the evolution of mating systems. The objective was to assess whether ovarian fluid enhances sperm performance based on relatedness of mates in lake trout, Salvelinus namaycush, an iteroparous salmonid. Twelve trios were used, each composed of a female and two male fish; one male was related (full sibling) to the female, whereas the other was unrelated. Sperm from each male was activated in hatchery water or ovarian fluid from each corresponding female. No significant difference in sperm velocity was detected between the related and unrelated male fish when activated in hatchery water. However, when sperm was activated in ovarian fluid, sperm velocity from the related male was significantly higher than that of the unrelated male fish. Overall, ovarian fluid enhanced sperm performance of related male fish and might act as part of a recognition system to select sperm of a specific genotype. PMID:23110953

Butts, Ian A E; Johnson, Katelynn; Wilson, Chris C; Pitcher, Trevor E

2012-12-01

297

Comparison of lake trout-egg survival at inshore and offshore and shallow-water and deepwater sites in Lake Superior  

USGS Publications Warehouse

We incubated lake trout (Salvelinus namaycush) eggs over winter at shallow (10 m) and deep locations (20 m) on Gull Island Shoal, Lake Superior; at a shallow-water (10 m) site off the mainland (bark point); and in flowing great lakes water at two laboratories. Survival to hatch was significantly higher in the laboratories and averaged 80.9%. In Lake Superior, egg survival among incubators at all sites was significantly higher (p < 0.0001) For incubators that remained buried in spawning substrates (15.1-21.0%) than for incubators that were partially or completely exposed to water currents (1.0-12.6%). Egg survival for incubators that remained buried at the shallow-water sites was significantly higher at bark point (44.6%) than at Gull Island Shoal (21.0%). Egg survival among incubators that remained buried at the deep (14.4%) and shallow-water sites (21.0%) on Gull Island Shoal was not significantly different. Because incubators that were completely buried or partially exposed only appeared to differ in their degree of exposure, we concluded that survival of eggs in the lake was reduced by mechanical stress associated with water turbulence. Lower egg survival at Gull Island Shoal, a known lake trout-spawning site, was not expected and appeared to have been caused by a strong gale that occurred when these eggs were in late epiboly, a sensitive embryological stage. We present a hypothesis suggesting that lake trout recruitment in the Great Lakes is limited by availability of spawning habitat.

Eshenroder, Randy L.; Bronte, Charles R.; Peck, James W.

1995-01-01

298

Effect of artificial sunlight on the retention of external calcein marks on lake trout  

USGS Publications Warehouse

When choosing a fish marking technique to address fishery related questions, it is important to consider factors that affect mark retention. Calcein, a chemical marking agent, is under investigation for potential use on fish. Two laboratory trials were conducted with calcein-marked lake trout Salvelinus namaycush to determine the effect of artificial sunlight on calcein mark intensity. In trial 1, fish exposed to 18,000 lx for 7 d lost 90% or more of the calcein mark intensity (relative to the colorimetric key, mg/L) on the head, body, ventral region, and pectoral fins relative to mark intensity in fish that were maintained in darkness. In trial 2, light intensity was reduced 2.5-3.0-fold. After 7 d of light exposure, calcein mark intensity on the head was reduced by 40-45% relative to mark intensity in fish that were held in darkness; by day 14, calcein mark intensity on the head was reduced by 55-60% relative to that of dark-treated fish. No further decline was observed in light-exposed fish, and head mark intensity values did not differ among days 14, 21, and 28 for this treatment group. Of the four areas evaluated, the head and pectoral fin were more easily read using a colorimetric key than the lateral or ventral regions of the fish. The concentration of calcein spotted on filter paper to devise the colorimetric key ranged from 1 to 100 mg/L. A difference of approximately 7 mg/L in apparent calcein mark intensity means for the head region could be detected using the colorimetric key. These trials showed that calcein mark intensity on lake trout declined when fish were exposed to artificial sunlight, and the use of a colorimetric key improved the objectivity of calcein mark intensity assessment.

Honeyfield, D.C.; Kehler, T.; Fletcher, J.W.; Mohler, J.W.

2008-01-01

299

Modeling data from double-tagging experiments to estimate heterogeneous rates of tag-shedding in lake trout (Salvelinus namaycush)  

USGS Publications Warehouse

Data from mark-recapture studies are used to estimate population rates such as exploitation, survival, and growth. Many of these applications assume negligible tag loss, so tag shedding can be a significant problem. Various tag shedding models have been developed for use with data from double-tagging experiments, including models to estimate constant instantaneous rates, time-dependent rates, and type I and II shedding rates. I n this study, we used conditional (on recaptures) multinomial models implemented using the program SURVIV (G.C. White. 1983. J. Wildl. Manage. 47: 716-728) to estimate tag shedding rates of lake trout (Salvelinus namaycush) and explore various potential sources of variation in these rates. We applied the models to data from several long-term double-tagging experiments with Lake Superior lake trout and estimated shedding rates for anchor tags in hatchery-reared and wild fish and for various tag types applied in these experiments. Estimates of annual tag retention rates for lake trout were fairly high (80-90%), but we found evidence (among wild fish only) that retention rates may be significantly lower in the first year due to type I losses. Annual retention rates for some tag types varied between male and female fish, but there was no consistent pattern across years. Our estimates of annual tag retention rates will be used in future studies of survival rates for these fish.

Fabrizio, M.C.; Nichols, J.D.; Hines, J.E.; Swanson, B.L.; Schram, S.T.

1999-01-01

300

Modeling data from double-tagging experiments to estimate heterogeneous rates of tag shedding in lake trout (Salvelinus namaycush)  

USGS Publications Warehouse

Data from mark-recapture studies are used to estimate population rates such as exploitation, survival, and growth. Many of these applications assume negligible tag loss, so tag shedding can be a significant problem. Various tag shedding models have been developed for use with data from double-tagging experiments, including models to estimate constant instantaneous rates, time-dependent rates, and type I and II shedding rates. In this study, we used conditional (on recaptures) multinomial models implemented using the program SURVIV (G.C. White. 1983. J. Wildl. Manage. 47: 716-728) to estimate tag shedding rates of lake trout (Salvelinus namaycush) and explore various potential sources of variation in these rates. We applied the models to data from several long-term double-tagging experiments with Lake Superior lake trout and estimated shedding rates for anchor tags in hatchery-reared and wild fish and for various tag types applied in these experiments. Estimates of annual tag retention rates for lake trout were fairly high (80-90%), but we found evidence (among wild fish only) that retention rates may be significantly lower in the first year due to type I losses. Annual retention rates for some tag types varied between male and female fish, but there was no consistent pattern across years. Our estimates of annual tag retention rates will be used in future studies of survival rates for these fish.

Fabrizio, Mary C.; Nichols, James D.; Hines, James E.; Swanson, Bruce L.; Schram, Stephen T.

1999-01-01

301

Bioaccumulation, biotransformation, and biochemical effects of brominated diphenyl ethers in juvenile lake trout (Salvelinus namaycush).  

PubMed

Juvenile lake trout (Salvelinus namaycush) were exposed to three dietary concentrations (0, approximately 2.5, and approximately 25 ng/g per BDE congener) of 13 BDE congeners (3-10 Br atoms) in the laboratory for 56 days, followed by 112 days of clean food, to examine bioaccumulation parameters and potential biochemical effects. The bioaccumulation of BDEs by the trout was highly influenced by biotransformation, via debromination, which resulted in bioaccumulation parameters that were much different than would be expected based on studies of chlorinated organic compounds (e.g., PCBs). Half-lives (t1/2's) for some BDE congeners (e.g., BDE-85 and -190) were much lower than expected based on their Kow, which was likely due to biotransformation, whereas t1/2's of other BDE congeners (e.g., BDE-66, -77, -153, and -154) were much longer than anticipated based on Kow. This was likely because the metabolites of BDE formed via debromination had the same chemical structure of these BDE congeners, which supplemented measured concentrations. The detection of three BDE congeners (an unknown penta, BDE-140, and an unknown hexa) in the fish that were not present in the food or in the control fish provide further evidence forthe debromination of BDEs. Half-lives of BDEs ranged from 38 +/- 9 to 346 +/- 173 days and biomagnification factors ranged from 1.6 (BDE-190) to 45.9 (BDE-100), but these bioaccumulation parameters need to be viewed with caution because they were highly influenced by debromination and relative abundance of individual BDEs that the fish were exposed to. CYP1A enzyme activity, measured as EROD, and free tri-iodothyronine (T3) concentrations in the plasma of lake trout varied significantly throughout the experiment but were not related to BDE exposure. In contrast, plasma levels of thyroxine levels (T4) were lower in both groups of PBDE-exposed fish compared with control fish after 56 days of exposure, and after 168 days in the high dose, suggesting that PBDEs may influence thyroid homeostasis at levels that are higher than what is normally found in the environment. PMID:15046352

Tomy, Gregg T; Palace, Vince P; Halldorson, Thor; Braekevelt, Eric; Danell, Robert; Wautier, Kerry; Evans, Bob; Brinkworth, Lyndon; Fisk, Aaron T

2004-03-01

302

Classifying sea lamprey marks on Great Lakes lake trout: Observer agreement, evidence on healing times between classes, and recommendations for reporting of marking statistics  

USGS Publications Warehouse

In 1997 and 1998 two workshops were held to evaluate how consistent observers were at classifying sea lamprey (Petromyzon marinus) marks on Great Lakes lake trout (Salvelinus namaycush) as described in the King classification system. Two trials were held at each workshop, with group discussion between trials. Variation in counting and classifying marks was considerable, such that reporting rates for A1-A3 marks varied two to three-fold among observers of the same lake trout. Observer variation was greater for classification of healing or healed marks than for fresh marks. The workshops highlighted, as causes for inconsistent mark classification, both departures from the accepted protocol for classifying marks by some agencies, and differences in how sliding and multiple marks were interpreted. Group discussions led to greater agreement in classifying marks. We recommend ways to improve the reliability of marking statistics, including the use of a dichotomous key to classify marks. Laboratory data show that healing times of marks on lake trout were much longer at 4??C and 1??C than at 10??C and varied greatly among individuals. Reported A1-A3 and B1-B3 marks observed in late summer and fall collections likely result from a mixture of attacks by two year classes of sea lamprey. It is likely that a substantial but highly uncertain proportion of attacks that occur in late summer and fall lead to marks that are classified as A1-A3 the next spring. We recommend additional research on mark stage duration.

Ebener, M.P.; Bence, J.R.; Bergstedt, R.A.; Mullett, K.M.

2003-01-01

303

Changes in mortality of lake trout (Salvelinus namaycush) in Michigan waters of Lake Superior in relation to sea lamprey (Petromyzon marinus) predation, 1968-78  

USGS Publications Warehouse

Total mortality rates of lake trout (Salvelinus namaycush) of age VII and older from eastern Lake Superior were estimated from catch curves of age distributions each year in 1968-78. The instantaneous rate of total mortality Z varied from 0.62 to 2.31 in close synchrony with sea lamprey (Petromyzon marinus) wounding rates on lake trout. The regression of transformed Z on the index of lamprey wounding accounted for over 89% of the variation in lake trout mortality (rA? = 0.893). An iterative method of estimating rates of exploitation u, instantaneous rates of fishing mortality F, K (a constant relating sample catch per unit effort to population size), instantaneous normal natural mortality rate M, and instantaneous rate of mortality due to sea lamprey predation L from the sample catch per unit effort and total catch by the fishery is presented. A second method using the results of a 1970-71 tagging study to estimate the mean F in 1970-77 yielded closely similar results to the above and is presented as corroboration. The estimates of u, F, and M appear to be reasonable. F ranged from 0.17 in 1974 to 0.42 in 1969 and M was estimated at 0.26. L varied from 0.21 in 1974 to 1.70 in 1968. Management implications of various policies concerning sea lamprey control, exploitation, and stocking are discussed.

Pycha, Richard L.

1980-01-01

304

Genetic identity of brook trout in Lake Superior south shore streams: Potential for genetic monitoring of stocking and rehabilitation efforts  

USGS Publications Warehouse

Rehabilitation of migratory ('coaster') brook trout Salvelinus fontinalis along Lake Superior's south shore is a topic of high interest among resource stakeholders and management agencies. Proposed strategies for rehabilitation of this brook trout life history variant in Wisconsin include supplemental stocking, watershed management, habitat rehabilitation, harvest regulations, or a combination thereof. In an effort to evaluate the success of coaster brook trout rehabilitation efforts, we collected genetic data from four populations of interest (Whittlesey Creek, Bois Brule River, Bark River, and Graveyard Creek) and the hatchery sources used in the Whittlesey Creek supplementation experiment. We characterized the genetic diversity of 30 individuals from each of four populations using 13 microsatellite DNA loci. Levels of genetic variation were consistent with those in similar studies conducted throughout the basin. Significant genetic variation among the populations was observed, enabling adequate population delineation through assignment tests. Overall, 208 of the 211 sampled fish (98.6%) were correctly assigned to their population of origin. Simulated F1 hybrids between two hatchery strains and the Whittlesey Creek population were identifiable in the majority of attempts (90.5-100% accuracy with 0-2.5% error). The genetic markers and analytical techniques described provide the ability to monitor the concurrent coaster brook trout rehabilitation efforts along Wisconsin's Lake Superior south shore, including the detection of hybridization between hatchery and native populations. ?? Copyright by the American Fisheries Society 2008.

Sloss, B.L.; Jennings, M.J.; Franckowiak, R.; Pratt, D.M.

2008-01-01

305

Mass-marking of otoliths of lake trout sac fry by temperature manipulation  

USGS Publications Warehouse

The otoliths of 676,000 sac fry of lake trout Salvelinus namaycush in 1986, and of 1,100,000 in 1987, were marked by daily manipulation of water temperature. The fish were stocked into Lake Huron in the spring. Otolith marks consisted of groups of daily growth rings accentuated into recognizable patterns by steadily raising and lowering the temperature about 10 degrees C (from a base of 1-4 degrees C) over 14 h. In 1987, groups of marked and control fish were held for 6 months. The otoliths were removed from samples of the fish, embedded in epoxy, thin sectioned by grinding in the sagittal plane, etched, and viewed by using a combination of a compound microscope (400-1000x) and a video enhancement system. One or more readable otolith sections were obtained from 39 of a sample of 40 fish. Three independent readers examined 41 otoliths for marks and correctly classified the otoliths, with accuracies of 85, 98, and 100%, as being from marked or unmarked fish. The exact number of rings in a recognizable pattern sometimes differed from the number of temperature cycles to which the fish were exposed. Counts of daily rings within groups of six rings varied less than counts within groups of rings.

Bergstedt, Roger A.; Eshenroder, Randy L.; Bowen, Charles; Seelye, James G.; Locke, Jeffrey C.

1990-01-01

306

Mass-marking of otoliths of lake trout sac fry by temperature manipulation  

USGS Publications Warehouse

The otoliths of 676,000 sac fry of lake trout Salvelinus namaycush in 1986, and of 1,100,000 in 1987, were marked by daily manipulation of water temperature. The fish were stocked into Lake Huron in the spring. Otolith marks consisted of groups of daily growth rings accentuated into recognizable patterns by steadily raising and lowering the temperature about IOA?C (from a base of 1-4A?C) over 14h. In 1987, groups of marked and control fish were held for 6 months. The otoliths were removed from samples of the fish, embedded in epoxy, thin-sectioned by grinding in the sagittal plane, etched, and viewed by using a combination of a compound microscope (400-1000x) and a video enhancement system. One or more readable otolith sections were obtained from 39 of a sample of 40 fish. Three independent readers examined 41 otoliths for marks and correctly classified the otoliths, with accuracies of 85, 98,and 100%, as being from marked or unmarked fish. The exact number of rings in a recognizable pattern sometimes differed from the number of temperature cycles to which the fish were exposed. Counts of daily rings within groups of six rings varied less than counts within groups of three rings.

Bergstedt, R.A.; Eshenroder, R.L.; Bowen, C. II; Seelye, J.G.; Locke, J.C.

