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1

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

2

Delineation of sympatric morphotypes of lake trout in Lake Superior  

USGS Publications Warehouse

Three morphotypes of lake trout Salvelinus namaycush are recognized in Lake Superior: lean, siscowet, and humper. Absolute morphotype assignment can be difficult. We used a size-free, whole-body morphometric analysis (truss protocol) to determine whether differences in body shape existed among lake trout morphotypes. Our results showed discrimination where traditional morphometric characters and meristic measurements failed to detect differences. Principal components analysis revealed some separation of all three morphotypes based on head and caudal peduncle shape, but it also indicated considerable overlap in score values. Humper lake trout have smaller caudal peduncle widths to head length and depth characters than do lean or siscowet lake trout. Lean lake trout had larger head measures to caudal widths, whereas siscowet had higher caudal peduncle to head measures. Backward stepwise discriminant function analysis retained two head measures, three midbody measures, and four caudal peduncle measures; correct classification rates when using these variables were 83% for leans, 80% for siscowets, and 83% for humpers, which suggests the measures we used for initial classification were consistent. Although clear ecological reasons for these differences are not readily apparent, patterns in misclassification rates may be consistent with evolutionary hypotheses for lake trout within the Laurentian Great Lakes.

Moore, Seth A.; Bronte, Charles R.

2001-01-01

3

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

4

Fat content of the flesh of siscowets and lake trout from Lake Superior  

USGS Publications Warehouse

Samples of flesh were excised from the middorsal region of 67 siscowets (Salvelinus namaycush siscowet) and 46 lake trout (Salvelinus n. namaycush) collected from Lake Superior. Chemical analysis of the samples revealed a range in fat content (dry weight) of 32.5 to 88.8 per cent in siscowets and 6.6 to 52.3 per cent in lake trout. Percentage fat increased progressively with increase in length of fish in both forms, but the average rate of increase was far greater for siscowets than for lake trout at lengths between 12 and 20 inches. Despite substantial individual variation, the percentage fat in the two forms was widely different and without overlap at all comparable lengths. The range in iodine number of the fat was 100 to 160 for siscowets and 103 to 161 for lake trout; average values were generally lower for siscowets than for lake trout among fish of comparable length. Percentage fat and relative weight were not correlated significantly in either subspecies. The fat content of flesh samples from a distinctive subpopulation of Lake Superior lake trout known as 'humpers' was more closely similar to that of typical lean lake trout than to siscowets, but the rate of increase in fat with increasing length was greater than for lean lake trout. Flesh samples from hatchery-reared stocks of lake trout, hybrid lake trout X siscowets, and siscowets tended to support the view that the wide difference in fat content between siscowets and lake trout is genetically determined.

Eschmeyer, Paul H.; Phillips, Arthur M., Jr.

1965-01-01

5

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

6

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

7

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

8

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

9

Patterns of organochlorine contamination in lake trout from Wisconsin waters of the Great Lakes  

USGS Publications Warehouse

To investigate spatial and temporal patterns of organochlorine contamination in lake trout from Wisconsin waters of the Great Lakes, we examined laboratory contaminant analysis data of muscle tissue samples from Lake Michigan (n=317) and Lake Superior (n=53) fish. Concentrations of polychlorinated biphenyls (PCBs), chlordane, and dieldrin, reported as mg/kg wet weight in 620 mm to 640 mm mean length Lake Michigan lake trout, decreased over time. Mean total PCB concentration declined exponentially from 9.7 in 1975 to 1.9 in 1990. Total chlordane concentration declined 63 percent from 0.48 in 1983 to 0.18 in 1990, and dieldrin declined 52 percent during this same period, from 0.21 to 0.10. The bioaccumulation rate of PCBs is significantly lower for lake trout inhabiting Lake Michigan's midlake reef complex, compared to lake trout from the nearshore waters of western Lake Michigan. Organochlorine compound concentrations were greater in Lake Michigan lake trout than Lake Superior fish. Lake Superior lean lake trout and siscowet exhibited similar rates of PCB bioaccumulation despite major differneces in muscle tissue lipid content between the two subspecies. The lack of a significant difference in the PCB bioaccumulation rates of lean trout and siscowet suggests that lipid content may not be an important factor influencing PCB bioaccumulation in lake trout, within the range of lipid concentrations observed. Relative concentrations of the various organochlorine contaminants found in lake trout were highly correlated, suggesting similar mass balance processes for these compounds. Evidence presented revealing spatial and temporal patterns of organochlorine contamination may be of value in reestablishing self-sustaining populations of lake trout in Lake Michigan.

Miller, Michael A.; Madenjian, Charles P.; Masnado, Robert G.

1992-01-01

10

Embryotoxicity of an extract from Great Lakes lake trout to rainbow trout and lake trout  

SciTech Connect

Aquatic ecosystems such as the Great Lakes are known to be contaminated with chemicals that are toxic to fish. However, the role of these contaminants in reproductive failures of fishes, such as lake trout recruitment, has remained controvertible. It was the objective to evaluate dioxin-like embryotoxicity of a complex mixture of chemicals and predict their potential to cause the lack of recruitment in Great Lakes lake trout. Graded doses of a complex environmental extract were injected into eggs of both rainbow trout and lake trout. The extract was obtained from whole adult lake trout collected from Lake Michigan in 1988. The extract was embryotoxic in rainbow trout, with LD50 values for Arlee strain and Erwin strain of 33 eggEQ and 14 eggEQ respectively. The LOAEL for hemorrhaging, yolk-sac edema, and craniofacial deformities in rainbow trout were 2, 2, and 4 eggEQ, respectively. Subsequent injections of the extract into lake trout eggs were likewise embryotoxic, with an LD50 value of 7 eggEQ. The LOAEL values for the extract in lake trout for hemorrhaging, yolk-sac edema, and craniofacial deformities were 0.1, 1, and 2 eggEQ, respectively. The current levels of contaminants in lake trout eggs are above the threshold for hemorrhaging and yolk-sac edema. The results also support the use of an additive model of toxicity to quantify PCDDs, PCDFs, Non-o-PCBs, and Mono-o-PCBs in relation to early life stage mortality in Lake Michigan lake trout.

Wright, P.J.; Tillitt, D.E. [National Biological Service, Columbia, MO (United States). Midwest Science Center

1995-12-31

11

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

12

Spatial Patterns in PCB Concentrations of Lake Michigan Lake Trout  

Microsoft Academic Search

Most of the PCB body burden in lake trout (Salvelinus namaycush) of the Great Lakes is from their food. PCB concentrations were determined in lake trout from three different locations in Lake Michigan during 1994–1995, and lake trout diets were analyzed at all three locations. The PCB concentrations were also determined in alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), bloater

Charles P. Madenjian; Timothy J. DeSorcie; Ralph M. Stedman; Edward H. Brown Jr.; Gary W. Eck; Larry J. Schmidt; Robert J. Hesselberg; Sergei M. Chernyak; Dora R. Passino-Reader

1999-01-01

13

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

14

Lake trout rehabilitation in Lake Ontario  

USGS Publications Warehouse

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 1971 and was enhanced when the tributaries of Oneida Lake and Lake Erie were treated in the 1980s. Annual stocking of hatchery fish was resumed with the 1972 year class and peaked at about 1.8 million yearlings and 0.3 million fingerlings from the 1985-1990 year classes. Survival of stocked yearlings declined over 50% in the 1980s and was negatively correlated with the abundance of lake trout > 550 mm long (r = -0.91, P < 0.01, N = 12). A slot length limit imposed by the state of New York for the 1988 fishing season reduced angler harvest. Angler harvest in Canadian waters was 3 times higher in eastern Lake Ontario than in western Lake Ontario. For the 1977-1984 year classes, mean annual survival rate of lake trout age 6 and older was 0.45 (range: 0.35-0.56). In U.S. waters during 1985-1992, the total number of lake trout harvested by anglers was about 2.4 Times greater than that killed by sea lampreys. The number of unmarked lake trout < 250 mm long in trawl catches in 1978-1992 was not different from that expected due to loss of marks and failure to apply marks at the hatchery, and suggested that recruitment of naturally-produced fish was nil. However, many of the obstacles which may have impeded lake trout rehabilitation in Lake Ontario during the 1980s are slowly being removed, and there are signs of a general ecosystem recovery. Significant recruitment of naturally produced lake trout by the year 2000, one interim objective of the rehabilitation plan for the lake, may be achieved.

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

1995-01-01

15

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

16

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

17

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

18

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

19

Evidence of Lake Trout Reproduction at Lake Michigan's Mid-lake Reef Complex  

Microsoft Academic Search

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

John Janssen; David J. Jude; Thomas A. Edsall; Robert W. Paddock; Nigel Wattrus; Mike Toneys; Pat Mckee

2006-01-01

20

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

21

Genetic strategies for lake trout rehabilitation: a synthesis  

USGS Publications Warehouse

The goal of lake trout rehabilitation efforts in the Great Lakes has been to reestablish inshore lake trout (Salvelinus namaycush) populations to self-sustaining levels. A combination of sea lamprey control, stocking of hatchery-reared lake trout, and catch restrictions were used to enhance remnant lake trout stocks in Lake Superior and reestablish lake trout in Lakes Michigan, Huron, Erie, and Ontario. Genetic diversity is important for the evolution and maintenance of successful adaptive strategies critical to population restoration. The loss of genetic diversity among wild lake trout stocks in the Great Lakes imposes a severe constraint on lake trout rehabilitation. The objective of this synthesis is to address whether the particular strain used for stocking combined with the choice of stocking location affects the success or failure of lake trout rehabilitation. Poor survival, low juvenile recruitment, and inefficient habitat use are three biological impediments to lake trout rehabilitation that can be influenced by genetic traits. Evidence supports the hypothesis that the choices of appropriate lake trout strain and stocking locations enhance the survival of lake trout stocked into the Great Lakes. Genetic strategies proposed for lake trout rehabilitation include conservation of genetic diversity in remnant stocks, matching of strains with target environments, stocking a greater variety of lake trout phenotypes, and rehabilitation of diversity at all trophic levels.

Burnham-Curtis, Mary K.; Krueger, Charles C.; Schreiner, Donald R.; Johnson, James E.; Stewart, Thomas J.; Horrall, Ross M.; MacCallum, Wayne R.; Kenyon, Roger; Lange, Robert E.

1995-01-01

22

Movements of hatchery-reared lake trout in Lake Superior  

USGS Publications Warehouse

The history of stocking of lake trout (Salvelinus namaycush) in the Great Lakes is reviewed. The study of movements is based on capture of 24,275 fin-clipped lake trout taken in experimental gill nets and trawls and commercial gill nets. Yearling lake trout planted from shore dispersed to 15-fath (27-m) depths in 3A? hr. Most fish remained within 2 miles (3.2 km) of the planting site 2 months, but within 4 months some fish had moved as much as 17 miles (27 km). The highest abundance of planted lake trout was in areas 2-4 miles (3.2-6.4 km) from the planting site even 3 years after release. Distance moved and size of fish were not correlated. Dispersal of lake trout begins at planting and probably continues until the fish are mature. Most movement was eastward in southern Lake Superior and followed the counterclockwise surface currents. Movement is most rapid in areas of strong currents and slowest in areas of weak currents or eddies. Movement to areas west of the Keweenaw Peninsula was insignificant from plantings in Keweenaw Bay and nil from other plantings farther east. Lake trout planted in the eastern third of the lake dispersed more randomly than those planted farther west. Few fish moved farther offshore than the 50-fath (91-m) contour. Lake trout planted in Canadian waters made insignificant contributions to populations in US waters.

Pycha, Richard L.; Dryer, William R.; King, George R.

1965-01-01

23

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

24

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

Microsoft Academic Search

Introduction of lake trout Salvelinus namaycush into a system can add a trophic level, potentially affecting organisms at lower trophic levels. Similar to many lakes and reservoirs in the western United States, lake trout were introduced into Yellowstone Lake, Wyoming. Previous studies showed that lake trout reduced the population and altered the size structure of native Yellowstone cutthroat trout Oncorhynchus

Lusha M. Tronstad; Robert O. Hall Jr; Todd M. Koel; Ken G. Gerow

2010-01-01

25

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

26

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

27

INDIVIDUAL TISSUE TO TOTAL BODY-WEIGHT RELATIONSHIPS AND TOTAL, POLAR, AND NON-POLAR LIPIDS IN TISSUES OF HATCHERY LAKE TROUT  

EPA Science Inventory

Tissue body weight relaltionships, total lipid, and major lipid subclasses were measured in 20 adult hatchery lake trout to obtain a more in-depth understanding of the major lipid compartments of the "lean" lake trout for use in modeling the disposition of xenobiotics. It is sug...

28

Progress toward lake trout restoration in Lake Michigan  

USGS Publications Warehouse

Progress toward lake trout restoration in Lake Michigan is described through 1993. Extinction of the native lake trout fishery by sea lamprey predation, augmented by exploitation and habitat destruction, resulted in an extensive stocking program of hatchery-reared lake trout that began in 1965. Sea lamprey abundance was effectively controlled using selective chemical toxicants. The initial stocking produced a measurable wild year class of lake trout by 1976 in Grand Traverse Bay, but failed to continue probably due to excessive exploitation. The overall lack of successful reproduction lakewide by the late 1970s led to the development and implementation in 1985 of a focused interagency lakewide restoration plan by a technical committee created through the Lake Committee structure of the Great Lakes Fishery Commission. Strategies implemented in 1985 by the plan included setting a 40% total mortality goal lakewide, creating two large refuges designed to encompass historically the most productive spawning habitat and protect trout stocked over their home range, evaluating several lake trout strains, and setting stocking priorities throughout the lake. Target levels for stocking in the 1985 Plan have never been reached, and are much less than the estimated lakewide recruitment of yearlings by the native lake trout stocks. Since 1985, over 90% of the available lake trout have been stocked over the best spawning habitat, and colonization of the historically productive offshore reefs has occurred. Concentrations of spawning lake trout large enough for successful reproduction, based on observations of successful hatchery and wild stocks, have developed at specific reefs. Continued lack of recruitment at these specific sites suggests that something other than stock abundance has limited success. Poor survival of lake trout eggs, assumed to be related to contaminant burden, occurred in the late 1970s and early 1980s, but survival has since increased to equal survival in the hatchery. A recent increase in lamprey wounding rates in northern Lake Michigan appears to be related to the uncontrolled build-up of lampreys in the St. Marys River a tributary of Lake Huron. If left uncontrolled, further progress toward restoration in the Northern Refuge may be limited.

Holey, Mark E.; Rybicki, Ronald W.; Eck, Gary W.; Brown, Edward H., Jr.; Marsden, J. Ellen; Lavis, Dennis S.; Toneys, Michael L.; Trudeau, Tom N.; Horrall, Ross M.

1995-01-01

29

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

30

Genetic diversity of wild and hatchery lake trout populations: Relevance for management and restoration in the Great Lakes  

USGS Publications Warehouse

The biological diversity of lake trout Salvelinus namaycush in the upper Great Lakes was historically high, consisting of many recognizable morphological types and discrete spawning populations. During the 1950s and 1960s, lake trout populations were extirpated from much of the Great Lakes primarily as a result of overfishing and predation by the parasitic sea lamprey Petromyzon marinus. Investigations of how genetic diversity is partitioned among remnant wild lake trout populations and hatchery broodstocks have been advocated to guide lake trout management and conservation planning. Using microsatellite genetic markers, we estimated measures of genetic diversity and the apportionment of genetic variance among 6 hatchery broodstocks and 10 wild populations representing three morphotypes (lean, humper, and siscowet). Analyses revealed that different hatchery broodstocks and wild populations contributed disproportionally to the total levels of genetic diversity. The genetic affinities of hatchery lake trout reflected the lake basins of origin of the wild source populations. The variance in allele frequency over all sampled extant wild populations was apportioned primarily on the basis of morphotype (??MT = 0.029) and secondarily among geographically dispersed populations within each morphotype (??ST = 0.024). The findings suggest that the genetic divergence reflected in recognized morphotypes and the associated ecological and physiological specialization occurred prior to the partitioning of large proglacial lakes into the Great Lakes or as a consequence of higher contemporary levels of gene flow within than among morphotypes. Information on the relative contributions of different broodstocks to total gene diversity within the regional hatchery program can be used to prioritize the broodstocks to be retained and to guide future stocking strategies. The findings highlight the importance of ecological and phenotypic diversity in Great Lakes fish communities and emphasize that the management of wild remnant lake trout populations and the restoration of extirpated populations should recognize and make greater use of the genetic diversity that still exists.

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

2004-01-01

31

MID-LAKE REEF COMPLEX LAKE TROUT REPORT EVALUATION OF LAKE TROUT SPAWNING HABITAT AND EGG, FRY,  

E-print Network

of lake trout spawning habitat by making improvements to the ROV based suction sampler to generate sac fry via ROV-based electroshocking than in previous years. Page 14 Ancillary accomplishments 1 We also collected, via ROV electroshocking, lake trout sac fry at sites M and S. Site N has not been

Janssen, John

32

Survival of Rainbow Trout and Lake Trout after Sea Lamprey Attack  

Microsoft Academic Search

Survival was significantly higher (P = 0.054) for rainbow trout Oncorhynchus mykiss (formerly Salmo gairdneri) than for lake trout Salvelinus namaycush when the fish were subjected in the laboratory to a single attack by a sea lamprey Petromyzon marinus. Of 77 rainbow trout, 40% died (35% by direct attack and 5% by secondary infection) and 60% survived; of 77 lake

William D. Swink; Lee H. Hanson

1989-01-01

33

Global warming impacts on lake trout in arctic lakes  

Microsoft Academic Search

Arctic freshwater ecosystems may be sensitive indicators of climatic warming trends because they have relatively few species and simple food webs. Many of these systems are dominated by lake trout, which act as keystone predators. For arctic Alaska Toolik Lake, we have a 16-yr record of physical, chemical, and biological data. Our temperature data show a 3°C increase in mean

Michael E. McDonald; Anne E. Hershey; Michael C. Miller

1996-01-01

34

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

35

Estimate of net trophic transfer efficiency of PCBs to Lake Michigan lake trout from their prey  

USGS Publications Warehouse

Most of the polychlorinated biphenyl (PCB) body burden accumulated by lake trout (Salvelinus namaycush) from the Laurentian Great Lakes is from their food. We used diet information, PCB determinations in both lake trout and their prey, and bioenergetics modeling to estimate the efficiency with which Lake Michigan lake trout retain PCBs from their food. Our estimates were the most reliable estimates to date because (a) the lake trout and prey fish sampled during our study were all from the same vicinity of the lake, (b) detailed measurements were made on the PCB concentrations of both lake trout and prey fish over wide ranges in fish size, and (c) lake trout diet was analyzed in detail over a wide range of lake trout size. Our estimates of net trophic transfer efficiency of PCBs to lake trout from their prey averaged from 0.73 to 0.89 for lake trout between the ages of 5 and 10 years old. There was no evidence of an upward or downward trend in our estimates of net trophic transfer efficiency for lake trout between the ages of 5 and 10 years old, and therefore this efficiency appeared to be constant over the duration of the lake trout's adult life in the lake. On the basis of our estimtes, lake trout retained 80% of the PCBs that are contained within their food.

Madenjian, Charles P.; Hesselberg, Robert J.; DeSorcie, Timothy J.; Schmidt, Larry J.; Stedman, Ralph M.; Quintal, Richard T.; Begnoche, Linda J.; Passino-Reader, Dora R.

1998-01-01

36

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

37

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

38

Survival and Growth of Rainbow Trout and Brown Trout in Farm Dugouts and Winterkill Lakes  

Microsoft Academic Search

Rainbow trout (Oncorhynchus mykiss, formerly Salmo gairdneri) and brown trout (Salmo trutta) were stocked sympatrically in four eutrophic winterkill lakes in 1987 and 1988 and allopatrically in 20 farm dugouts (elsewhere called stock tanks) in 1987. Fish survival and growth were monitored to ascertain the feasibility of using brown trout as an alternative species in prairie aquaculture. In dugouts, survival

C. L. Glenn; A. O. Bush; R. C. Rounds

1989-01-01

39

AIRBORNE LIDAR MAPPING OF INVASIVE LAKE TROUT IN YELLOWSTONE LAKE Joseph A. Shaw1  

E-print Network

AIRBORNE LIDAR MAPPING OF INVASIVE LAKE TROUT IN YELLOWSTONE LAKE Joseph A. Shaw1 , James H season, an airborne lidar was flown over Yellowstone Lake to locate pockets of spawning lake trout to aid in the effort of identifying and eradicating this invasive species from the lake. The lidar data were used

Shaw, Joseph A.

40

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

41

Rehabilitation of lake trout in the Apostle Islands region of Lake Superior  

USGS Publications Warehouse

Marked success of rehabilitation of lake trout in Lake Superior has been due principally to the control of the sea lamprey and closure of the lake trout fishery in 1962 and large-scale plantings of yearling lake trout in 1959-66. After the sea lamprey became established in the late 1940s, spawning stocks of lake trout began to decrease and were almost nonexistent by 1960-61. After control of the sea lamprey and closure of the commercial fishery for lake trout in 1962, the abundance of spawning stocks began to rise and reached the highest levels on record in 1964-66. Successful spawning in 1964 and 1965 was demonstrated by catches of age-0 lake trout in 1965 and 1966, the first evidence of natural reproduction since 1959. Plantings of hatchery-reared lake trout in Wisconsin waters of Lake Superior began in 1952. The percentage of hatchery-reared fish in catches of juvenile lake trout increased almost steadily from 1953 to 1965 (when nearly all were of hatchery origin). The abundance of juvenile fish increased from 1959 to 1962 and remained nearly constant in 1962-66. The success of lake trout plantings was highest in 1959-61 but generally declined after 1961; the success of the plantings was inversely related to the abundance of older lake trout. Annual increments of growth of hatchery-reared lake trout varied from 1.1 to 5.0 inches after planting. The average lengths of fish of identical age-groups varied according to gear of capture, depth of water, and season. More than 65% of the season's growth of age-III lake trout took place after September. The findings indicate that the present rate of stocking lake trout may be higher than necessary to maintain optimum abundance.

Dryer, William R.; King, George R.

1968-01-01

42

Relative Survival of Hatchery-Reared Lake Trout, Brook Trout, and F1 Splake Stocked in Low-pH Lakes  

Microsoft Academic Search

A matched-planting experiment was conducted to determine the most suitable salmonid genotype for stocking in former lake trout lakes that currently are too acidic to support lake trout reproduction. Hatchery-reared lake trout Salvelinus namaycush, brook trout Salvelinus fontinalis, and F1 splake S. namaycush × S. fontinalis were planted in May 1989 at age 18–19 months in four lakes with pH

E. J. Snucins

1992-01-01

43

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

44

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

45

Lake trout population dynamics in the Northern Refuge of Lake Michigan: implications for future rehabilitation  

USGS Publications Warehouse

The Northern Refuge was established in 1985 as part of the lake trout Salvelinus namaycush rehabilitation effort for Lake Michigan. To evaluate progress toward lake trout rehabilitation in the Northern Refuge, we conducted annual (1991–2008) gill-net surveys in the fall to assess the adult population and beam trawl surveys in the spring to assess naturally reproduced age-0 lake trout. Our criteria for evaluating progress included the density of “wild” age-0 fish within the Northern Refuge, the proportion of wild fish within the adult population, density of spawners, adult survival, growth, and wounding rate by sea lampreys Petromyzon marinus. No wild age-0 lake trout were caught in the Northern Refuge during 1991–2008. Overall, wild lake trout did not recruit to the adult population to any detectable degree. The mean density of spawning lake trout decreased from 45 fish·305 m of gill net?1·d?1 during 1991–1999 to only 4 fish·305 m?1·d?1 during 2000–2008. Although the sea lamprey wounding rate more than doubled between these two time periods, catch curve analysis revealed that mortality of adult lake trout actually decreased between the two periods. Therefore, the 90% decrease in abundance of spawning lake trout between the two periods could not be attributed to increased sea lamprey predation but instead was probably due in part to the reduced lake trout stocking rate during 1995–2005. The paucity of natural reproduction in the Northern Refuge during 1991–2008 most likely resulted from alewife Alosa pseudoharengus interference with lake trout reproduction and from the relatively low lake trout spawner density during 2000–2008. Our results suggest that the annual stocking rate of lake trout yearlings should be increased to at least 250,000 fish/reef to achieve greater densities of spawners.

Madenjiana, Charles P.; DeSorcie, Timothy J.

2010-01-01

46

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

PubMed

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. PMID:10864274

Muzzall, P M; Bowen, C A

2000-06-01

47

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

48

Status of lake trout rehabilitation on Six Fathom Bank and Yankee Reef in Lake Huron  

USGS Publications Warehouse

Six Fathom Bank, an offshore reef in the central region of Lake Huron's main basin, was stocked annually with hatchery-reared lake trout Salvelinus namaycush during 1985-1998, and nearby Yankee Reef was stocked with hatchery-reared lake trout in 1992, 1997, and annually during 1999-2001. We conducted gill-net surveys during spring and fall to evaluate performances of each of the various strains of lake trout, as well as the performance of the entire lake trout population (all strains pooled), on these two offshore reefs during 1992-2000. Criteria to evaluate performance included the proportion of 'wild' fish within the population, spawner density, adult survival, growth, maturity, and wounding rate by sea lamprey Petromyzon marinus. Although naturally reproduced age-0 lake trout fry were caught on Six Fathom Bank and Yankee Reef, wild lake trout did not recruit to the adult population to any detectable degree. The density of spawning lake trout on Six Fathom Bank (>100 fish/305 m of gill net) during 1995-1998 appeared to be sufficiently high to initiate a self-sustaining population. However, annual mortality estimates for all lake trout strains pooled from catch curve analyses ranged from 0.48 to 0.62, well exceeding the target level of 0.40 suggested for lake trout rehabilitation. Annual mortality rate for the Seneca Lake strain (0.34) was significantly lower than that for the Superior-Marquette (0.69) and Lewis Lake (0.69) strains. This disparity in survival among strains was probably attributable to the lower sea-lamprey-induced mortality experienced by the Seneca Lake strain. The relatively high mortality experienced by adult lake trout partly contributed to the lack of successful natural recruitment to the adult population on these offshore reefs, but other factors were probably also involved. We recommend that both stocking of the Seneca Lake strain and enhanced efforts to reduce sea lamprey abundance in Lake Huron be continued.