1990-01-01

307

Importance of rearing-unit design and stocking density to the behavior, growth and metabolism of lake trout ( Salvelinus namaycush)  

Microsoft Academic Search

Juvenile lake trout (Salvelinus namaycush) were held at different stocking densities (48 and 96 kg m?3) in rearing-units of different design (rectangular plug-flow, circular and cylindrical cross-flow) and the effects on behavior, growth and metabolism were examined. Ambient light levels and current velocities were measured in each of three tank sectors (upstream, middle and downstream) to determine their relative contributions

Robert M Ross; Barnaby J Watten

1998-01-01

308

Short-term fate of dietary dieldrin in the digestive tract of juvenile lake trout (Salvelinus namaycush)  

USGS Publications Warehouse

Short-term fate of dietary dieldrin in the digestive tract of fishes is poorly known. Studies of the uptake, distribution, and elimination of chlorinated hydrocarbons have suggested that uptake or degradation is rapid in the intestine (GROSS 1969; MACEK et al. 1970; GRZENDA et al. 1970, 1971). The present study was designed to determine the short-term fate of a single oral dose of dieldrin in the digestive tract of lake trout (Salvelinus namaycush).

Stewart, Donald J.; Stein, Roy A.

1974-01-01

309

Efficacy of hydrogen peroxide versus formalin treatments to control mortality associated with saprolegniasis on lake trout eggs  

USGS Publications Warehouse

We compared the efficacy of hydrogen peroxide versus formalin treatments to control fungal infections on eggs of lake trout Salvelinus namaycush incubated at a hatchery in Wisconsin. Four strains of lake trout eggs were incubated in six vertical-flow Heath incubators; three replicate incubators for each chemical. Each incubator had 13 trays containing approximately 25,000-30,000 eggs/tray. Formalin (1,667 mg/L) or hydrogen peroxide (1,000 mg/L) treatments were administered once daily for 15 min up to the development of visible eye spots in the eggs (eyed egg stage). Eyed and dead eggs were separated using a photoelectric egg sorter, and the number of live and dead eggs was determined volumetrically. In the hydrogen peroxide test group, the bottom trays of each incubator had fungus present on the eggs, whereas no fungus was observed on eggs treated with formalin. The mean percentage of eyed eggs for an incubator treated with formalin (75%) was significantly greater than an incubator treated with hydrogen peroxide (70%). Formalin was the most efficacious therapeutant; however, both therapeutants were effective in increasing lake trout egg survival up to the eyed egg stage. ?? Copyright by the American Fisheries Society 2005.

Rach, J.J.; Redman, S.; Bast, D.; Gaikowski, M.P.

2005-01-01

310

beta-naphthoflavone induction of CYP1A in brain of juvenile lake trout (Salvelinus namaycush Walbaum).  

PubMed

Many environmental pollutants induce expression of the cytochrome P450 (CYP) 1A subfamily of genes. We integrated cellular and molecular biological techniques to examine the effects of beta-naphthoflavone (BNF) exposure in lake trout brain CYP1A distribution and dynamics. Over a 32-day time-course, real time quantitative reverse transcription polymerase chain reaction (Q-RT-PCR) results showed that CYP1A mRNA induction in response to BNF exposure occurred rapidly and continued to rise in the BNF-treated lake trout after 4 h, with a peak at or after 2 days. Messenger RNA levels fell after 4 days, and this trend continued after 16 days of exposure. In situ hybridization indicated that CYP1A mRNA was universally elevated in the brain of BNF-exposed fish and was mainly expressed in the endothelia and occasionally in the glial cells. CYP1A immunoreactivity was induced in the olfactory bulb and valvula cerebelli of BNF-treated fish. Other brain areas showed constitutive CYP1A immunoreactivity in both control and BNF-treated fish. Some BNF-treated fish contained multifocal hemorrhages in the brain tissue, and these fish had overall depressed CYP1A immunoreactivity in the brain. The relationship between transcriptional and translational effects of BNF exposure in the brain of juvenile lake trout is discussed. PMID:15037647

Chung-Davidson, Yu-Wen; Rees, Christopher B; Wu, Hong; Yun, Sang-Seon; Li, Weiming

2004-04-01

311

Population Density of Brown Trout ( Salmo trutta ) in Extremely Dilute Water Qualities in Mountain Lakes in Southwestern Norway  

Microsoft Academic Search

We have examined populations of brown trout in low-conductivity mountain lakes (5.0–13.7 ?S\\/cm and 0.14–0.41 mg\\/l Ca) in southwestern\\u000a Norway during the period 2000–2010. Inlets to the lakes were occasionally even more dilute (2007; conductivity?=?2.9–4.8 ?S\\/cm\\u000a and Ca?=?0.06–0.17 mg\\/l). The combination of pH and conductivity was the best predictor to fish status (CPUE), indicating\\u000a that availability of essential ions was the primary restricting factor

Espen Enge; Frode Kroglund

2011-01-01

312

Molecular markers of yolk sac fry development in nine families of lake trout.  

PubMed

Salmonids in certain areas of North America and northern Europe suffer from reproductive disturbances manifested through the death of yolk sac fry. These disturbances are referred to as early mortality syndrome (EMS) in the Great Lakes region and M74 in the Baltic Sea. Both of these syndromes have been associated with reduced concentrations of thiamine in affected females and their eggs. However, large variations in signs and mortality, both within and between the individual syndromes, have been reported. Yolk sac fry mortality (M74) in Atlantic salmon Salmo salar has been shown to be associated with reduced DNA binding of the hypoxia-inducible transcription factor 1 (HIF-1), reduced production of vascular endothelial growth factor (VEGF) protein, decreased capillary density, and down-regulation of adult-type globin gene transcription (which is responsible for the protein part of adult hemoglobin). One of the main effects of all of these changes is reduced oxygen transport to the tissues of affected fry. In this study, the developmental patterns of HIF-1 DNA binding, VEGF protein expression, and adult-type globin gene transcription were analyzed in nine family groups of Lake Michigan lake trout Salvelinus namaycush. The results indicate that HIF-1 DNA binding and globin gene transcription increase from hatch to the end of yolk sac stage. Interindividual and between-family biological variations were detected, especially in VEGF protein expression and globin gene transcription. Our results demonstrate the possibility of using these molecular markers in investigating the etiology of EMS and making comparisons between the mechanisms of different salmonid yolk sac fry mortalities. PMID:20218502

Vuori, Kristiina A; Paavilainen, Tiia; Nikinmaa, Mikko; Czesny, Sergiusz; Rinchard, Jacques

2009-12-01

313

Pine Creek and Eagle Lake Rainbow Trout Study 2007 Spawner Migration,  

E-print Network

and Rearing Survey, and Bogard Spring Creek Brook Trout Removal Experiment Report to the Pine Creek ELRT given the apparent high level of competition from brook trout? The overall goal of the project the temporary removal of competing non-native brook trout. In spring 2007 stream flows were low

Thompson, Lisa C.

314

The accumulation, distribution, and toxicological effects of dietary arsenic exposure in lake whitefish (Coregonus clupeaformis) and lake trout (Salvelinus namaycush).  

PubMed

A 20-day experiment was conducted to compare the accumulation, distribution, and toxicological effects of dietary As, as arsenate, in lake whitefish (LWF, Coregonus clupeaformis) and lake trout (LT, Salvelinus namaycush). Results of this experiment were used to design an experiment of longer duration in which one of the fish species was selected and exposed three times per week to lower dietary As doses. In the present study each treatment group was exposed to a combination of one of three doses of As (0, 100, or 1000 microg As/g) and one of two types of diet, no brine shrimp (NS) or with brine shrimp (WS) for a total of eight dosing events. Brine shrimp were added to determine whether their presence enhanced consumption of As-contaminated food. Modified feeding behavior occurred in both fish species fed As contaminated diets, with the exception of the 100 microg As/g NS food. Brine shrimp addition did not affect feed consumption of the As contaminated diets. Significant As accumulation occurred in stomach, pyloric caeca, intestine, liver, kidney, and gallbladder, but not in bile or muscle. As exposure did not have a significant effect on hepatic and renal metallothionein concentrations. Concentrations of lipid peroxides were only significantly elevated in the plasma of LT fed the 1000 microg As/g WS food. Liver somatic indices decreased significantly in both species, whereas hematological parameters were not affected in either species. Histological lesions occurred in gallbladder, liver, kidney, pyloric caeca and intestine from LWF. These lesions were not observed in LT; however, gallbladders were not examined in this species. Weight gain was lower in both species fed As contaminated diets, however, condition factors were not affected. PMID:11796327

Pedlar, R M; Ptashynski, M D; Wautier, K G; Evans, R E; Baron, C L; Klaverkamp, J F

2002-01-01

315

Accumulation, distribution and toxicology of dietary nickel in lake whitefish (Coregonus clupeaformis) and lake trout (Salvelinus namaycush).  

PubMed

An 18-day experiment was conducted to investigate the uptake and sublethal toxicity of dietary Ni in adult lake whitefish (LWF, Coregonus clupeaformis) and lake trout (LT, Salvelinus namaycush) fed diets containing 0, 1000 and 10000 microg Ni/g, prepared with and without brine shrimp. The results of this experiment were used to design an experiment of longer duration in which one of the fish species was selected and exposed to lower dietary Ni doses. In the present study feed refusal was observed in LT and LWF fed 10000 microg Ni/g, after three and 4-5 feedings, respectively. LT fed Ni-contaminated diets exhibited different patterns of Ni accumulation than LWF. Increased Ni concentrations in all LWF tissues, except the intestine, were associated with increased doses of Ni. Copper and Zn concentrations in kidney and liver of LWF were altered. Metallothionein concentrations in kidneys of LT fed 1000 microg Ni/g and 10000 microg Ni/g and LWF fed 10000 microg Ni/g and in livers of LWF fed 10000 microg Ni/g (diet without shrimp only) increased significantly. Increased lipid peroxide production in the plasma of LT fed 10000 microg Ni/g was observed. Blood glucose and electrolytes were affected by Ni exposure. Histopathological alterations were observed in kidneys of LWF fed low and high dose diets, livers of whitefish fed high dose diets, and intestines of LWF fed high dose diets and LT fed low and high dose diets. LT fed high dose diets exhibited significant decreases in weight. PMID:11574285

Ptashynski, M D; Pedlar, R M; Evans, R E; Wautier, K G; Baron, C L; Klaverkamp, J F

2001-10-01

316

Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project, Annual Report 2001-2002.  

SciTech Connect

The construction of Chief Joseph and Grand Coulee Dams completely and irrevocably blocked anadromous fish migrations to the Upper Columbia River. Historically this area hosted vast numbers of salmon returning to their natal waters to reproduce and die. For the native peoples of the region, salmon and steelhead were a principle food source, providing physical nourishment and spiritual sustenance, and contributing to the religious practices and the cultural basis of tribal communities. The decaying remains of spawned-out salmon carcasses contributed untold amounts of nutrients into the aquatic, aerial, and terrestrial ecosystems of tributary habitats in the upper basin. Near the present site of Kettle Falls, Washington, the second largest Indian fishery in the state existed for thousands of years. Returning salmon were caught in nets and baskets or speared on their migration to the headwater of the Columbia River in British Columbia. Catch estimates at Kettle Falls range from 600,000 in 1940 to two (2) million around the turn of the century (UCUT, Report No.2). The loss of anadromous fish limited the opportunities for fisheries management and enhancement exclusively to those actions addressed to resident fish. The Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project is a mitigation project intended to enhance resident fish populations and to partially mitigate for anadromous fish losses caused by hydropower system impacts. This substitution of resident fish for anadromous fish losses is considered in-place and out-of-kind mitigation. Upstream migration and passage barriers limit the amount of spawning and rearing habitat that might otherwise be utilized by rainbow trout. The results of even limited stream surveys and habitat inventories indicated that a potential for increased natural production exists. However, the lack of any comprehensive enhancement measures prompted the Upper Columbia United Tribes Fisheries Center (UCUT), Colville Confederated Tribes (CCT), Spokane Tribe of Indians (STI) and Washington Department of Fish and Wildlife (WDFW) to develop and propose a comprehensive fishery management plan for Lake Roosevelt. The Rainbow Trout Habitat/Passage Improvement Project (LRHIP) was designed with goals directed towards increasing natural production while maintaining genetic integrity among current tributary stocks. The initial phase of the Lake Roosevelt Habitat Improvement Project (Phase I, baseline data collection: 1990-91) was focused on the assessment of limiting factors, including the quality and quantity of available spawning gravel, identification of passage barriers, and assessment of other constraints. After the initial assessment of stream parameters, five streams meeting specific criteria were selected for habitat/passage improvement projects (Phase II, implementation -1992-1995). Four of these projects were on the Colville Indian Reservation South Nanamkin, North Nanamkin, Louie and Iron Creeks and one Blue Creek was on the Spokane Indian Reservation. At the completion of project habitat improvements, the final phase (Phase III, monitoring-1996-2000) began. This phase assessed the changes and determined the success achieved through the improvements. Data analysis showed that passage improvements are successful for increasing habitat availability and use. The results of in-stream habitat improvements were inconclusive. Project streams, to the last monitoring date, have shown increases in fish density following implementation of the improvements. In 2000 Bridge Creek, on the Colville Reservation was selected for the next phase of improvements. Data collection, including baseline stream survey and population data collection, was carried out during 2001 in preparation for the design and implementation of stream habitat/passage improvements. Agencies cooperating on the project include the Colville Confederated Tribes (CCT), Natural Resource Conservation Service (NRCS, Ferry County District), Ferry County Conservation District, and Ferry County. The Bonneville Power Administration (BPA) provided

Sears, Sheryl

2003-01-01

317

Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project, Annual Report 2002-2003.  

SciTech Connect

The construction of Chief Joseph and Grand Coulee Dams completely and irrevocably blocked anadromous fish migrations to the Upper Columbia River. Historically this area hosted vast numbers of salmon returning to their natal waters to reproduce and die. For the native peoples of the region, salmon and steelhead were a principle food source, providing physical nourishment and spiritual sustenance, and contributing to the religious practices and the cultural basis of tribal communities. The decaying remains of spawned-out salmon carcasses contributed untold amounts of nutrients into the aquatic, aerial, and terrestrial ecosystems of tributary habitats in the upper basin. Near the present site of Kettle Falls, Washington, the second largest Indian fishery in the state existed for thousands of years. Returning salmon were caught in nets and baskets or speared on their migration to the headwater of the Columbia River in British Columbia. Catch estimates at Kettle Falls range from 600,000 in 1940 to two (2) million around the turn of the century (UCUT, Report No.2). The loss of anadromous fish limited the opportunities for fisheries management and enhancement exclusively to those actions addressed to resident fish. The Lake Roosevelt Rainbow Trout Habitat/Passage Improvement Project is a mitigation project intended to enhance resident fish populations and to partially mitigate for anadromous fish losses caused by hydropower system impacts. This substitution of resident fish for anadromous fish losses is considered in-place and out-of-kind mitigation. Upstream migration and passage barriers limit the amount of spawning and rearing habitat that might otherwise be utilized by rainbow trout. The results of even limited stream surveys and habitat inventories indicated that a potential for increased natural production exists. However, the lack of any comprehensive enhancement measures prompted the Upper Columbia United Tribes Fisheries Center (UCUT), Colville Confederated Tribes (CCT), Spokane Tribe of Indians (STI) and Washington Department of Fish and Wildlife (WDFW) to develop and propose a comprehensive fishery management plan for Lake Roosevelt. The Rainbow Trout Habitat/Passage Improvement Project (LRHIP) was designed with goals directed towards increasing natural production while maintaining genetic integrity among current tributary stocks. The initial phase of the Lake Roosevelt Habitat Improvement Project (Phase I, baseline data collection: 1990-91) was focused on the assessment of limiting factors, including the quality and quantity of available spawning gravel, identification of passage barriers, and assessment of other constraints. After the initial assessment of stream parameters, five streams meeting specific criteria were selected for habitat/passage improvement projects (Phase II, implementation -1992-1995). Four of these projects were on the Colville Indian Reservation South Nanamkin, North Nanamkin, Louie and Iron Creeks and one Blue Creek was on the Spokane Indian Reservation. At the completion of project habitat improvements, the final phase (Phase III, monitoring-1996-2000) began. This phase assessed the changes and determined the success achieved through the improvements. Data analysis showed that passage improvements are successful for increasing habitat availability and use. The results of in-stream habitat improvements were inconclusive. Project streams, to the last monitoring date, have shown increases in fish density following implementation of the improvements. In 2000 Bridge Creek, on the Colville Reservation was selected for the next phase of improvements. Data collection, including baseline stream survey and population data collection, was carried out during 2001 in preparation for the design and implementation of stream habitat/passage improvements. Agencies cooperating on the project include the Colville Confederated Tribes (CCT), Natural Resource Conservation Service (NRCS, Ferry County District), Ferry County Conservation District, and Ferry County. The Bonneville Power Administration (BPA) provided

Sears, Sheryl

2004-01-01

318

A legacy of divergent fishery management regimes and the resilience of rainbow and cutthroat trout populations in Lake Crescent, Olympic National Park, Washington  

USGS Publications Warehouse

As a means to increase visitation, early fisheries management in the National Park Service (NPS) promoted sport harvest and hatchery supplementation. Today, NPS management objectives focus on the preservation of native fish. We summarized management regimes of Olympic National Park's Lake Crescent, which included decades of liberal sport harvest and hatchery releases of 14.3 million salmonids. Notably, nonnative species failed to persist in the lake. Complementary analyses of annual redd counts (1989–2012) and genetics data delineated three sympatric trout (one rainbow; two cutthroat) populations that exhibited distinct spatial and temporal spawning patterns, variable emergence timings, and genetic distinctiveness. Allacustrine rainbow trout spawned in the lake outlet from January to May. Cutthroat trout spawned in the major inlet tributary (Barnes Creek) from February to June and in the outlet river (Lyre) from September to March, an unusual timing for coastal cutthroat trout. Redd counts for each species were initially low (rainbow = mean 89; range 37–159; cutthroat = mean 93; range 18–180), and significantly increased for rainbow trout (mean 306; range 254–352) after implementation of catch-and-release regulations. Rainbow and cutthroat trout reached maximum sizes of 10.4 kg and 5.4 kg, respectively, and are among the largest throughout their native ranges. Morphometric analyses revealed interspecific differences but no intraspecific differences between the two cutthroat populations. Genetic analyses identified three distinct populations and low levels (9–17%) of interspecific hybridization. Lake Crescent rainbow trout were genetically divergent from 24 nearby Oncorhynchus mykiss populations, and represented a unique evolutionary legacy worthy of protection. The indigenous and geographically isolated Lake Crescent trout populations were resilient to overharvest and potential interactions with introduced fish species.