Madenjian, Charles P.; DeSorcie, Timothy J.; McClain, Jerry R.; Woldt, Aaron P.; Holuszko, Jeffrey D.; Bowen, Charles A., II

2004-01-01

49

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

E-print Network

the most spawning and rearing habitat for endemic Eagle Lake rainbow trout Oncorhynchus mykiss aquilarum (Rieman et al. 2006), and golden trout O. mykiss aguabonita (Moyle 2002). Established populations been implicated in the decline of many salmonid species, including Chinook salmon Oncorhynchus

García-Berthou, Emili

50

Status of lake trout rehabilitation in the Northern Refuge of Lake Michigan  

USGS Publications Warehouse

The Northern Refuge in Lake Michigan was established in 1985 as part of a rehabilitation program to stock yearling lake trout Salvelinus namaycush in areas with the best potential for success. Stocking of hatchery-reared lake trout within the refuge began in 1986 at three reefs: Boulder Reef, Gull Island Reef, and Richards Reef. On each reef from 1991 to 1997 we conducted gill-net surveys during the fall spawning season to evaluate performance of adult lake trout, and we conducted beam trawl surveys for naturally reproduced age-0 lake trout in the spring. Criteria to evaluate performance included spawner density, growth, maturity, and mortality. We found no evidence of natural reproduction by lake trout from our surveys. Nevertheless, density of spawning lake trout on Boulder Reef (69 fish/305 m of gill net/night) and Gull Island Reef (34 fish/305 m of gill net/night) appeared to be sufficiently high to initiate a self-sustaining population. Growth and maturity rates of lake trout in the Northern Refuge were similar to those for lake trout stocked in the nearshore region of Lake Michigan. In the Northern Refuge, growth rate for the Marquette strain of lake trout was slightly higher than for the Lewis Lake strain. Annual mortality estimates from catch curve analyses ranged from 0.46 to 0.41, and therefore, these estimates approached a level that was considered to be sufficiently low to allow for a self-sustaining population. Thus, it appeared that the lack of evidence for natural reproduction by lake trout in the Northern Refuge should not be attributed to inability of the population to attain a sufficiently large stock of spawners.

Madenjian, Charles P.; DeSorcie, Timothy J.

1999-01-01

51

Conservation Genetics of Inland Lake Trout in the Upper Mississippi River Basin: Stocked or Native Ancestry?  

Microsoft Academic Search

Although stocking for sport fishery enhancement has been practiced by resource managers for decades, the potential genetic effects of these stocking practices have remained largely unknown. We investigated the genetic contributions of stocking lake trout Salvelinus namaycush in two inland lakes in Wisconsin (Trout and Black Oak lakes in Vilas County), which represent the only known indigenous lake trout populations

Kyle R. Piller; Chris C. Wilson; Carol Eunmi Lee; John Lyons

2005-01-01

52

Total and methyl mercury accumulation in 1994–1995 Lake Michigan lake trout and forage fish  

Microsoft Academic Search

As part of the Lake Michigan Mass Balance Project, total and methyl mercury were determined for lake trout (Salvelinus namaycush) and five forage fish species collected from Lake Michigan near Saugatuck, Michigan, and Port Washington, Sheboygan Reef, and Sturgeon Bay, Wisconsin, between 1994 and 1995. With a mean concentration of 179 ng\\/g wet wt., whole lake trout total mercury (HgT) concentrations

Brian Raymond; Ronald Rossmann

2009-01-01

53

Genetic evaluation of a Great Lakes lake trout hatchery program  

USGS Publications Warehouse

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 lake trout hatchery program were examined to determine how effective hatchery practices have been in minimizing the loss of genetic diversity in broodstock adults and in progeny stocked. Microsatellite loci were used to estimate allele frequencies, measures of genetic diversity, and relatedness for wild source populations, hatchery broodstocks, and juveniles. We also estimated the effective number of breeders for each broodstock. Hatchery records were used to track destinations of fertilized eggs from all spawning dates to determine whether adult contributions to stocking programs were proportional to reproductive effort. Overall, management goals of maintaining genetic diversity were met across all stages of the hatchery program; however, we identified key areas where changes in mating regimes and in the distribution of fertilized gametes and juveniles could be improved. Estimates of effective breeding population size (Nb) were 9-41% of the total number of adults spawned. Low estimates of Nb were primarily attributed to spawning practices, including the pooling of gametes from multiple males and females and the reuse of males. Nonrandom selection and distribution of fertilized eggs before stocking accentuated declines in effective breeding population size and increased levels of relatedness of juveniles distributed to different rearing facilities and stocking locales. Adoption of guidelines that decrease adult reproductive variance and promote more equitable reproductive contributions of broodstock adults to juveniles would further enhance management goals of maintaining genetic diversity and minimize probabilities of consanguineous matings among stocked individuals when sexually mature. ?? Copyright by the American Fisheries Society 2005.

Page, K.S.; Scribner, K.T.; Bast, D.; Holey, M.E.; Burnham-Curtis, M. K.

2005-01-01

54

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

USGS Publications Warehouse

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.

Honeyfield, D.C.; Fitzsimons, J.D.; Tillitt, D.E.; Brown, S.B.

2009-01-01

55

Ecological consequences of invasive lake trout on river otters in Yellowstone National Park  

Microsoft Academic Search

The introduction of lake trout (Salvelinus namaycush) to Yellowstone Lake in Yellowstone National Park has contributed to a significant decline in the endangered Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri), leading to concern over the persistence of this subspecies but also to piscivorous predators in this community. We assessed the impact of lake trout on a key piscivore, the river otter

William R. Wengeler; Douglas A. Kelt; Michael L. Johnson

2010-01-01

56

Predation of lake trout and lake whitefish embryos by crayfish: Implications of shifts in crayfish dominance in Lake Simcoe  

Microsoft Academic Search

We compared predation rates of two Lake Simcoe crayfish, Orconectes virilis and Orconectes propinquus, on lake trout and lake whitefish eggs and alevins in laboratory experiments and assessed the potential impact of predation on egg survival in the lake. Experiments were conducted at 4 and 8°C on gravel and one or three layers of cobble substrate. Predation rates on lake

Kristine Mason; David O. Evans

2011-01-01

57

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

58

Ecology, Evolution, and Conservation of Lake-Migratory Brook Trout: A Perspective from Pristine Populations  

E-print Network

, we review research on the population structuring and evolution of migratory brook trout Salvelinus fontinalis in a relatively undisturbed, postglacial lake (Mistassini Lake, Quebec). We provide information

Bernatchez, Louis

59

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

60

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

61

Causes of declining survival of lake trout stocked in U.S. waters of Lake Superior in 1963-1986  

USGS Publications Warehouse

Survival of the 1963-1982 year-classes of stocked yearling lake trout Salvelinus namaycush declined significantly over time in Lake Superior. To investigate possible causes of this decline, a Ricker model of stock-recruitment was used to describe the catch per effort (CPE) of age-7 stocked lake trout in the Michigan, Minnesota, and Wisconsin waters of Lake Superior as functions of the numbers of yearlings stocked 6 years earlier (an index of density dependence), the density (CPE) of wild adult lake trout (an index of predation), and large-mesh (a?Y 114-mm stretch-measure) gill-net fishing effort (an index of fishing mortality). Declining CPE of stocked lake trout in Michigan and Wisconsin was significantly associated with increasing large-mesh gillnet fishing effort. Declining CPE of stocked lake trout in Minnesota was significantly associated with increasing density of wild lake trout. Declining survival of stocked lake trout may therefore have been caused by increased mortality in large-mesh gill-net fisheries in Michigan and Wisconsin, and by predation by wild lake trout that recently recolonized the Minnesota area. We recommend that experimental management be pursued to determine the relative importance of large-mesh gillnet fishing effort and of predation by wild lake trout on the survival of stocked lake trout in U.S. waters of Lake Superior.

Hansen, Michael J.; Ebener, Mark P.; Schorfhaar, Richard G.; Schram, Stephen T.; Schreiner, Donald R.; Selgeby, James H.; Taylor, William W.

1996-01-01

62

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

63

Lake trout population dynamics at Drummond Island Refuge in Lake Huron: Implications for future rehabilitation  

USGS Publications Warehouse

The Drummond Island Refuge (DIR) was established in 1985 as part of the rehabilitation effort for lake trout Salvelinus namaycush in Lake Huron. Since then, several strains of hatchery-reared lake trout have been stocked annually at the DIR. An intensive lampricide treatment of the St. Marys River during 1998-2001 was expected to lower the abundance of sea lamprey Petromyzon marinus within the DIR by 2000. We conducted annual gill-net surveys during spring and fall to evaluate the performance of each of the strains of lake trout as well as that of the entire lake trout population (all strains pooled) in the DIR during 1991-2005. The criteria to evaluate performance included the proportion of "wild" fish within the population, spawner density, adult survival, growth, maturity, and wounding rate by sea lampreys. Wild lake trout did not recruit to the adult population to any detectable degree. During 1991-2005, the average density of spawning lake trout appeared to be marginally sufficient to initiate a self-sustaining population. Survival of the Seneca Lake (SEN) strain of lake trout was significantly higher than that of the Superior-Marquette (SUP) strain, in part because of the higher sea-lamprey-induced mortality suffered by the SUP strain. However, other factors were also involved. Apparently SUP fish were more vulnerable to fishing conducted in waters near the refuge boundaries than SEN fish. The St. Marys River treatment appeared to be effective in reducing the sea lamprey wounding rate on SEN fish. We recommend that the stocking of SEN lake trout in the DIR, control of sea lampreys in the St. Marys River, and reduction of commercial fishery effort in waters near the DIR be maintained. ?? Copyright by the American Fisheries Society 2008.

Madenjian, C.P.; Ebener, M.P.; Desorcie, T.J.

2008-01-01

64

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...

65

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

66

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

67

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

68

Reference points for angler effort directed at wild stocks of rainbow trout in mixed species lakes  

E-print Network

rates by 30% in ten years. Rainbow trout are the most popular game fish for freshwater anglers and have for recreational fishing on small wild rainbow trout lakes with non-game fish species present. Growing concernsReference points for angler effort directed at wild stocks of rainbow trout in mixed species lakes

Miami, University of

69

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

70

Patterns of egg deposition by lake trout and lake whitefish at Tawas artificial Reef, Lake Huron, 1990-1993  

USGS Publications Warehouse

In August 1987, the Michigan Department of Natural Resources (MDNR), with the help and co-sponsorship of Walleyes for Iosco County, constructed Tawas artificial reef to improve recreational fishing in Tawas Bay. Post-construction assessment in October, 1987, by the MDNR found twice as many adult lake trout in a gill net set on the reef as in a similar net set off the reef, indicating that lake trout already had begun to investigate this new habitat. Similar netting efforts in October 1989 caught three times as many adults on the reef as off it, even though the on-reef net was set for less than one third as long a period. Using a remotely operated vehicle (ROV), we detected prespawning aggregations of lake trout on the reef in fall 1989, and MDNR biologists set emergent fly traps on the reef in April-May 1990-1991. These fry traps captured several newly emerged lake trout and lake whitefish fry, demonstrating that eggs of both species has hatched successfully. Gill netting in 1992-1993 by U.S. Fish and Wildlife Service biologists netted large numbers of ripe lake trout in late October and ripe lake whitefish in early to mid-November. The purpose of this paper is to describe the relative quantities of eggs deposited and the spatial patterns of egg deposition by lake trout and lake whitefish at Tawas artificial reef during 1990-1993.

Foster, N.R.; Kennedy, G.W.

1995-01-01

71

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

72

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

73

Bathythermal Habitat Use by Strains of Great Lakes and Finger LakesOrigin Lake Trout in Lake Huron after a Change in Prey Fish Abundance and Composition  

Microsoft Academic Search

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

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

2012-01-01

74

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

75

Genetic variation among wild lake trout populations: the 'wanted' and the 'unwanted'  

USGS Publications Warehouse

In this study we examine genetic variation within and among self-sustaining lake trout populations from the Great Lakes basin, the Rainy Lake basin, and Yellowstone Lake. We used RFLP analysis and direct sequencing to examine DNA sequence variation among several mitochondrial and nuclear genes, including highly conserved loci (e.g. cytochrome b, nuclear exon regions) and highly variable loci (e.g. mitochondrial d-loop and nuclear intron regions). Native Lake Superior lake trout populations show high levels of genetic diversity, while populations from the Rainy Lake basin show little or none. The lake trout population sampled from Yellowstone Lake shows moderate genetic diversity, possibly representative of a relatively large source population closely related to lake trout from Lewis Lake, Wyoming. There has been significant social and management controversy involving these lake trout populations, particularly those that are located in National Parks. In the Great Lakes and Rainy Lake basins, the controversy involves the degree to which hatchery supplementation can contribute to or negatively impact self-sustaining populations which are highly desired by recreational and commercial fisheries. In Yellowstone Lake, the lake trout are viewed as an undesirable intruder that may interfere with resident populations of highly prized native cutthroat trout.

Burnham-Curtis, Mary K.; Kallemeyn, Larry W.; Bronte, Charles R.

1997-01-01

76

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

77

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

78

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

79

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

80

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

81

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

82

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

83

Abundance Indices for Determining the Status of Lake Trout Restoration in Michigan Waters of Lake Superior  

Microsoft Academic Search

Self-sustaining populations of lake trout Sal vet in us namaycush have returned to most areas in Lake Superior, but progress toward achieving historic commercial yields has been difficult to measure because of unrecorded losses to predation by sea lamprey Petromyzon marinus and to fisheries. Consequently, we developed restoration targets (catch per effort, CPE; geometric mean number per kilometer of 114-mm

MICHAEL J. HANSEN; RICHARD G. SCHORFHAAR; JAMES W. PECK; JAMES H. SELGEBY; WILLIAM W. TAYLOR

1995-01-01

84

GillNet Saturation by Lake Trout in Michigan Waters of Lake Superior  

Microsoft Academic Search

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

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

1998-01-01

85

An evaluation of lake trout reproductive habitat on Clay Banks Reef, northwestern Lake Michigan  

USGS Publications Warehouse

The extinction of the native populations of lake trout (Salvelinus namaycush) in Lake Michigan in about 1956 has been followed by a decades-long attempt to reestablish self-sustaining populations of this valuable species in habitats it formerly occupied throughout the lake. One of the most recent management strategies designed to facilitate recovery was to make a primary management objective the establishment of sanctuaries where stocked lake trout could be protected and self-sustaining populations reestablished. In the present study we employed habitat survey and mapping techniques, field and laboratory bioassays, egg traps, sediment traps, and gill nets to examine the potential for successful natural reproduction by stocked lake trout on Clay Banks Reef in the Door-Kewaunee sanctuary in Wisconsin waters of Lake Michigan. Our study revealed (1) there was suitable habitat on the reef to support the production of viable fry, (2) spawner abundance on the reef was the highest recorded in the great lakes, and (3) eggs taken from spawners on the reef and held on the reef in plexiglas incubators hatched and produced fry that survived through swim-up. We conclude that Clay Banks Reef has the potential to support successful natural reproduction by stocked lake trout.

Edsall, Thomas A.; Holey, Mark E.; Manny, Bruce A.; Kennedy, Gregory W.

1995-01-01

86

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...

87

Returns of hatchery-reared lake trout in southern Lake Superior, 1955-62  

USGS Publications Warehouse

Experimental plantings of fin-clipped lake trout (Salvelinus namaycush) of various ages have been made in southern Lake Superior since 1952. The catch of planted lake trout by the commercial fishery was used to measure the success of stocking. Estimates of total returns were based on samples of 8.2 to 21.2% of the Wisconsin catches in 1955-62 and 36.4 to 46.8% of the Michigan catches in 1959-62. Marked lake trout were assigned to various plantings according to the fin mark, length of fish, readings of age from scales, and locations of capture. Estimated returns from Wisconsin plantings of 9-month-old lake trout varied from 2.1 to 6.4%. Wisconsin releases of 16-month-old fish yielded returns of 5.7 to 37.3%. Returns from plantings in Michigan were 0.3% for 9-month-old fish and 1.5 to 3.8% for 16-month-old fish. The ratios of the returns from plantings of 16-month-old fish to those of 9-month-old fish were 3.9:1 for Wisconsin releases and 6.7:1 for Michigan releases. Lake trout planted in Wisconsin generally survived better than those released in Michigan. Returns from fish planted at ages of 17 to 40 months in Michigan in 1958-59 were far greater than those from 16-month-old fish released in Michigan, but were not as high as from the most successful plantings of 16-month-old fish in Wisconsin. Lake trout released in 1960 from shore and from boats survived equally well. Average size of lake trout at release was more closely related to survival than any other factor. All except 1 of 10 highly successful releases were of fish larger than 22 per lb, and all 6 poor releases were of fish smaller than 34 per lb. Fish that ran 22 to 33 per lb survived only moderately well. A size of 17 to 20 fish per lb appears to be close to optimum. Abundance of native lake trout, American smelt (Osmerus mordax), and sea lampreys (Petromyzon marinus) all appeared to be unrelated to stocking success. The only apparent method of rapidly improving the success of stocking is to rear all lake trout to an average size of 17 to 20 per lb.

Pycha, Richard L.; King, George R.

1967-01-01

88

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

89

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

90

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

91

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

92

Historical relationships between organochlorines and stable isotopes in Lake Trout from Lake Ontario  

SciTech Connect

Large fluctuation in the organochlorine contamination reported in Lake Ontario lake trout has been attributed to temporal changes in diet composition. As part of an annual monitoring program a tissue archive of Great Lakes fish has been maintained since the late 1970`s. Archive samples of four year old lake trout from the eastern basin of Lake Ontario collected between 1978 and 1 992 were analyzed for organochlorines, including coplanar PCBs and dioxin/furan isomers, and stable isotope ratios of carbon and nitrogen. The isotope signature of nitrogen remained relatively constant over the study period while the isotope signature of carbon declined significantly since the mid 1980`s. Collections of net plankton, mysids, amphipods, forage fish (sculpin, alewife, smelt) and lake trout from 1992 showed a distinctive increase in the nitrogen signature with increasing trophic level. There was a very strong correlation between PCB, DDE and mirex concentrations and stable isotope signatures of nitrogen. A difference in carbon signatures in the forage fish species is consistent with a diet change (based on gut contents) and a carbon signature shift observed in lake trout. However, the carbon signatures in the foodchain are not correlated with the organochlorine contaminant levels. Changes in the carbon signature at the lower end of the foodchain in response to reduced nutrient availability could also result in a similar shift at the higher trophic levels.

Servos, M.; Huestis, S.; Kiriluk, R.; Whittle, M. [Great Lakes Lab. for Fisheries and Aquatic Sciences, Burlington, Ontario (Canada); Rasmussen, J. [McGill Univ., Montreal, Quebec (Canada)

1994-12-31

93

Genetic assessment of strain-specific sources of lake trout recruitment in the Great Lakes  

USGS Publications Warehouse

Populations of wild lake trout Salvelinus namaycush have been extirpated from nearly all their historical habitats across the Great Lakes. Efforts to restore self-sustaining lake trout populations in U.S. waters have emphasized the stocking of coded-wire-tagged juveniles from six hatchery strains (Seneca Lake, Lewis Lake, Green Lake, Apostle Islands, Isle Royale, and Marquette) into vacant habitats. Strain-specific stocking success has historically been based on estimates of the survival and catch rates of coded-wire-tagged adults returning to spawning sites. However, traditional marking methods and estimates of relative strain abundance provide no means of assessing strain fitness (i.e., the realized contributions to natural recruitment) except by assuming that young-of-the-year production is proportional to adult spawner abundance. We used microsatellite genetic data collected from six hatchery strains with likelihood-based individual assignment tests (IA) and mixed-stock analysis (MSA) to identify the strain composition of young of the year recruited each year. We show that strain classifications based on IA and MSA were concordant and that the accuracy of both methods varied based on strain composition. Analyses of young-of-the-year lake trout samples from Little Traverse Bay (Lake Michigan) and Six Fathom Bank (Lake Huron) revealed that strain contributions differed significantly from estimates of the strain composition of adults returning to spawning reefs. The Seneca Lake strain contributed the majority of juveniles produced on Six Fathom Bank and more young of the year than expected within Little Traverse Bay. Microsatellite markers provided a method for accurately classifying the lake trout hatchery strains used for restoration efforts in the Great Lakes and for assessment of strain-specific reproductive success.

Page, Kevin S.; Scribner, Kim T.; Bennett, Kristine R.; Garzel, Laura M.; Burnham-Curtis, Mary K.

2003-01-01

94

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

95

Habitat suitability for brook trout (Salvelinus fontinalis) reproduction in Adirondack Lakes  

NASA Astrophysics Data System (ADS)

The relationships between habitat characteristics and reproductive status of Adirondack brook trout populations were examined utilizing the Adirondack Lake Survey Corporation data base, which includes physical, chemical, and biological data for 1469 lakes. The only variables strongly related to brook trout natural reproduction were indices of groundwater influence on surface water chemistry, specifically silica and sodium concentrations. This finding supports the hypothesis that lake spawning populations of brook trout are strongly dependent on groundwater seepage for successful reproduction. Spawning habitat in small headwater lakes impounded by beaver activity may be degraded as a result of siltation of nearshore zones and diminished groundwater seepage. Adirondack lakes situated in thick-till basins receive proportionally greater groundwater input than thin-till lake types and thick-till lakes also had the highest proportion of self-sustaining brook trout populations. Acidification is most pronounced in thin-till basins, which also exhibited a low frequency of self-sustaining brook trout populations. Although brook trout fisheries may be maintained in acidic lakes by liming and stocking, the establishment of self-sustaining brook trout populations is not a likely outcome of these management practices. Additionally, there appears to be limited potential for restoration of lake spawning brook trout populations in currently acidic, fishless lakes should acidic inputs decline as a result of reductions in acid-forming emissions.

Schofield, Carl L.

1993-04-01

96

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

97

Seasonal Food Habits of Bull Trout from a Small Alpine Lake in the Canadian Rocky Mountains  

Microsoft Academic Search

We investigated the seasonal diet of a native, undisturbed population of bull trout Salvelinus confluentus in an alpine lake to examine predation patterns between fish size-classes and in relation to available invertebrate prey. The diets of small (?250 mm in fork length, FL) and large (>250 mm FL) bull trout were similar. Bull trout fed on seasonally abundant prey species.

Frank M. Wilhelm; Brian R. Parker; David W. Schindler; David B. Donald

1999-01-01

98

Fleet dynamics of the commercial lake trout fishery in Michigan waters of Lake Superior during 1929-1961  

USGS Publications Warehouse

Understanding fishing fleet dynamics is important when using fishery dependent data to infer the status of fish stocks. We analyzed data from mandatory catch reports from the commercial lake trout (Salvelinus namaycush) fishery in Michigan waters of Lake Superior during 1929-1961, a period when lake trout populations collapsed through the combined effects of overfishing and sea lamprey (Petromyzon marinus) predation. The number of full-time fishermen increased during 1933-1943 and then decreased during 1943-1957. Addition of new fishermen was related to past yield, market prices, World War II draft exemptions, and lost fishing opportunities in Lake Huron and Lake Michigan. Loss of existing fishermen was related to declining lake trout density. Large mesh (a?Y 114-mm stretch-measure) gill net effort increased during 1929-1951 because fishermen fished more net inshore as lake trout density declined, even though catch per effort (CPE) was often higher in deeper waters. The most common gill net mesh size increased from 114-mm to 120-mm stretch-measure during 1929-1957, as lake trout growth increased. More effort was fished inshore than offshore and the amount of inshore effort was less variable over time than offshore effort. Relatively stable yield was maintained by increasing gill net effort and by moving some effort to better grounds. Because fishing-up caused yield and CPE to remain high despite declining lake trout abundance, caution must be used when basing goals for lake trout restoration on historical fishery indices.

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

2004-01-01

99

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

100

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

101

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

102

Eagle Lake Rainbow Trout Spawner Migration Study 2006 Report to the Pine Creek CRMP  

E-print Network

Eagle Lake Rainbow Trout Spawner Migration Study ­ 2006 Report to the Pine Creek CRMP 15 November , and Ken Weaver6 1 Wildlife, Fish, & Conservation Biology Department, University of California Davis 2 Service, Susanville, CA Lassen County Publication #12;Eagle Lake Rainbow Trout Spawner Migration Study

Thompson, Lisa C.

103

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

104

The Accumulation of DDT in Lake Trout and the Effect on Reproduction  

Microsoft Academic Search

Hatchery losses of lake trout fry from areas of high DDT use led to a 4-year study of the accumulation of the chemical in fish flesh and eggs from a number of waters in New York. Graphs are presented to indicate the range of DDT content of ether-extracted oils from spawning female lake trout and a comparison of the amount

G. E. Burdick; E. J. Harris; H. J. Dean; T. M. Walker; Jack Skea; David Colby

1964-01-01

105

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

106

Trends in the Lake Trout Fishery of Lake Huron Through 1946  

Microsoft Academic Search

The production of lake trout, Cristivomer namaycush (Walbaum), in the United States waters of Lake Huron was highest in the earliest years for which there are statistical records, averaging 2,362,000 pounds in 1879–1894. The general level of yield was much lower but relatively stable in 1895–1939, during which period the catch averaged 1,685,000 pounds. The most recent years have seen

Ralph Hile

1949-01-01

107

Simulation of the effects of time and size at stocking on PCB accumulation in lake trout  

USGS Publications Warehouse

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 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 weigh 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.

Madenjian, Charles P.; Carpenter, Stephen R.

1993-01-01

108

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

109

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

110

Reestablishing a spawning population of lake trout in Lake Superior with fertilized eggs in artificial turf incubators  

USGS Publications Warehouse

Fertilized eggs from lake trout Salvelinus namaycush were placed in artificial turf incubators and deployed on Devils Island Shoal, Lake Superior, in an attempt to reestablish a spawning population on this once important spawning area. Efficacy was measured by the changes in catch rates, age composition, and origin of adult lake trout returning to the shoal in the fall in subsequent years. The abundance of lake trout spawners without fin clips, which implies that these fish hatched in the lake, increased throughout the sampling period, whereas the abundance of hatchery-reared fish (indicated by one or more fin clips) stocked for restoration purposes remained low. Year-class-specific stock-recruitment analysis suggested that the recruitment of unclipped spawners was related to the number of eggs planted in previous years rather than to spawning by the few adult lake trout visiting the reef. Increases in adult fish at Devils Island Shoal were independent of trends at adjacent sites, where unclipped spawner abundances remained low. Enhanced survival to hatch and apparent site imprinting of young lake trout make this technique a viable alternative to stocking fingerling and yearling lake trout to reestablish spawning populations on specific sites in the Great Lakes.

Bronte, Charles R.; Schram, Stephen T.; Selgeby, James H.; Swanson, Bruce L.

2002-01-01

111

Factors associated with stocked cutthroat trout populations in high-mountain lakes  

USGS Publications Warehouse

High-mountain lakes provide important fisheries in the Rocky Mountains; therefore we sought to gain an understanding of the relationships among environmental factors, accessibility to anglers, stocking rates, and features of stocks of cutthroat trout Oncorhynchus clarki in high-mountain lakes of the Bighorn Mountains, Wyoming. We sampled fish with experimental gill nets, measured lake habitat features, and calculated factors affecting angler access among 19 lakes that lacked sufficient natural reproduction to support salmonid fisheries and that were stocked at 1-, 2-, or 4-year intervals with fingerling cutthroat trout. We found that angler accessibility was probably the primary factor affecting stock structure, whereas stocking rates affected the densities of cutthroat trout among lakes. The maximum number of years survived after stocking appeared to have the greatest affect on biomass and population structure. Our findings suggest that control of harvest and manipulation of stocking densities can affect the density, biomass, and structure of cutthroat trout stocks in high-elevation lakes.

Bailey, Paul E.; Hubert, W.A.

2003-01-01

112

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

113

Crepidostomum percopsisi n. sp. (Digenea: Allocreadiidae) from the trout perch (Percopsis omiscomaycus) of Dauphin Lake, Canada.  

PubMed

Crepidostomum percopsisi n. sp. is described from the small intestine of the trout perch (Percopsis omiscomaycus) in Dauphin Lake, Manitoba. It is morphologically similar to Crepidostomum isostomum, which has been reported from the trout perch and several other species of fish. It differs from C. isostomum based on the vitellaria confined to the hindbody of the worm, size and shape of the cirrus, size of the testes, and its greater body length. A comparison of our specimens with those illustrated and identified as C. isostomum from trout perch indicates that such specimens are identical to larger specimens of C. percopsisi recovered by us from trout perch in May. To date, C. percopsisi has only been reported from the trout perch of Dauphin Lake, Lake Winnipeg, and Oneida Lake, which suggests host specificity. PMID:9406794

Nelson, P A; Choudhury, A; Dick, T A

1997-12-01

114

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

115

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

116

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 about how differing ecosystem and biological characteristics can drive Hg bioaccumulation in top predators. The present 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. Mercury 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 3 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). Mercury biomagnification factors (BMF) determined between lake trout and rainbow smelt, lake trout's primary prey, were significantly correlated with fish age and differed across the 3 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. Environ Toxicol Chem 2014;9999:1-5. © 2014 SETAC. PMID:25402744

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

2015-02-01

117

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

118

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

119

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

120

Inter-relationships between the spawning migration of Eagle Lake rainbow trout, streamflow, snowpack, and air temperature  

E-print Network

exception of one fish, tagged Eagle Lake rainbow trout haverainbow trout, streamflow, snowpack, and air temperature Lisa C. Thompson Wildlife, Fish,fish species present in the upper Pine Creek watershed are: Lahontan redside (Richardsonius egregius), rainbow

Thompson, Lisa C

2009-01-01

121

Lake trout status in the main basin of Lake Huron, 1973-2010  

USGS Publications Warehouse

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•305mof gill net-1•million stocked yearlings-1) increased from 0.56 for the 1973-1990 year-classes to 0.92 for the 1991-2001 year-classes. Total CPE (fish/305 m of gill net) declined from 16.4 fish in 1996 to 4.1 fish in 2010, but the percentage of age-5 and younger lake trout steadily decreased from more than 70% before 1996 to less than 10% by 2009. The modal age in gill-net catches increased from age 5 before 1996 to age 7 by 2005. The average adult CPE increased from 2.8 fish/305 m of gill net during 1978-1995 to 5.34 fish/305 m of gill net during 1996-2010. The 1995-2010 year-classes of wild fish weremore abundant than previous year-classes and were associated with the relatively high adult abundance during 1996-2010. Until the 2002 year-class, there was no decline in age-7 CPE/R; until 2008, there was no decline in adult CPE. Low survival of the 2002 and 2003 year-classes of stocked fish was related to the event of alewife Alosa pseudoharengus population collapse in 2003-2004. Lake trout in the main basin of Lake Huron are undergoing a transition from a hatchery stock to a wild stock, accompanied by an increased uncertainty in delayed recruitment. Future management should pay more attention to the protection of wild recruitment and the abundance of the spawning stock.

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

2012-01-01

122

Heritage strain and diet of wild young of year and yearling lake trout in the main basin of Lake Huron  

USGS Publications Warehouse

Restoration of lake trout Salvelinus namaycush stocks in Lake Huron is a fish community objective developed to promote sustainable fish communities in the lake. Between 1985 and 2004, 12.65 million lake trout were stocked into Lake Huron representing eight different genetic strains. Collections of bona fide wild fish in USGS surveys have increased in recent years and this study examined the ancestry and diet of fish collected between 2004 and 2006 to explore the ecological role they occupy in Lake Huron. Analysis of microsatellite DNA revealed that both pure strain and inter-strain hybrids were observed, and the majority of fish were classified as Seneca Lake strain or Seneca Lake hybrids. Diets of 50 wild age-0 lake trout were examined. Mysis, chironomids, and zooplankton were common prey items of wild age-0 lake trout. These results indicate that stocked fish are successfully reproducing in Lake Huron indicating a level of restoration success. However, continued changes to the benthic macroinvertebrate community, particularly declines of Mysis, may limit growth and survival of wild fish and hinder restoration efforts.

Roseman, E.F.; Stott, W.; O'Brien, T. P.; Riley, S.C.; Schaeffer, J.S.

2009-01-01

123

Simulation of the Effect of Rainbow Trout Introduction in Lake Washington  

Microsoft Academic Search

We developed a simulation model based on energetics, habitat selection, feeding selectivity, and population dynamics to examine the effect of introductions of rainbow trout Oncorhynchus mykiss on parr of sockeye salmon O. nerka and longfin smelt Spirinchus thaleichthys resident in Lake Washington (Washington State). We modeled growth and population dynamics of rainbow trout cohorts introduced between 1981 and 1984, and

Gordon L. Swartzman; David A. Beauchamp

1990-01-01

124

Post Audit of Lake Michigan Lake Trout PCB Model Forecasts  

EPA Science Inventory

The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

125

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

126

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

127

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

128

Lake Trout Consumption and Recent Changes in the Fish Assemblage of Flaming Gorge Reservoir  

Microsoft Academic Search

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

Daniel L. Yule; Chris Luecke

1993-01-01

129

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

Microsoft Academic Search

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

DANIEL L. YULE; CHRIS LUECKE

1993-01-01

130

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

131

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

132

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

133

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

134

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...

135

Predator-Prey Relations and Competition for Food Between Age0 Lake Trout and Slimy Sculpins in the Apostle Island Region of Lake Superior  

Microsoft Academic Search

Slimy sculpins (Cottus cognatus) are an important component of the fish community on reefs and adjacent nursery areas of the Great Lakes and overlap spatially with age-0 lake trout (Salvelinus namaycush). Important interactions between these fishes are possible during the lake trout's first year of life, which could include predation on each other's eggs and larvae, and competition for food

Patrick L. Hudson; Jacqueline F. Savino; Charles R. Bronte

1995-01-01

136

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

137

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

138

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

139

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

140

Predator-prey relations and competition for food between age-0 lake trout and slimy sculpins in the Apostle Island region of Lake Superior  

USGS Publications Warehouse

Slimy sculpins (Cottus cognatus) are an important component of the fish community on reefs and adjacent nursery areas of the Great Lakes and overlap spatially with age-0 lake trout (Salvelinus namaycush). Important interactions between these fishes are possible during the lake trout's first year of life, which could include predation on each other's eggs and larvae, and competition for food resources. We investigated the diets of age-0 lake trout and slimy sculpins on a lake trout spawning reef (Gull Island Shoal) and adjacent nursery area (near Michigan Island) in the Apostle Island Region of western Lake Superior during June through September from 1988 through 1991. Organisms in stomachs of 511 lake trout and 562 sculpins were identified and counted. Of the 11 major food types found in age-0 lake trout stomachs from both areas, Mysis was the dominant food item (mean volume in stomachs = 68%) and occurred in about 3/4 of the fish analyzed. Copepods, cladocerans, chironomid pupae, fish, and Bythotrephes were also common in the diet (frequency of occurrence > 4%). Diets of lake trout were more diverse on the reef than on the nursery area where Mysis dominated the diet. Slimy sculpins were only found in lake trout greater than 50 mm. Mysis was an important food item of slimy sculpins over the reef but not over the nursery area, where Diporeia was by far the most important taxon. A variety of benthic invertebrates (Asellus, chironomids, benthic copepods, and snails) comprised the bulk of the sculpin diet over the reef. Sculpins also ate lake trout eggs in November. Based on cluster analysis, diets were most similar over the reef where both consumed Mysis, calanoid copepods and chironomid pupae. Diets diverged over the nursery areas where sculpins were strictly benthic feeders and lake trout maintained their planktonic diet. In Lake Superior, where lake trout recruitment through natural reproduction has become well established, the coexistence of the two species appears amicable. However, in other Great Lakes with higher sculpin to lake trout ratios on a reef the coexistence of the two species may be a bottleneck for age-0 lake trout survival beginning with egg deposition and ending when age-0 lake trout move off the reef and the two species no longer compete for a common food resource.

Hudson, Patrick L.; Savino, Jacqueline F.; Bronte, Charles R.

1995-01-01

141

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

142

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

143

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

144

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

145

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

146

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

147

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

148

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

149

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

150

Surficial substrates and bathymetry of five historical lake trout spawning reefs in near-shore waters of the Great Lakes  

USGS Publications Warehouse

The reestablishment of self-sustaining stocks of lake trout (Salvelinus namaycush) in the lower four Great Lakes has been substantially impeded because planted fish do not produce enough progeny that survive and reproduce. The causes for this failure are unknown, but many historical spawning sites of lake trout have been degraded by human activities and can no longer produce viable swim-up fry. In this study, we used side-scan sonar and an underwater video camera to survey, map, and evaluate the sustainability of one reef in each of the five Great Lakes for lake trout spawning and fry production. At four of the reef sites, we found good-to-excellent substrate for spawning and fry production by the shallow-water strains of lake trout that are now being planted. These substrates were in water 6-22 m deep and were composed largely of rounded or angular rubble and cobble. Interstitial spaces in these substrates were 20 cm or deeper and would protect naturally spawned eggs and fry from predators, ice scour, and buffeting by waves and currents. Subsequent studies of egg survival by other researchers confirmed our evaluation that the best substrates at two of these sites still have the potential to produce viable swim-up fry.

Edsall, Thomas A.; Brown, Charles L.; Kennedy, Gregory W.; French, John R. P., III

1992-01-01

151

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

152

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

153

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

154

Hatching, dispersal, and bathymetric distribution of age-0 wild lake trout at the Gull Island Shoal complex, Lake Superior  

USGS Publications Warehouse

We studied age-0 lake trout (Salvelinus namaycush) associated with spawning and nursery areas of the Gull Island Shoal complex in western Lake Superior. Post-emergent age-0 lake trout were captured on rocky spawning substrate with a 3-m beam trawl and at the nursery area with a bottom trawl from June to September 1990 and June to August 1991. Catch data suggested that age-0 lake trout move distances of 7-11 km to the nursery area over a 3-month period. Water currents, measured at Gull Island Shoal, may be a part of the transport mechanism. Examination of daily-growth increments on the sagittae and back-calculation from the date of capture revealed that most fish hatched between 6 June and 19 July in 1990 and between 30 April and 30 May in 1991. The duration of the hatch was 100 days in 1990 and 120 days in 1991, and the estimated incubation period is about 7 months for lake trout eggs at this site. Similar hatch-date distributions of age-0 captured on different sampling dates suggested that natural mortality was low.

Bronte, Charles R.; Selgeby, James H.; Saylor, James H.; Miller, Gerald S.; Foster, Neal R.

1995-01-01

155

Abundance indices for determining the status of lake trout restoration in Michigan waters of Lake Superior  

USGS Publications Warehouse

Self-sustaining populations of lake trout Salvelinus namaycush have returned to most areas in Lake Superior, but progress toward achieving historic commercial yields has been difficult to measure because of unrecorded losses to predation by sea lamprey Petromyzon marinus and to fisheries. Consequently, we developed restoration targets (catch per effort, CPE; geometric mean number per kilometer of 114-mm stretch-meaure gill net during 1929-1943, when historic yields were sustained) from linear relationships between CPE in commercial and assessment fisheries in Michigan. Target CPEs for lake trout restoration were higher and less variable than the modern CPEs in all areas. Modern CPEs generally increased during the 1970s and early 1980s but declined during the late 1980s and early 1990s. Modern CPEs were highest in western Michigan from the Keweenaw Peninsula to Marquette (71 to 81% of target CPEs), but coefficients of variation (CV,SD/mean) of mean CPEs were 1.4 to 2.4 times greater than target CVs. Around Munising, the modern CPE was lower (41% of the target CPE), whereas the CV was 1.9 times greater than the target CV. Around Grand Marais, the modern CPE was lowest among all areas (17% of the target CPE), but the CV was nearly the same (1.1 times the target CV). In Whitefish Bay, the modern CPE was only 28% of the target CPE and the CV was 9.0 times greater, though the modern period was based on only the years 1979-1982 and 1984-1985. Further progress in restoration in most areas can be achieved only if fishery managers adequately protect existing stocks of wild fish from sea lamprey predation and fishery exploitation.

Hansen, Michael J.; Schorfhaar, Richard G.; Peck, James W.; Selgeby, James H.; Taylor, William W.

1995-01-01

156

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

157

PAHs, nitro-PAHs, hopanes, and steranes in lake trout from Lake Michigan.  

PubMed

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 (?9 PAH) 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 (?9 NPAH) 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 (?5 Sterane) and total hopane (?2 Hopane) 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

2014-08-01

158

Evidence that lake trout served as a buffer against sea lamprey predation on burbot in Lake Erie  

USGS Publications Warehouse

The population of burbot Lota lota in Lake Erie recovered during 1986-2003, mainly because of the control of sea lamprey Petromyzon marinus, which began in 1986, Burbot populations continued to grow during 1996-1998, when sea lamprey control was substantially reduced. We calculated mortality parameters for burbot in Lake Erie by estimating age at capture for 2,793 burbot caught in annual gill-net surveys of eastern Lake Erie from 1994 to 2003. Based on catch-curve analysis, annual mortality in Lake Erie during 1994-2003 was estimated as 33%. Annual mortality of the 1992 year-class of burbot was estimated as 30%. The mortality of burbot during the years of reduced sea lamprey control was not different from that during the 3 years preceding reduced control and was significantly lower than that during the entire portion of the time series in which full sea lamprey control was conducted. These results suggest that the reduction in sea lamprey control did not lead to increased burbot mortality. The catch per gill-net lift of large burbot (total length > 600 mm), the size preferred by sea lampreys, was lower than that of adult lake trout Salvelinus namaycush (age 5 and older; total length > 700 mm) before lampricide application was reduced. Although adult lake trout populations declined, the abundance of large burbot did not change during the period of reduced lampricide application. These results support a hypothesis that a healthy population of adult lake trout can serve as a buffer species, acting to reduce predation of burbot by sea lampreys when sea lamprey populations increase. Burbot attained sexual maturity at a relatively early age (3 or 4 years) and a total length (approximately 500 mm) that was smaller than the preferred prey size for sea lampreys. These characteristics and the buffering effect of the lake trout population enabled growth of the burbot population during the brief period when lamprey control was reduced.

Stapanian, M.A.; Madenjian, C.P.

2007-01-01

159

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

160

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

161

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

162

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

163

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

164

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

165

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

166

Comparison of Glucose and Lipid Metabolic Gene Expressions between Fat and Lean Lines of Rainbow Trout after a Glucose Load  

PubMed Central

Two experimental rainbow trout lines developed through divergent selection for low (Lean ‘L’ line) or high (Fat ‘F’ line) muscle fat content were used as models to study the genetic determinism of fat depots. Previous nutritional studies suggested that the F line had a better capability to use glucose than the L line during feeding trials. Based on that, we put forward the hypothesis that F line has a greater metabolic ability to clear a glucose load effectively, compared to L line. In order to test this hypothesis, 250 mg/kg glucose was intraperitoneally injected to the two rainbow trout lines fasted for 48 h. Hyperglycemia was observed after glucose treatment in both lines without affecting the phosphorylation of AMPK (cellular energy sensor) and Akt-TOR (insulin signaling) components. Liver glucokinase and glucose-6-phosphate dehydrogenase expression levels were increased by glucose, whereas mRNA levels of ?-oxidation enzymes (CPT1a, CPT1b, HOAD and ACO) were down-regulated in the white skeletal muscle of both lines. Regarding the genotype effect, concordant with normoglycemia at 12 h after glucose treatment, higher muscle glycogen was found in F line compared to L line which exhibited hyperglycemia. Moreover, mRNA levels of hepatic glycolytic enzymes (GK, 6PFK and PK), gluconeogenic enzyme PEPCK and muscle fatty acid oxidation enzymes (CPT1a, CPT1b and HOAD) were concurrently higher in the F line. Overall, these findings suggest that F line may have a better ability to maintain glucose homeostasis than L line. PMID:25141351

Jin, Junyan; Médale, Françoise; Kamalam, Biju Sam; Aguirre, Peyo; Véron, Vincent; Panserat, Stéphane

2014-01-01

167

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

168

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

169

Age, growth, spawning season, and fecundity of the trout-perch (Percopsis omiscomaycus) in southeastern Lake Michigan  

USGS Publications Warehouse

Growth of trout-perch (Percopsis omiscomaycus) in the first 2 years of life was somewhat slower in southeastern Lake Michigan (average length at end of second year, 83 mm) than in Lower Red Lake, Minnesota (90 mm), but considerably faster than in Lake Superior (58 mm); size differences in later years were slightly less pronounced. Young fish began growing earlier in the year (some before June 20) than older ones (as late as August). Females tended to live longer than males, as they do in Lower Red Lake and Lake Superior. Trout-perch spawned from late June or early July until late September, somewhat later than in Lower Red Lake (May to August) or Lake Erie (June to August). Fecundity was similar to that in Lake Erie; mature females 94-146 mm long contained from 126 to 1329 yolked eggs.

House, Robert; Wells, LaRue

1973-01-01

170

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

171

Tc 1Like Transposable Elements in the Genome of Lake Trout ( Salvelinus namaycush )  

Microsoft Academic Search

.   This study reports on the DNA sequence of a Tc1-like transposable element Tsn1 from lake trout (Salvelinus namaycush). Tc1-like elements were amplified by PCR using an oligonucleotide primer based on the Tdr1 element of zebrafish. One full-length and two partial-length copies of the transposon were sequenced. In addition, partial\\u000a Tsn1 elements were recovered from PCR reactions run with primers

Kent M. Reed

1999-01-01

172

Natal?stream rearing in three populations of rainbow trout in Lake Taupo, New Zealand  

Microsoft Academic Search

Scales were taken from adult rainbow trout (Oncorhynchus mykiss, previously Salmo gairdneri) from the Waimarino, Tokaanu, and Hinemaiaia Rivers; these are tributaries of Lake Taupo, New Zealand. The scales showed both widely?spaced outer, and narrowly?spaced inner, circulus zones. Although there were no among?population differences in average circulus spacing in the outer growth zone, there were significant among?population differences in the

Marvin L. Rosenau

1991-01-01

173

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

174

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

175

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

176

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

177

An evaluation of restoration efforts in fishless lakes stocked with exotic trout  

USGS Publications Warehouse

Detrimental effects of introduced fishes on native amphibian populations have prompted removal of introduced cutthroat (Oncorhynchus clarki), rainbow (Oncorhynchus mykiss), and brook trout (Salvelinus fontinalis) from naturally fishless lakes at Mt. Rainier National Park, Washington (U.S.A.). Using paleolimnological indicators (diatoms, invertebrates, and sediment characteristics) in eight 480-year-old sediment cores from eight lakes, we (1) derived estimates of baseline environmental conditions and natural variation, (2) assessed the effects of stocking naturally fishless lakes, and (3) determined whether lakes returned to predisturbance conditions after fish removal (restoration). Diatom floras were relatively stable between 315 and 90 years before present in all lakes; we used this time period to define lake-specific "baseline" conditions. Dissimilarity analyses of diatoms revealed sustained, dramatic changes in diatom floras that occurred approximately 80 years ago (when fish were introduced) in four of five stocked lakes, whereas the diatom floras in two unstocked lakes had not changed significantly in the last 315 years. Diatoms were not preserved in an eighth lake. State changes also occurred in two lakes over 200 years before European settlement of the Pacific Northwest. Preserved invertebrate densities fluctuated dramatically over time in all cores, providing a poor reference for assessing the effects of fishes. Nevertheless, fish-invertebrate interactions have been demonstrated in other paleolimnological studies and may be useful for lower-elevation or more productive lakes. Because diatom communities have not returned to predisturbance assemblages in restored lakes, even 20-30 years after fish removal, we conclude that Mt. Rainier lakes were not successfully restored by the removal of fishes.

Drake, D.C.; Naiman, R.J.

2000-01-01

178

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

179

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

180

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

181

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

182

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

183

Relative Abundance, Site Fidelity, and Survival of Adult Lake Trout in Lake Michigan from 1999 to 2001: Implications for Future Restoration Strategies  

Microsoft Academic Search

We compared the relative abundance of lake trout Salvelinus namaycush spawners in gill nets during fall 1999-2001 in Lake Michigan at 19 stocked spawning sites with that at 25 unstocked sites to evaluate how effective site-specific stocking was in recolonizing historically important spawning reefs. The abundance of adult fish was higher at stocked onshore and offshore sites than at unstocked

Charles R. Bronte; Mark E. Holey; Charles P. Madenjian; Jory L. Jonas; Randall M. Claramunt; Patrick C. McKee; Michael L. Toneys; Mark P. Ebener; Brian Breidert; Guy W. Fleischer; Richard Hess; Archie W. Martell; Erik J. Olsen

2007-01-01

184

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

185

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

186

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

187

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

188

Lake trout otolith chronologies as multidecadal indicators of high-latitude freshwater ecosystems  

USGS Publications Warehouse

High-latitude ecosystems are among the most vulnerable to long-term climate change, yet continuous, multidecadal indicators by which to gauge effects on biology are scarce, especially in freshwater environments. To address this issue, dendrochronology (tree-ring analysis) techniques were applied to growth-increment widths in otoliths from lake trout (Salvelinus namaycush) from the Chandler Lake system, Alaska (68.23°N, 152.70°W). All otoliths were collected in 1987 and exhibited highly synchronous patterns in growth-increment width. Increments were dated, the widths were measured, and age-related growth declines were removed using standard dendrochronology techniques. The detrended time series were averaged to generate an annually resolved chronology, which continuously spanned 1964–1984. The chronology positively and linearly correlated with August air temperature over the 22-year interval (p < 0.01), indicating that warmer summers were beneficial for growth, perhaps by increasing fish metabolic rate or lake productivity. Given the broad distribution of lake trout within North America, this study suggests that otolith chronologies could be used to examine responses between freshwater ecosystems and environmental variability across a range of temporal and spatial scales.

Black, B.A.; Von Biela, V.R.; Zimmerman, C.E.; Brown, R.J.

2013-01-01

189

Winter ecology of Arctic charr ( Salvelinus alpinus ) and brown trout ( Salmo trutta ) in a subarctic lake, Norway  

Microsoft Academic Search

We studied habitat choice, diet, food consumption and somatic growth of Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) during the ice-covered winter period of a subarctic lake in northern Norway. Both Arctic charr and brown trout predominantly\\u000a used the littoral zone during winter time. Despite very cold winter conditions (water temperature <1°C) and poor light conditions,\\u000a both fish

Per-Arne Amundsen; Rune Knudsen

2009-01-01

190

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

191

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

192

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

193

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

194

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

195

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

196

EVALUATION OF NEW DEEPWATER TECHNOLOGIES FOR STUDYING LAKE TROUT EGGS AND FRY IN DEEP-WATER HABITATS, WITH PRELIMNARY  

E-print Network

to this work we would appreciate contacting us first. For video of ROV-based sampling techniques go to: http. Facilitate sampling of lake trout eggs and sac-fry by improving the ROV based suction sampler to generate. Use ROV-based electroshocking to map sac-fry habitat and, if possible, provide specimens to determine

Janssen, John

197

Relative abundance, site fidelity, and survival of adult lake trout in Lake Michigan from 1999 to 2001: Implications for future restoration strategies  

USGS Publications Warehouse

We compared the relative abundance of lake trout Salvelinus namaycush spawners in gill nets during fall 1999-2001 in Lake Michigan at 19 stocked spawning sites with that at 25 unstocked sites to evaluate how effective site-specific stocking was in recolonizing historically important spawning reefs. The abundance of adult fish was higher at stocked onshore and offshore sites than at unstocked sites. This suggests that site-specific stocking is more effective at establishing spawning aggregations than relying on the ability of hatchery-reared lake trout to find spawning reefs, especially those offshore. Spawner densities were generally too low and too young at most sites to expect significant natural reproduction. However, densities were sufficiently high at some sites for reproduction to occur and therefore the lack of recruitment was attributable to other factors. Less than 3% of all spawners could have been wild fish, which indicates that little natural reproduction occurred in past years. Wounding by sea lamprey Petromyzon marinus was generally lower for Seneca Lake strain fish and highest for strains from Lake Superior. Fish captured at offshore sites in southern Lake Michigan had the lowest probability of wounding, while fish at onshore sites in northern Lake Michigan had the highest probability. The relative survival of the Seneca Lake strain was higher than that of the Lewis Lake or the Marquette strains for the older year-classes examined. Survival differences among strains were less evident for younger year-classes. Recaptures of coded-wire-tagged fish of five strains indicated that most fish returned to their stocking site or to a nearby site and that dispersal from stocking sites during spawning was about 100 km. Restoration strategies should rely on site-specific stocking of lake trout strains with good survival at selected historically important offshore spawning sites to increase egg deposition and the probability of natural reproduction in Lake Michigan. ?? Copyright by the American Fisheries Society 2007.