Brenkman, Samuel J.; Duda, Jeff; Kennedy, Philip R.; Baker, Bruce M.

2014-01-01

319

A Comparison of Lake Trout Spawning, Fry Emergence, and Habitat Use in Lakes Michigan, Huron, and Champlain  

E-print Network

is underway in all of the Great Lakes and Lake Champlain, but restoration has only been achieved in Lake Huron, in Lake Michi- gan, and in Lake Champlain in 2000­2003. Divers surveyed and assessed abundance in Lake Michi- gan and Parry Sound, and very high at one site in Lake Champlain. Egg deposition was lowest

Marsden, Ellen

320

Sample size requirements and analysis of tag recoveries for paired releases of lake trout  

USGS Publications Warehouse

A simple chi-square test can be used to analyze recoveries from a paired-release experiment to determine whether differential survival occurs between two groups of fish. The sample size required for analysis is a function of (1) the proportion of fish stocked, (2) the expected proportion at recovery, (3) the level of significance (a) at which the null hypothesis is tested, and (4) the power (1-I?) of the statistical test. Detection of a 20% change from a stocking ratio of 50:50 requires a sample of 172 (I?=0.10; 1-I?=0.80) to 459 (I?=0.01; 1-I?=0.95) fish. Pooling samples from replicate pairs is sometimes an appropriate way to increase statistical precision without increasing numbers stocked or sampling intensity. Summing over time is appropriate if catchability or survival of the two groups of fish does not change relative to each other through time. Twelve pairs of identical groups of yearling lake trout Salvelinus namaycush were marked with coded wire tags and stocked into Lake Ontario. Recoveries of fish at ages 2-8 showed differences of 1-14% from the initial stocking ratios. Mean tag recovery rates were 0.217%, 0.156%, 0.128%, 0.121%, 0.093%, 0.042%, and 0.016% for ages 2-8, respectively. At these rates, stocking 12,100-29,700 fish per group would yield samples of 172-459 fish at ages 2-8 combined.

Elrod, Joseph H.; Frank, Anthony

1990-01-01

321

Waterborne ethynylestradiol induces vitellogenin and alters metallothionein expression in lake trout (Salvelinus namaycush).  

PubMed

Estrogenic contaminants isolated from waters receiving sewage treatment plant effluents are known to induce the egg yolk precursor vitellogenin (VTG) in male fish. Levels of the metal binding protein metallothionein (MT) have also been shown to be affected by estrogens in fish. It has been postulated that MT declines in estrogen exposed fish to facilitate transfer of the essential metal Zn to cellular components required for VTG synthesis. To examine the changes in MT and VTG concentrations in fish exposed to an estrogen contaminant, lake trout (Salvelinus namaycush) were exposed to waterborne ethynylestradiol at 0, 4, 40 or 400 ng/l(-1) for 21 days. Blood and tissues were collected after 21 days of exposure to measure circulating levels of VTG as well as MT concentrations in liver and kidney. VTG increased in male and female fish from all three exposure groups compared to control fish. MT in liver significantly decreased in males and females compared to the controls, in the two highest exposures. MT in kidney was significantly higher in both sexes of fish exposed to the two highest concentrations of ethynylestradiol. These data are supportive of a relationship between estrogen exposure and the regulation of MT. Further studies to examine the specific links between estrogen exposure, VTG induction and regulation of essential metals like Zn are required. PMID:12595171

Werner, Julieta; Wautier, Kerry; Evans, Robert E; Baron, Christopher L; Kidd, Karen; Palace, Vince

2003-02-26

322

Thyroid hormone kinetics in lake trout (Salvelinus namaycush) exposed to PCB 126  

SciTech Connect

Recent studies indicate that co-planar PCB congeners or their metabolites can distort thyroid function in mammals. Although co-planar PCBs have been detected at pg/kg levels in fish from contaminated areas, few studies have examined the potential of co-planar PCBs to alter thyroid function in fish. The authors treated immature lake trout, Salvelinus namaycush, with a single oral gelatin gavage containing 3,3{prime},4,4{prime},5-pentachlorobiphenyl (PCB 126) at nominal concentrations of 0, 3, 10 or 30 {micro}g/kg fish weight. After 3 and 23 weeks PCB exposure, fish were catheterized and allowed 1 week to recover from the surgical procedures. Then a single bolus of L-[3{prime},5{prime}{sup 125}l] thyroxine in plasma vehicle was administered through the catheter. Blood samples were removed at 5, 13, 45, 120, 480, 960, 1440 and 2880 min after tracer injection. PCB 126 doses greater than 3{micro}g/kg accelerated the plasma clearance rate and modified tissue distribution of L-thyroxine. The altered L-thyroxine kinetics appear correlated to higher activities of hepatic conjugating enzymes. The possibility exists that some of the organismal effects of co-planar PCB exposure may be mediated by disruptions in thyroid function.

Brown, S.B.; Vandenbyllaardt, L. [Department of Fisheries and Oceans, Winnipeg, Manitoba (Canada)

1995-12-31

323

Classifying sea lamprey marks on Great Lakes lake trout: observer agreement, evidence on healing times between classes and recommendations for reporting of marking statistics  

USGS Publications Warehouse

In 1997 and 1998 two workshops were held to evaluate how consistent observers were at classifying sea lamprey (Petromyzon marinus) marks on Great Lakes lake trout (Salvelinus namaycush) as described in the King classification system. Two trials were held at each workshop, with group discussion between trials. Variation in counting and classifying marks was considerable, such that reporting rates for A1-A3 marks varied two to three-fold among observers of the same lake trout. Observer variation was greater for classification of healing or healed marks than for fresh marks. The workshops highlighted, as causes for inconsistent mark classification, both departures from the accepted protocol for classifying marks by some agencies, and differences in how sliding and multiple marks were interpreted. Group discussions led to greater agreement in classifying marks. We recommend ways to improve the reliability of marking statistics, including the use of a dichotomous key to classify marks. Laboratory data show that healing times of marks on lake trout were much longer at 4A?C and 1A?C than at 10A?C and varied greatly among individuals. Reported A1-A3 and B1-B3 marks observed in late summer and fall collections likely result from a mixture of attacks by two year classes of sea lamprey. It is likely that a substantial but highly uncertain proportion of attacks that occur in late summer and fall lead to marks that are classified as A1-A3 the next spring. We recommend additional research on mark stage duration.

Ebener, Mark P.; Bence, James R.; Bergstedt, Roger A.; Mullet, Katherine M.

2003-01-01

324

Biota--sediment accumulation factors for polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans in southern Lake Michigan lake trout (Salvelinus namaycush).  

PubMed

A set of high-quality, age-specific biota-sediment accumulation factors (BSAFs) for polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) have been determined from concentrations measured with high-resolution gas chromatography/high-resolution mass spectrometry, by use of the 13C isotopic dilution technique, in lake trout and surficial (0-2 cm) sediment samples from southern Lake Michigan. BSAFs ranged from <0.1 to 18 for PCBs and from <0.001 to 0.32 for PCDDs and PCDFs detected in the fish. PCBs with zero or one chlorine in an ortho position had smaller BSAFs than other PCBs. PCDDs and PCDFs with chlorines at the 2,3,7,8-positions had larger BSAFs than most other PCDDs and PCDFs. The fidelity of the relative bioaccumulation potential data between independent lake trout samples, within and among age classes, suggests that differences in slight rates of net metabolism in the food chain are important and contribute to the apparent differences in BSAFs, not only for PCDDs and PCDFs but also possibly for some PCBs. A complicating factor for non-ortho- and mono-ortho-PCBs is the uncertain contribution of enhanced affinity for black carbon (and possibly volatility) acting in concert with metabolism to reduce measured BSAFs for lake trout. On the basis of the association between chemicals with apparent slight rates of metabolism and measured dioxin-like toxicity, several PCDFs with similar measured BSAFs but unknown toxicity may be candidates for toxicity testing. PMID:15543729

Burkhard, Lawrence P; Cook, Philip M; Lukasewycz, Marta T

2004-10-15

325

Microsatellite and mtDNA analysis of lake trout, Salvelinus namaycush, from Great Bear Lake, Northwest Territories: impacts of historical and contemporary evolutionary forces on Arctic ecosystems  

PubMed Central

Resolving the genetic population structure of species inhabiting pristine, high latitude ecosystems can provide novel insights into the post-glacial, evolutionary processes shaping the distribution of contemporary genetic variation. In this study, we assayed genetic variation in lake trout (Salvelinus namaycush) from Great Bear Lake (GBL), NT and one population outside of this lake (Sandy Lake, NT) at 11 microsatellite loci and the mtDNA control region (d-loop). Overall, population subdivision was low, but significant (global FST ? = 0.025), and pairwise comparisons indicated that significance was heavily influenced by comparisons between GBL localities and Sandy Lake. Our data indicate that there is no obvious genetic structure among the various basins within GBL (global FST = 0.002) despite the large geographic distances between sampling areas. We found evidence of low levels of contemporary gene flow among arms within GBL, but not between Sandy Lake and GBL. Coalescent analyses suggested that some historical gene flow occurred among arms within GBL and between GBL and Sandy Lake. It appears, therefore, that contemporary (ongoing dispersal and gene flow) and historical (historical gene flow and large founding and present-day effective population sizes) factors contribute to the lack of neutral genetic structure in GBL. Overall, our results illustrate the importance of history (e.g., post-glacial colonization) and contemporary dispersal ecology in shaping genetic population structure of Arctic faunas and provide a better understanding of the evolutionary ecology of long-lived salmonids in pristine, interconnected habitats. PMID:23404390

Harris, Les N; Howland, Kimberly L; Kowalchuk, Matthew W; Bajno, Robert; Lindsay, Melissa M; Taylor, Eric B

2013-01-01

326

Lake Roosevelt Volunteer Net Pens, Lake Roosevelt Rainbow Trout Net Pens, 2002-2003 Annual Report.  

SciTech Connect

The completion of Grand Coulee Dam for power production, flood control, and irrigation resulted in the creation of a blocked area above the dam and in the loss of anadromous fish. Because of lake level fluctuations required to meet the demands for water release or storage, native or indigenous fish were often threatened. For many years very little effort was given to stocking the waters above the dam. However, studies by fish biologists showed that there was a good food base capable of supporting rainbow and kokanee (Gangmark and Fulton 1949, Jagielo 1984, Scholz etal 1986, Peone etal 1990). Further studies indicated that artificial production might be a way of restoring or enhancing the fishery. In the 1980's volunteers experimented with net pens. The method involved putting fingerlings in net pens in the fall and rearing them into early summer before release. The result was an excellent harvest of healthy fish. The use of net pens to hold the fingerlings for approximately nine months appears to reduce predation and the possibility of entrainment during draw down and to relieve the hatcheries to open up available raceways for future production. The volunteer net pen program grew for a few years but raising funds to maintain the pens and purchase food became more and more difficult. In 1995 the volunteer net pen project (LRDA) was awarded a grant through the Northwest Power Planning Council's artificial production provisions.

Smith, Gene

2003-11-01

327

In vitro toxicity and interactions of environmental contaminants (Arochlor 1254 and mercury) and immunomodulatory agents (lipopolysaccharide and cortisol) on thymocytes from lake trout (Salvelinus namaycush)  

USGS Publications Warehouse

The immunotoxicity of chemical combinations commonly encountered by the lake trout (Salvelinus namaycush) immune system was the focus of this study. It was hypothesised that combinations of an environmental contaminant (mercuric chloride or Aroclor 1254) and an immunomodulatory agent (bacterial endotoxin or cortisol) might interact to produce a greater toxicity than that of the environmental contaminant alone at concentrations typically encountered in piscine blood and other tissues. Thus lake trout thymocytes were isolated and treated with mercuric chloride or Aroclor 1254 in the presence and absence of cortisol or lipopolysaccharide. Incubations were performed for 6 or 20h at 4A?C or 10A?C. Lipopolysaccharide did not affect the toxicity of either contaminant. In contrast, cortisol enhanced the toxicity of both environmental contaminants. Hence, stressors that lead to increased cortisol production, but not lipopolysaccharide directly, may increase the toxicity of mercury and Aroclor 1254 to lake trout thymocytes.

Miller, Gregory G.; Sweet, Leonard I.; Adams, Jean V.; Omann, Geneva M.; Passino-Reader, Dora R.; Meier, Peter G.

2002-01-01

328

REARING AND DISTRIBUTING TROUT TO HELP MAINTAIN  

E-print Network

temperatures are rising. In hatcheries, domesticated rainbow brood trout spawn in the fall or winter. The brook widely distributed brown trout were introduced from Europe. Brook and brown trouts spawn in the fall, rearing; brook, brown, cutthroat, and rainbow trout, and some lake trout, as well as the landlocked

329

Effects of coancestry on accuracy of individual assignments to population of origin: examples using Great Lakes lake trout (Salvelinus namaycush).  

PubMed

Methods for assigning individuals to population of origin are widely used in ecological genetics, resources management, and forensics. Characteristics of genetic data obtained from putative source populations that enhance accuracy of assignment are well established. How non-independence within and among unknown individuals to be classified [i.e., gene correlations within individual (inbreeding) and gene correlations among individuals within group (coancestry)] affect assignment accuracy is poorly understood. We used empirical data for six microsatellite loci and offspring from full-sib crosses of hatchery strains of lake trout (Salvelinus namaycush; Salmonidae) representing known levels of coancestry (mean theta = 0.006 and 0.06) within families to investigate how gene correlations can affect assignment. Additional simulations were conducted to further investigating the influence of allelic diversity (2, 6 or 10 alleles per locus) and inbreeding (F = 0.00, 0.05, and 0.15) on assignment accuracy for cases of low and high inter-population variance in allele frequency (mean F (st) = 0.01 and 0.1, respectively). Inbreeding had no effect on accuracy of assignments. In contrast, variance in assignment accuracy across replicated simulations, and for each empirical case study increased with increasing coancestry, reflecting non-independence of probabilities of correct assignment among members of kin groups. Empirical estimates of assignment error rates should be interpreted with caution if appreciable levels of coancestry are suspected. Additional emphasis should be placed on sampling designs (spatially and temporally) that define or minimize the potential for sampling related individuals. PMID:16850237

Guinand, Bruno; Scribner, Kim T; Page, Kevin S; Filcek, Kristi; Main, Laura; Burnham-Curtis, Mary K

2006-05-01

330

A real-time PCR method for the quantification of the two isoforms of metallothionein in Lake Trout (Salvelinus namaycush).  