Bronte, C.R.; Holey, M.E.; Madenjian, C.P.; Jonas, J.L.; Claramunt, R.M.; McKee, P.C.; Toneys, M.L.; Ebener, M.P.; Breidert, B.; Fleischer, G.W.; Hess, R.; Martell, A.W.; Olsen, E.J.

2007-01-01

198

Evaluation of Disease Resistance of the Fish Lake–DeSmet, Wounded Man, and Harrison Lake Strains of Rainbow Trout Exposed to Myxobolus cerebralis  

Microsoft Academic Search

Several tests evaluated the whirling disease resistance of three stocks of rainbow trout Oncorhynchus mykiss: the Fish Lake–DeSmet (FD), Wounded Man (WM), and Harrison Lake (HL) strains. In one series, FD fish were exposed to Myxobolus cerebralis triactinomyxons (TAMs; one exposure of 1,000 TAMs\\/fish). Histological scores ranged from 4.28 to 4.95 (MacConnnell?Baldwin scale) among FD fish from three different hatcheries.

Eric J. Wagner; Chris Wilson; Ronney Arndt; Patrick Goddard; Mark Miller; Ana Hodgson; Richard Vincent; Karen Mock

2006-01-01

199

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

200

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

201

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

202

Evaluation of the effects of the Lake Audubon on ground- and surface-water levels in the Lake Nettie area, eastern McLean County, North Dakota  

USGS Publications Warehouse

Flooding of some roads and agricultural lands has occurred in the Lake Nettie area of eastern McLean County. Part of the flooding was caused by the raising of the level of Lake Audubon to an elevation of 1,848 feet and the construction and filling of the McClusky Canal. Water levels have risen in the Lake Nettie aquifer as a result of raising the level of Lake Audubon. As of 1982, water levels have risen as much as 4 feet in the lower unit of the Lake Nettie aquifer and between 1 and 2 feet in the upper unit of the Lake Nettie aquifer, which is hydraulically connected to Lake Nettie and Crooked Lake. Water levels have risen in the Turtle Lake aquifer both as a result of raising the water level in Lake Audubon and the filling of McClusky Canal. Water levels have risen as much as 6 feet near the canal, but generally are less than 1 foot higher at distances of about 0.5 mile. (USGS)

Armstrong, C.A.

1983-01-01

203

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

204

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

205

Historical demography of brown trout (Salmo trutta) in the Adriatic drainage including the putative S. letnica endemic to Lake Ohrid.  

PubMed

We explore the historical demography of the Adriatic lineage of brown trout and more explicitly the colonization and phylogenetic placement of Ohrid trout, based on variation at 12 microsatellite loci and the mtDNA control region. All Adriatic basin haplotypes reside in derived positions in a network that represents the entire lineage. The central presumably most ancestral haplotype in this network is restricted to the Iberian Peninsula, where it is very common, supporting a Western Mediterranean origin for the lineage. The expansion statistic R2, Bayesian based estimates of demographic parameters, and star-like genealogies support expansions on several geographic scales, whereas application of pairwise mismatch analysis was somewhat ambiguous. The estimated time since expansion (155,000 years ago) for the Adriatic lineage was supported by a narrow confidence interval compared to previous studies. Based on microsatellite and mtDNA sequence variation, the endemic Ohrid trout represents a monophyletic lineage isolated from other Adriatic basin populations, but nonetheless most likely evolving from within the Adriatic lineage of brown trout. Our results do not support the existence of population structuring within Lake Ohrid, even though samples included two putative intra-lacustrine forms. In the interests of protecting the unique biodiversity of this ancient ecosystem, we recommend retaining the taxonomic epithet Salmo letnica for the endemic Ohrid trout. PMID:17046289

Susnik, Simona; Snoj, Ales; Wilson, Iain F; Mrdak, Danilo; Weiss, Steven

2007-07-01

206

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

207

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

208

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

209

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

210

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

211

Dieldrin and DDT: accumulation from water and food by lake trout (Salvelinus namaycush) in the laboratory  

USGS Publications Warehouse

In the laboratory we measured the amounts of dieldrin and p,p'DDT accumulated by fish from contaminated water and food to determine how fish from Lake Michigan accumulate high concentrations of these insecticides from an environment where the concentrations in water are generally less than 0.01 ppb. Eight groups of yearling lake trout (Salvelinus namaycush) were exposed to different combinations of dieldrin and p,p'DDT in water and food. Concentrations of dieldrin and p,p'DDT ranged from 0.006 to 0.010 ppb in water and from 1,700 to 2,300 ppb in food (Oregon moist pellets). After 152 days of exposure to insecticides in water, fish had accumulated an average of 478 ppb dieldrin or 352 ppb p,p'DDT. Fish exposed to dieldrin and p,p'DDT in food accumulated 470 and 648 ppb, respectively. However, it was difficult to determine exactly how much of either insecticide was accumulated from the food because trace amounts (0.003-0.004 ppb) had leached from food or feces. After exposure to the insecticide was terminated, fish eliminated dieldrin at a much faster rate than p,p'DDT. In fish exposed to a combination of dieldrin and p,p'DDT in water and then held for 125 days in uncontaminated water, the total amount of dieldrin (I?g) declined 89%, but the total amount of p,p'DDT remained unchanged. We used data from this study to estimate how much p,p'DDT adult Lake Michigan coho salmon (Oncorhynchus kisutch) accumulated from water and from food during a 104-day period (May-August 1968). The estimates suggest that during these months coho salmon accumulated most of the body burden of p,p'DDT from food.

Reinert, Robert E.; Stone, Linda J.; Bergman, Harold L.

1974-01-01

212

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

213

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

214

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, Jeffrey J.; Kennedy, Philip R.; Baker, Bruce M.

2014-01-01

215

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

216

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

217

Subchronic metabolic effects and toxicity of a simulated pulp mill effluent on juvenile lake trout, Salmo trutta m. lacustris  

SciTech Connect

Juvenile lake trout (Salmo trutta m. lacustris) were exposed for 7 weeks to 0.05X and 0.2X 96-hr LC50 concentrations of simulated bleached kraft pulp mill effluent (KME - Sa + CP). A sulfate soap preparation, composed mainly of resin and fatty acids, with added chlorophenols (CP, tri-, tetra-, and penta-CP) was used as the toxicant mixture. Concentrations of free CP in plasma and free and conjugated CP in bile were proportional to their concentrations in the water. The greatest total gradient between bile and water CP was 5.2 X 10(4) for pentachlorophenol. The activity of a liver polysubstrate monooxygenase (PSMO) system, assayed with three model substrates, increased 40 to 67% due to KME - Sa + CP. However, the increase was not directly dependent on the exposure concentration. In contrast to PSMO, activities of conjugating enzymes (p-nitrophenol UDP-glucuronosyl and glutathione transferases) were decreased in the liver. Increased concentration of glutathione was noted in the liver and kidney. In addition, a small (9%) but significant decrease in blood hemoglobin concentration was observed at the higher exposure concentration. Although growth rate of lake trout was markedly decreased due to KME - Sa + CP, hydromineral balance and carbohydrate metabolism in fish were unaffected, indicating possible physiological compensation. On the other hand, lethality tests with lake trout preexposed to KME - Sa + CP at 0.2 X LC50 revealed decreased tolerance, whereas at the lower exposure concentration it was unchanged. We therefore conclude that various physiological adjustments in trout during subchronic exposures were not adaptive in terms of short-term tolerance.

Oikari, A.; Linstroem-Seppae, P.Ku.; Kukkonen, J.

1988-12-01

218

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

219

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

220

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

221

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

222

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

223

Thermal stratification of Dilute Lakes. Evaluation of regulatory processes and biological effects before and after base addition: Effects on brook trout habitat and growth. Technical report series  

SciTech Connect

The authors address the significance of changes in summer thermal stratification patterns of Adirondack lakes affected by acidification to cold-water fish populations inhabiting these sensitive lakes. The brook trout (Salvelinus fontinalis) is the primary cold-water fish species indigenous to acid-sensitive lakes in the Adirondack region of northern New York State; the ability of these lakes to sustain this important sport species is highly dependent on the availability of adequate summer habitat, consisting of cool, well-oxygenated water. The authors hypothesized that acidification-induced reductions in the thermal stability of sensitive Adirondack lakes could lead to degradation of potential brook trout habitat. These hypotheses were addressed in the study by utilizing data available from previous lake liming studies in the Adirondack region, brook trout growth data from management studies in the region, and the extensive Adirondack Lake Survey Corporation (ALSC) data base. More than 70% of the small, shallow ALSC lakes were classified as predominantly weakly stratified systems that would be potentially sensitive to changes in thermal stratification status resulting from relatively small changes in color and transparency.

Schofield, C.L.; Josephson, D.; Keleher, C.; Gloss, S.P.

1993-04-01

224

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

225

Genetic and Phenotypic Catalog of Native Resident Trout of the interior Columbia River Basin : FY-2001 Report : Populations in the Wenatchee, Entiat, Lake Chelan and Methow River Drainages.  

SciTech Connect

The 1994 Fish and Wildlife Program of the Northwest Power Planning Council specifies the recovery and preservation of population health of native resident fishes of the Columbia River Basin. Among the native resident species of concern are interior rainbow trout of the Columbia River redband subspecies Oncorhynchus mykiss gairdneri 1 and westslope cutthroat trout O. clarki lewisi. The westslope cutthroat trout has been petitioned for listing under the U. S. Endangered Species Act (American Wildlands et al. 1997). Before at-risk populations can be protected, their presence and status must be established. Where introgression from introduced species is a concern, as in the case of both westslope cutthroat trout and redband rainbow trout, genetic issues must be addressed as well. As is true with native trout elsewhere in the western United States (Behnke 1992), most of the remaining pure populations of these species in the Columbia River Basin are in relatively remote headwater reaches. The objective of this project was to photo-document upper Columbia Basin native resident trout populations in Washington, and to ascertain their species or subspecies identity and relative genetic purity using a nonlethal DNA technique. FY-2001 was year three (and final year) of a project in which we conducted field visits to remote locations to seek out and catalog these populations. In FY-2001 we worked in collaboration with the Wenatchee National Forest to catalog populations in the Wenatchee, Entiat, Lake Chelan, and Methow River drainages of Washington State.

Trotter, Patrick C.

2001-10-01

226

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

227

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

228

Diet overlap between introduced European minnow ( Phoxinus phoxinus ) and young brown trout ( Salmo trutta ) in the lake, Øvre Heimdalsvatn: a result of abundant resources or forced niche overlap?  

Microsoft Academic Search

A study of the diet of native brown trout (Salmo trutta) parr and introduced European minnow (Phoxinus phoxinus) in the subalpine lake, Øvre Heimdalsvatn, showed that the two species had considerable dietary overlap, both in the littoral\\u000a zone and in the outlet of the lake. Chironomidae constituted a substantial proportion of the diet of the two species in both\\u000a habitats.

Jon Museth; Reidar Borgstrøm; John E. Brittain

2010-01-01

229

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...

230

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

231

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

232

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

233

Nearshore Habitat and Fish Community Associations of Coaster Brook Trout in Isle Royale, Lake Superior  

Microsoft Academic Search

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

Owen T. Gorman; Seth A. Moore; Andrew J. Carlson; Henry R. Quinlan

2008-01-01

234

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

235

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

236

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

Microsoft Academic Search

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

Sear; Sheri

2001-01-01

237

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

Microsoft Academic Search

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

Charles D

1999-01-01

238

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

Microsoft Academic Search

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

Charles D

2000-01-01

239

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

240

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

241

The brown trout ( Salmo trutta ) in the lake, Øvre Heimdalsvatn: long-term changes in population dynamics due to exploitation and the invasive species, European minnow ( Phoxinus phoxinus )  

Microsoft Academic Search

Studies of the brown trout (Salmo trutta) population in the Norwegian subalpine lake, Øvre Heimdalsvatn, over a 50-year period have revealed major changes in population\\u000a dynamics. In 1958, the population density was high, with individuals stagnating in growth at lengths below 30 cm. After heavy\\u000a exploitation during the years 1958–1969, the number of older fish declined substantially, and growth rates increased

Reidar Borgstrøm; Jon Museth; John E. Brittain

2010-01-01

242

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

243

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

244

Loss of genetic integrity in wild lake trout populations following stocking: insights from an exhaustive study of 72 lakes from Québec, Canada  

PubMed Central

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

2014-01-01

245

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......

246

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

247

Quality of water used during cage cultivation of rainbow trout (Oncorhynchus mykiss) in Bereket HES IV Dam Lake (Mu?la, Turkey).  

PubMed

A thorough investigation of the impact of rainbow trout (Oncorhynchus mykiss) cultivation on surface water quality in the area known as Bereket HES IV Dam Lake was conducted. Water samples were collected from October 2009 to June 2010 from four stations in the Dam Lake and analyzed for water temperature, pH, dissolved oxygen, electrical conductivity, nitrite nitrogen, nitrate nitrogen, and orthophosphate. Surface water quality was then evaluated based on the comparison of samples collected from three stations located near fish cages to those collected from a reference station outside the cultivation area as well as by the comparison with standards specified in the Water Pollution Registration Act. According to the Water Pollution Registration Act, the surface water quality of the Dam Lake was class I. Additionally, there were no significant differences in water quality within the Dam Lake among any of the sampling stations, including the reference station. Overall, these findings indicate that cage cultivation of rainbow trout may have a negative impact on the entire Dam Lake. PMID:25204896

Ozdemir, Nedim; Demirak, Ahmet; Keskin, Feyyaz

2014-12-01

248

Lake Michigan Mass Balance Study Post Audit: Integrated, Multi-media PCB Modeling and Forecasting for Lake Trout  

EPA Science Inventory

The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

249

Lake Michigan Mass Balance Study Post Audit: Integrated, Multi-media PCB Modeling and Forecasting for Lake Trout, Presentation  

EPA Science Inventory

The Lake Michigan (LM) Mass Balance Study was conducted to measure and model polychlorinated biphenyls (PCBs) and other anthropogenic substances to gain a better understanding of the transport, fate, and effects of these substances within the system and to aid managers in the env...

250

[Spatiotemporal variation characteristics of heavy metals pollution in the water, soil and sediments environment of the Lean River-Poyang Lake Wetland].  

PubMed

Overlying water, sediments, surface soils in the typical wetland areas of Lean River and Poyang Lake which were rich in non-ferrous metal mineral resources on both sides of the river, were chosen for monitoring heavy metals including copper, lead and cadmium of base flow in average season, flood season, and dry season in 2012. Statistical analysis methods were coupled to characterize the spatiotemporal variation of heavy metals pollution and identify the main sources. The results indicated that the concentrations of copper were the highest in all samples of each sampling sites in the Lean River-Poyang Lake wetland. And the content values of copper, lead and cadmium in different samples of different sampling sites also showed that the content values of copper were higher than those of lead, and the content values of lead were also higher than those of cadmium. The results also showed that the heavy metals pollution of copper, lead and cadmium in flood season was the heaviest whereas the heavy metals pollution in dry season was comparatively light. The results of the contents of the three kinds of heavy metals elements in different sampling sites of the watersheds of lean River showed that the contents of copper in the samples from the upstream sampling sites of Lean River were higher than those of other samples from other sites. And the contents of lead in the samples from the downstream sampling sites of Lean River were higher than those of other samples from other sampling sites. The contents of cadmium in the samples from the midstream sampling sites of Lean River were higher than those of other samples from other sites. The first principal component representing copper pollution explained 36. 99% of the total variance of water quality. The second principal component concerning representing lead pollution explained 30. 12% of the total variance. The correlation analysis results showed that there were significant positive correlations among the contents of copper in sediments and the contents of copper in overlying water. And there was also significant positive correlation between the contents of copper in sediments and the contents of copper in the surface soils. And the correlation analysis showed that there were significant positive correlations among the contents of cadmium in sediments and the contents of cadmium in surface soils. The above results reflected that the copper pollution or cadmium sources of water, soil and sediments were consistent, which were mainly from heavy metal acidic waste of mining emissions. The correlations between other components were not very obvious, which reflected the sources of pollutants were different. PMID:25055663

Jian, Min-Fei; Li, Ling-Yu; Xu, Peng-Fei; Chen, Pu-Qing; Xiong, Jian-Qiu; Zhou, Xue-Ling

2014-05-01

251

Genetic and Morphological Divergence in Three Strains of Brook Trout Salvelinus fontinalis Commonly Stocked in Lake Superior  

PubMed Central

Fitness related traits often show spatial variation across populations of widely distributed species. Comparisons of genetic variation among populations in putatively neutral DNA markers and in phenotypic traits susceptible to selection (QST FST analysis) can be used to determine to what degree differentiation among populations can be attributed to selection or genetic drift. Traditionally, QST FST analyses require a large number of populations to achieve sufficient statistical power; however, new methods have been developed that allow QST FST comparisons to be conducted on as few as two populations if their pedigrees are informative. This study compared genetic and morphological divergence in three strains of brook trout Salvelinus fontinalis that were historically or currently used for stocking in the Lake Superior Basin. Herein we examined if morphological divergence among populations showed temporal variation, and if divergence could be attributed to selection or was indistinguishable from genetic drift. Multivariate QST FST analysis showed evidence for divergent selection between populations. Univariate analyses suggests that the pattern observed in the multivariate analyses was largely driven by divergent selection for length and weight, and moreover by divergence between the Assinica strain and each of the Iron River and Siskiwit strains rather than divergent selection between each population pair. While it could not be determined if divergence was due to natural selection or inadvertent artificial selection in hatcheries, selected differences were consistent with patterns of domestication commonly found in salmonids. PMID:25479612

McKinney, Garrett J.; Varian, Anna; Scardina, Julie; Nichols, Krista M.

2014-01-01

252

Genetic and morphological divergence in three strains of brook trout Salvelinus fontinalis commonly stocked in Lake Superior.  

PubMed

Fitness related traits often show spatial variation across populations of widely distributed species. Comparisons of genetic variation among populations in putatively neutral DNA markers and in phenotypic traits susceptible to selection (QST FST analysis) can be used to determine to what degree differentiation among populations can be attributed to selection or genetic drift. Traditionally, QST FST analyses require a large number of populations to achieve sufficient statistical power; however, new methods have been developed that allow QST FST comparisons to be conducted on as few as two populations if their pedigrees are informative. This study compared genetic and morphological divergence in three strains of brook trout Salvelinus fontinalis that were historically or currently used for stocking in the Lake Superior Basin. Herein we examined if morphological divergence among populations showed temporal variation, and if divergence could be attributed to selection or was indistinguishable from genetic drift. Multivariate QST FST analysis showed evidence for divergent selection between populations. Univariate analyses suggests that the pattern observed in the multivariate analyses was largely driven by divergent selection for length and weight, and moreover by divergence between the Assinica strain and each of the Iron River and Siskiwit strains rather than divergent selection between each population pair. While it could not be determined if divergence was due to natural selection or inadvertent artificial selection in hatcheries, selected differences were consistent with patterns of domestication commonly found in salmonids. PMID:25479612

McKinney, Garrett J; Varian, Anna; Scardina, Julie; Nichols, Krista M

2014-01-01

253

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

254

Diet of landlocked sockeye salmon (Oncorhynchus nerka) and trout in the Waitaki lakes, New Zealand  

Microsoft Academic Search

Landlocked sockeye salmon (Oncorhynchus nerka), ranging in fork length (FL) from 105 to 313 mm, were captured in fine?mesh gill nets set in the limnetic zone of the Waitaki hydro lakes (44° 30? S, 170° 10’ E) in the South Island, New Zealand. A total of 443 stomachs was examined and the frequency of occurrence, volume and weight of prey

E. Graynoth; L. C. Bennett; J. C. Pollard

1986-01-01

255

Influence of Thiamine Deficiency on Lake Trout Larval Growth, Foraging, and Predator Avoidance  

Microsoft Academic Search

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

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

2009-01-01

256

Ontogenetic Shifts in Habitat and Diet of Cutthroat Trout in Lake Washington, Washington  

Microsoft Academic Search

Salmonids often display a series of ontogenetic shifts in habitat, and these may also be associated with changes in diet. For example, adfluvial populations rear in streams for several years and then migrate to lakes. The patterns of habitat use, trophic ecology, and movements of such populations are commonly studied during the riverine stages. The lacustrine period is typically less

Gretchen M. Nowak; Roger A. Tabor; Eric J. Warner; Kurt L. Fresh; Thomas P. Quinn

2004-01-01

257

Evolutionary Ecology of Redband Trout  

Microsoft Academic Search

We examined genetic differences at 29 enzyme encoding loci among 10,541 rainbow trout Oncorhynchus mykiss from 240 collections throughout the species' range, including redband trout (i.e., several rainbow trout subspecies) in pluvial lake basins of the northern Great Basin that have had largely internal drainage with no connection to the Pacific Ocean. Differences among groups accounted for 29.2% of the

Kenneth P. Currens; Carl B. Schreck; Hiram W. Li

2009-01-01

258

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

259

Management Implications of Ecological Segregation between Two Introduced Populations of Cutthroat Trout in a Small Colorado Lake  

Microsoft Academic Search

Ecological differences reflected in food and habitat preference and angling vulnerability were investigated between two introduced sympatric populations of cutthroat trout, Salmo clarki. The Pikes Peak cutthroat fed to a large extent on Daphnia (68% by volume), whereas the Snake River cutthroat fed primarily on terrestrial insects (68% by volume). Other food habit differences were observed in the brook trout,

John R. Trojnar; Robert J. Behnke

1974-01-01

260

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

261

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

262

Lake Roosevelt Fisheries Evaluation Program; Evaluation of Limiting Factors for Stocked Kokanee and Rainbow Trout in Lake Roosevelt, Washington, 1999 Annual Report  

Microsoft Academic Search

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

Casey Baldwin; Matt Polacek

2009-01-01

263

Physiologic, toxicologic, and population responses of brook trout to acidification: Interim report of the lake acidification and fisheries project: Final report  

SciTech Connect

This report overviews investigations of the ''Lake Acidification and Fisheries'' (LAF) project into the effects of surface water acidification on brook trout (Salvelinus fontinalis) populations. Of the six life stages examined, freshly-fertilized eggs were the most sensitive to reduced pH. In contrast, aluminum was most toxic to fry, juvenile, and adult fish. Increased calcium concentrations reduced the toxic effects of acid/aluminum exposure at all life stages. Little evidence was found to indicate that exposure to acidic waters affects oocyte development or production, suggesting that direct mortality plays a larger role in losses of brook trout populations from acidic waters. For fry and adult fish, the major toxic mechanism of acid/aluminum exposure seems to be disturbance of normal ion regulation at the gill, but aluminum exposure can cause respiratory impairment as well. Using results from LAF toxicity studies and available field data, a modeling framework was developed that predicts the probability of presence or absence of brook trout populations, based ion surface water chemistry. In addition, this framework can be used to evaluate changes in this probability caused by changes in water chemistry (e.g., liming), stocking rates, or fishing pressure. 129 refs., 37 figs., 8 tabs.

Mount, D.R.; Marcus, M.D. (eds.); Breck, J.E.; Christensen, S.W.; Gern, W.A.; Ingersoll, C.G.; Gulley, D.D.; McDonald, D.G.; Parkhurst, B.R.; Van Winkle, W.

1989-02-01

264

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

265

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

266

Trophic relationships between a native and a nonnative predator in a system of natural lakes  

USGS Publications Warehouse

Bull trout, a species of char listed as threatened under the US Endangered Species Act, have been displaced from portions of their historic range following the introduction of nonnative lake trout. It has been suggested that competitive exclusion as a result of trophic overlap between bull trout and lake trout may be the causal mechanism associated with displacement of bull trout. This study used stable isotope data to evaluate trophic relationships among native bull trout, nonnative lake trout and other fishes in seven lakes in Glacier National Park (GNP), Montana. Bull trout and lake trout had greater ?15N values relative to other fishes among lakes (?15N = 3.0?). Lake trout had greater ?15N values relative to bull trout (?15N = +1.0?). Bull trout had greater ?13C values relative to lake trout in six of the seven lakes examined. Although both bull trout and lake trout had greater ?15N values relative to other fishes within lakes in GNP, differences in ?15N and 13C between bull trout and lake trout suggest that they are consuming different prey species or similar prey species in different proportions. Therefore, displacement of bull trout as a direct result of complete overlap in food resource use is not anticipated unless diet shifts occur or food resources become limiting. Additionally, future studies should evaluate food habits to identify important prey species and sources of partial dietary overlap between bull trout and lake trout.

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

2011-01-01

267

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

268

Lean Manufacturing  

NSDL National Science Digital Library

For instructors looking for a basic outline of what lean manufacturing is, this website provides the information in a brief, easy to read format. Students will learn about the history of lean manufacturing, the basic goals of lean manufacturing and key processes involved. An interesting section at the end of the webpage asks students to take a lean manufacturing viewpoint in regards to their own lives, considering areas like overproduction, waiting, inventory and overprocessing.

269

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

270

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

271

Intense infections with a variant of Myxobolus procerus (Myxosporea) in muscle of trout-perch (Percopsis omiscomaycus) in Duluth Harbor, Lake Superior.  

PubMed

Intense infections of a variant of Myxobolus procerus (Kudo, 1934) are described from trout-perch (Percopsis omiscomaycus (Walbaum)) collected in Duluth Harbor, Lake Superior, USA. This particular population of parasites has spores that are identical in shape (narrow pyriform) to those described for M. procerus except that they are significantly smaller (13-14.5 microm long versus 15-17 microm long). In contrast to what was originally described for M. procerus, the plasmodia develop primarily within red and white striated muscle fibres and only rarely among the subdermal connective tissue. Most plasmodia were at or near the same stage of development. Typical development involves growth within the fibre. The parasite eventually replaces the entire content of the host cell and appears to halt development before rupturing the outer cell membrane. The only obvious host response was an occasional cyst being invaded by a localized cellular infiltrate. Infected fish appeared of normal health and no grossly evident myoliquefaction was seen. The infections involved several hundred plasmodia per fish and the question of why such unusually high levels of infection would develop in hosts inhabiting a polluted habitat is raised. It is suggested that proliferation of a pollution tolerant oligochaete (the suspected alternate host) in the harbour and/or a compromised host immune system may have increased the probability of successful transmission and development in trout-perch living in the harbour. PMID:9229571

Cone, D; Eurell, T; Axler, R; Rau, D; Beasley, V

1997-01-01

272

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

273

Genetic Inventory of Bull Trout and Westslope Cutthroat Trout in the Pend Oreille Subbasin, 2002-2003 Annual Report.  

SciTech Connect

In 2002, the Kalispel Natural Resource Department (KNRD) collected tissue samples for genetic analysis from 280 bull trout and 940 westslope cutthroat. The Washington Department of Fish and Wildlife developed and applied microsatellite DNA screening protocols for the analysis of bull trout at 13 loci and 24 loci for cutthroat trout. This project will continue collection and analysis of additional samples for the next 2 years. At that time, a final annual report will be compiled for the three-year study that will describe the genetic characteristics for bull trout and westslope cutthroat trout. The extent of hybridization of bull trout (with brook trout) and westslope cutthroat trout (with Yellowstone cutthroat trout and rainbow trout) in the Priest Lake and Lower Pend Oreille subbasins will also be examined.

Maroney, Joseph R. (Kalispel Tribe of Indians, Usk, WA); Shaklee, James B.; Young, Sewall F. (Washington Department of Fish and Wildlife, Olympia, WA)

2003-10-01

274

Genetic Inventory of Bull Trout and Westslope Cutthroat Trout in Pend Oreille Subbasin, 2003-2004 Annual Report.  

SciTech Connect

In 2003, the Kalispel Natural Resource Department (KNRD) collected tissue samples for genetic analysis from 209 bull trout and 1,276 westslope cutthroat. The Washington Department of Fish and Wildlife developed and applied microsatellite DNA screening protocols for the analysis of bull trout at 13 loci and 24 loci for cutthroat trout. This project will continue collection and analysis of additional samples next year. At that time, a final annual report will be compiled for the three-year study that will describe the genetic characteristics for bull trout and westslope cutthroat trout. The extent of hybridization of bull trout (with brook trout) and westslope cutthroat trout (with Yellowstone cutthroat trout and rainbow trout) in the Priest Lake and Lower Pend Oreille subbasins will also be examined.

Olson, Jason; Maroney, Joseph R.; Andersen, Todd (Kalispel Department of Natural Resources, Usk, WA)

2004-11-01

275

Ulcer disease of trout  

USGS Publications Warehouse

During the summer of 1933, lesions of a disease were noted among some fingerling brook, rainbow, blackspotted, and lake trout at the Cortland (New York) trout hatchery. Although these lesions bore a marked superficial resemblance to those of furunculosis, they were sufficiently atypical to warrant further investigation. A more detailed examination of the lesions proved them to be of a distinct disease, which for lack of a better name is herein called "ulcer disease," for the lesions closely resemble those described by Calkins (1899) under this name. Because of the marked resemblance to furunculosis, ulcer disease has not been generally recognized by trout culturists, and any ulcer appearing on fish has been ascribed by them to furunculosis without further question.

Fish, F.F.

1934-01-01

276

Mitochondrial DNA differentiation between two forms of trout Salmo letnica, endemic to the Balkan Lake Ohrid, reflects their reproductive isolation.  

PubMed

Mitochondrial haplotype diversity in sympatric populations of Ohrid trout, Salmo letnica was investigated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the mtDNA control region and ND1, ND3/4, ND5/6 segments. A 310 bp fragment at the 5' end, and a 340-572 bp fragment at the 3' end of the control region were sequenced from representatives of the populations studied. Based on pairwise comparison of the sequences, five new haplotypes were identified plus one identical with the brown trout Andalusian haplotype from the southern Iberian Peninsula. The combination of both RFLP and sequence data sets yielded a total of 10 composite haplotypes. A high degree of genetic subdivision between S. letnica typicus and S. letnica aestivalis populations was observed. The notion of a sympatric origin for the two morphs is discussed. Length variation of the mtDNA control region due to the presence of an 82 bp unit, tandemly repeated one to four times, in the region between the conserved sequence block-3 (CSB-3) and the gene for phenylalanine tRNA is reported. Further, we demonstrate that a single duplication of the approximately 82 bp repeat unit is a common element of the salmonid mitochondrial control region. The unique genetic structure of Ohrid trout represents a highly valuable genetic resource that deserves appropriate management and conservation. PMID:15548279

Sell, J; Spirkovski, Z

2004-12-01

277

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

278

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

279

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; ?entürk, Murat

2015-03-01

280

Lean Six Sigma Lean Six Sigma  

E-print Network

Lean Six Sigma Lean Six Sigma Lean Six Sigma is a fundamental and comprehensive approach to solve at Toyota, and companies in other sectors that have followed Toyota's example, while Six Sigma evolved from, among others. This program will allow individuals with little or no knowledge of the Six Sigma or Lean

McGraw, Kevin J.

281

Seasonally Dynamic Diel Vertical Migrations of Mysis diluviana, Coregonine Fishes, and Siscowet Lake Trout in the Pelagia of Western Lake Superior  

Microsoft Academic Search

Diel vertical migrations are common among many aquatic species and are often associated with changing light levels. The underlying mechanisms are generally attributed to optimizing foraging efficiency or growth rates and avoiding predation risk (?). The objectives of this study were to (1) assess seasonal and interannual changes in vertical migration patterns of three trophic levels in the Lake Superior

Tyler D. Ahrenstorff; Thomas R. Hrabik; Jason D. Stockwell; Daniel L. Yule; Greg G. Sass

2011-01-01

282

Lean manufacturing: a perspective of lean suppliers  

Microsoft Academic Search

The main thrust of this paper empirically examines the connection between lean production and various aspects of the logistics system. This paper performs a comparison analysis to find whether significant performance\\/practice differences exist between lean suppliers and non-lean suppliers. The research findings indicate that, even given the same organizational constraints and resources, lean suppliers gain significant competitive advantages over non-lean

Yen Chun Wu

2003-01-01

283

Genetic and Phenotypic Catalog of Native Resident Trout of the interior Columbia River Basin : FY2001 Report : Populations in the Wenatchee, Entiat, Lake Chelan and Methow River Drainages  

Microsoft Academic Search

The 1994 Fish and Wildlife Program of the Northwest Power Planning Council specifies the recovery and preservation of population health of native resident fishes of the Columbia River Basin. Among the native resident species of concern are interior rainbow trout of the Columbia River redband subspecies Oncorhynchus mykiss gairdneri 1 and westslope cutthroat trout O. clarki lewisi. The westslope cutthroat

Trotter; Patrick C

2001-01-01

284

Lean consumption.  

PubMed

During the past 20 years, the real price of most consumer goods has fallen worldwide, the variety of goods and the range of sales channels offering them have continued to grow, and product quality has steadily improved. So why is consumption often so frustrating? It doesn't have to be--and shouldn't be--the authors say. They argue that it's time to apply lean thinking to the processes of consumption--to give consumers the full value they want from goods and services with the greatest efficiency and the least pain. Companies may think they save time and money by off-loading work to the consumer but, in fact, the opposite is true. By streamlining their systems for providing goods and services, and by making it easier for customers to buy and use those products and services, a growing number of companies are actually lowering costs while saving everyone time. In the process, these businesses are learning more about their customers, strengthening consumer loyalty, and attracting new customers who are defecting from less user-friendly competitors. The challenge lies with the retailers, service providers, manufacturers, and suppliers that are not used to looking at total cost from the standpoint of the consumer and even less accustomed to working with customers to optimize the consumption process. Lean consumption requires a fundamental shift in the way companies think about the relationship between provision and consumption, and the role their customers play in these processes. It also requires consumers to change the nature of their relationships with the companies they patronize. Lean production has clearly triumphed over similar obstacles in recent years to become the dominant global manufacturing model. Lean consumption, its logical companion, can't be far behind. PMID:15768676

Womack, James P; Jones, Daniel T

2005-03-01

285

Shifts in abundance and growth of slimy sculpin in response to changes in the predator population in an arctic Alaskan lake  

Microsoft Academic Search

Lake trout (Salvelinus namaycush) in Toolik Lake are tightly coupled to the benthos, since they have no pelagic forage fishes. Slimy sculpins (Cottus cognatus) are a prey of lake trout and the soft sediment chironomids are an important prey for the sculpin. Our previous work showed\\u000a that the median size of lake trout in Toolik Lake had decreased significantly between

Michael E. McDonald; Anne E. Hershey

1992-01-01

286

lean obese-4 obese-8 lean obese-4 obese-8  

E-print Network

T2* (ms) lean obese-4 obese-8 PDFF (%) lean obese-4 obese-8 T2* (ms) lean obese-4 obese-8leanleanlean obese-4obese-4 obese-8obese-8 PDFF (%) lean obese-4 obese-8lean obese-4 obese-8 FIG. 2 visible in the lean and obese-4 examples. It is indistinguishable from surrounding WAT in the obese-8

Southern California, University of

287

Genetic Structure of Columbia River Redband Trout Populations in the Kootenai River Drainage, Montana, Revealed by Microsatellite and Allozyme Loci  

Microsoft Academic Search

We describe the genetic divergence among 10 populations of redband trout Oncorhynchus mykiss gairdneri from the upper Columbia River drainage. Resident redband trout from two watersheds in the Kootenai River drainage and hatchery stocks of migratory Kamloops redband trout from Kootenay Lake, British Columbia, were analyzed using allele frequency data from microsatellite and allozyme loci. The Kamloops populations have significantly

Kathy L. Knudsen; Clint C. Muhlfeld; George K. Sage; Robb F. Leary

2002-01-01

288

Hybridization and Introgression in a Managed, Native Population of Yellowstone Cutthroat Trout: Genetic Detection and Management Implications  

Microsoft Academic Search

Since the mid-1920s, the Idaho Department of Fish and Game has cultured Yellowstone cutthroat trout Oncorhynchus clarki bouvieri at Henrys Lake to offset declines in natural production and for use in stocking programs throughout Idaho. Since the mid-1970s, they have also produced F1 hybrids: female Yellowstone cutthroat trout × male rainbow trout O. mykiss. The ability of fishery managers, when

Matthew R. Campbell; Jeff Dillon; Madison S. Powell

2002-01-01

289

Bull Trout Distribution and Abundance in the Waters on and Bordering the Warm Springs Reservation : 2002 Annual Report  

Microsoft Academic Search

The range of bull trout (Salvelinus confluentus) in the Deschutes River basin has decreased from historic levels due to many factors including dam construction, habitat degradation, brook trout introduction and eradication efforts. While the bull trout population appears to be healthy in the Metolius River-Lake Billy Chinook system they have been largely extirpated from the upper Deschutes River (Buchanan et

Christopher V. Brun; Rebekah Dodson

2003-01-01

290

Lake  

ERIC Educational Resources Information Center

The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

Wien, Carol Anne

2008-01-01

291

Lean blowoff detection sensor  

DOEpatents

Apparatus and method for detecting incipient lean blowoff conditions in a lean premixed combustion nozzle of a gas turbine. A sensor near the flame detects the concentration of hydrocarbon ions and/or electrons produced by combustion and the concentration monitored as a function of time are used to indicate incipient lean blowoff conditions.

Thornton, Jimmy (Morgantown, WV); Straub, Douglas L. (Morgantown, WV); Chorpening, Benjamin T. (Morgantown, WV); Huckaby, David (Morgantown, WV)

2007-04-03

292

PROJECT REPORT Great Lakes Fishery Trust  

E-print Network

Objectives: 1. Facilitate location of lake trout spawning habitat by making improvements to the ROV based densities on Sheboygan and East Reef 4. Collect lake trout post sac-fry using a beam trawl and improve ROV sac fry via ROV-based electroshocking than in previous years. Page 13 Ancillary accomplishments 1 We

Janssen, John

293

Toxaphene congeners in the Canadian Great Lakes basin: temporal and spatial food web dynamics  

Microsoft Academic Search

Samples of a top predator fish species, lake trout (Salvelinus namaycush) and predominant forage species including smelt (Osmerus mordax), alewife (Alosa pseudoharengus), slimy sculpin (Cottus cognatus), deepwater sculpin (Myoxocephalus quadricornis) and lake herring (Coregonus artedii) were, collected from throughout 4 of the 5 Great Lakes (Superior, Huron, Erie and Ontario) (Fig. 1). Lake trout were also collected from three isolated

D. M. Whittle; R. M. Kiriluk; A. A. Carswell; M. J. Keir; D. C. MacEachen

2000-01-01

294

DEVELOPMENT OF A CARBON-BASED PHYTOPLANKTON MODEL FOR LAKE MICHIGAN AS PART OF A SEQUENCE OF MODELS USED IN THE LAKE MICHIGAN MASS BALANCE PROJECT  

EPA Science Inventory

Different from earlier Great Lakes models, our objective is to link autochthonous carbon production to the toxic chemical concentration within the lake and ultimately to components of the foodchain, such as Lake Trout and Coho Salmon....

295

Native Westslope Cutthroat Trout  

USGS Multimedia Gallery

Native westslope cutthroat trout swim in the north fork of the Flathead River in northwestern Montana. The region is recognized as a range-wide stronghold for genetically pure westslope cutthroat trout. However, rainbow trout invasion and hybridization threatens these p...

296

Native Westslope Cutthroat Trout  

USGS Multimedia Gallery

Native westslope cutthroat trout swim in the north fork of the Flathead River in northwestern Montana. This region is recognized as a range-wide stronghold for genetically pure westslope cutthroat trout. However, rainbow trout invasion and hybridization threatens these ...

297

The Lego Lean Game  

NASA Astrophysics Data System (ADS)

After revolutionizing the automobile industry, Lean principles have been applied to different knowledge areas, such as software development. However, many people haven’t been introduced to the concepts that made Lean successful. In this interactive session, the participants will work in a small LegoTM production line, experiencing the problems and applying Lean practices to overcome them. The workshop will also discuss the similarities and differences between the production line scenario and the software development industry.

Sato, Danilo; Trindade, Francisco

298

Changes in Wisconsin's Lake Michigan salmonid sport fishery, 1969-1985  

USGS Publications Warehouse

The modern sport fishery for salmonids in Wisconsin waters of Lake Michigan was begun during 1963-1969 with the stocking of rainbow trout (Oncorhynchus mykiss), lake trout (Salvelinus namaycush), brook trout (S. fontinalis), brown trout (Salmo trutta), coho salmon (O. kisutch), and chinook salmon (O. tshawytscha). The fishery grew rapidly during 1969-1985 as angler effort increased 10-fold, catch rate doubled, and catch increased 20-fold. The stocking and catch became increasingly dominated by chinook salmon, with coho salmon and lake trout of secondary importance and brown, rainbow, and brook trout of least importance. Trolling dominated the fishery, particularly by launched-boat anglers and, more recently, by moored-boat anglers. Charter boat trolling grew the most continuously and had the highest catch rates. The catch by trollers was dominated by chinook and coho salmon and lake trout. Pier, stream, and shore anglers fished less overall, but had catch rates that were similar to launched-boat anglers. The catch by pier and shore anglers was spread among chinook and coho salmon, and lake, brown and rainbow trout. The catch by stream anglers was dominated by chinook salmon. The percentage of stocked fish that were subsequently caught (catch ratio) was highest for fingerling chinook salmon (12.9%). Yearling brook trout, brown trout, coho salmon, lake trout, and rainbow trout had intermediate catch ratios (5.1-9.8%). Fingerling brook trout, brown trout, and lake trout had the lowest catch ratios (2.5-3.5%). The catch ratio for rainbow trout dropped from 9.8 to 5.1% after stocking with a different strain (the Shasta strain). Fingerling rainbow trout produced the lowest returns (<0.5%). We derived stocking recommendations for each species and life stage based on these catch ratios, and catch objectives based on maintaining catch levels recorded during 1983-1985.

Hansen, Michael J.; Schultz, Paul T.; Lasee, Becky A.

1990-01-01

299

lean-ISD.  

ERIC Educational Resources Information Center

Explains lean instructional systems design/development (ISD) as it relates to curriculum architecture design, based on Japan's lean production system. Discusses performance-based systems; ISD models; processes for organizational training and development; curriculum architecture to support job performance; and modular curriculum development. (LRW)

Wallace, Guy W.

2001-01-01

300

An Overview of Fisheries Management for Lake Simcoe  

Microsoft Academic Search

Eutrophication, increased fishing pressure, habitat destruction and invasion of non-native plants and animals have transformed Lake Simcoe and its assemblage of fishes over the past 150 years. Notable changes include die extirpation of lake sturgeon (Acipenser fulvescens), decline of muskellunge (Esox masquinongy), and failure of recruitment of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis). Many species, including lake

McMurtry M. J; C. C. Willox; T. C. Smith

1997-01-01

301

Evidence for allochthonous prey delivery to Lake Michigan's Mid-Lake Reef Complex: Are deep reefs analogs to oceanic sea mounts?  

Microsoft Academic Search

Lake Michigan's Sheboygan Reef is contained in a refuge for lake trout (Salvelinus namaycush) restoration, and is one of several deep midlake reefs that historically were productive spawning and fishery grounds. The summits of these reefs are rocky and deeper than the photic zone. We propose that the basis of trophic support for lake trout and their prey is allochthonous

Christopher J. Houghton; Charles R. Bronte; Robert W. Paddock; John Janssen

2010-01-01

302

The Effect of Some Sulfonamides on the Growth of Brook Trout, Brown Trout, and Rainbow Trout  

Microsoft Academic Search

Sulfonamides such as sulfisoxazole (Gantrisin), sulfamerazine, and a mixture of sulfamerazine with sulfaguanidine were fed to apparently normal fingerlings of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and rainbow trout (Salmo gairdneri). None of these drugs had any growth-affecting influence on rainbow trout. Growth of brook trout was somewhat retarded by sulfamerazine. The retardation of the growth of brown

S. F. Snieszko; E. M. Wood

1955-01-01

303

Ecotypic differentiation of native rainbow trout ( Oncorhynchus mykiss ) populations from British Columbia  

Microsoft Academic Search

We sampled 34 native rainbow trout (Oncorhynchus mykiss) populations over a wide geographic area of British Columbia to determine whether variation in morphology is related to differences in habitat or fish community characteristics experienced by a population. After correcting for differences in body size, the most dramatic differences occurred in external characteristics between stream- and lake-dwelling populations. Rainbow trout from

E. R. Keeley; E. A. Parkinson; E. B. Taylor

2005-01-01

304

Use of space and food by resident and migrant brown trout, Salmo trutta  

Microsoft Academic Search

Parr and resident forms of brown trout,Salmo trutta, from Vangsvatnet Lake, Norway live in freshwater, while migrant forms live in coastal waters during summer and in freshwater during winter. About 80% of parr and residents live at depths <5 m, smolts and migrants are more confined to near-surface water. Brown trout partly segregate by size, age and sex from spring

Bror Jonsson; Finn R. Gravem

1985-01-01

305

Bull Trout Distribution and Abundance in the Waters on and Bordering the Warm Springs Indian Reservation, 2000 Annual Report.  

SciTech Connect

The range of bull trout (Salvelinus confluentus) in the Deschutes River basin has decreased from historic levels due to many factors including dam construction, habitat degradation, brook trout introduction and eradication efforts. While the bull trout population appears to be stable in the Metolius River-Lake Billy Chinook system they have been largely extirpated from the upper Deschutes River (Buchanan et al. 1997). Little was known about bull trout in the lower Deschutes basin until BPA funded project No.9405400 began during 1998. In this progress report we describe the findings from the third year (2000) of the multi-year study aimed at determining the life history, genetics, habitat needs and limiting factors of bull trout in the lower Deschutes subbasin. Juvenile bull trout and brook trout (Salvelinus fontinalis) relative abundance was assessed in the Warm Springs River and Shitike Creek by night snorkeling. In the Warm Springs R. juvenile bull trout were slightly more numerous than brook trout, however, both were found in low densities. Relative densities of both species declined from 1999 observations. Juvenile bull trout vastly out numbered brook trout in Shitike Cr. Relative densities of juvenile bull trout increased while brook trout abundance was similar to 1999 observations in eight index reaches. The utility of using index reaches to monitor trends in juvenile bull trout and brook trout relative abundance was assessed in the Warm Springs R. for the second year. Mean relative densities of both species, within the index reaches was slightly higher than what was observed in a 2.4 km control reach. Mill Creek was surveyed for the presence of juvenile bull trout. The American Fisheries Society ''Interim protocol for determining bull trout presence'' methodology was field tested. No bull trout were found in the 2 km survey area.

Brun, Christopher

2000-01-01

306

Anthropogenic and habitat correlates of hybridization between hatchery and wild brook trout  

E-print Network

of hybridization between hatchery and wild brook trout (Salvelinus fontinalis) occupying lakes in Algonquin Park'hybridation d'ombles de fontaine (Salvelinus fontinalis) sauvages et issus d'écloserie dans des lacs du parc

Fraser, Dylan J.

307

Salmonid diet and the size, distribution, and density of benthic invertebrates in an arctic lake  

Microsoft Academic Search

Size selective predation on molluscs was apparent for lake trout (Salvelinus namaycush) and round whitefish (Prosopium cylindraceum), but not for arctic grayling (Thymallus arcticus), in the Toolik Lake region of arctic Alaska during the summer of 1986. Lake trout consumed significantly larger molluscs\\u000a of all taxa than did round whitefish, and selected larger molluscs than were available on either rocky

Glenn W. Merrick; Anne E. Hershey; Michael E. McDonald

1992-01-01

308

Organochlorine transfer in the food web of subalpine Bow Lake, Banff National Park  

Microsoft Academic Search

Lake trout (Salvelinus namaycush) from subalpine Bow Lake, near the Continental Divide in Banff National Park, have been reported to have higher concentrations of toxaphene than other lake trout populations of the Rocky Mountains. Our original hypothesis was that unusually high biomagnification via a long food chain was responsible for elevated levels of toxaphene and other persistent organochlorines in the

Linda M. Campbell; David W. Schindler; Derek C. G. Muir; David B. Donald; Karen A. Kidd

2000-01-01

309

77 FR 33230 - Notice of Intent To Prepare an Environmental Impact Statement for Proposed Strategies for Lake...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Statement for Proposed Strategies for Lake Trout Population Reductions To Benefit Native Fish Species, Flathead Lake, MT AGENCY: Bureau of Indian Affairs...proposed fisheries management in Flathead Lake, Montana. DATES: Written comments...

2012-06-05

310

Rainbow trout (Salmo gairdneri) stocking and Contracaecum spp.  

PubMed

A stocking program with rainbow trout (Salmo gairdneri) at High Rock Lake, Manitoba failed due to infections with large numbers of Contracaecum spp. larvae. Nematode larvae in the intestinal tract, body cavity and musculature made the fish unmarketable. A combination of experimental infections of rainbow trout and pelicans (Pelecanus erythrorhynchos), observations on the behavior of fish-eating birds, and numbers of larval Contracaecum spp. in minnow species led to the following conclusions. The introduction of rainbow trout attracted large numbers of fish-eating birds, particularly pelicans. Concurrent predation by rainbow trout on fathead minnows (Pimephales promelas), five-spined sticklebacks (Culaea inconstans), and nine-spined sticklebacks (Pungitius pungitius), concentrated the parasites. The combined increase in densities of the introduced fish host and fish-eating birds, and the short life cycle of the parasite, increased the numbers of parasites in rainbow trout over a season and in the indigenous minnow species between years. Numbers of larvae in the indigenous minnow species declined when stocking of rainbow trout was stopped and use of the lake by fish-eating birds, particularly pelicans, returned to normal levels. PMID:3586201

Dick, T A; Papst, M H; Paul, H C

1987-04-01

311

Lean Manufacturing Engineering Certification  

NSDL National Science Digital Library

This website from Best Practice Research features online business training courses including lean manufacturing and six sigma certification training courses. The courses are available for purchase and may be taken online.