PubMed

Metallothioneins (MTs) are low-molecular-weight proteins whose physiologic roles are the regulation of essential metals Cu and Zn, sequestration of heavy metals, and free radical scavenging. Induced production of MTs in a wide variety of organisms exposed to heavy metals has made them popular exposure indicators. While it has been postulated that the three different isoforms of MT play different physiologic roles, methods to discern induction separately have not been available. The development of real-time polymerase chain reaction (real-time PCR) primers and TaqMan probes to measure the two MT isoforms found in salmonid fish are described. Assuming a high degree of homology between the isoforms and within different groups of salmonids, the sequences for MT-I and MT-II from rainbow trout were used to develop primers and probes for lake trout using the Primer3 program. Two sections of each isoform that varied by only a few nucleotides were targeted. SYBR Green validated the primer specificity, and melt curve analysis further ensured that only one product was amplified. Analysis of archived samples from fish captured in unmanipulated reference lakes or from lakes experimentally treated with cadmium or ethynylestradiol (EE2) afforded an examination of seasonal and contaminant influences on MT-I and MT-II mRNA expression. PMID:17687585

Werner, Julieta; Palace, Vince; Baron, Christopher; Shiu, Robert; Yarmill, Alison

2008-01-01

331

Influence of lake trophic structure on iodine-131 accumulation and subsequent cumulative radiation dose to trout thyroids.  

PubMed

Iodine-131 is a major component of the atmospheric releases following reactor accidents, and the passage of (131)I through food chains from grass to human thyroids has been extensively studied. By comparison, the fate and effects of (131)I deposition onto lakes and other aquatic systems have been less studied. In this study we: (1) reanalyze 1960s data from experimental releases of (131)I into two small lakes; (2) compare the effects of differences in lake trophic structures on the accumulation of (131)I by fish; (3) relate concentrations in fish and fish tissues to that in the water column using empirically estimated uptake (L kg(-1) d(-1)) and loss (d(-1)) parameters; and (4) show that the largest concentrations in the thyroids of trout (Oncorhynchus mykiss) may occur from 8 to 32 days after initial release. Iodine-131 concentration in trout thyroids at 30-days post release may be >1000 times that in the water. Estimates of cumulative radiation dose (mGy) to thyroids computed using an anatomically-appropriate model of trout thyroid structure within the Monte Carlo N-particle modeling software predicted cumulative thyroid doses that increased approximately linearly after the first 8 days and resulted in 32-day cumulative thyroid doses that ranged from 6 mGy g(-1) to 18 mGy g(-1) per 1 Bq mL(-1) of initial (131)I in the water depending upon fish size. The majority of this dose is due to beta emissions, and the dose varies with positions in the thyroid tissue. PMID:24210373

Martinez, Nicole E; Johnson, Thomas E; Pinder, John E

2014-05-01

332

Effects of selected polybrominated diphenyl ether flame retardants on lake trout (Salvelinus namaycush) thymocyte viability, apoptosis, and necrosis  

USGS Publications Warehouse

Polybrominated diphenyl ether (PBDE) flame-retardants have been identified as an emergent contaminants issue in many parts of the world. In vitro analyses were conducted to test the hypothesis that selected PBDEs congeners affect viability, apoptosis, and necrosis of thymocytes from laboratory-reared lake trout (Salvelinus namaycush). At current environmental levels (<1 mg/L), effects of the tested PBDEs on thymocytes were negligible. However, at 100 mg/L, major effects were seen for congener brominated diphenyl ether 47 (BDE-47) and minor effects were seen for congener BDE-99.

Birchmeier, Kelly L.; Smith, Kimberly A.; Passino-Reader, Dora R.; Sweet, Leonard I.; Chernyak, Sergei M.; Adams, Jean V.; Omann, Geneva M.

2005-01-01

333

Fate of PBDEs in juvenile lake trout estimated using a dynamic multichemical fish model.  

PubMed

Biotransformation half-lives (HL) and gut absorption efficiencies (GAE) of PBDE congeners in fish are poorly known and challenging to quantify experimentally. These values are needed in order to accurately assess their food web dynamics, and in turn, for policy development We recently developed a multichemical aquatic food web model, which was used to estimate HL of four PBDE congeners in a simple Arctic food web. However, an application of this model to more complex food webs would dramatically increase the uncertainties in the results due to the large number of unknowns that would need to be considered simultaneously. As such, an in-depth analysis of possible HL and GAE of additional PBDE congeners at the scale of individual fish species would facilitate model application to more complex food webs. For this purpose, we developed a fugacity-based dynamic multichemical fish model and applied it to previously published experimental laboratory data. The model was calibrated by maximizing correspondence between the modeled and observed concentrations for each of the thirteen congeners at two dietary concentrations in juvenile lake trout (Salvelinus namaycush) during uptake and depuration phases mainly by varying HL and GAE. A robust parametrization and calibration procedure gave us confidence in our back-calculated congener-specific HL of 42-420 days and GAE of 20-45%. These values can be used as a starting point for model applications to natural fish populations. The fate/transport results suggest that not only loss of PBDE congeners via degradation, but also input through biotransformation of higher brominated congeners, should be accounted for in order to accurately portray dynamics of PBDEs in fish. PMID:18546714

Bhavsar, Satyendra P; Gandhi, Nilima; Gewurtz, Sarah B; Tomy, Gregg T

2008-05-15

334

Lake Roosevelt Fisheries Evaluation Program; Evaluation of Limiting Factors for Stocked Kokanee and Rainbow Trout in Lake Roosevelt, Washington, 1999 Annual Report.  

SciTech Connect

Hatchery supplementation of kokanee Oncorhynchus nerka and rainbow trout O. mykiss has been the primary mitigation provided by Bonneville Power Administration for loss of anadromous fish to the waters above Grand Coulee Dam (GCD). The hatchery program for rainbow trout has consistently met management goals and provided a substantial contribution to the fishery; however, spawner returns and creel survey results for kokanee have been below management goals. Our objective was to identify factors that limit limnetic fish production in Lake Roosevelt by evaluating abiotic conditions, food limitations, piscivory, and entrainment. Dissolved oxygen concentration was adequate throughout most of the year; however, levels dropped to near 6 mg/L in late July. For kokanee, warm water temperatures during mid-late summer limited their nocturnal distribution to 80-100 m in the lower section of the reservoir. Kokanee spawner length was consistently several centimeters longer than in other Pacific Northwest systems, and the relative weights of rainbow trout and large kokanee were comparable to national averages. Large bodied daphnia (> 1.7 mm) were present in the zooplankton community during all seasons indicating that top down effects were not limiting secondary productivity. Walleye Stizostedion vitreum were the primary piscivore of salmonids in 1998 and 1999. Burbot Lota lota smallmouth bass Micropterus dolomieui, and northern pikeminnow Ptychocheilus oregonensis preyed on salmonids to a lesser degree. Age 3 and 4 walleye were responsible for the majority (65%) of the total walleye consumption of salmonids. Bioenergetics modeling indicated that reservoir wide consumption by walleye could account for a 31-39% loss of stocked kokanee but only 6-12% of rainbow trout. Size at release was the primary reason for differential mortality rates due to predation. Entrainment ranged from 2% to 16% of the monthly abundance estimates of limnetic fish, and could account for 30% of total mortality of limnetic fishes, depending on the contribution of littoral zone fishes. Inflow to GCD forebay showed the strongest negative relationship with entrainment whereas reservoir elevation and fish vertical distribution had no direct relationship with entrainment. Our results indicate that kokanee and rainbow trout in Lake Roosevelt were limited by top down impacts including predation and entrainment, whereas bottom up effects and abiotic conditions were not limiting.

Baldwin, Casey; Polacek, Matt

2009-03-01

335

On the rate of decline of persistent organic contaminants in lake trout (Salvelinus namaycush) from the Great Lakes, 1970-2003.  

PubMed

Thirty-four years of data from the Great Lakes Fish Monitoring Program (GLFMP) show significant changes in the behavior of most contaminants in lake trout over time consistent with changes in contaminant inputs following regulation and remediation. Polybrominated diphenyl ethers (PBDEs) show positive apparent first-order rate constants falling to near zero. Dieldrin shows relatively unchanging half-lives of around 10 years except in Lake Superior (approximately 25 years). Mirex, consistently detected only in Lake Ontario fish, shows a slow decrease until the 1990s, when remediation of a source site occurred, after which half-lives are 2-3 years. Half-lives of oxychlordane, polychlorinated biphenyls (PCBs), and dichloro-diphenyl-trichlorethane (DDT) and its metabolites were typically 3-6 years until the mid 1980s; since then, the newest data confirm half-lives are usually around 15-30 years. For PCBs, an increasing half-life is found in other media as well. Changes in food web structure, fishery dynamics, and climate undoubtedly affect concentrations but cannot explain observed long-term trends across several media. Concentrations of legacy contaminants in the Great Lakes are likely to continue to decline only slowly and pose a health concern for decades without identifying and containing remaining sources. PMID:20163091

Carlson, Daniel L; De Vault, David S; Swackhamer, Deborah L

2010-03-15

336

Food of alewives, yellow perch, spottail shiners, trout-perch, and slimy and fourhorn sculpins in southeastern Lake Michigan  

USGS Publications Warehouse

Stomachs of 1,064 alewives (Alosa pseudoharengus), 1,103 yellow perch (Perca flavescens), 246 spottail shiners (Notropis hudsonius), 288 trout-perch (Percopsis omiscomaycus), 454 slimy sculpins (Cottus cognatus), and 562 fourhorn sculpins (Myoxocephalus quadricornis) from Lake Michigan were examined for food contents. Fish were sampled primarily from March to November and nearly all were caught at the bottom in the southeastern part of the lake near Saugatuck, Michigan. Depths of capture (m) were: alewives, 5 to 110; yellow perch, 5 to 26; spottail shiners, 5 to 31; trout-perch, 9 to 46; slimy sculpins, 31 to 91; and fourhorn sculpins, 73 to 110. Alewives, particularly those less than 140 mm long, fed chiefly on zooplankton; Pontoporeia usually constituted most of the rest of the food, although Mysis and immature midges were occasionally eaten in considerable quantity. Yellow perch ate primarily Pontoporeia, fish eggs, Mysis, and crayfish; Pontoporeia was consumed most heavily by perch less than 250 mm long and those in relatively deep water, fish (mainly slimy sculpins) by those 200 mm long or longer, Mysis by those in deep water, and crayfish by those on rocky bottom. Spottail shiners fed most commonly on immature midges, Pontoporeia, zooplankton, fingernail clams, and (in July only) fish eggs; immature midges were eaten mainly by shiners in shallow water; and Pontoporeia by those in deeper areas. The diet of trout-perch was strongly dominated by Pontoporeia and immature midges. Slimy sculpins ate Pontoporeia almost exclusively. Fourhorn sculpins fed almost entirely on Mysis and Pontoporeia; Pontoporeia was particularly important in the diet of the larger fish.

Wells, LaRue

1980-01-01

337

Fish Management Problems of High Western Lakes with Returns from Marked Trout Planted in Upper Angora Lake California  

Microsoft Academic Search

Upper Angora Lake in the high Sierra Mountains was selected for an experimental study conducted from 1934 to 1936, inclusive. It is a small 5-acre lake lying at an elevation of 7,800 feet, 7 miles south of Lake Tahoe. General ecological conditions and management problems of such high lakes are discussed. Low water temperatures over most of the year limit

Paul R. Needham; Frank K. Sumner

1942-01-01

338

In vitro toxicity and interactions of environmental contaminants (Arochlor 1254 and mercury) and immunomodulatory agents (lipopolysaccharide and cortisol) on thymocytes from lake trout ( Salvelinus namaycush )  

Microsoft Academic Search

The immunotoxicity of chemical combinations commonly encountered by the lake trout (Salvelinus namaycush) immune system was the focus of this study. It was hypothesised that combinations of an environmental contaminant (mercuric chloride or Aroclor 1254) and an immunomodulatory agent (bacterial endotoxin or cortisol) might interact to produce a greater toxicity than that of the environmental contaminant alone at concentrations typically

Gregory G. Miller; Leonard I. Sweet; Jean V. Adams; Geneva M. Omann; Dora R. Passino-Reader; Peter G. Meier

2002-01-01

339

Habitat and diet differentiation by two strains of rainbow trout in Lake Superior based on archival tags, stable isotopes, and bioenergetics  

EPA Science Inventory

Two strains of potamodromous rainbow trout Oncorhynchus mykiss in the Minnesota waters of Lake Superior exhibited differences in behavior and temperature tolerance at egg and fry stages, but the extent of these differences was not well understood in adult fish. To gain a better u...

340

Microsatellite and mtDNA analysis of lake trout, Salvelinus namaycush, from Great Bear Lake, Northwest Territories: impacts of historical and contemporary evolutionary forces on Arctic ecosystems.  

PubMed

Resolving the genetic population structure of species inhabiting pristine, high latitude ecosystems can provide novel insights into the post-glacial, evolutionary processes shaping the distribution of contemporary genetic variation. In this study, we assayed genetic variation in lake trout (Salvelinus namaycush) from Great Bear Lake (GBL), NT and one population outside of this lake (Sandy Lake, NT) at 11 microsatellite loci and the mtDNA control region (d-loop). Overall, population subdivision was low, but significant (global F(ST) ? = 0.025), and pairwise comparisons indicated that significance was heavily influenced by comparisons between GBL localities and Sandy Lake. Our data indicate that there is no obvious genetic structure among the various basins within GBL (global F(ST) = 0.002) despite the large geographic distances between sampling areas. We found evidence of low levels of contemporary gene flow among arms within GBL, but not between Sandy Lake and GBL. Coalescent analyses suggested that some historical gene flow occurred among arms within GBL and between GBL and Sandy Lake. It appears, therefore, that contemporary (ongoing dispersal and gene flow) and historical (historical gene flow and large founding and present-day effective population sizes) factors contribute to the lack of neutral genetic structure in GBL. Overall, our results illustrate the importance of history (e.g., post-glacial colonization) and contemporary dispersal ecology in shaping genetic population structure of Arctic faunas and provide a better understanding of the evolutionary ecology of long-lived salmonids in pristine, interconnected habitats. PMID:23404390

Harris, Les N; Howland, Kimberly L; Kowalchuk, Matthew W; Bajno, Robert; Lindsay, Melissa M; Taylor, Eric B

2012-01-01

341

Potency of 3,3{prime},4,4{prime},5-pentachlorobiphenyl (PCB 126) and 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), to produce lake trout early life stage mortality  

SciTech Connect

Toxic equivalency factors (TEFs) relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) have been determined in rainbow trout for certain polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) using endpoints of early life stage mortality. Rainbow trout are a convenient model fish species. However, one of the major species at risk in the Great Lakes, and the fish species most sensitive to TCDD, is lake trout. The current study sought to (1) determine in lake trout the toxic potency of 3,3{prime},4,4{prime},5-pentachlorobiphenyl (PCB 126) in order to test the validity of generalizing TEFs across related species and (2) determine whether PCB 126 and TCDD act in an additive manner at a ratio similar to that found in feral lake trout eggs from the Great Lakes. Newly fertilized lake trout (Salvelinus namaycush) eggs were exposed to TCDD, PCB 126, or their combination at a ratio of 75:1, and sac fry mortality was used to determine toxic potencies. Signs of PCB 126 toxicity in lake trout early life stages were yolk-sac edema, multifocal hemorrhages, craniofacial malformations and mortality, identical to toxicity caused by TCDD. The TEF for PCB 126 was 0.003, which is similar to the TEF of 0.005 determined for rainbow trout early life stage mortality, suggesting that TEFs for the same endpoint are similar across related fish species. The dose-response curve for the congener mixture based on TCDD toxic equivalence was not significantly different from TCDD alone, suggesting that the congener combination acted additively to produce lake trout early life stage mortality.

Zabel, E.W.; Peterson, R.E. [Univ. of Wisconsin, Madison, WI (United States); Cook, P.M. [Environmental Protection Agency, Duluth, MN (United States)

1995-12-31

342

Multiscale Terrain Analysis of Multibeam Bathymetry Data for Lake Trout Spawning Habitat Mapping in the Drummond Island Refuge, northern Lake Huron  

NASA Astrophysics Data System (ADS)

Until the 1950s, lake trout supported a valuable commercial fishery in the Great Lakes. The introduction of sea lamprey into the Great Lakes and overfishing resulted in the loss of most populations. Despite consistent stocking efforts since the 1960s, restoration of these populations has been slow. The reasons are numerous, but may be related to differences in the spawning behavior between hatchery and wild trout. A four-year study initiated in 2010, utilizes acoustic telemetry to characterize and compare the spawning behaviors of hatchery and wild lake trout in the Drummond Island Refuge in northern Lake Huron. In this project, the movement of tagged fish are monitored by an array of over 125 lake floor hydrophones during the fall spawning period. Fish behavior is overlaid over detailed bathymetric and substrate data and compared with environmental variables (e.g. water temperature, wind speed and direction, and wave height and direction) to develop a conceptual behavioral model. Sites suspected of being spawning sites based upon telemetry data are verified through the use of divers and trapping eggs and fry. Prior to this study, the factors that influenced how the spawning fish utilize the lake floor shoals have been poorly understood. Among the factors thought to impact spawning success were: bathymetry and substrate composition. Diver and telemetry data suggest that the fish(both hatchery raised and wild) are particularly attracted to rocky substrates and that fragment size is important. High resolution multibeam bathymetric surveys conducted in 2010 and 2011 have been used to characterize the shape and composition of the lake floor in the study area. Classification of the substrate is a labor intensive process requiring divers, drop cameras and sediment sampling. To improve this, the traditional approach has been to use supervised and unsupervised classification techniques that are based upon measured acoustic backscatter from an echosounder or sidescan sonar. Bottom classification based upon backscatter measurements from the collected multibeam sonar data using Quester Tangent's Multiview software does not appear to readily resolve the various classes of rocky substrate, for example it appears to have difficulty differentiating between areas dominated by boulder sized rocks from areas covered predominantly by cobble sized fragments. The extremely shallow nature of the reef areas utilized by the spawning fish (z_av < 10 m) ensures that the bathymetric data has a very high spatial resolution (dx ~ 0.1m). Visual inspection of the bathymetry of the reefs clearly show variations in the texture and morphology of the lake floor that correlate with divers' observations of aggregations of fish in spawning condition. We describe the results of a study to investigate the application of terrain analysis for subdividing the reefs into regions based upon their texture and morphology. A variety of descriptors are evaluated as is the influence of scale on the analyses.

Wattrus, N. J.; Binder, T.

2012-12-01

343

Development of Two New Sampling Techniques for Assessing Lake Trout Reproduction in Deep Water  

E-print Network

reefs, two new methods (deepwater egg traps and remote electrofishing) were tested in Lake Champlain types of gear at shallow sites in Lake Champlain. After testing, the new egg traps were deployed in Lake and was used to detect fry in Lake Champlain. The remote electrofisher detected fry in 90% of laboratory trials

Marsden, Ellen

344

Brominated and chlorinated flame retardants in Lake Ontario, Canada, lake trout (Salvelinus namaycush) between 1979 and 2004 and possible influences of food-web changes.  

PubMed

Concentrations of non-polybrominated diphenyl ether (PBDE) brominated (hexabromocyclododecane [HBCD], 1,2-bis[2,4,6-tribromophenoxy]ethane [BTBPE], and pentabromoethylbenzene [PEB]) and chlorinated (Dechlorane Plus [DP] as well as short- and medium-chain chlorinated paraffins [SCCP and MCCP, respectively]) flame retardants were evaluated in archived Lake Ontario, Canada, lake trout (Salvelinus namaycush) samples collected between 1979 and 2004. Polybrominated diphenyl ethers also were analyzed to provide a point of reference for comparison to previous studies. Concentrations of the dominant PBDE congeners (BDEs 28, 47, 99, 100, 153, and 154) increased significantly from 1979 until the mid-1990s, then either leveled off or decreased significantly between 1998 and 2004, a result that corresponds to those of previous studies. In contrast, BDE 209 increased approximately fourfold between 1998 and 2004. The temporal trends of the non-PBDE flame retardants varied, with sum (sigma) HBCD and DP showing significant overall decreases; BTBPE, sigmaSCCP, and sigmaMCCP showing parabolic trends; and PEB showing no overall change during the study period. Because many of the non-PBDE chemicals may be used as replacements for penta- and octa-BDE mixtures, these results will provide a baseline to evaluate future usage patterns. Possible changes in food-web structure, evaluated through stable nitrogen isotopes (delta15N), may be influencing our interpretations of contaminant trends in lake trout and are hypothesized to be partially responsible for the observed decrease in concentrations of BDEs 28, 47, 99, 100, 153, and 154 between 1998 and 2004. Retrospective analyses evaluating temporal trends in stable isotope values at the base of the food web, however, are recommended to test this hypothesis further. PMID:19049258

Ismail, Nargis; Gewurtz, Sarah B; Pleskach, Kerri; Whittle, D Michael; Helm, Paul A; Marvin, Chris H; Tomy, Gregg T

2009-05-01

345

Factors influencing trends of polychlorinated naphthalenes and other dioxin-like compounds in lake trout (Salvelinus namaycush) from Lake Ontario, North America (1979-2004).  

PubMed

Concentrations of polychlorinated naphthalenes (PCNs) were determined in archived lake trout (Salvelinus namaycush) from Lake Ontario, North America, collected between 1979 and 2004 to evaluate their temporal trends and the factors influencing their trends. Concentrations of PCNs, as well as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and non- and mono-ortho-substituted polychlorinated biphenyls (DL-PCBs), which were measured for comparative purposes, declined by eight-, seven-, and fivefold, respectively, between 1979 and 2004. Apparent elimination rate constants (k2) were calculated as the slopes of the regression lines of concentration versus time for PCN, DL-PCB, and PCDD/F congeners to compare the rate of decrease among congeners within and between compound classes. The k2 values for PCNs that had two pairs or three adjacent carbons unsubstituted with chlorine (congeners that can be biotransformed by vertebrates) were not significantly different from zero, indicating no decline in fish. For PCN congeners having no adjacent carbons unsubstituted with chlorine, the k2 values generally increased with hydrophobicity and degree of chlorination. This pattern differed from that of PCDD/Fs and DL-PCBs and from previous findings for non-DL-PCBs, for which the rate of contaminant decline decreased with hydrophobicity, and the pattern also differed from expectations based on thermodynamics. Differences in the rate of decline of PCN congeners may be caused by changes in source or mixture formulations over time and/or metabolic dechlorination of the less stable, higher-chlorinated PCNs 73, 74, and 75 to lower-chlorinated congeners. Based on suggested dioxin toxic equivalency factors, PCN concentrations in these whole lake trout may be sufficient to trigger consumption restrictions in Ontario, Canada, and our results suggest that PCNs merit incorporation into monitoring and assessment programs. PMID:19055315

Gewurtz, Sarah B; Lega, Rocsana; Crozier, Patrick W; Whittle, D Michael; Fayez, Laila; Reiner, Eric J; Helm, Paul A; Marvin, Chris H; Tomy, Gregg T

2009-05-01

346

Sustainability of the Lake Superior fish community: Interactions in a food web context  

USGS Publications Warehouse

The restoration and rehabilitation of the native fish communities is a long-term goal for the Laurentian Great Lakes. In Lake Superior, the ongoing restoration of the native lake trout populations is now regarded as one of the major success stories in fisheries management. However, populations of the deepwater morphotype (siscowet lake trout) have increased much more substantially than those of the nearshore morphotype (lean lake trout), and the ecosystem now contains an assemblage of exotic species such as sea lamprey, rainbow smelt, and Pacific salmon (chinook, coho, and steelhead). Those species play an important role in defining the constraints and opportunities for ecosystem management. We combined an equilibrium mass balance model (Ecopath) with a dynamic food web model (Ecosim) to evaluate the ecological consequences of future alternative management strategies and the interaction of two different sets of life history characteristics for fishes at the top of the food web. Relatively rapid turnover rates occur among the exotic forage fish, rainbow smelt, and its primary predators, exotic Pacific salmonids. Slower turnover rates occur among the native lake trout and burbot and their primary prey - lake herring, smelt, deepwater cisco, and sculpins. The abundance of forage fish is a key constraint for all salmonids in Lake Superior. Smelt and Mysis play a prominent role in sustaining the current trophic structure. Competition between the native lake trout and the exotic salmonids is asymmetric. Reductions in the salmon population yield only a modest benefit for the stocks of lake trout, whereas increased fishing of lake trout produces substantial potential increases in the yields of Pacific salmon to recreational fisheries. The deepwater or siscowet morphotype of lake trout has become very abundant. Although it plays a major role in the structure of the food web it offers little potential for the restoration of a valuable commercial or recreational fishery. Even if a combination of strong management actions is implemented, the populations of lean (nearshore) lake trout cannot be restored to pre-fishery and pre-lamprey levels. Thus, management strategy must accept the ecological constraints due in part to the presence of exotics and choose alternatives that sustain public interest in the resources while continuing the gradual progress toward restoration.

Kitchell, James F.; Cox, Sean P.; Harvey, Chris J.; Johnson, Timothy B.; Mason, Doran M.; Schoen, Kurt K.; Aydin, Kerim; Bronte, Charles; Ebener, Mark; Hansen, Michael; Hoff, Michael; Schram, Steve; Schreiner, Don; Walters, Carl J.

2000-01-01

347

Chryseobacterium aahli sp. nov., isolated from lake trout (Salvelinus namaycush) and brown trout (Salmo trutta), and emended descriptions of Chryseobacterium ginsenosidimutans and Chryseobacterium gregarium.  

PubMed

Two strains (T68T and T62) of a Gram-reaction-negative, yellow-pigmented bacterium containing flexirubin-type pigments were recovered from the kidney of a cultured lake trout (Salvelinus namaycush) and necrotic fins of a brown trout (Salmo trutta) during disease surveillance in 2009. Both isolates possessed catalase and cytochrome oxidase activities and degraded multiple substrates (e.g. gelatin, casein, elastin and Tweens 20 and 80). The mean DNA G+C content of strain T68T was 34.1 mol%. 16S rRNA gene sequencing demonstrated that strains T68T and T62 had nearly identical sequences (?99?% similarity) and placed the bacterium within the genus Chryseobacterium, where Chryseobacterium ginsenosidimutans THG 15T (97.8%), C. gregarium DSM 19109T (97.7%) and C. soldanellicola PSD1-4T (97.6%) were its closest relatives. Subsequent phylogenetic analyses using neighbour-joining, maximum-parsimony and Bayesian methodologies demonstrated that strains T68T and T62 formed a well-supported clade (bootstrap values of 100 and 97%; posterior probability 0.99) that was distinct from other species of the genus Chryseobacterium. The major fatty acids of strains T68T and T62 were characteristic of the genus Chryseobacterium and included iso-C15:0, summed feature 3 (C16:1?6c and/or C16:1?7c), iso-C17:0 3-OH, C16:0 and C16:0 3-OH. The mean DNA-DNA relatedness of strain T68T to C. ginsenosidimutans JCM 16719T and C. gregarium LMG 24952T was 24 and 21%, respectively. Based on the results from our polyphasic characterization, strains T68T and T62 represent a novel species of the genus Chryseobacterium, for which the name Chryseobacterium aahli sp. nov. is proposed. The type strain is T68T (=LMG 27338T=ATCC BAA-2540T). Emended descriptions of Chryseobacterium ginsenosidimutans and Chryseobacterium gregarium are also proposed. PMID:24480907

Loch, Thomas P; Faisal, Mohamed

2014-05-01

348

Climate change expands the spatial extent and duration of preferred thermal habitat for lake Superior fishes.  

PubMed

Climate change is expected to alter species distributions and habitat suitability across the globe. Understanding these shifting distributions is critical for adaptive resource management. The role of temperature in fish habitat and energetics is well established and can be used to evaluate climate change effects on habitat distributions and food web interactions. Lake Superior water temperatures are rising rapidly in response to climate change and this is likely influencing species distributions and interactions. We use a three-dimensional hydrodynamic model that captures temperature changes in Lake Superior over the last 3 decades to investigate shifts in habitat size and duration of preferred temperatures for four different fishes. We evaluated habitat changes in two native lake trout (Salvelinus namaycush) ecotypes, siscowet and lean lake trout, Chinook salmon (Oncorhynchus tshawytscha), and walleye (Sander vitreus). Between 1979 and 2006, days with available preferred thermal habitat increased at a mean rate of 6, 7, and 5 days per decade for lean lake trout, Chinook salmon, and walleye, respectively. Siscowet lake trout lost 3 days per decade. Consequently, preferred habitat spatial extents increased at a rate of 579, 495 and 419 km(2) per year for the lean lake trout, Chinook salmon, and walleye while siscowet lost 161 km(2) per year during the modeled period. Habitat increases could lead to increased growth and production for three of the four fishes. Consequently, greater habitat overlap may intensify interguild competition and food web interactions. Loss of cold-water habitat for siscowet, having the coldest thermal preference, could forecast potential changes from continued warming. Additionally, continued warming may render more suitable conditions for some invasive species. PMID:23638023

Cline, Timothy J; Bennington, Val; Kitchell, James F

2013-01-01

349

Climate Change Expands the Spatial Extent and Duration of Preferred Thermal Habitat for Lake Superior Fishes  

PubMed Central

Climate change is expected to alter species distributions and habitat suitability across the globe. Understanding these shifting distributions is critical for adaptive resource management. The role of temperature in fish habitat and energetics is well established and can be used to evaluate climate change effects on habitat distributions and food web interactions. Lake Superior water temperatures are rising rapidly in response to climate change and this is likely influencing species distributions and interactions. We use a three-dimensional hydrodynamic model that captures temperature changes in Lake Superior over the last 3 decades to investigate shifts in habitat size and duration of preferred temperatures for four different fishes. We evaluated habitat changes in two native lake trout (Salvelinus namaycush) ecotypes, siscowet and lean lake trout, Chinook salmon (Oncorhynchus tshawytscha), and walleye (Sander vitreus). Between 1979 and 2006, days with available preferred thermal habitat increased at a mean rate of 6, 7, and 5 days per decade for lean lake trout, Chinook salmon, and walleye, respectively. Siscowet lake trout lost 3 days per decade. Consequently, preferred habitat spatial extents increased at a rate of 579, 495 and 419 km2 per year for the lean lake trout, Chinook salmon, and walleye while siscowet lost 161 km2 per year during the modeled period. Habitat increases could lead to increased growth and production for three of the four fishes. Consequently, greater habitat overlap may intensify interguild competition and food web interactions. Loss of cold-water habitat for siscowet, having the coldest thermal preference, could forecast potential changes from continued warming. Additionally, continued warming may render more suitable conditions for some invasive species. PMID:23638023

Cline, Timothy J.; Bennington, Val; Kitchell, James F.

2013-01-01

350

J. Great Lakes Res. 33:714 Internat. Assoc. Great Lakes Res., 2007  

E-print Network

­8, and 10­12°C) on consumption of lake trout (Salvelinus namaycush) and rainbow trout (Oncorhynchus mykiss Predation on early life stages of lake trout (Salvelinus namaycush) has been suggested as an important

Marsden, Ellen

351

Landscape influences on genetic differentiation among bull trout populations in a stream-lake network.  