312

Creel Analysis and Economic Impact of Pennsylvania's Lake Erie Tributary Fisheries in Erie County, Pennsylvania, with Special Emphasis on Landlocked Steelhead Trout (Oncorhynchus mykiss)  

Microsoft Academic Search

Pennsylvania's steelhead fishery on the Lake Erie tributaries provides a unique angling experience for Pennsylvania anglers. An abundance of fish, public access and high angler catch rates make steelhead an attractive fishery for many non-resident anglers as well. Overall angler effort estimates (trips) have nearly tripled in the last decade, increasing from 72,413 trips in 1993 to 200,816 trips in

313

Growth, Morphology, and Developmental Instability of Rainbow Trout, Yellowstone Cutthroat Trout, and Four Hybrid Generations  

Microsoft Academic Search

Hybridization of cutthroat trout Oncorhynchus clarkii with nonindigenous rainbow trout O. mykiss contributes to the decline of cutthroat trout subspecies throughout their native range. Introgression by rainbow trout can swamp the gene pools of cutthroat trout populations, especially if there is little selection against hybrids. We used rainbow trout, Yellowstone cutthroat trout O. clarkii bouvieri, and rainbow trout × Yellowstone

C. O. Ostberg; J. J. Duda; J. H. Graham; S. Zhang; K. P. Haywood III; B. Miller; T. L. Lerud

2011-01-01

314

Water quality in relation to survival of brook trout Salvelinus fontinalis (Mitchill)  

SciTech Connect

Periodic water analyses and simultaneous observations on the survival of various groups of test fish made in Honnedaga Lake during 1960 and 1961 indicated a relationship between water quality and trout survival. Periods of high acidity and heavy metals content, during the summer, were coincident with heavy mortality of brook trout from a hard-water and a soft-water hatchery; trout from a second hard-water hatchery, which contained zinc in its water supply, survived transfer to Honnedaga Lake. Chemical analyses of 30 nearby Adirondack Lakes revealed two lakes of lower salinity, two of higher acidity, and one with a heavy metals content equal to that of Honnedaga. No other lakes exhibited the combined features of very low salinity, high acidity, and relatively high heavy metals content. 3 figures, 5 tables.

Schofield, C.L. Jr.

1984-01-01

315

Bioaccumulation of Toxaphene Congeners in the Lake Superior Food Web  

Microsoft Academic Search

The bioaccumulation and biotransformation of toxaphene was examined in the food webs of Lake Superior and Siskiwit Lake (Isle Royale) using congener specific analysis as well as stable isotope ratios of carbon and nitrogen to characterize food webs. Toxaphene concentrations (calculated using technical toxaphene) in lake trout (Salvelinus namaycush) from the western basin of Lake Superior (N = 95) averaged

Derek C. G. Muir; D. Michael Whittle; David S. De Vault; Charles R. Bronte; Heidi Karlsson; Sean Backus; Camilla Teixeira

2004-01-01

316

Reappearance of Highly Acid-Sensitive Invertebrates After Liming of an Alpine Lake Ecosystem  

Microsoft Academic Search

The amphipod Gammarus lacustris was earlier a main food item of brown trout in Lake Svartavatnet at the Hardangervidda mountain plateau in South Norway. In the middle of the 1980's, G. lacustris disappeared from the trout diet due to increased acidification. In order to preserve a unique genetic variant of brown trout living in the area, a liming programme was

Arne Fjellheim; Åsmund Tysse; Vilhelm Bjerknes

2001-01-01

317

Lean Implementation Lean Concept : Application & Simulation in Healthcare  

E-print Network

Lean Implementation Lean Concept : Application & Simulation in Healthcare 6-7 July 2011 #12 - Project owner, Team · (Kaizen) · (Kaizen) · · Continuous Improvement PDCA #12; Lean project · Continuous flow · Pull system · Automatic stops · Andon · Person-machine · Common Goals g g · Cross-trained

Laksanacharoen, Sathaporn

318

Development of lean NOx catalyst for lean burn gasoline engine  

Microsoft Academic Search

Lean NOx catalyst for a lean burn gasoline engine was developed. This catalyst could constantly reduce NOx under lean burn driving condition by using hydrocarbon as a reducing agent. This catalyst consists of platinum (Pt), iridium (Ir) and rhodium (Rh) as active metals and H-MFI type zeolite as a support material. This catalyst had high thermal durability that was caused

H. Iwakuni; A. Takami; K. Komatsu

1999-01-01

319

Strategies for Lean Product Development  

E-print Network

The essence of lean is very simple, but from a research and implementation point of view overwhelming. Lean is the search for perfection through the elimination of waste and the insertion of practices that contribute to ...

Walton, Myles

320

Survival and hepatic metallothionein in developing rainbow trout exposed to a mixture of zinc, copper, and cadmium  

SciTech Connect

Rainbow trout (Salmo gairdneri) in Buttle Lake on Vancouver Island, B.C. are exposed to metal contamination originating from a copper and zinc mining operation at Myra Falls near the head of the lake. In order to properly assess the risk to a population of rainbow trout in Buttle Lake, the authors initiated a long-term exposure of rainbow trout from hatch including the swim-up stage. Copper, zinc or cadmium are known to induce metallothionein in mammals and as a mixture of metals, induce hepatic metallothionein in rainbow trout. Investigation of hepatic metallothionein concentrations in wild rainbow trout from Buttle Lake and in lakes of the Campbell River downstream showed a correlation with metal concentrations in the water. Rainbow trout held in situ for 4 weeks showed the same correlation. In this report they determined whether or not the degree of contamination was correlated with concentrations of metallothionein in the livers of rainbow trout exposed to the mixture of metals during the early life stages.

Roch, M.; McCarter, J.A.

1986-02-01

321

Lean Gasoline Engine Reductant Chemistry During Lean NOx Trap Regeneration  

SciTech Connect

Lean NOx Trap (LNT) catalysts can effectively reduce NOx from lean engine exhaust. Significant research for LNTs in diesel engine applications has been performed and has led to commercialization of the technology. For lean gasoline engine applications, advanced direct injection engines have led to a renewed interest in the potential for lean gasoline vehicles and, thereby, a renewed demand for lean NOx control. To understand the gasoline-based reductant chemistry during regeneration, a BMW lean gasoline vehicle has been studied on a chassis dynamometer. Exhaust samples were collected and analyzed for key reductant species such as H2, CO, NH3, and hydrocarbons during transient drive cycles. The relation of the reductant species to LNT performance will be discussed. Furthermore, the challenges of NOx storage in the lean gasoline application are reviewed.

Choi, Jae-Soon [ORNL] [ORNL; Prikhodko, Vitaly Y [ORNL] [ORNL; Partridge Jr, William P [ORNL] [ORNL; Parks, II, James E [ORNL; Norman, Kevin M [ORNL] [ORNL; Huff, Shean P [ORNL] [ORNL; Chambon, Paul H [ORNL] [ORNL; Thomas, John F [ORNL] [ORNL

2010-01-01

322

Duckling response to changes in the trophic web of acidified lakes  

Microsoft Academic Search

We reared American Black Duck (Anas rubripes Brewster) and Common Goldeneye (Bucephala clangula Linnaeus) ducklings on two Quebec laurentian lakes in which we manipulated brook trout populations (Salvelinus fontinalis Mitchill), lake acidity and lake productivity to relate waterfowl foraging to trophic status of lakes. We developed a preliminary model to assess the effects of lake acidity and productivity, fish predation

Jean-Luc DesGranges; Christian Gagnon

1994-01-01

323

Leaning Tower of PESA  

ERIC Educational Resources Information Center

There is a certain similarity between the Philosophy of Education Society of Australasia (PESA) and the leaning tower of Pisa. Both have a certain presence on the landscape: the tower has a commanding appearance on the Italian countryside while PESA has left its mark on the academic fabric of Australasia. Both are much loved: Pisa by visiting…

Clark, John

2009-01-01

324

Mercury in the muscle tissue of fish from three northern Maine lakes  

SciTech Connect

We report the levels of mercury in the muscle tissue of brook trout (Salvelinus fontinalis) and lake trout (S. namaycush) from three northern Maine lakes. Mercury levels in fish from two wilderness lakes in the same drainage basin were compared with each other, and in turn with those in fish from a lake in a separate drainage basin. The fish species composition in one of the wilderness lakes, Cliff Lake, is different from that in the other two lakes, enabling us to analyze the effects of trophic structure on mercury concentration in top carnivores. It is unlikely that mercury from agricultural, geological, or local industrial sources occurs in these lakes.

Akielaszek, J.J.; Haines, T.A.

1981-08-01

325

HEAVY METAL ACCUMULATION IN SEDIMENT AND FRESHWATER FISH IN U.S. ARCTIC LAKES  

EPA Science Inventory

Metal concentrations in sediment and two species of freshwater fish (lake trout [Salvelinus namaycush], and grayling [Thymallus arcticus]} were examined in four Arctic lakes in Alaska. Concentrations of several metals were naturally high in the sediment relative to uncontaminated...

326

ORGANOCHLORINE PESTICIDES AND POLYCHLORINATED BIPHENYLS (PCBS) IN SEDIMENTS AND BIOTA FROM FOUR US ARCTIC LAKES  

EPA Science Inventory

Organochlorine (OC) concentrations in surface sediment, snails (Lymnea sp.), and two freshwater fish species (grayling, Thymallus arcticus; and lake trout, Salvelinus namaycush) from four lakes in the US Arctic were determined. In surface sediment, chlorinated benzenes (including...

327

HYDROACOUSTIC ESTIMATES OF ABUNDANCE AND SPATIAL DISTRIBUTION OF PELAGIC PREY FISHES IN WESTERN LAKE SUPERIOR  

EPA Science Inventory

Lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) are a valuable prey resource for the recovering lake trout (Salvelinus namaycush). However, their respective biomasses may be insufficient to support the current predator demand. In August 1977, we assessed the ...

328

Appendix 39 Historic Records of Bull Trout Occurrence in the North and  

E-print Network

trout were present in Big, Hay, Whale, Moose, Red Meadow, and Coal creeks in the North Fork Sheep, Bear, Red Meadow Creek, Whale Creek, Big Creek, Hallowat Creek, Coal Creek, Kishenehn Creek, the North Fork Frozen Lake and Upper White&h Lake, collected in 1957, is also published in Peters (1964). Morton (1968

329

Some phases of the life history of the trout-perch  

USGS Publications Warehouse

The trout-perch, Percopsis omiscomaycus (Walbaum), is one of the more abundant forage fishes in the larger lakes of midwestern United States and central Canada where walleye, Stizostedion v. vitreum (Mitchill), yellow perch, Perca flavescens (Mitchill), and coregonids predominate. It has been suggested that it may have considerable effect on perch and walleye populations of these lakes. The present study describes growth, food habits, population structure, year-class strengths, and reproductive capacity of the trout-perch in relation to its population dynamics in lower Red Lake, Minnesota.

Magnuson, John L.; Smith, Lloyd L.

1963-01-01

330

Sustainability of the Lake Superior Fish Community: Interactions in a Food Web Context  

Microsoft Academic Search

The restoration and rehabilitation of the native fish communities is a long-term goal for the Laurentian Great Lakes. In Lake\\u000a Superior, the ongoing restoration of the native lake trout populations is now regarded as one of the major success stories\\u000a in fisheries management. However, populations of the deepwater morphotype (siscowet lake trout) have increased much more substantially\\u000a than those of

James F. Kitchell; Sean P. Cox; Chris J. Harvey; Timothy B. Johnson; Doran M. Mason; Kurt K. Schoen; Kerim Aydin; Charles Bronte; Mark Ebener; Michael Hansen; Michael Hoff; Steve Schram; Don Schreiner; Carl J. Walters

2000-01-01

331

Diurnal stream habitat use of juvenile Atlantic salmon, brown trout and rainbow trout in winter  

USGS Publications Warehouse

The diurnal winter habitat of three species of juvenile salmonids was examined in a tributary of Skaneateles Lake, NY to compare habitat differences among species and to determine if species/age classes were selecting specific habitats. A total of 792 observations were made on the depth, velocity, substrate and cover (amount and type) used by sympatric subyearling Atlantic salmon, subyearling brown trout and subyearling and yearling rainbow trout. Subyearling Atlantic salmon occurred in shallower areas with faster velocities and less cover than the other salmonid groups. Subyearling salmon was also the only group associated with substrate of a size larger than the average size substrate in the study reach during both winters. Subyearling brown trout exhibited a preference for vegetative cover. Compared with available habitat, yearling rainbow trout were the most selective in their habitat use. All salmonid groups were associated with more substrate cover in 2002 under high flow conditions. Differences in the winter habitat use of these salmonid groups have important management implications in terms of both habitat protection and habitat enhancement.

Johnson, J.H.; Douglass, K.A.

2009-01-01

332

Molecular analysis of population genetic structure and recolonization of rainbow trout following the Cantara spill  

USGS Publications Warehouse

Mitochondrial DNA (mtDNA) sequence and allelic frequency data for 12 microsatellite loci were used to analyze population genetic structure and recolonization by rainbow trout, Oncorhynchus mykiss, following the 1991 Cantara spill on the upper Sacramento River, California. Genetic analyses were performed on 1,016 wild rainbow trout collected between 1993 and 1996 from the mainstem and in 8 tributaries. Wild trout genotypes were compared to genotypes for 79 Mount Shasta Hatchery rainbow trout. No genetic heterogeneity was found 2 years after the spill (1993) between tributary populations and geographically proximate mainstem fish, suggesting recolonization of the upper mainstem directly from adjacent tributaries. Trout collections made in 1996 showed significant year-class genetic variation for mtDNA and microsatellites when compared to fish from the same locations in 1993. Five years after the spill, mainstem populations appeared genetically mixed with no significant allelic frequency differences between mainstem populations and geographically proximate tributary trout. In our 1996 samples, we found no significant genetic differences due to season of capture (summer or fall) or sampling technique used to capture rainbow trout, with the exception of trout collected by electrofishing and hook and line near Prospect Avenue. Haplotype and allelic frequencies in wild rainbow trout populations captured in the upper Sacramento River and its tributaries were found to differ genetically from Mount Shasta Hatchery trout for both years, with the notable exception of trout collected in the lower mainstem river near Shasta Lake, where mtDNA and microsatellite data both suggested upstream colonization by hatchery fish from the reservoir. These data suggest that the chemical spill in the upper Sacramento River produced significant effects over time on the genetic population structure of rainbow trout throughout the entire upper river basin.

Nielsen, J.L.; Heine, E.L.; Gan, C.A.; Fountain, M.C.

2000-01-01

333

Introduced trout sever trophic connections in watersheds: consequences for a declining amphibian.  

PubMed

Trophic linkages between terrestrial and aquatic ecosystems are increasingly recognized as important yet poorly known features of food webs. Here we describe research to understand the dynamics of lake food webs in relation to a native riparian amphibian and its interaction with introduced trout. The mountain yellow-legged frog Rana muscosa is endemic to alpine watersheds of the Sierra Nevada Mountains and the Transverse Ranges of California, but it has declined to a small fraction of its historical distribution and abundance. Although remaining frogs and introduced trout feed in different habitats of alpine lakes, our stable-isotope analyses clearly show that the same resource base of benthic invertebrates sustains their growth. During one period, insect emergence from naturally fishless lakes was nearly 20-fold higher compared to adjacent lakes with trout, showing that fish reduce availability of aquatic prey to amphibious and terrestrial consumers. Although trout cannot prey on adult frogs due to gape limitation, foraging post-metamorphic frogs are 10 times more abundant in the absence of trout, suggesting an important role for competition for prey by trout in highly unproductive alpine watersheds. Most Sierran lakes contain fish, and those that do not are usually small isolated ponds; in our study, these two lake types supported the lowest densities of post-metamorphic frogs, and these frogs were less reliant on local, benthic sources of productivity. Since Rana muscosa was formerly the most abundant vertebrate in the Sierra Nevada, the reduction in energy flow from lake benthos to this consumer due to fish introductions may have had negative consequences for its numerous terrestrial predators, many of which have also declined. We suggest that disruptions of trophic connections between aquatic and terrestrial food webs are an important but poorly understood consequence of fish introduction to many thousands of montane lakes and streams worldwide and may contribute to declines of native consumers in riparian habitats. PMID:17918397

Finlay, Jacques C; Vredenburg, Vance T

2007-09-01

334

A comparative and experimental evaluation of performance of stocked diploid and triploid brook trout  

USGS Publications Warehouse

Despite numerous negative impacts, nonnative trout are still being stocked to provide economically and socially valuable sport fisheries in western mountain lakes. We evaluated relative performance and potential differences in feeding strategy and competitive ability of triploid versus diploid brook trout Salvelinus fontinalis in alpine lakes, as well as behavioral and performance differences of diploid and triploid brook trout in two controlled experimental settings: behavioral experiments in the laboratory and performance evaluations in ponds. Across lakes, catch per unit effort (CPUE) and relative weight (Wr ) were not significantly different between ploidy levels. Mean sizes were also similar between ploidy levels except in two of the larger lakes where diploids attained slightly larger sizes (approximately 20 mm longer). We observed no significant differences between diploids and triploids in diet, diet preference, or trophic structure. Similarly, growth and condition did not differ between ploidy levels in smaller-scale pond experiments, and aggressive behavior did not differ between ploidy levels (fed or unfed fish trials) in the laboratory. Independent of ploidy level, the relative performance of brook trout varied widely among lakes, a pattern that appeared to be a function of lake size or a factor that covaries with lake size such as temperature regime or carrying capacity. In summary, we observed no significant differences in the relative performance of brook trout from either ploidy level across a number of indices, systems, and environmental conditions, nor any indication that one group is more aggressive or a superior competitor than the other. Collectively, these results suggest that triploid brook trout will offer a more risk-averse and promising management opportunity when they are stocked to these lakes and elsewhere to simultaneously meet the needs for the sport fishery and conservation objectives.

Budy, Phaedra E.; Thiede, G.P.; Dean, A.; Olsen, D.; Rowley, G.

2012-01-01

335

Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin to brook trout (salvelinus fontinalis) during early development  

SciTech Connect

The sensitivity of early life stages of brook trout (Salvelinus fontinalis) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxicity was investigated. Newly fertilized eggs were exposed for 48 h to water containing either acetone or a range of concentrations of [[sup 3]H]TCDD dissolved in acetone. Eggs were then transferred to TCDD-free water and observed through development. TCDD concentrations of 101 to 470 pg/g in the eggs caused dose-related increases in sac-fry mortality associated with yolk-sac edema, hemorrhages, and arrested development. These signs of TCDD-induced toxicity resemble blue-sac disease. The NOELs and LOELs for sac-fry mortality were 135 and 185 pg TCDD/g egg, respectively, whereas the LD50 and LD100 were 200 and 324 pg/g egg, respectively. The time course and signs of TCDD toxicity to brook trout during early development are essentially identical to those observed in both rainbow trout and lake trout following TCDD exposure of their eggs via water or injection, and in lake trout exposed to maternally derived TCDD. Brook trout sac fry are intermediate in sensitivity to TCDD-induced lethality compared to lake trout and rainbow trout.

Walker, M.K.; Peterson, R.E. (Univ. of Wisconsin, Madison, WI (United States))

1994-05-01

336

Halogenated contaminants in farmed salmon, trout, tilapia, pangasius, and shrimp.  

PubMed

Polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzo-p-furans (PCDD/Fs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane diastereomers (HBCDs), and perfluorinated compounds (PFCs) were analyzed in popular farmed fish such as salmon, trout, tilapia, and pangasius and in farmed shrimp. The samples originated from southeast Asia, Europe, and South America. Results show the following: (i) Carnivorous species contained higher contaminant concentrations than omnivorous species. (ii) Contaminant concentrations generally decreased per species in the following order of salmon > trout > tilapia approximately equal to pangasius approximately equal to shrimp. (iii) Most contaminant concentrations decreased in the following order of PCBs approximately equal to dichloro-diphenyl-trichloroethanes (DDTs) > hexachlorobenzene approximately equal to pentachlorobenzene approximately equal to dieldrin approximately equal to PBDEs approximately equal to alpha-HBCD approximately equal to perfluorooctane sulfonate (PFOS) > World Health Organization toxic equivalents (WHO-TEQ) [PCDD/Fs and dioxin-like (dl)-PCBs]. (iv) Contaminant concentrations were very low (mostly <1 ng/g wet weight) and far below the European and Dutch legislative limits. (v) Contaminant concentrations in farmed shrimp, pangasius, and tilapia were lower than those in wild fish, whereas contaminant concentrations in farmed salmon and trout were higher than those in lean wild marine fish. From the five species investigated, salmon is predominantly responsible (97%) for human exposure to the sum of the investigated contaminants. The contribution of trout, tilapia, pangasius, and shrimp is small (3%) because contaminant concentrations and consumption volumes were much lower. PMID:19569323

van Leeuwen, S P J; van Velzen, M J M; Swart, C P; van der Veen, I; Traag, W A; de Boer, J

2009-06-01

337

AMERICAN KESTRELS EAT TROUT FINGERLINGS  

Microsoft Academic Search

American Kestrels (Falco sparverius) captured and ate brook trout (Salvelinus fontinalis), a type of prey not previously recorded for kestrels. A trout was pirated from a Common Grackle (Quiscalus quiscula) in one instance, and a trout inadvertently cast up on the bank was taken in the second. The use of fish as food illustrates the plasticity in foraging behavior of

MES A. PARKHURST; ROBERT P. BROOKS

338

Variable migratory patterns of different adult rainbow trout life history types in a southwest Alaska watershed  

USGS Publications Warehouse

Radiotelemetry was used to document population structure in adult rainbow trout Oncorhynchus mykiss from the Alagnak River, southwest Alaska. Rainbow trout (N = 134) longer than 440 mm were implanted with radio transmitters and tracked for varying periods from July 1997 to April 1999. Fifty-eight radio-tagged fish were tracked for sufficient duration (at least 11 months) to allow description of seasonal migratory patterns. Unique seasonal movements of fish suggested discrete, within-basin population structure. Telemetry data documented the existence of multiple migratory and nonmigratory groups of rainbow trout, indicating unique life history patterns. The observed groups consisted of what we defined as a lake-resident ecotype, a lake-river ecotype, and a riverine ecotype; the riverive ecotype demonstrated both highly migratory and nonmigratory movement behavior. Considerable variation in movement patterns was found within both the lake-river group and the river migratory group. Radio-tagged trout did not migrate between the two Alagnak watershed lakes in either year of the study, suggesting lake fidelity in the population structure. Alagnak River rainbow trout may have evolved the observed seasonal movement patterns to optimize winter thermal refugia and summer food availability of salmon eggs and carcasses.

Meka, J.M.; Knudsen, E.E.; Douglas, D.C.; Benter, R.B.

2003-01-01

339

Lake Pend Oreille Predation Research, Annual Report 2002-2003.  

SciTech Connect

During August 2002 we conducted a hydroacoustic survey to enumerate pelagic fish >406 mm in Lake Pend Oreille, Idaho. The purpose of this survey was to determine a collective lakewide biomass estimate of pelagic bull trout Salvelinus confluentus, rainbow trout Oncorhynchus mykiss, and lake trout S. namaycush and compare it to pelagic prey (kokanee salmon O. nerka) biomass. By developing hydroacoustic techniques to determine the pelagic predator to prey ratio, we can annually monitor their balance. Hydroacoustic surveys were also performed during December 2002 and February 2003 to investigate the effectiveness of autumn and winter surveys for pelagic predators. The inherent problem associated with hydroacoustic sampling is the inability to directly identify fish species. Therefore, we utilized sonic tracking techniques to describe rainbow trout and lake trout habitat use during our winter hydroacoustic survey to help identify fish targets from the hydroacoustic echograms. During August 2002 we estimated there were 39,044 pelagic fish >406 mm in Lake Pend Oreille (1.84 f/ha). Based on temperature and depth utilization, two distinct groups of pelagic fish >406 mm were located during August; one group was located between 10 and 35 m and the other between 40 and 70 m. The biomass for pelagic fish >406 mm during August 2002 was 73 t (metric ton). This would account for a ratio of 1 kg of pelagic predator for every 2.63 kg of kokanee prey, assuming all pelagic fish >406 mm are predators. During our late fall and winter hydroacoustic surveys, pelagic fish >406 mm were observed at lake depths between 20 and 90 m. During late fall and winter, we tracked three rainbow trout (168 habitat observations) and found that they mostly occupied pelagic areas and predominantly stayed within the top 10 m of the water column. During late fall (one lake trout) and winter (four lake trout), we found that lake trout (184 habitat observations) utilized benthic-nearshore areas 65% of the time and were found in the pelagic area only 35% of the time. Lake trout were found at depths between 10 and 90 m (average was approximately 30 m). Based on hydroacoustic surveys of pelagic fish >406 mm and habitat use of sonic tagged rainbow trout and lake trout during late fall and winter, we conclude that hydroacoustic sampling during those times would be ineffective at acquiring an accurate pelagic predator population estimate and recommend conducting abundance estimates for pelagic predators when Lake Pend Oreille is thermally stratified (i.e. August).

Bassista, Thomas

2004-02-01

340

Toxic effects of cadmium on three generations of brook trout (Salvelinus fontinalis)  

Microsoft Academic Search

Three generations of brook trout (Salvelinus fontinalis) were exposed to several concentrations of total cadmium (0.06-6.4 ..mu..g Cd\\/liter). Significant numbers of first- and second-generation adult males died during spawning at 3.4 ..mu..g Cd\\/liter. This concentration also significantly retarded growth of juvenile second- and third-generation offspring. The maximum acceptable toxicant concentration (MATC) for brook trout exposed to cadmium in Lake Superior

DUANE A. BENOIT; EDWARD N. LEONARD; GLENN M. CHRISTENSEN; JAMES T. FIANDT

1976-01-01

341

Assessment of the Outcome of Eight Decades of Trout Stocking in the Mountain National Parks, Canada  

Microsoft Academic Search

The majority of the 1,464 lakes in the Canadian mountain national parks (22,376 km 2) were devoid of fish prior to the 20th century, and those lakes that supported fish populations were usually dominated by either mountain whitefish Prosopium williamsoni or longnose suckers Catostomus catostomus. From the early 1900s to 1980, about 305 lakes were stocked with either cutthroat trout

D. B. Donald

1987-01-01

342

Organizational change through Lean Thinking.  