PubMed

This study examined the influence of landscape heterogeneity on genetic differentiation between migratory bull trout (Salvelinus confluentus) populations in Glacier National Park, Montana. An information-theoretic approach was used to compare different conceptual models of dispersal associated with barriers, different models of isolation by distance, and the combined effects of barriers, waterway distance, patch size, and intra- and inter-drainage distribution of populations on genetic differentiation between bull trout populations. The effect of distance between populations on genetic differentiation was best explained by partitioning the effects of mainstem and tributary stream sections. Models that categorized barriers as having a one-way effect (i.e. allowed downstream dispersal) or a two-way effect were best supported. Additionally, patch size and the distribution of populations among drainages influenced genetic differentiation. Genetic differentiation between bull trout populations in Glacier National Park is linked to landscape features that restrict dispersal. However, this analysis illustrates that modelling variability within landscape features, such as dispersal corridors, will benefit landscape genetic analyses. Additionally, the framework used for evaluating the effects of barriers must consider not just barrier presence, but also potential asymmetries in barrier effects with respect to the organism under investigation. PMID:20723065

Meeuwig, Michael H; Guy, Christopher S; Kalinowski, Steven T; Fredenberg, Wade A

2010-09-01

352

Estimates of egg deposition and effects of lake trout (Salvelinus namaycush) egg predators  

E-print Network

propinquus. In Lake Champlain, sculpin (Cottus spp.) were the most common interstitial predator, yet error = 15.5 ± 0.4 predators·m­2 ) were twice those in Lake Champlain or Parry Sound (6 ± 1 predators·m­2 ). Densities of eggs were higher in Lake Champlain (2994.1 ± 398.3 eggs·m­2 ) and Parry Sound (454

Marsden, Ellen

353

Sensitivity of maximum sustainable harvest rates to intra-specific life history variability of lake trout ( Salvelinus namaycush) and walleye ( Sander vitreus)  

Microsoft Academic Search

Using lake trout (Salvelinus namaycush) and walleye (Sander vitreus) we examined the extent of error that is created when non-population-specific or non-sex-specific data are used to develop fishery sustainability models. To put biases in perspective we first compared relative differences in sustainable harvest rate estimates of fast and slow growing populations to the mean difference between species. Few estimates of

C. F. Purchase; N. C. Collins; B. J. Shuter

2005-01-01

354

DIAGNOSIS OF 20TH CENTURY LAKE ONTARIO LAKE TROUT POPULATION TRENDS IN A CONSTANTLY CHANGING, MULTI-STRESSOR ENVIRONMENT  

EPA Science Inventory

Early mortality syndrome (EMS) in Great Lakes salmonids is thought to reduce recruitment through a thiamine deficiency in embryos that is related to dietary input of thiaminase by the female. This may be complicated......

355

Loss of genetic integrity in wild lake trout populations following stocking: insights from an exhaustive study of 72 lakes from Québec, Canada.  

PubMed

Stocking represents the most important management tool worldwide to increase and sustain commercial and recreational fisheries in a context of overexploitation. Genetic impacts of this practice have been investigated in many studies, which examined population and individual admixture, but few have investigated determinants of these processes. Here, we addressed these questions from the genotyping at 19 microsatellite loci of 3341 adult lake trout (Salvelinus namaycush) from 72 unstocked and stocked lakes. Results showed an increase in genetic diversity and a twofold decrease in the extent of genetic differentiation among stocked populations when compared to unstocked. Stocked populations were characterized by significant admixture at both population and individual levels. Moreover, levels of admixture in stocked populations were strongly correlated with stocking intensity and a threshold value of total homogenization between source and stocked populations was identified. Our results also suggest that under certain scenarios, the genetic impacts of stocking could be of short duration. Overall, our study emphasizes the important alteration of the genetic integrity of stocked populations and the need to better understand determinants of admixture to optimize stocking strategies and to conserve the genetic integrity of wild populations. PMID:25067947

Valiquette, Eliane; Perrier, Charles; Thibault, Isabel; Bernatchez, Louis

2014-06-01

356

Radionuclides and heavy metals in rainbow trout from Tsichomo, Nana Ka, Wen Povi, and Pin De Lakes in Santa Clara Canyon  

SciTech Connect

Radionuclide ({sup 3}H, {sup 90}Sr, {sup 137}Cs, {sup 238}Pu, {sup 239}Pu, and total uranium) and heavy metal (Ag, As, Ba, Be, Cd, Cr, Hg, Ni, Pb, Sb, Se, and TI) concentrations were determined in rainbow trout collected from Tsichomo, Nana Ka, Wen Povi, and Pin De lakes in Santa Clara Canyon in 1997. Most radionuclide and heavy metal concentrations in fish collected from these four lakes were within or just above upper limit background concentrations (Abiquiu reservoir), and as a group were statistically (p < 0.05) similar in most parameters to background.

Fresquez, P.R.; Armstrong, D.R.; Naranjo, L. Jr.

1998-04-01

357

Effect of brook trout removal from a spawning stream on an adfluvial population of Lahontan cutthroat trout  

USGS Publications Warehouse

Independence Lake (Nevada and Sierra counties, California) harbors the only extant native population of Lahontan cutthroat trout Oncorhynchus clarkii henshawi in the Truckee River system and one of two extant adfluvial populations in the Lahontan basin. The persistence of this population has been precarious for more than 50 years, with spawning runs consisting of only 30–150 fish. It is assumed that this population was much larger prior to the introduction of nonnative brook trout Salvelinus fontinalis. Brook trout overlap with cutthroat trout in upper Independence Creek, where the cutthroat trout spawn and their resulting progeny emigrate to Independence Lake. In 2005, we began removing brook trout from upper Independence Creek using electrofishers and monitored the cutthroat trout population. Stomach analysis of captured brook trout revealed cutthroat trout fry, and cutthroat trout fry survival increased significantly from 4% to 12% with brook trout removal. Prior to brook trout removal, the only Lahontan cutthroat trout progeny emigrating to Independence Lake were fry; with brook trout removal, juveniles were found entering the lake. In 2010, 237 potential spawners passed a prefabricated weir upstream of Independence Lake. Although the results of this study suggest that brook trout removal from upper Independence Creek has had a positive influence on the population dynamics of Independence Lake Lahontan cutthroat trout, additional years of removal are needed to assess the ultimate effect this action will have upon the cutthroat trout population.

Scoppettone, G. Gary; Rissler, Peter H.; Shea, Sean P.; Somer, William

2012-01-01

358

Ecology, Evolution, and Conservation of Lake-Migratory Brook Trout: A Perspective from Pristine Populations  

Microsoft Academic Search

Reintroduction or rehabilitation plans for fish populations in many systems (e.g., lakes) are complicated by limited data on ecological and genetic characteristics before human disturbances occurred. While no two lakes have identical physical and biological characteristics, a growing body of empirical evidence nevertheless indicates that parallel patterns of population structuring may evolve within northern temperate fish species. Examining the population

Dylan J. Fraser; Louis Bernatchez

2008-01-01

359

Mammalian and teleost cell line bioassay and chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent concentrations in lake trout (Salvelinus namaycush) from Lake Superior and Lake Ontario, North America  

SciTech Connect

For livers of lake trout from three Great Lakes sites, the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent concentrations (TEQs) were determined in four ways. Bioassay-derived (BD) TEQs were measured with rat (H4IIE) and rainbow trout (RTL-W1) cell lines, and chemistry-derived (CD) TEQs were calculated with TCDD equivalency factors (TEFs) derived with H4IIE and RTL-W1. Generally, BD-TEQs and CD-TEQs for individual samples did not differ significantly for either H4IIE or RTL-W1, indicating that all of the AhR-active compounds in a sample were accounted for by the congener analysis and that these compounds acted in an additive fashion in both mammalian and piscine systems. However, contributions of individual chemicals to overall CD-TEQs differed with H4IIE and RTL-W1 TEFs, and for some individual samples. TEQs did depend on the method used. Hepatic TEQs and ethoxyresorufin-O-deethylase (EROD) levels differed significantly between sites. For TEQs, the order was Glenora > Jackfish Bay > Black Bay; for EROD activity, the order was Jackfish Bay > Glenora = Black Bay. No correlation was found between hepatic TEQs and EROD activity, which suggests that the two measurements are evaluating different but related consequences of contaminant exposure.

Whyte, J.J.; Heuvel, M.R. van den; Clemons, J.H.; Dixon, D.G.; Bols, N.C. [Univ. of Waterloo, Ontario (Canada). Dept. of Biology; Huestis, S.Y. [Dept. of Fisheries and Oceans, Burlington, Ontario (Canada); Servos, M.R. [Environment Canada, Burlington, Ontario (Canada). National Water Research Inst.

1998-11-01

360

Ecology, Evolution, and Conservation of Lake-Migratory Brook Trout: A Perspective from Pristine Populations  

E-print Network

, Quebec G1K 7P4, Canada Abstract.--Reintroduction or rehabilitation plans for fish populations in many on lake habitat use, the morphology and life history characteristics of populations, diets, lakewide

Bernatchez, Louis

361

Altered thyroid status in lake trout (Salvelinus namaycush) exposed to co-planar 3,3',4,4',5-pentachlorobiphenyl.  

PubMed

Recent studies indicate that co-planar 3,3',4,4',5-pentachlorobiphenyl (PCB) congeners or their metabolites may disrupt thyroid function in fishes. Although co-planar PCB have been detected at microgram per kilogram levels in fish from contaminated areas, few studies have examined mechanisms whereby, co-planar PCBs may alter thyroid function in fish. We treated immature lake trout by intraperitoneal (i.p.)-injection or dietary gavage with vehicle containing 0, 0.7, 1.2, 25 or 40 microg 3,3',4,4',5-pentachlorobiphenyl (PCB 126) per kgBW. Blood and tissue samples were collected at various times up to 61 weeks following exposure. The treatments produced sustained dose-dependent elevations of tissue (PCB 126) concentrations. Thyroid epithelial cell height (TECH), plasma thyroxine (T4) and 3,3',5-triiodo-l-thyronine (T3) concentrations, hepatic 5'-monodeiodinase, hepatic glucuronidation of T4 and T3, as well as plasma T4 kinetics and fish growth were analyzed. Exposure to the highest doses of PCB 126 caused increased TECH, plasma T4 dynamics and T4-glucuronidation (T4-G). PCB 126 did not affect 5'-monodeiodinase and T3-glucuronidation (T3-G) and there were no effects on fish growth or condition. Because T3 status and growth were unaffected, the thyroid system was able to compensate for the alterations caused by the PCB 126 exposure. It is clear that concentrations of co-planar PCBs similar to those found in predatory fish from contaminated areas in the Great Lakes are capable of enhancing metabolism of T4. These changes may be of significance when T4 requirements are high for other reasons (e.g. periods of rapid growth, warm temperatures, metamorphosis, and parr-smolt transformation). PMID:15019252

Brown, Scott B; Evans, Robert E; Vandenbyllardt, Lenore; Finnson, Ken W; Palace, Vince P; Kane, Andrew S; Yarechewski, Alvin Y; Muir, Derek C G

2004-03-30

362

Genetic monitoring reveals temporal stability over 30 years in a small, lake-resident brown trout population  

PubMed Central

Knowledge of the degree of temporal stability of population genetic structure and composition is important for understanding microevolutionary processes and addressing issues of human impact of natural populations. We know little about how representative single samples in time are to reflect population genetic constitution, and we explore the temporal genetic variability patterns over a 30-year period of annual sampling of a lake-resident brown trout (Salmo trutta) population, covering 37 consecutive cohorts and five generations. Levels of variation remain largely stable over this period, with no indication of substructuring within the lake. We detect genetic drift, however, and the genetically effective population size (Ne) was assessed from allele-frequency shifts between consecutive cohorts using an unbiased estimator that accounts for the effect of overlapping generation. The overall mean Ne is estimated as 74. We find indications that Ne varies over time, but there is no obvious temporal trend. We also estimated Ne using a one-sample approach based on linkage disequilibrium (LD) that does not account for the effect of overlapping generations. Combining one-sample estimates for all years gives an Ne estimate of 76. This similarity between estimates may be coincidental or reflecting a general robustness of the LD approach to violations of the discrete generations assumption. In contrast to the observed genetic stability, body size and catch per effort have increased over the study period. Estimates of annual effective number of breeders (Nb) correlated with catch per effort, suggesting that genetic monitoring can be used for detecting fluctuations in abundance. PMID:22828900

Charlier, J; Laikre, L; Ryman, N

2012-01-01

363

Detecting contaminant-induced apoptosis and necrosis in lake trout thymocytes via flow cytometry.  

USGS Publications Warehouse

This chapter details the cytofluorometric techniques employed to assess levels of active (apoptosis) and passive (necrotic) cell death in untreated and contaminant-treated fish thymocytes. The thymus is believed to be a central component of hematopoiesis and immune function in teleosts (Abelli et al., 1996). Hence, chemically-elicited adverse effects to the thymus may result in immunomodulation and organ dysfunction. However, it is not well documented that environmental contaminants induce apoptosis, or programmed cell death. There is some evidence suggesting that low level exposure to waterborne contaminants can specifically induce cell death in the olfactory epithelium of rainbow trout (Julliard et al., 1996). Presently, only limited information is available in the literature regarding apoptotic death in piscine immune cells (Alford et al., 1994; Greenlee et al., 1991).

Sweet, Leonard I.; Passino-Reader, Dora R.; Meier, Peter G.; Omann, Geneva M.

1997-01-01

364

Introgression of domesticated alleles into a wild trout genotype and the impact on seasonal survival in natural lakes  

PubMed Central

We tested the fitness consequences of introgression of fast-growing domesticated fish into a wild population. Fry from wild and domesticated rainbow trout (Oncorhynchus mykiss) crosses, F1 hybrids, and first- and second-generation backcrosses were released into two natural lakes. Parentage analysis using microsatellite loci facilitated the identification of survivors, so fitness was estimated in nature from the first-feeding stage. Results indicated that under certain conditions, domesticated fish survived at least as well as wild fish within the same environment. Relative growth and survival of the crosses, however, were highly dependent on environment. During the first summer, fastest-growing crosses had the highest survival, but this trend was reversed after one winter and another summer. Although the F1 hybrids showed evidence of outbreeding depression because of the disruption of local adaptation, there was little evidence of outbreeding depression in the backcrosses, and the second-generation backcrosses exhibited a wild-type phenotype. This information is relevant for assessing the multigenerational risk of escaped or released domesticated fish should they successfully interbreed with wild populations and provides information on how to minimize detrimental impacts of a conservation breeding and/or management programme. These data also further understanding of the selection pressures in nature that maintain submaximal rates of growth.

Vandersteen, Wendy; Biro, Pete; Harris, Les; Devlin, Robert

2012-01-01

365

Influence of Physical Processes on Fish Recruitment Variability in the Great Lakes  

E-print Network

, and Lake Champlain. For Lake Trout in Grand Traverse Bay, we will combine in-situ measures of temperature, and for Lake Trout in Lake Champlain. #12;For Lake Trout and Lake Whitefish in Thunder Bay Lake Huron, we Ruberg ReCON project) to predict spawning, egg incubation times, and fry emergence and dispersal. In Lake

366

Concentrations of mercury and other trace elements in walleye, smallmouth bass, and rainbow trout in Franklin D. Roosevelt Lake and the upper Columbia River, Washington, 1994  

USGS Publications Warehouse

Three species of sportfish--walleye, smallmouth bass, and rainbow trout--were collected from Franklin D. Roosevelt Lake and the upstream reach of the Columbia River within the state of Washington, to determine the concentrations of mercury and other selected trace elements in fish tissue. Concentrations of total mercury in walleye fillets ranged from 0.11 to 0.44 milligram per kilogram, with the higher concentrations in the larger fish. Fillets of smallmouth bass and rainbow trout also contained mercury, but generally at lower concentrations. Other selected trace elements were found in fillet samples, but the concentrations were generally low depending on species and the specific trace element. The trace elements cadmium, copper, lead, and zinc were found in liver tissue of these same species with zinc consistently present in the highest concentration.

Munn, M.D.; Cox, S.E.; Dean, C.J.

1995-01-01

367

Simulation of climate-change effects on streamflow, lake water budgets, and stream temperature using GSFLOW and SNTEMP, Trout Lake Watershed, Wisconsin  

USGS Publications Warehouse

Although groundwater and surface water are considered a single resource, historically hydrologic simulations have not accounted for feedback loops between the groundwater system and other hydrologic processes. These feedbacks include timing and rates of evapotranspiration, surface runoff, soil-zone flow, and interactions with the groundwater system. Simulations that iteratively couple the surface-water and groundwater systems, however, are characterized by long run times and calibration challenges. In this study, calibrated, uncoupled transient surface-water and steady-state groundwater models were used to construct one coupled transient groundwater/surface-water model for the Trout Lake Watershed in north-central Wisconsin, USA. The computer code GSFLOW (Ground-water/Surface-water FLOW) was used to simulate the coupled hydrologic system; a surface-water model represented hydrologic processes in the atmosphere, at land surface, and within the soil-zone, and a groundwater-flow model represented the unsaturated zone, saturated zone, stream, and lake budgets. The coupled GSFLOW model was calibrated by using heads, streamflows, lake levels, actual evapotranspiration rates, solar radiation, and snowpack measurements collected during water years 1998–2007; calibration was performed by using advanced features present in the PEST parameter estimation software suite. Simulated streamflows from the calibrated GSFLOW model and other basin characteristics were used as input to the one-dimensional SNTEMP (Stream-Network TEMPerature) model to simulate daily stream temperature in selected tributaries in the watershed. The temperature model was calibrated to high-resolution stream temperature time-series data measured in 2002. The calibrated GSFLOW and SNTEMP models were then used to simulate effects of potential climate change for the period extending to the year 2100. An ensemble of climate models and emission scenarios was evaluated. Downscaled climate drivers for the period 2010–2100 showed increases in maximum and minimum temperature over the scenario period. Scenarios of future precipitation did not show a monotonic trend like temperature. Uncertainty in the climate drivers increased over time for both temperature and precipitation. Separate calibration of the uncoupled groundwater and surface-water models did not provide a representative initial parameter set for coupled model calibration. A sequentially linked calibration, in which the uncoupled models were linked by means of utility software, provided a starting parameter set suitable for coupled model calibration. Even with sequentially linked calibration, however, transmissivity of the lower part of the aquifer required further adjustment during coupled model calibration to attain reasonable parameter values for evaporation rates off a small seepage lake (a lake with no appreciable surface-water outlets) with a long history of study. The resulting coupled model was well calibrated to most types of observed time-series data used for calibration. Daily stream temperatures measured during 2002 were successfully simulated with SNTEMP; the model fit was acceptable for a range of groundwater inflow rates into the streams. Forecasts of potential climate change scenarios showed growing season length increasing by weeks, and both potential and actual evapotranspiration rates increasing appreciably, in response to increasing air temperature. Simulated actual evapotranspiration rates increased less than simulated potential evapotranspiration rates as a result of water limitation in the root zone during the summer high-evapotranspiration period. The hydrologic-system response to climate change was characterized by a reduction in the importance of the snow-melt pulse and an increase in the importance of fall and winter groundwater recharge. The less dynamic hydrologic regime is likely to result in drier soil conditions in rainfed wetlands and uplands, in contrast to less drying in groundwater-fed systems. Seepage lakes showed larger forecast stage declines related to climate change th

Hunt, Randall J.; Walker, John F.; Selbig, William R.; Westenbroek, Stephen M.; Regan, Robert S.

2013-01-01

368

Effects of dietary vitamin B? (thiamine) and magnesium on the survival, growth and histological indicators in lake trout (Salvelinus namaycush) juveniles.  

PubMed

An interaction of two essential nutrients, thiamine and magnesium (Mg) has been documented in in vitro and in vivo studies in mammalian metabolism. However, the role of this association in poikilothermic vertebrates, such as fish, remains elusive. The purpose of this study was first to investigate the effects of dietary thiamine and Mg, and their interaction in lake trout and second to better understand the mechanism leading to early mortality syndrome (EMS), which is caused by a low thiamine level in embryos of many species of salmonids in the wild. Semi-purified diets (SPD) were prepared to accomplish 2 × 2 factorial design that were either devoid of or supplemented with thiamine mononitrate (20 mg/kg diet), magnesium oxide (700 mg/kg diet), or both. Lake trout alevins at the swim-up stage were fed for 10 wk one of the SPD diets or a commercial diet at the same rate (2.0-1.5%) based on recorded biomass. Our results showed that the concentrations of thiamine in the trunk muscle and Mg of whole body were closely associated with the dietary level of two nutrients. The interaction of low dietary Mg and thiamine resulted in apparently worsened overt symptoms of thiamine deficiency in lake trout leading to a higher mortality of fish during the seven week long trial (P<0.05). The fish fed a thiamine-devoid and Mg-supplemented diet were presumed to survive longer (10 wk) than the fish fed diets devoid of both nutrients (discontinued after 7th wk due to high mortality). However, we did not observe histopathological changes in the brain and liver corresponding to thiamine concentrations in tissues. These data suggest that Mg enhanced utilization of the thiamine remaining in the fish body and its interdependence was consistent with observations in mammals. EMS severity might be worsened when Mg is deficient in parental diets (and consequently in yolk sac) and/or first feed. PMID:22456309

Lee, Bong-Joo; Jaroszewska, Marta; Dabrowski, Konrad; Czesny, Sergiusz; Rinchard, Jacques

2012-07-01

369

Water quality (2000-08) and historical phosphorus concentrations from paleolimnological studies of Swamp and Speckled Trout Lakes, Grand Portage Reservation, northeastern Minnesota  

USGS Publications Warehouse

A paleolimnological approach was taken to aid the Grand Portage Reservation, in northeastern Minnesota, in determining reference conditions for lakes on the reservation. The U.S. Geological Survey, in cooperation with the Grand Portage Band of Chippewa Indians and the Science Museum of Minnesota, conducted a study to describe water quality (2000-08) and historical total phosphorus concentrations (approximately 1781-2006) for Swamp and Speckled Trout Lakes. Results from this study may be used as a guide in establishing nutrient criteria in these and other lakes on the Grand Portage Reservation. Historical phosphorus concentrations were inferred through paleolimnological reconstruction methods involving diatom analysis and lead-210 dating of lake-sediment cores. Historical diatom-inferred total phosphorus concentrations in Swamp Lake ranged from 0.017 to 0.025 milligrams per liter (mg/L) based on diatom assemblages in sediment samples dated 1781-2005. Historical diatom-inferred total phosphorus concentrations in Speckled Trout Lake ranged from 0.008 to 0.014 mg/L based on diatom assemblages in sediment samples dated 1825-2006. In both lakes, historical changes in diatom-inferred total phosphorus concentrations did not exceed model error estimates, indicating that there has been minimal change in total phosphorus concentrations in the two lakes over about two centuries. Nutrient concentrations in monthly water samples collected May through October during 2000, 2002, 2004, 2006, and 2008 were compared to the diatom-inferred total phosphorus concentrations. Total phosphorus concentrations from water samples collected from Swamp Lake during 2000-08 ranged from less than 0.002 to 0.160 mg/L (median= 0.023 mg/L) compared to diatom-inferred total phosphorus concentrations of 0.018 to 0.020 mg/L for 2002 to 2005. Total phosphorus concentrations in water samples collected from Speckled Trout Lake during 2000-08 were similar to those of Swamp Lake, ranging from less than 0.002 to 0.147 mg/L (median=0.012 mg/L), whereas the diatom-inferred total phosphorus concentrations were smaller, ranging from 0.009 to 0.010 mg/L for 2003 to 2006. Differences in total phosphorus concentrations between the two lakes may be because of differences in watershed characteristics, particularly the number of wetlands in the two watersheds. Similarities between recent total phosphorus concentrations in water-quality samples and diatom-inferred total phosphorus indicate that diatom-inferred phosphorus reconstructions might be used to help establish reference conditions. Nutrient criteria for Grand Portage Reservation lakes may be established when a sampling program is designed to ensure representative phosphorus concentrations in water samples are comparable to diatom-inferred concentrations.

Christensen, Victoria G.; Jones, Perry M.; Edlund, Mark B.; Ramstack, Joy M.

2010-01-01

370

Use of oviduct-inserted acoustic transmitters and positional telemetry to estimate timing and location of spawning: a feasibility study in lake trout, Salvelinus namaycush  

USGS Publications Warehouse

Our results satisfied the three assumptions of oviduct tagging and suggested that oviduct transmitters can be used with positional telemetry to estimate time and location of spawning in lake trout and other species. In situations where oviduct transmitters may be difficult to position once expelled into substrate, pairing oviduct transmitters with a normal-sized fish transmitter that remains in the fish is recommended, with spawning inferred when the two tags separate in space. Optimal transmitter delay will depend on expected degree of spawning site residency and swim speed.

Binder, Thomas R.; Holbrook, Christopher M.; Miehls, Scott M.; Thompson, Henry T.; Krueger, Charles C.

2014-01-01

371

Mixed-function oxidase enzyme activity and oxidative stress in lake trout (Salvelinus namaycush) exposed to 3,3â²,4,4â²5-pentachlorobiphenyl (PCB126)  

Microsoft Academic Search

Juvenile lake trout were intraperitoneally injected with corn oil containing nominal concentrations of 0, 0.6, 6.3, or 25 μg [¹⁴C]-3,3â²,4,4â²,5-pentachlorobiphenyl (PCB-126) per gram of body weight. The PCB-126 accumulated in liver in a dose-dependent manner to a sustained concentration by 6 weeks and remained elevated for the 30-week experimental period. Mixed-function oxidase (MFO) enzyme activity was elevated in the two

Vince P. Palace; Jack F. Klaverkamp; W. Lyle Lockhart; Don A. Metner; Derek C. G. Muir; Scott B. Brown

1996-01-01

372

Genetic Analysis of Bull Trout in Glacier National Park  

E-print Network

that is genetically distinct from adfluvial bull trout that use Flathead Lake during part of their life cycle. WeGenetic Analysis of Bull Trout in Glacier National Park Report 02/102 Wild Trout and Salmon Paul Spruell* Jonathan J. Huie Marirose Spade and Fred W. Allendorf Wild Trout and Salmon Genetics Lab

373

Environmental associations with gene transcription in Babine Lake rainbow trout: evidence for local adaptation  

PubMed Central

The molecular genetic mechanisms facilitating local adaptation in salmonids continue to be poorly characterized. Gene transcription is a highly regulated step in the expression of a phenotype and it has been shown to respond to selection and thus may be one mechanism that facilitates the development of local adaptation. Advances in molecular genetic tools and an increased understanding of the functional roles of specific genes allow us to test hypotheses concerning the role of variable environments in shaping transcription at known-function candidate loci. To address these hypotheses, wild rainbow trout were collected in their first summer and subjected to metabolic and immune challenges. We assayed gene transcription at candidate loci that play a role in the molecular genetic response to these stresses, and correlated transcription with temperature data from the streams and the abundance and diversity of bacteria as characterized by massively parallel pyrosequencing. Patterns of transcriptional regulation from resting to induced levels varied among populations for both treatments. Co-inertia analysis demonstrated significant associations between resting levels of metabolic gene transcription and thermal regime (R2 = 0.19, P = 0.013) as well as in response to challenge (R2 = 0.39, P = 0.001) and resting state and challenged levels of cytokine gene transcription with relative abundances of bacteria (resting: R2 = 0.25, P = 0.009, challenged: R2 = 0.65, P = 0.001). These results show that variable environments, even within a small geographic range (<250 km), can drive divergent selection among populations for transcription of genes related to surviving stress. PMID:23762507

Wellband, Kyle W; Heath, Daniel D

2013-01-01

374

Myxobolus cerebralis (Hofer) infection risk in native cutthroat trout Oncorhynchus clarkii (Richardson) and its relationships to tributary environments in the Yellowstone Lake Basin.  

PubMed

Conservation of native species is challenged by the introduction of non-native pathogens and diseases into aquatic and terrestrial environments worldwide. In the Yellowstone Lake basin, Yellowstone National Park, the invasive parasite causing salmonid whirling disease Myxobolus cerebralis (Hofer) has been identified as one factor contributing to population declines of native Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri (Jordan & Gilbert). In 2002 and 2003, we examined relationships between the stream environment and severity of M. cerebralis infection in native trout. Coefficients of variation of environmental features were calculated to examine variability. Ten years later, we reassessed infection levels at 22 tributaries broadly across the system. Results of principal component analysis (PCA) of physical features (2003) were negatively correlated with infection severity, mostly in lower jaw cartilage of cutthroat trout, and PCA of chemical features (and temperature) correlated with infection severity in cranial cartilage. Pelican Creek, where M. cerebralis prevalence and severity was high 2002-2003, remained high in 2012. We did not find evidence that the parasite had dispersed further within the system. Variable environmental features (physiological stress) across short spatiotemporal scales within a stream or season may possibly predispose salmonids to infection in the wild and facilitate parasite establishment. PMID:24953674

Murcia, S; Kerans, B L; Koel, T M; MacConnell, E

2014-06-23

375

Allantoinase in lake trout (Salvelinus namaycush): in vitro effects of PCBs, DDT and metals  

USGS Publications Warehouse

1. Allantoinase, an enzyme in the purine-urea cycle, was found in livers of Salvelinus namaycush (Osteichthyes: Salmoniformes). 2. The enzyme was active from pH 6.6 to 8.2 at 37°C and from pH 7.4 to 9.0 at 10°C and had an Arrhenius energy of activation of 11.0 kcal/mol and a temperature quotient of 2.0. The Km of the enzyme homogenate was 8.4 mM allantoin. 3. The concentration of inorganic metals at which 50% inhibition occurred during in vitro exposure were 6.0 mg/l Cu2+, 6.7 mg/l Cd2+, 34 mg/l Hg2+ and 52 mg/l Pb2+. The in vitro sensitivity to PCBs, DDT and DDE and kinetics in the presence of metals were determined. 4. Allantoinase activity was negatively correlated with body length for fish from Lake Michigan but not from Lake Superior or the laboratory.

Passino, Dora R. May; Cotant, Carol A.

1979-01-01

376

Effects of Brook Trout Predation on a Crayfish Population  

Microsoft Academic Search

A study was made of the effect of trout predation upon the crayfish population of a marl lake. The study provided a measurement of the efficiency of energy transfer between trophic levels in the lake and the assessment of the relative importance of fish predation as an interspecies interaction.Trout fed only on crayfish less than one year old. Only trout

Walter T. Momot

1967-01-01

377

Trophic connections in Lake Superior Part II: the nearshore fish community  

USGS Publications Warehouse

We use detailed diet analyses of the predominant planktivorous, benthivorous and piscivorous fish species from Lake Superior to create a nearshore (bathymetric depths Mysis diluviana and Diporeia spp). Although the piscivorous fishes like lean lake trout (Salvelinus namaycush) fed to a lesser extent on Diporeia and Mysis, they were still strongly connected to these macroinvertebrates, which were consumed by their primary prey species (sculpin spp., rainbow smelt Osmerus mordax, and coregonines). The addition of Bythotrephes to summer/fall cisco and lake whitefish diets, and the decrease in rainbow smelt in lean lake trout diets (replaced by coregonines) were the largest observed differences relative to historic Lake Superior diet studies. Although the offshore food web of Lake Superior was simpler than nearshore in terms of number of fish species present, the two areas had remarkably similar food web structures, and both fish communities were primarily supported by Mysis and Diporeia. We conclude that declines in Mysis or Diporeia populations would have a significant impact on energy flow in Lake Superior. The food web information we generated can be used to better identify management strategies for Lake Superior.

Gamble, A.E.; Hrabik, T.R.; Yule, D.L.; Stockwell, J.D.

2011-01-01

378

Genetic mixed-stock analysis of lake-run brown trout Salmo trutta fishery catches in the Inari Basin, northern Finland: implications for conservation and management.  