PubMed

In production and manufacturing plants, Lean Thinking has been used to improve processes by eliminating waste and thus enhancing efficiency. In health care, Lean Thinking has emerged as a comprehensive approach towards improving processes embedded in the diagnostic, treatment and care activities of health-care organizations with cost containment results. This paper provides a case study example where Lean Thinking is not only used to improve efficiency and cost containment, but also as an approach to effective organizational change. PMID:18647948

Tsasis, Peter; Bruce-Barrett, Cindy

2008-08-01

343

PERSPECTIVE / PERSPECTIVE Fish community change in Lake Superior,  

E-print Network

to 2000. Lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) stocks have grands corégones (Coregonus clupeaformis) se sont considérablement accrus et sont peut-être en train d increased substantially and may be approaching ancestral states. Lake herring (Coregonus artedi) have also

344

Snail populations in arctic lakes: competition mediated by predation?  

Microsoft Academic Search

For 2 species of snails in arctic Alaskan lakes, I studied the patterns of snail distribution with respect to habitat, distribution of predatory fish, and the potential for interspecific competition. The snails Lymnaea elodes and Valvata lewisi co-exist in these arctic lakes, either in the presence of lake trout, Salvelinus namaycush, or in the absence of predation. Intensive sediment core

Anne E. Hershey

1990-01-01

345

Fish community change in Lake Superior, 1970–2000  

Microsoft Academic Search

Abstract: Changes,in Lake Superior’s fish community,are reviewed,from 1970 to 2000. Lake trout (Salvelinus namaycush) and lake whitefish (Coregonus,clupeaformis) stocks have increased substantially and may,be approaching ancestral states. Lake herring (Coregonus artedi) have also recovered, but under sporadic recruitment. Contaminant levels have declined and are in equilibrium with inputs, but toxaphene levels are higher than in all other Great Lakes. Sea

Charles R. Bronte; Mark P. Ebener; Donald R. Schreiner; David S. DeVault; Michael M. Petzold; Douglas A. Jensen; Carl Richards; Steven J. Lozano

2003-01-01

346

Wigwam River Juvenile Bull Trout and Fish Habitat Monitoring Program : 2002 Data Report.  

SciTech Connect

The Wigwam River bull trout (Salvelinus confluentus) and fish habitat monitoring program is a trans-boundary initiative implemented by the British Columbia Ministry of Water, Land, and Air Protection (MWLAP), in cooperation with Bonneville Power Administration (BPA). The Wigwam River is an important fisheries stream located in southeastern British Columbia that supports healthy populations of both bull trout and Westslope cutthroat trout (Figure 1). This river has been characterized as the single most important bull trout spawning stream in the Kootenay Region (Baxter and Westover 2000, Cope 1998). In addition, the Wigwam River supports some of the largest Westslope cutthroat trout (Oncorhynchus clarki lewisi) in the Kootenay Region. These fish are highly sought after by anglers (Westover 1999a, 1999b). Bull trout populations have declined in many areas of their range within Montana and throughout the northwest including British Columbia. Bull trout were blue listed as vulnerable in British Columbia by the B.C. Conservation Data Center (Cannings 1993) and although there are many healthy populations of bull trout in the East Kootenay they remain a species of special concern. Bull trout in the United States portion of the Columbia River were listed as threatened in 1998 under the Endangered Species Act by the U.S. Fish and Wildlife Service. The upper Kootenay River is within the Kootenai sub-basin of the Mountain Columbia Province, one of the eleven Eco-provinces that make up the Columbia River Basin. MWLAP applied for and received funding from BPA to assess and monitor the status of wild, native stocks of bull trout in tributaries to Lake Koocanusa (Libby Reservoir) and the upper Kootenay River. This task is one of many that were undertaken to ''Monitor and Protect Bull Trout for Koocanusa Reservoir'' (BPA Project Number 2000-04-00).

Cope, R.S. [Westslope Fisheries, Cranbrook, BC, Canada

2003-03-01

347

Wigwam River Juvenile Bull Trout and Fish Habitat Monitoring Program : 2000 Data Report.  

SciTech Connect

The Wigwam River bull trout (Salvelinus confluentus) and fish habitat monitoring program is a trans-boundary initiative implemented by the British Columbia Ministry of Environment, Lands and Parks (MOE), in cooperation with Bonneville Power Administration (BPA). The Wigwam River is an important fisheries stream located in southeastern British Columbia that supports healthy populations of both bull trout and Westslope cutthroat trout (Figure 1.1). This river has been characterized as the single most important bull trout spawning stream in the Kootenay Region (Baxter and Westover 2000, Cope 1998). In addition, the Wigwam River supports some of the largest Westslope cutthroat trout (Oncorhynchus clarki lewisi) in the Kootenay Region. These fish are highly sought after by anglers (Westover 1999a, 1999b). Bull trout populations have declined in many areas of their range within Montana and throughout the northwest including British Columbia. Bull trout were blue listed as vulnerable in British Columbia by the B.C. Conservation Data Center (Cannings 1993) and although there are many healthy populations of bull trout in the East Kootenays they remain a species of special concern. Bull trout in the United States portion of the Columbia River were listed as threatened in 1998 under the Endangered Species Act by the U.S. Fish and Wildlife Service. The upper Kootenay River is within the Kootenai sub-basin of the Mountain Columbia Province, one of the eleven Eco-provinces that make up the Columbia River Basin. MOE applied for and received funding from BPA to assess and monitor the status of wild, native stocks of bull trout in tributaries to Lake Koocanusa (Libby Reservoir) and the upper Kootenay River. This task is one of many that was undertaken to ''Monitor and Protect Bull Trout for Koocanusa Reservoir'' (BPA Project Number 2000-04-00).

Cope, R.S.; Morris, K.J.

2001-03-01

348

Lean transformation of a supply chain organization  

E-print Network

There are two basic schools of thought regarding how to approach a Lean transformation. Either start with introducing Lean tools or start with driving a Lean cultural change. Academic researchers like Steve Spear (Harvard/MIT), ...

Walsh, Daniel Andres

2008-01-01

349

Lean enterprise in the construction industry  

E-print Network

This thesis explores the application of the Lean Enterprise Model (LEM) to construction firms. LEM is a framework derived from lean manufacturing principles by MIT's Lean Aerospace Initiative (LAI) for the aerospace industry. ...

Marchini-Blanco, Juan, 1971-

2004-01-01

350

Information and Communication in Lean Product Development  

E-print Network

In this thesis, the implications and influences that information and communication impose on lean product development in general, as well as the development of a lean Product Development Value Stream Display (lean PDVSD) ...

Graebsch, Martin

351

A Simulation of Lean Manufacturing: The Lean Lemonade Tycoon 2  

ERIC Educational Resources Information Center

This article discusses the functions and effectiveness of games and simulations in the learning processes, in particular as an experiential learning methodology. The application of the game Lemonade Tycoon in the development of lean manufacturing concepts is described. This article addresses the use of the game to teach the principles of lean

Ncube, Lisa B.

2010-01-01

352

Kootenai River Fisheries Investigations : Rainbow Trout Recruitment : Period Covered: 1997.  

SciTech Connect

The objective of this study was to determine if juvenile production is limiting the population of rainbow trout Oncorbynchus mykiss in the Idaho reach of the Kootenai River. We used snorkeling and electrofishing techniques to estimate juvenile rainbow trout abundance in, and outmigration from, the Deep, Boulder, and Myrtle creek drainages in Idaho. The total population estimates for the three drainages estimated in 1997 were 30,023; 763; and 235; respectively. A rotary-screw trap was utilized to capture juvenile outmigrants for quantification of age at outmigration and total outmigration from the Deep Creek drainage to the Kootenai River. The total outmigrant estimate for 1997 from the Deep Creek drainage was 38,206 juvenile rainbow trout. Age determination based largely on scales suggests that most juvenile rainbow trout outmigration from the Deep Creek drainage occurs at age-l, during the spring runoff period. Forty-three adult rainbow trout captured in the Deep Creek drainage were tagged with $10.00 reward T-bar anchor tags in 1997. A total of three of these fish were harvested, all in Kootenay Lake, British Columbia. This suggests the possibility of an adfluvial component in the spawning population of the Deep Creek drainage.

Downs, Chris

1999-02-02

353

Gizzard and other lean mass components increase, yet Basal Metabolic Rates decrease, when red knots Calidris canutus are shifted from soft to hard-shelled food  

Microsoft Academic Search

We measured basal metabolic rate (BMR), body mass, lean mass, and gizzard mass of captive red knots Calidris canutus islandica maintained on a trout chow diet (soft- texture, low ash and water content) for several years and then shifted to small mussels Mytilus edulis (hard-texture, high ash and water content). During a 3-week period of feeding on mussels, body mass,

Theunis Piersma; James A. Gessaman; Anne Dekinga; G. Henk Visser

2004-01-01

354

Introducing lean manufacturing at ESI  

Microsoft Academic Search

Summary form only given. Lean production is a collection of techniques to identify and reduce waste in the manufacturing process. By reducing waste, enormous gains in throughput and reductions in WIP inventory and cycle time can be achieved with no increase in resources. It was the promise of these advantages that caused ESI to begin the move to lean manufacturing

D. Mottershead

2001-01-01

355

Lean indicators and manufacturing strategies  

Microsoft Academic Search

Develops and tests an integrated check-list to assess manufacturing changes towards lean production. Using the results from a survey to manufacturing plants located in the Spanish region of Aragon, analyzes which lean production indicators are more used to assess the company’s improvements in their production systems, and the determinants on the use of these indicators.

Angel Martínez Sánchez; Manuela Pérez Pérez

2001-01-01

356

The Leaning Tower of Pisa  

Microsoft Academic Search

THIS famous tower will doubtless always be a question, like the man in the iron mask and other historical mysteries. Most architects, however, will be very slow to believe that it would have been built intentionally leaning on the general grounds that, however adventurous the architect, the clients would not have stood it. The analogy of the leaning towers of

Arthur T. Bolton

1910-01-01

357

Cutthroat Trout Virus  

USGS Multimedia Gallery

Electron micrograph of the cutthroat trout virus (CTV) showing the small, round virions of approximately 30 nanometers in diameter containing a single-stranded RNA genome. CTV, whose genome was first characterized by USGS researchers, is being used in research into the human virus Hepatitis E....

358

Universal Indicator Rainbow Trout  

NSDL National Science Digital Library

In this activity on page 2 of the PDF, learners discover how color changes can help scientists distinguish between acids and bases. Learners create colorful rainbow trout artwork using universal indicator solution and various household liquids. Safety note: learners must wear safety goggles.

2013-07-08

359

Hydroacoustic Estimates of Abundance and Spatial Distribution of Pelagic Prey Fishes in Western Lake Superior  

Microsoft Academic Search

Lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) are a valuable prey resource for the recovering lake trout (Salvelinus namaycush) in Lake Superior. However, prey biomass may be insufficient to support the current predator demand. In August 1997, we assessed the abundance and spatial distribution of pelagic coregonines and rainbow smelt in western Lake Superior by combining a 120

Doran M. Mason; Timothy B. Johnson; Chris J. Harvey; James F. Kitchell; Stephen T. Schram; Charles R. Bronte; Michael H. Hoff; Steven J. Lozano; Anett S. Trebitz; Donald R. Schreiner; E. Conrad Lamon; Thomas Hrabik

2005-01-01

360

Bull Trout Population Assessment in the White Salmon and Klickitat Rivers, Columbia River Gorge, Washington, 2001 Annual Report.  

SciTech Connect

We utilized night snorkeling and single pass electroshocking to determine the presence or absence of bull trout Salvelinus confluentus in 26 stream reaches (3,415 m) in the White Salmon basin and in 71 stream reaches (9,005 m) in the Klickitat River basin during summer and fall 2001. We did not find any bull trout in the White Salmon River basin. In the Klickitat River basin, bull trout were found only in the West Fork Klickitat River drainage. We found bull trout in two streams not previously reported: Two Lakes Stream and an unnamed tributary to Fish Lake Stream (WRIA code number 30-0550). We attempted to capture downstream migrant bull trout in the West Fork Klickitat River by fishing a 1.5-m rotary screw trap at RM 4.3 from July 23 through October 17. Although we caught other salmonids, no bull trout were captured. The greatest limiting factor for bull trout in the West Fork Klickitat River is likely the small amount of available habitat resulting in a low total abundance, and the isolation of the population. Many of the streams are fragmented by natural falls, which are partial or complete barriers to upstream fish movement. To date, we have not been able to confirm that the occasional bull trout observed in the mainstem Klickitat River are migrating upstream into the West Fork Klickitat River.

Thiesfeld, Steven L.; McPeak, Ronald H.; McNamara, Brian S. (Washington Department of Fish and Wildlife); Honanie, Isadore (Confederated Tribes and Bands, Yakama Nation)

2002-01-01

361

Application of Lean Concepts to the Teaching of Lean Systems  

NSDL National Science Digital Library

Lean manufacturing organizations, such as Toyota Motor Corporation (TMC), are often described through their outward attributes: just-in-time inventory control, kaizen, emphasis on quality-at-the-source, empowered workers and teams, standardized work, etc. We maintain that these visible characteristics of Lean organizations are intended to support the organization as a continuous learning organization. The systems associated with lean are implemented to enhance the learning of the individuals and the organization itself in a drive for continuous improvement. When successfully implemented, these systems establish a problem-solving culture within the organization, where teams and groups continuously learn, adapt, and improve on a daily basis. In teaching Lean manufacturing in a university setting, educators must teach the content (tools, techniques, and structures) of Lean. Educators should also teach about the culture of lean. If we believe that the structures of lean are effective in enhancing learning in the industry setting and in building a problem-solving culture, then we should consider how these same structures can be translated into the classroom setting. The goal is not only to improve learning, but also to practice what we preach. The teaching of a continuous improving lean system curriculum, at its core, is contingent on developing and deploying a well institutionalized, continuous improving, problem solving culture within the classroom. This paper will argue that TMCs continuous learning lean system is applicable in teaching a lean curriculum at the university college of engineering level. In the next section, we describe the way in which a lean manufacturing organization is a continuous learning system. This is presented in the context of the universal continuous learning model of Fujio Cho during his 1986-1995 startup activities at TMCs Georgetown, Kentucky facility. In subsequent sections, we consider the four elements of continuous learning systems. For each element, we overview what that element means within an industrial setting, and how those ideas are translated into a classroom setting to support a curriculum for undergraduate and graduate education in Lean manufacturing at the University of Kentucky. Section 6 outlines a Lean manufacturing curriculum as it is implemented at one university. Section 7 concludes with some summary statements.

Hall, Arlie

362

Great Lakes water quality scenario models: Operational feasibility -Lake Michigan Mass Balance models  

EPA Science Inventory

An overview of the Lake Michigan Mass Balance models were provided (eutrophication/nutrients, atrazine, mercury, and PCBs) with emphasis on the PCB model post-audit and forecast for Lake Trout. Provided were modeling construct, model description, and primary results. An assessm...

363

Accumulation of polychlorinated biphenyl congeners from Lake Champlain sediments by Mysis relicta  

Microsoft Academic Search

Polychlorinated biphenyl (PCB) levels in lake trout (Salvelinus namaycush) from Lake Champlain often exceed the F.D.A. tolerance level of 2 [mu]g\\/g (wet weight). Of added concern are recent studies that suggest a relationship between the dioxin-like properties of non-ortho-substituted PCB congeners and impaired lake trout egg hatchability. Dietary accumulation of PCBs is thought to be an important exposure route for

Deborah C. Lester; Alan McIntosh

1994-01-01

364

Interacting effects of water temperature and swimming activity on body composition and mortality of fasted juvenile rainbow trout  

USGS Publications Warehouse

Abstract: We assessed changes in proximate body composition, wet mass, and the occurrence of mortality among sedentary and actively swimming (15 cm/s) juvenile rainbow trout (Oncorhynchus mykiss) (120-142 mm total length) that were held at 4.0, 7.5, or 15.0 ??C and fasted for 140 days. Warmer water temperatures and swimming activity accentuated declines in lipid mass, but they did not similarly affect lean mass and wet mass. Swimming fish conserved lean mass independent of water temperature. Because lean mass exceeded lipid mass, wet mass was not affected substantially by decreases in lipid mass. Consequently, wet mass did not accurately reflect the effects that water temperature and swimming activity had on mortality of fasted rainbow trout. Rather, lipid mass was more accurate in predicting death from starvation. Juvenile rainbow trout survived long periods without food, and fish that died of starvation appeared to have similar body composition. It appears that the ability of fish to endure periods without food depends on the degree to which lipid mass and lean mass can be utilized as energy sources.

Simpkins, D.G.; Hubert, W.A.; Martinez Del Rio, C.; Rule, D.C.

2003-01-01

365

The effects of Medieval dams on genetic divergence and demographic history in brown trout populations  

PubMed Central

Background Habitat fragmentation has accelerated within the last century, but may have been ongoing over longer time scales. We analyzed the timing and genetic consequences of fragmentation in two isolated lake-dwelling brown trout populations. They are from the same river system (the Gudenå River, Denmark) and have been isolated from downstream anadromous trout by dams established ca. 600–800 years ago. For reference, we included ten other anadromous populations and two hatchery strains. Based on analysis of 44 microsatellite loci we investigated if the lake populations have been naturally genetically differentiated from anadromous trout for thousands of years, or have diverged recently due to the establishment of dams. Results Divergence time estimates were based on 1) Approximate Bayesian Computation and 2) a coalescent-based isolation-with-gene-flow model. Both methods suggested divergence times ca. 600–800 years bp, providing strong evidence for establishment of dams in the Medieval as the factor causing divergence. Bayesian cluster analysis showed influence of stocked trout in several reference populations, but not in the focal lake and anadromous populations. Estimates of effective population size using a linkage disequilibrium method ranged from 244 to?>?1,000 in all but one anadromous population, but were lower (153 and 252) in the lake populations. Conclusions We show that genetic divergence of lake-dwelling trout in two Danish lakes reflects establishment of water mills and impassable dams ca. 600–800 years ago rather than a natural genetic population structure. Although effective population sizes of the two lake populations are not critically low they may ultimately limit response to selection and thereby future adaptation. Our results demonstrate that populations may have been affected by anthropogenic disturbance over longer time scales than normally assumed. PMID:24903056

2014-01-01

366

A leanness measure of manufacturing systems for quantifying impacts of lean initiatives  

Microsoft Academic Search

Various lean tools and techniques have been developed for process improvement. In order to track the progress, lean metrics were developed correspondingly. However, an integrated and quantitative measure of overall leanness level has not been established. This paper proposes a unit-invariant leanness measure with a self-contained benchmark to quantify the leanness level of manufacturing systems. Evolved from the concept of

Hung-da Wan; F. Frank Chen

2008-01-01

367

Lean, Energy, and Savings: Energy Impacts of Lean Manufacturing  

E-print Network

- often suffer from a perceived inability to accurately quantify resulting savings. The last few decades have seen a proliferation of Lean Manufacturing practices across industry, where organizations focus on eliminating waste. Energy is often a component...

Milward, R.; Gilless, C.; Brown, K.

2013-01-01

368

Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications  

SciTech Connect

Distributed energy is an approach for meeting energy needs that has several advantages. Distributed energy improves energy security during natural disasters or terrorist actions, improves transmission grid reliability by reducing grid load, and enhances power quality through voltage support and reactive power. In addition, distributed energy can be efficient since transmission losses are minimized. One prime mover for distributed energy is the natural gas reciprocating engine generator set. Natural gas reciprocating engines are flexible and scalable solutions for many distributed energy needs. The engines can be run continuously or occasionally as peak demand requires, and their operation and maintenance is straightforward. Furthermore, system efficiencies can be maximized when natural gas reciprocating engines are combined with thermal energy recovery for cooling, heating, and power applications. Expansion of natural gas reciprocating engines for distributed energy is dependent on several factors, but two prominent factors are efficiency and emissions. Efficiencies must be high enough to enable low operating costs, and emissions must be low enough to permit significant operation hours, especially in non-attainment areas where emissions are stringently regulated. To address these issues the U.S. Department of Energy and the California Energy Commission launched research and development programs called Advanced Reciprocating Engine Systems (ARES) and Advanced Reciprocating Internal Combustion Engines (ARICE), respectively. Fuel efficiency and low emissions are two primary goals of these programs. The work presented here was funded by the ARES program and, thus, addresses the ARES 2010 goals of 50% thermal efficiency (fuel efficiency) and <0.1 g/bhp-hr emissions of oxides of nitrogen (NOx). A summary of the goals for the ARES program is given in Table 1-1. ARICE 2007 goals are 45% thermal efficiency and <0.015 g/bhp-hr NOx. Several approaches for improving the efficiency and emissions of natural gas reciprocating engines are being pursued. Approaches include: stoichiometric engine operation with exhaust gas recirculation and three-way catalysis, advanced combustion modes such as homogeneous charge compression ignition, and extension of the lean combustion limit with advanced ignition concepts and/or hydrogen mixing. The research presented here addresses the technical approach of combining efficient lean spark-ignited natural gas combustion with low emissions obtained from a lean NOx trap catalyst aftertreatment system. This approach can be applied to current lean engine technology or advanced lean engines that may result from related efforts in lean limit extension. Furthermore, the lean NOx trap technology has synergy with hydrogen-assisted lean limit extension since hydrogen is produced from natural gas during the lean NOx trap catalyst system process. The approach is also applicable to other lean engines such as diesel engines, natural gas turbines, and lean gasoline engines; other research activities have focused on those applications. Some commercialization of the technology has occurred for automotive applications (both diesel and lean gasoline engine vehicles) and natural gas turbines for stationary power. The research here specifically addresses barriers to commercialization of the technology for large lean natural gas reciprocating engines for stationary power. The report presented here is a comprehensive collection of research conducted by Oak Ridge National Laboratory (ORNL) on lean NOx trap catalysis for lean natural gas reciprocating engines. The research was performed in the Department of Energy's ARES program from 2003 to 2007 and covers several aspects of the technology. All studies were conducted at ORNL on a Cummins C8.3G+ natural gas engine chosen based on industry input to simulate large lean natural gas engines. Specific technical areas addressed by the research include: NOx reduction efficiency, partial oxidation and reforming chemistry, and the effects of sulfur poisons on the partial oxidation

Parks, II, James E [ORNL; Storey, John Morse [ORNL; Theiss, Timothy J [ORNL; Ponnusamy, Senthil [ORNL; Ferguson, Harley Douglas [ORNL; Williams, Aaron M [ORNL; Tassitano, James B [ORNL

2007-09-01

369

The Rationale of Lean and TPM  

E-print Network

TPM is mostly regarded as an integral part of Lean. TPM role in maintenance is similar to TQM in Quality. This paper aims to reach a prescription about the best attitude toward Lean and TPM as well as their implementation. Two companies which have implemented TPM without considering Lean were investigated. They had implemented TPM before Lean, but now believe that a company should start with Lean and grow Lean thinking among the employees. In this paper, Lean and TPM comparison proves that they have several common tools and concepts.

Mohammad R. Arashpour; Mohammad R. Enaghani; Roy Andersson

2010-01-01

370

Rainbow Trout (Oncorhynchus mykiss)  

Microsoft Academic Search

Nano materials have unique antimicrobial properties. The toxic level of nanosilver, with the commercial name of Nanocid was studied. Rainbow trout (Oncorhynchus mykiss) with median weight of 1.049 g, was treated with 1, 2, 5, 10 and 20 ppm of nanosilver. The results were analyzed after 24, 48, 72, and 96 h and the lethality dose obtained between 1.25-10 ppm.

Delavar Shahbazzadeh; Hamed Ahari; Narges Mohammad Rahimi; Farhad Dastmalchi; Mahdi Soltani; Mansour Fotovat; Jafar Rahmannya; Neda Khorasani

371

Competition and Predation as Mechanisms for Displacement of Greenback Cutthroat Trout by Brook Trout  

E-print Network

, Boulder, Colorado 80309-0216, USA Abstract.--Cutthroat trout Oncorhynchus clarkii frequently are displaced cutthroat trout. The greenback cutthroat trout Oncorhynchus clarkii stomias, which is endemic to the South subspecies of cutthroat trout O. clarkii, greenback cutthroat trout declined in abundance during the late

Colorado at Boulder, University of

372

How High Can Brook Trout Jump? A Laboratory Evaluation of Brook Trout Jumping Performance  

Microsoft Academic Search

Quantitative data on how high brook trout Salvelinus fontinalis can jump are crucial for efforts by fisheries managers to exclude brook trout from streams containing native cutthroat trout Oncorhynchus clarkii subspp. and to build effective fishways for brook trout migration. We identified factors that could influence brook trout jumping ability and demonstrated how this knowledge could be applied to improve

Matthew C. Kondratieff; Christopher A. Myrick

2006-01-01

373

Erratum: How High Can Brook Trout Jump? A Laboratory Evaluation of Brook Trout Jumping Performance  

Microsoft Academic Search

Quantitative data on how high brook trout Salvelinus fontinalis can jump are crucial for efforts by fisheries managers to exclude brook trout from streams containing native cutthroat trout Oncorhynchus clarkii subspp. and to build effective fishways for brook trout migration. We identified factors that could influence brook trout jumping ability and demonstrated how this knowledge could be applied to improve

Matthew C. Kondratieff; Christopher A. Myrick

2006-01-01

374

Phylogeographic structure and demographic patterns of brown trout in North-West Africa.  