PubMed

Genetic mixed-stock analysis (MSA) of wild lake-run brown trout Salmo trutta fishery catches (n?=?665) from the Inari Basin (northern Finland) between 2006 and 2008 was carried out using a previously characterized baseline with 30 populations (n?=?813) and 13 microsatellite loci. Altogether, 12 populations contributed significantly to mixed-stock fisheries, with the Ivalojoki system being the major contributor (70%) to the total catch. When catches were analysed regionally, geographically nearby populations were the main contributors to the local catches, indicating that a large proportion of S. trutta occupy lacustrine areas near the natal river mouth rather than dispersing throughout the lake. Similarly, far upstream populations contributed insignificantly to catches. These findings have important implications for the conservation and sustainable fishery management of the Inari system. PMID:23991877

Swatdipong, A; Vasemägi, A; Niva, T; Koljonen, M-L; Primmer, C R

2013-09-01

379

Fishery Notes Great Lakes Fish Stocking Hits New High  

E-print Network

released in smaller quantities during the year were brook trout, splake (brook x lake trout hy- brid), Atlantic salmon, and tiger trout (brook x brown trout hybrid). Other species planted in singular locations stages.) The principal species planted during 1976 were (in millions): lake trout 7.4, chinook salmon 6

380

Some bioaccumulation factors and biota-sediment accumulation factors for polycyclic aromatic hydrocarbons in Lake Trout  

SciTech Connect

Bioaccumulation factors (BAFs) and biota-sediment accumulation factors (BSAFs) for phenanthrene, fluoranthene, pyrene, benz[a]anthracene, and chrysene/triphenylene were calculated using the tissue data of Zabik et al. for Salvelinus namaycush siscowet with a 20.5% lipid content, the water data of Baker and Eisenreich, and the sediment data of Baker and Eisenreich for the Lake Superior ecosystem. Log BAFs, both lipid normalized and based on the freely dissolved concentration of the chemical in the water, of 1.95, 3.22, 4.72, 4.73, and 3.61 were calculated for phenanthrene, fluoranthene, pyrene, benz[a]anthracene, and chrysene/triphenylene, respectively. The BSAFs for phenanthrene, fluoranthene, pyrene, benz[a]anthracene, and chrysene/tripenylene were 0.00011, 0.00016, 0.0071, 0.0054, and 0.00033, respectively.

Burkhard, L.P.; Lukasewycz, M.T.

2000-05-01

381

Lean production  

Microsoft Academic Search

“Lean production”, or rather “lean management”, is an intellectual approach consisting of a system of measures and methods which when taken all together have the potential to bring about a lean and therefore particularly competitive state in a company. The main fields of activity concerned are product development, the chain of supply, shop floor management and to a lesser extent

H. J. Warnecke; M. Hüser

1995-01-01

382

SEA LAMPREY CONTROL ON THE GREAT LAKES  

E-print Network

: Sea lamprey Silver lamprey American br»ok igtmpiE£ Bowfin Rainbow trout Brown trout Lake trout Brook of streams and related problems 21 Literature cited 26 #12;SEA LAMPREY CONTROL ON THE GREAT LAKES 1953 trout Round whitefish Smelt White sucker Longnose sucker Hog sucker Silver redhorse Petromyzon marinus

383

Does spatial variation in egg thiamine and fatty-acid concentration of Lake Michigan lake trout Salvelinus namaycush lead to differential early mortality syndrome and yolk oedema mortality in offspring?  

PubMed

Individual variation in fatty-acid and thiamine concentrations were determined in lake trout Salvelinus namaycush eggs collected at two spawning grounds in Lake Michigan. A suite of predictor variables, including spawning location, egg fatty-acid and thiamine concentrations, were used to attempt to explain cause-and-effect in early life stage mortality among S. namaycush families. Lipid and fatty-acid composition of S. namaycush eggs differed between spawning locations. Salvelinus namaycush offspring from south-western Lake Michigan were affected by a high occurrence of yolk oedema, whereas a higher frequency of early mortality syndrome (EMS) was observed among offspring from the north-western part of the lake. Random-forest regressions revealed location as the most influential predictor of yolk oedema mortality, whereas thiamine level in eggs was the strongest predictor of EMS-related mortality. Several polyunsaturated fatty acids were also found to be predictors of both mortalities. There is evidence of spatial variability in egg fatty-acid concentration among S. namaycush in Lake Michigan that, together with diminished thiamine concentration, contribute to low survival of S. namaycush progeny. PMID:22650429

Czesny, S J; Rinchard, J; Lee, B-J; Dabrowski, K; Dettmers, J M; Cao, Y

2012-06-01

384

Genotypic characterization of an MHC class II locus in lake trout ( Salvelinus namaycush) from Lake Superior by single-stranded conformational polymorphism analysis and reference strand-mediated conformational analysis.  

PubMed

This study compares the genotypic information provided by reference strand-mediated conformational analysis and single-stranded confirmational polymorphism (SSCP) analysis for the major histocompatibility complex (MHC) II locus in lake trout. For this study 80 wild-caught animals from the Apostle Islands of Lake Superior were genotyped using both RSCA and SSCP analysis. Their genotypes were recorded using both methods and compared. The genotypic information provided by the 2 methods was essentially the same although some inconsistencies were observed. Both methods detected approximately 65 genotypes, and both were able to distinguish heterozygous and homozygous animals. The analyses determined that only approximately 20% of alleles were shared between 2 morphologically different populations within the sample set, and identified the dominant alleles. SSCP analysis was quicker, simple, and more robust than RSCA. SSCP analysis using fluorescence technologies could be the method of choice for future genotypic analysis of the MHC II locus in salmonids. PMID:14502399

Noakes, Marc A; Reimer, Tara; Phillips, Ruth B

2003-01-01

385

Effects of an Introduced Piscivore on Native Trout: Insights from a Demographic Model  

Microsoft Academic Search

Introductions of exotic species pose a significant threat to the persistence of many native populations, including many inland fishes. In 1994, piscivorous lake trout (Salvelinus namaycush) were discovered in Yellowstone Lake, Yellowstone National Park, Wyoming, USA, one of the last strongholds of the native Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri). Predation by lake trout is expected to lead to a

Paul Stapp; Gregory D. Hayward

2002-01-01

386

Size-selective Predation on Daphnia by Rainbow Trout and Yellow Perch  

Microsoft Academic Search

The size of the zooplankton consumed by rainbow trout and yellow perch was studied in two Michigan lakes and compared with the size of the limnetic zooplankton. One of the study lakes was managed for both rainbow trout and warmwater game fish (a “combination” lake), and the other was managed solely for rainbow trout after it was reclaimed with toxaphene.

Merle G. Galbraith Jr

1967-01-01

387

A REVIEW OF THE SALMONOID FISHES OF THE GREAT LAKES WITH NOTES ON THE WHITEFISHES OF OTHER REGIONS  

E-print Network

. Genus SALVELINUS (Nilsson) Richardson. Salvelinus fontinalis (Mitchill). Eastern Brook Trout. The common OF THE BUREAU OF FISHERiES. Genus CRISTIVOMER Gill & Jordan. Cristivomer namaycush (Walbaum). Lake Trout; Great Lakes Trout; Mackinaw Trout; Togue; Lonqe; Namaycush; Siscowet. (PI. 1.) The Great Lakes trout

388

Laurance LakeLaurance Lake Lost LakeLost Lake  

E-print Network

Lost Lake gler2frnh2hm owerdle2hm Hood River Subbasin 1:200,000 Bull Trout Rainbow Cutthroat BarrierHood River Odell Parkdale Laurance LakeLaurance Lake Lost LakeLost Lake gler2frnh2hm owerdle2hm HoodRiver NealCreek DogRive r Evans Creek TonyCreek Eagle Creek LaddCreek W e st Fork H ood River La ke

389

Retinoid metabolism in lake trout (Salvelinus namaycush) orally exposed to 3,3{prime},4,4{prime},5-pentalchlorobiphenyl (PCB 126)  

SciTech Connect

Juvenile lake trout were orally exposed to 0, 3, 10 or 30 {micro}g PCB 126 kg{sup {minus}1} bodyweight for 12 weeks. Catheters were then inserted to the dorsal aorta and {sup 3}H-retinol was injected as a bolus in charcoal stripped plasma through the catheter. Blood samples were obtained 15 and 30 minutes and 1, 3, 6, 15, 30, 50 and 75 hours after the injection. The plasma recovery profiles were compared for each PCB dose group and were not significantly different for any of the treatments. However, bile radioactivity indicates accelerated metabolism of{sup 3}H-retinol with increasing PCB dose. Tissue distributions of retinol and retinol metabolites will be described. These measures, in addition to the mixed-function oxidase and conjugating enzyme activities allow an assessment of possible mechanisms for depletion of retinoid stores in PCB exposed fish.

Palace, V.P. [Univ. of Manitoba, Winnipeg, Manitoba (Canada); Klaverkamp, J.F.; Baron, C.L.; Brown, S.B. [Department of Fisheries and Oceans, Winnipeg, Manitoba (Canada)

1995-12-31

390

Mixed-function oxidase enzyme activity and oxidative stress in lake trout (Salvelinus namaycush) exposed to 3,3{prime},4,4{prime}5-pentachlorobiphenyl (PCB-126)  

SciTech Connect

Juvenile lake trout were intraperitoneally injected with corn oil containing nominal concentrations of 0, 0.6, 6.3, or 25 {micro}g [{sup 14}C]-3,3{prime},4,4{prime},5-pentachlorobiphenyl (PCB-126) per gram of body weight. The PCB-126 accumulated in liver in a dose-dependent manner to a sustained concentration by 6 weeks and remained elevated for the 30-week experimental period. Mixed-function oxidase (MFO) enzyme activity was elevated in the two highest dose groups relative to the control group, but not in the low-dose group throughout the 30 weeks. Oxidative stress, measured by the thiobarbituric acid reactive substances test, was correlated with ethoxyresorufin O-deethylase and was elevated in liver of the two highest PCB dose groups but not the low-dose group. The activities of the enzymatic antioxidants superoxide dismutase, catalase, and glutathione peroxidase were unaffected by PCB-126 exposure. The nonenzymatic antioxidants superoxide dismutase, catalase, and glutathione peroxidase were unaffected by PCB-126 exposure. The nonenzymatic antioxidant tocopherol was depleted to approximately 75% of the control concentration in liver of all three PCB-dosed groups. Hepatic ascorbic acid levels were not different in any of the treatment groups. Retinol was depleted by greater than an order of magnitude in liver of the two highest dose groups but not in the los-dose group. This study demonstrates a correlation between hepatic MFO activity and oxidative stress in PCB-exposed lake trout. Tocopherol and retinol may be important mediators of oxidative stress but additional study is required to confirm the antioxidant activity of retinol.

Palace, V.P. [Univ. of Manitoba, Winnipeg, Manitoba (Canada). Dept. of Zoology; Klaverkamp, J.F.; Lockhart, W.L. [Univ. of Manitoba, Winnipeg, Manitoba (Canada). Dept. of Zoology]|[Department of Fisheries and Oceans, Winnipeg, Manitoba (Canada). Freshwater Inst.; Metner, D.A.; Muir, D.C.G.; Brown, S.B. [Department of Fisheries and Oceans, Winnipeg, Manitoba (Canada). Freshwater Inst.

1996-06-01

391

SECTION 46 Table of Contents 46 Lake Rufus Woods Subbasin Assessment Aquatic ...........................2  

E-print Network

..........................................................................7 46.5 Focal Species ­ Brook Trout (Hunner and Jones 1996). These species include brook trout (Salvelinus fontinalis), brown trout (Salmo stocked populations of rainbow trout and/or eastern brook trout, while Buffalo Lake is the only lake

392

Differential Susceptibility of Three Species of Stocked Trout to Bird Predation  

Microsoft Academic Search

Piscivorous birds can remove substantial proportions of stocked salmonids from lakes. To determine whether susceptibility to bird predation differs among trout species, 321 brook trout Salvelinus fontinalis, 330 rainbow trout Oncorhynchus mykiss, and 321 splake Salvelinus namaycush × S. fontinalis were stocked in a small lake in Duck Mountain Provincial Park, Manitoba, in spring 1982. Principal avian predators were common

Shelley M. D. Matkowski

1989-01-01

393

Purification and Characterization of Carbonic Anhydrase from A?r? Bal?k Lake Trout Gill (Salmo trutta labrax) and Effects of Sulfonamides on Enzyme Activity.  

PubMed

Carbonic anhydrase (CA) was purified from A?r? Bal?k Lake trout gill (fCA) by affinity chromatography on a sepharose 4B-tyrosine-sulfanilamide column. The fCA enzyme was purified with about a 303.9 purification factor, a specific activity 4130.4 EU (mg-protein)(-1) , and a yield of 79.3 by using sepharose-4B-l tyrosine-sulfanilamide affinity gel chromatography. The molecular weight determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was found to be about 29.9 kDa. The kinetic parameters, KM and Vmax were determined for the 4-nitrophenyl acetate hydrolysis reaction. Some sulfonamides were tested as inhibitors against the purified CA enzymes. The Ki constants for mafenide (1), p-toluenesulfonamide (2), 2-bromo-benzene sulfonamide (3), 4-chlorobenzene sulfonamide (4), 4-amino-6-chloro-1-3 benzenedisulfonamide (5), sulfamethazine (6), sulfaguanidine (7), sulfadiazine (8), and acetozazolamide (9) were in the range of 7.5-108.75 ?M. PMID:25345690

Demirdag, Ramazan; Comakli, Veysal; Kuzu, Muslum; Yerlikaya, Emrah; Sentürk, Murat

2014-10-26

394

Phylogenetic status of brown trout Salmo trutta populations in five rivers from the southern Caspian Sea and two inland lake basins, Iran: a morphogenetic approach.  

PubMed

Interrelationships, origin and phylogenetic affinities of brown trout Salmo trutta populations from the southern Caspian Sea basin, Orumieh and Namak Lake basins in Iran were analysed from complete mtDNA control region sequences, 12 microsatellite loci and morphological characters. Among 129 specimens from six populations, seven haplotypes were observed. Based on mtDNA haplotype data, the Orumieh and southern Caspian populations did not differ significantly, but the Namak basin-Karaj population presented a unique haplotype closely related to the haplotypes of the other populations (0·1% Kimura two-parameter, K2P divergence). All Iranian haplotypes clustered as a distinct group within the Danube phylogenetic grouping, with an average K2P distance of 0·41% relative to other Danubian haplotypes. The Karaj haplotype in the Namak basin was related to a haplotype (Da26) formerly identified in the Tigris basin in Turkey, to a Salmo trutta oxianus haplotype from the Aral Sea basin, and to haplotype Da1a with two mutational steps, as well as to other Iranian haplotypes with one to two mutational steps, which may indicate a centre of origin in the Caspian basin. In contrast to results of the mtDNA analysis, more pronounced differentiation was observed among the populations studied in the morphological and microsatellite DNA data, except for the two populations from the Orumieh basin, which were similar, possibly due to anthropogenic causes. PMID:23020557

Hashemzadeh Segherloo, I; Farahmand, H; Abdoli, A; Bernatchez, L; Primmer, C R; Swatdipong, A; Karami, M; Khalili, B

2012-10-01

395

Can biotransformation of BDE-209 in lake trout cause bioaccumulation of more toxic, lower-brominated PBDEs (BDE-47, -99) over the long term?  

PubMed

Much debate exists on the future direction of policy related to the deca-brominated diphenyl ethers (deca-BDE) mixture. This debate, in part, results from the fact that BDE-209 can debrominate to more toxic lower-polybrominated diphenyl ethers (PBDEs). However, such debromination is difficult to study using measured concentrations alone because of the short-term nature of laboratory experiments and the presence of lower-brominated congeners in the environment. Here, a rigorously calibrated, multichemical, dynamic fish model (Bhavsar et al. 2008, Environ. Sci. Technol., 42, 3724-3731) is used to predict the debromination of BDE-209 to more toxic lower-brominated PBDEs over a 15-year life period of piscivorous- and non-piscivorous lake trout (pLT, npLT; Salvelinus namaycush). A sensitivity analysis was performed by changing BDE-209 dietary dose, gut absorption efficiency and half-life for generally conservative scenarios. Estimated BDE-209, -99 and -47 concentrations were compared with human fish consumption guidelines developed using the draft U.S.EPA tolerable daily intakes. The model predicted that bioaccumulation of BDE-209 as well as BDE-47 and -99 due to dietary exposure to deca-BDE over the 15-year period would not be appreciable in pLT (generally unrestricted consumption advisory) and would be moderate in npLT (unrestricted to 2 meals/month advisory) even for worst-case scenarios. PMID:20888045