PubMed

The objectives of the study were to determine the phylogeographic structure of brown trout (Salmo trutta) in Morocco, elucidate their colonization patterns in North-West Africa and identify the mtDNA lineages involved in this process. We also aimed to resolve whether certain brown trout entities are also genetically distinct. Sixty-two brown trout from eleven locations across the Mediterranean and the Atlantic drainages in Morocco were surveyed using sequence analysis of the mtDNA control region and nuclear gene LDH, and by genotyping twelve microsatellite loci. Our study confirms that in Morocco both the Atlantic and Mediterranean basins are populated by Atlantic mtDNA lineage brown trout only, demonstrating that the Atlantic lineage (especially its southern clade) invaded initially not only the western part of the Mediterranean basin in Morocco but also expanded deep into the central area. Atlantic haplotypes identified here sort into three distinct groups suggesting Morocco was colonized in at least three successive waves (1.2, 0.4 and 0.2-0.1 MY ago). This notion becomes more pronounced with the finding of a distinct haplotype in the Dades river system, whose origin appears to coalesce with the nascent stage of the basal mtDNA evolutionary lineages of brown trout. According to our results, Salmo akairos, Salmo pellegrini and "green trout" from Lake Isli do not exhibited any character states that distinctively separate them from the other brown trout populations studied. Therefore, their status as distinct species was not confirmed. PMID:21645626

Snoj, Aleš; Mari?, Saša; Bajec, Simona Sušnik; Berrebi, Patrick; Janjani, Said; Schöffmann, Johannes

2011-10-01

375

Genetic structure of Columbia River redband trout populations in the Kootenai River drainage, Montana, revealed by microsatellite and allozyme loci  

USGS Publications Warehouse

We describe the genetic divergence among 10 populations of redband trout Oncorhynchus mykiss gairdneri from the upper Columbia River drainage. Resident redband trout from two watersheds in the Kootenai River drainage and hatchery stocks of migratory Kamloops redband trout from Kootenay Lake, British Columbia, were analyzed using allele frequency data from microsatellite and allozyme loci. The Kamloops populations have significantly different allele frequencies from those of the Kootenai River drainage. Of the total genetic variation detected in the resident redband trout, 40.7% (microsatellites) and 15.5% (allozymes) were due to differences between populations from the two Kootenai River watersheds. The divergence among populations within each watershed, however, was less than 3.5% with both techniques. Our data indicate that watershed-specific broodstocks of redband trout are needed by fisheries managers for reintroduction or the supplementation of populations at risk of extinction.

Knudsen, K.-L.; Muhlfeld, C.C.; Sage, G.K.; Leary, R.F.

2002-01-01

376

Defect reduction through Lean methodology  

NASA Astrophysics Data System (ADS)

Lean manufacturing is a systematic method of identifying and eliminating waste. Use of Lean manufacturing techniques at the IBM photomask manufacturing facility has increased efficiency and productivity of the photomask process. Tools, such as, value stream mapping, 5S and structured problem solving are widely used today. In this paper we describe a step-by-step Lean technique used to systematically decrease defects resulting in reduced material costs, inspection costs and cycle time. The method used consists of an 8-step approach commonly referred to as the 8D problem solving process. This process allowed us to identify both prominent issues as well as more subtle problems requiring in depth investigation. The methodology used is flexible and can be applied to numerous situations. Advantages to Lean methodology are also discussed.

Purdy, Kathleen; Kindt, Louis; Densmore, Jim; Benson, Craig; Zhou, Nancy; Leonard, John; Whiteside, Cynthia; Nolan, Robert; Shanks, David

2010-09-01

377

Lean premixed/prevaporized combustion  

NASA Technical Reports Server (NTRS)

Recommendations were formulated on the status and application of lean premixed/prevaporized combustion to the aircraft gas turbine for the reduction of pollutant emissions. The approach taken by the NASA Stratospheric Cruise Emission Reduction Program (SCERP) in pursuing the lean premixed/prevaporized combustion technique was also discussed. The proceedings contains an overview of the SCERP program, the discussions and recommendations of the participants, and an overall summary.

Lefebvre, A. H. (editor)

1977-01-01

378

Transitioning to a Lean Enterprise: A Guide for Leaders, Volume II, Transition-to-Lean Roadmap  

E-print Network

Volume II of this guide is a standalone reference model for assisting lean change agents and lean implementation teams in transforming the enterprise to a lean state. It is also of value to enterprise leaders and senior ...

Lean Advancement Initiative

2000-01-01

379

Trout in the Classroom  

NASA Astrophysics Data System (ADS)

Trout in the Classroom (TIC) is a conservation-oriented environmental education program for elementary, middle, and high school students. During the year each teacher tailors the program to fit his or her curricular needs. Therefore, each TIC program is unique. TIC has interdisciplinary applications in science, social studies, mathematics, language arts, fine arts, and physical education. In the program, students and teachers raise trout from fertilized eggs supplied by Virginia Department of Game and Inland Fisheries (VGIF) hatcheries, in aquariums equipped with special chillers designed to keep the water near 50 degrees F. The students make daily temperature measurements, and monitor pH, dissolved oxygen, conductivity, and ammonia levels. They record their data, plot trends, and make sure that the water quality is sufficient to support trout development. The fingerlings, which hatch in late October, are almost an inch and a half long by mid-January. And towards the end of the school year, students will release the fry into VGIF approved watersheds. TIC programs have been in place all across the country for more than 20 years, and are the result of numerous collaborations between teachers, volunteers, government agencies, and local organizations like Trout Unlimited. The programs were designed specifically for teachers who wanted to incorporate more environmental education into their curriculum. While the immediate goal of Trout in the Classroom is to increase student knowledge of water quality and cold water conservation, its long-term goal is to reconnect an increasingly urbanized population of youth to the system of streams, rivers, and watersheds that sustain them. Successful programs have helped: connect students to their local environments and their local watersheds; teach about watershed health and water quality, and; get students to care about fish and the environment. In Virginia, the TIC program is now in its 8th year. Over the past year, the program experienced an amazing growth spurt. Thanks to AEP and Dominion grants and chapter fundraising efforts, we now have more than 200 classrooms throughout the state, ranging from elementary school through high school.

Heath, Thomas

2014-05-01

380

SALMON AND TROUT GO TO SCHOOL  

E-print Network

SALMON AND TROUT GO TO SCHOOL An lnstruction Manual for Hatching Salmon and Trout Eggs in Classroom and Game Native Salmonids of California Map \\|/try Hatcheries? Activities Fish Journals Habitats of Salmon and Trout 11 Seagoing Salmon and Steelhead 12 Trout Life Cycle 13 Salmon and Steelhead Life Cycle 14 Making

Schladow, S. Geoffrey

381

Seasonal patterns in growth, blood consumption, and effects on hosts by parasitic-phase sea lampreys in the Great Lakes: An individual-based model approach  

USGS Publications Warehouse

An individual-based model (IBM) was developed for sea lamprey (Petromyzon marinus) populations in the Laurentian Great Lakes. The IBM was then calibrated to observed growth, by season, for sea lampreys in northern Lake Huron under two different water temperature regimes: a regime experienced by Seneca-strain lake trout (Salvelinus namaycush) and a regime experienced by Marquette-strain lake trout. Modeling results indicated that seasonal blood consumption under the Seneca regime was very similar to that under the Marquette regime. Simulated mortality of lake trout directly due to blood removal by sea lampreys occurred at nearly twice the rate during August and September under the Marquette regime than under the Seneca regime. However, cumulative sea lamprey-induced mortality on lake trout over the entire duration of the sea lamprey's parasitic phase was only 7% higher for the Marquette regime compared with the Seneca regime. Thus, these modeling results indicated that the strain composition of the host (lake trout) population was not important in determining total number of lake trout deaths or total blood consumption attributable to the sea lamprey population, given the sea lamprey growth pattern. Regardless of water temperature regime, both blood consumption rate by sea lampreys and rate of sea lamprey-induced mortality on lake trout peaked in late October. Elevated blood consumption in late October appeared to be unrelated to changes in water temperature. The IBM approach should prove useful in optimizing control of sea lampreys in the Laurentian Great Lakes.

Madenjian, C.P.; Cochran, P.A.; Bergstedt, R.A.

2003-01-01

382

Seasonal patterns in growth, blood consumption, and effects on hosts by parasitic-phase sea lampreys in the Great Lakes: an individual-based model approach  

USGS Publications Warehouse

An individual-based model (IBM) was developed for sea lamprey (Petromyzon marinus) populations in the Laurentian Great Lakes. The IBM was then calibrated to observed growth, by season, for sea lampreys in northern Lake Huron under two different water temperature regimes: a regime experienced by Seneca-strain lake trout (Salvelinus namaycush) and a regime experienced by Marquette-strain lake trout. Modeling results indicated that seasonal blood consumption under the Seneca regime was very similar to that under the Marquette regime. Simulated mortality of lake trout directly due to blood removal by sea lampreys occurred at nearly twice the rate during August and September under the Marquette regime than under the Seneca regime. However, cumulative sea lamprey-induced mortality on lake trout over the entire duration of the sea lamprey's parasitic phase was only 7% higher for the Marquette regime compared with the Seneca regime. Thus, these modeling results indicated that the strain composition of the host (lake trout) population was not important in determining total number of lake trout deaths or total blood consumption attributable to the sea lamprey population, given the sea lamprey growth pattern. Regardless of water temperature regime, both blood consumption rate by sea lampreys and rate of sea lamprey-inuced mortality on lake trout peaked in late October. Elevated blood consumption in late October appeared to be unrelated to changes in water temperature. The IBM approach should prove useful in optimizing control of sea lampreys in the Laurentian Great Lakes.

Madenjian, Charles P.; Cochran, Philip A.; Bergstedt, Roger A.

2003-01-01

383

Status of Oregon's Bull Trout.  

SciTech Connect

Limited historical references indicate that bull trout Salvelinus confluentus in Oregon were once widely spread throughout at least 12 basins in the Klamath River and Columbia River systems. No bull trout have been observed in Oregon's coastal systems. A total of 69 bull trout populations in 12 basins are currently identified in Oregon. A comparison of the 1991 bull trout status (Ratliff and Howell 1992) to the revised 1996 status found that 7 populations were newly discovered and 1 population showed a positive or upgraded status while 22 populations showed a negative or downgraded status. The general downgrading of 32% of Oregon's bull trout populations appears largely due to increased survey efforts and increased survey accuracy rather than reduced numbers or distribution. However, three populations in the upper Klamath Basin, two in the Walla Walla Basin, and one in the Willamette Basin showed decreases in estimated population abundance or distribution.

Buchanan, David V.; Hanson, Mary L.; Hooton, Robert M.

1997-10-01

384

Temporary Restoration of Bull Trout Passage at Albeni Falls Dam  

SciTech Connect

This study was designed to monitor movements of bull trout that were provided passage above Albeni Falls Dam, Pend Oreille River. Electrofishing and angling were used to collect bull trout below the dam. Tissue samples were collected from each bull trout and sent to the U. S. Fish and Wildlife Service Abernathy Fish Technology Center Conservation Genetics Lab, Washington. The DNA extracted from tissue samples were compared to a catalog of bull trout population DNA from the Priest River drainage, Lake Pend Oreille tributaries, and the Clark Fork drainage to determine the most probable tributary of origin. A combined acoustic radio or radio tag was implanted in each fish prior to being transported and released above the dam. Bull trout relocated above the dam were able to volitionally migrate into their natal tributary, drop back downstream, or migrate upstream to the next dam. A combination of stationary radio receiving stations and tracking via aircraft, boat, and vehicle were used to monitor the movement of tagged fish to determine if the spawning tributary it selected matched the tributary assigned from the genetic analysis. Seven bull trout were captured during electrofishing surveys in 2008. Of these seven, four were tagged and relocated above the dam. Two were tagged and left below the dam as part of a study monitoring movements below the dam. One was immature and too small at the time of capture to implant a tracking tag. All four fish released above the dam passed by stationary receivers stations leading into Lake Pend Oreille and no fish dropped back below the dam. One of the radio tags was recovered in the tributary corresponding with the results of the genetic test. Another fish was located in the vicinity of its assigned tributary, which was impassable due to low water discharge at its mouth. Two fish have not been located since entering the lake. Of these fish, one was immature and not expected to enter its natal tributary in the fall of 2008. The other fish was large enough to be mature, but at the time of capture its sex was unable to be determined, indicating it may not have been mature at the time of capture. These fish are expected to enter their natal tributaries in early summer or fall of 2009.

Paluch, Mark; Scholz, Allan; McLellan, Holly [Eastern Washington University Department of Biology; Olson, Jason [Kalispel Tribe of Indians Natural Resources Department

2009-07-13

385

Growth rate differences between resident native brook trout and non-native brown trout  

E-print Network

was examined by tagging and recapturing individual brook trout Salvelinus fontinalis and brown trout Salmo in the decline and displacement of native brook trout Salvelinus fontinalis (Mitchell) (Fausch & White, 1981

Carlson, Stephanie

386

Alberta's ‘Pothole’ Trout Fisheries  

Microsoft Academic Search

Scattered across the prairies and foothills of Alberta lie a series of warm, shallow, rich lakes and reservoirs that vary in size from 15 to 100 acres. These “potholes” are distinguished from the larger lakes of the province by their lack of inlets and outlets. Some contain northern pike and yellow perch; others have small cyprinids only, or cyprinids and

Richard B. Miller; Ronald C. Thomas

1957-01-01

387

Temporary Restoration of Bull Trout Passage at Albeni Falls Dam, 2008 Progress Report.  

SciTech Connect

The goal of this project is to provide temporary upstream passage of bull trout around Albeni Falls Dam on the Pend Oreille River, Idaho. Our specific objectives are to capture fish downstream of Albeni Falls Dam, tag them with combination acoustic and radio transmitters, release them upstream of Albeni Falls Dam, and determine if genetic information on tagged fish can be used to accurately establish where fish are located during the spawning season. In 2007, radio receiving stations were installed at several locations throughout the Pend Oreille River watershed to detect movements of adult bull trout; however, no bull trout were tagged during that year. In 2008, four bull trout were captured downstream of Albeni Falls Dam, implanted with transmitters, and released upstream of the dam at Priest River, Idaho. The most-likely natal tributaries of bull trout assigned using genetic analyses were Grouse Creek (N = 2); a tributary of the Pack River, Lightning Creek (N = 1); and Rattle Creek (N = 1), a tributary of Lightning Creek. All four bull trout migrated upstream from the release site in Priest River, Idaho, were detected at monitoring stations near Dover, Idaho, and were presumed to reside in Lake Pend Oreille from spring until fall 2008. The transmitter of one bull trout with a genetic assignment to Grouse Creek was found in Grouse Creek in October 2008; however, the fish was not found. The bull trout assigned to Rattle Creek was detected in the Clark Fork River downstream from Cabinet Gorge Dam (approximately 13 km from the mouth of Lightning Creek) in September but was not detected entering Lightning Creek. The remaining two bull trout were not detected in 2008 after detection at the Dover receiving stations. This report details the progress by work element in the 2008 statement of work, including data analyses of fish movements, and expands on the information reported in the quarterly Pisces status reports.

Bellgraph, Brian J. [Pacific Northwest National Laboratory

2009-03-31

388

Potential Effects of Climate Warming on Fish Habitats in Temperate Zone Lakes with Special Reference to Lake 239 of the Experimental Lakes Area (ELA), North-Western Ontario  

Microsoft Academic Search

We used simple statistics (e.g. mean temperature, degree days, cumulative volume days) to describe present thermal habitats for cool water (yellow perch, Perca flavescens) and cold water (lake trout, Salvelinus namaycush) fish of a small boreal lake. We then modelled changes in the vertical and temporal extent of these habitats under various scenarios of climatic change that included increases in

Wolfgang Jansen; Raymond H. Hesslein

2004-01-01

389

Some Influences of Domestication upon Three Stocks of Brook Trout (Salvelinus fontinalis Mitchill)  

Microsoft Academic Search

Three stocks of brook trout–domestic, wild, and first generation removed from wild stock–were tested and observed for effects of domestication. The domestic stock had been selectively bred for 90 years, whereas the wild stock came from an isolated lake in the Adirondack Mountains. To reduce differential environmental influence to a minimum, the three lots were reared from eggs in adjacent

Robert E. Vincent

1960-01-01

390

Experimental analysis of trout effects on survival, growth, and habitat use of two species of western Ambystomatid salamanders  

USGS Publications Warehouse

Introduced fish have been implicated as reducing abundance or eliminating ambystomatid salamanders from montane lakes in western North America. We tested the null hypotheses that survivorship, growth, and refuge use of larvae reared for 30 d did not differ between artificial ponds with trout and without trout. Larval survivorship for both A. macrodactylum and A. gracile was significantly lower in ponds with trout than in fishless ponds. Both species had significantly lower snout-vent lengths in ponds with trout than in fishless ponds at the conclusion of the experiments. Only A. gracile had significantly lower body weight in ponds with trout than in ponds without trout. For both species, substrate locations of larvae were significantly influenced by trout at the conclusion of the experiments. Larvae of both species were found in a narrower range of substrates in ponds with fish than in control ponds. Our findings support inferences from field studies that the presence of trout have negative impacts on larval A. macrodactylum and A. gracile.

Tyler, T.; Liss, W.J.; Hoffman, Robert L.; Ganio, L.

1998-01-01

391

Phthalate biotransformation by rainbow trout  

SciTech Connect

The biotransformation of di(2-ethylhexyl)phthalate (DEHP) was studied in rainbow trout because DEHP bioconcentration is limited by metabolism. Biological fluids were collected following intravascular administration. Methylesterified metabolites were identified using rodent-derived standards and nonlinear gradient elution HPLC; metabolites were confirmed by gas chromatography. Similarities between the biotransformation of DEHP by rainbow trout and mammalian species included: (1) mono-2-ethylhexyl phthalate (MEHP) appeared to be the obligatory first step in DEHP metabolism; (2) the phthalate ring was not oxidized; (3) phthalic acid was a minor metabolite; and (4) several metabolites contained multiple oxidations of the 2-ethylhexyl moiety of MEHP. No metabolites unique to rainbow trout were identified. However, fewer oxidized metabolites were identified in rainbow trout than in mammalian species, possibly due to limited mitochondrial metabolism of MEHP in rainbow trout. The amount of biliary MEHP glucuronide after intravascular administration of DEHP was substantially less than reported in rainbow trout exposed to DEHP via the water. The results confirmed that DEHP metabolism in rainbow trout proceeds by initial rapid formation of MEHP, followed by excretion or extensive oxidation by microsomal P450.

Barron, M.G. [RCG/Hagler Bailly, Boulder, CO (United States); Albro, P.W. [NIEHS, Research Triangle Park, NC (United States); Hayton, W.L. [Ohio State Univ., Columbus, OH (United States)

1994-12-31

392

Lean Transformations in Supply Chain, the autocatalytic nature of lean principles, and tactics for implementing lean tools  

E-print Network

Expanding Lean principles beyond the manufacturing floor, ultimately to entail a comprehensive Lean Enterprise, has gained increasing attention among corporations. This thesis entails a detailed case study of initiating a ...

Gardner, Bryan (Bryan Jay)

2008-01-01

393

Control of the sea lamprey (Petromyzon marinus) in Lake Superior, 1953-70  

USGS Publications Warehouse

Although sea lamprey control and heavy plantings of hatchery-reared stock had restored lake trout abundance to prelamprey levels in many areas by 1970, the trout had not yet become self-sustaining. Additional effort will be required to further reduce the effects of lamprey predation.

Smith, Bernard R.; Tibbles, J. James; Johnson, B.G.H.

1974-01-01

394

Caloric Densities of Three Predatory Fishes and Their Prey in Lake Oahe, South Dakota  

Microsoft Academic Search

We determined mean seasonal caloric density of walleye Stizostedion vitreum, chinook salmon Oncorhynchus tschawytscha, rainbow trout Oncorhynchus mykiss and ten species of prey fish from Lake Oahe, South Dakota. Age 3 and older walleye, chinook salmon, and rainbow trout showed distinct seasonal patterns in mean caloric density during May through September, 1994. Energy content of these fish was lowest during

Scott D. Bryan; Craig A. Soupir; Walter G. Duffy; Chris E. Freiburger

1996-01-01

395

Ecology and Control of the Columbia Squawfish in Northern Idaho Lakes  

Microsoft Academic Search

Columbia squawfish, Ptychocheilus oregonensis, and trout were found to occupy similar niches, resulting in competition for food and space, and predation on each other. Mature squawfish are piscivorous with food habits similar to Dolly Varden, Salvelinus malma, rainbow trout, Salmo gairdneri, and brown bullhead, Ictalurus nebulosus. Age and growth data are presented and in northern Idaho lakes a 13-year-old female

Paul W. Jeppson; William S. Platts

1959-01-01

396

Quantitative evaluation of macrophage aggregates in brook trout Salvelinus fontinalis and rainbow trout Oncorhynchus mykiss  

USGS Publications Warehouse

Macrophage aggregates (MAs) occur in various organs of fishes, especially the kidney, liver and spleen, and contain melanin, ceroid/lipofuscin and hemosiderin pigments. They have been used as indicators of a number of natural and anthropogenic stressors. Macrophage aggregates occur in salmonids but are poorly organized, irregularly shaped, and are generally smaller than those in derived teleosts. These features complicate quantification, and thus these fishes have seldom been used in studies correlating MAs with environmental stressors. To alleviate these complications, we developed color filtering algorithms for use with the software package ImagePro Plus?? (Media Cybernetics) that select and quantify pigmented area (i.e. colors ranging from gold to brown to black) in tissue sections. Image analysis results compared well with subjective scoring when tested on brook trout Salvelinus fontinalis and rainbow trout Oncorhynchus mykiss captured from high-elevation lakes or hatcheries. Macrophage aggregate pigments correlated positively with age and negatively with condition factor. Within individual fish, pigmentation correlated positively among organs, suggesting that the kidney, liver or spleen are suitable indicator organs. In age-matched fishes, MA pigments were not different between hatcheries and lakes in the organs examined. Between lakes, differences in pigments were observed in the kidney and spleen, but were not explained by age, condition factor, sex or maturation state. Our results indicate that quantification of the area occupied by MA pigments is an efficient and accurate means of evaluating MAs in salmonid organs and that organ pigmentation correlates with age and condition factor, as seen in studies with more derived fishes. ?? Inter-Research 2006.

Schwindt, A.R.; Truelove, N.; Schreck, C.B.; Fournie, J.W.; Landers, D.H.; Kent, M.L.

2006-01-01

397

Observations on the Longnose Sucker in Yellowstone Lake  

Microsoft Academic Search

An investigation was made of the food, spawning runs, age and growth, and distribution of the longnose sucker Catostomus catostomus in Yellowstone Lake during the summers of 1951 and 1952. This fish was probably accidentally introduced into Yellowstone Lake by bait fishermen in the early thirties. As many as 2,000 specimens were observed with the annual cutthroat-trout runs in Pelican

C. J. D. Brown; Richard J. Graham

1954-01-01

398

Biomass of deepwater demersal forage fishes in Lake Huron, 1994–2007: Implications for offshore predators  

Microsoft Academic Search

We estimated the biomass of deepwater demersal forage fishes (those species common in the diets of lake trout and Chinook salmon) in Lake Huron during the period 1994–2007. The estimated total lake-wide biomass of deepwater demersal fishes in 2007 was reduced by 87 percent of that observed in 1994. Alewife biomass remained near the record low observed in 2004. Biomass

Edward F. Roseman; Stephen C. Riley

2009-01-01

399

Mercury in fish from the Pinchi Lake Region, British Columbia, Canada  

Microsoft Academic Search

Water, surface sediments, and <40cm rainbow trout (Oncorhynchus mykiss) and northern pikeminnow (Ptychocheilus oregonensis) were collected from Pinchi Lake, British Columbia, and from several nearby reference lakes. Hg concentrations in sediment samples from Pinchi L. were highly elevated compared to sediments from reference lakes, especially in sites adjacent to and downstream of a former Hg mine. In both fish species

S. A. Weech; A. M. Scheuhammer; J. E. Elliott; K. M. Cheng

2004-01-01

400

Concentration of Selected Priority Organic Contaminants in Fish Maintained on Formulated Diets in Lake Ontario Waters  

Microsoft Academic Search

Fish were grown in Lake Ontario water under conditions simulating commercial aquaculture and then analyzed for 10 priority organic contaminants. Black bullheads (Ameiurus melas) were grown in cages placed in a bay of Lake Ontario. Rainbow trout (Oncorhynchus mykiss) were grown in terrestrial raceways served with Lake Ontario water. Yearlings were reared on a commercial ration in these systems, which

Joseph K. Buttner; Joseph C. Makarewicz; Theodore W. Lewis

1995-01-01

401

VITELLOGENIN GENE EXPRESSION IN FATHEAD MINNOWS EXPOSED TO EE2 IN A WHOLE LAKE DOSING EXPERIMENT  

EPA Science Inventory

A whole-lake endocrine disruption experiment was conducted by Fisheries and Oceans Canada at the Experimental Lakes Area (ELA), northwestern Ontario in 2001 and 2002. This experiment examined population, organism, biochemical and cellular-level effects in lake trout, white sucke...

402

AGE DEPENDENT MODEL OF PCB IN A LAKE MICHIGAN FOOD CHAIN  

EPA Science Inventory

An age-dependent food chain model that considers species bioenergetics and toxicant exposure through water and food was developed. It was successfully applied to PCB contamination in the Lake Michigan lake trout food chain represented by phytoplankton, Mysis, alewife, and lake tr...

403

Mt. St. Helens ash in lakes in the Lower Grand Coulee, Washington State  

SciTech Connect

In 1979, an experiment to assess the effects of an introduced predator, cutthroat trout (Salmo clarki henshawi), on the biota of two alkaline lakes, Soap Lake and Lake Lenore, in Washington was initiated. This report discusses the effects of the Mt. St. Helens eruption and associated ash fall on the experiment. (ACR)

Edmondson, W.T.; Litt, A.H.

1983-01-01

404

A comparison of slimy sculpin ( Cottus cognatus ) populations in arctic lakes with and without piscivorous predators  

Microsoft Academic Search

Arctic slimy sculpin were sampled by passive trapping in lakes containing the predators lake trout and burbot (LT lakes),\\u000a and lakes lacking sculpin predators (NoLT lakes). Sculpin food abundance (chironomid biomass) from the rocky littoral zone\\u000a was compared with that from the deep water sediment zone. Distribution, size, growth, age, condition and relative abundance\\u000a of sculpin were examined.\\u000a \\u000a Spatial distribution

Kristi L. Hanson; Anne E. Hershey; Michael E. McDonald

1992-01-01

405

Impacts of trout predation on fitness of sympatric sticklebacks and their hybrids.  

PubMed Central

Predation may be a significant factor in the divergence of sympatric species although its role has been largely overlooked. This study examines the consequences of predation on the fitness of a pair of lacustrine stickleback species (Gasterosteus aculeatus complex) and their F(1) hybrids. Benthic sticklebacks are found in the littoral zone of lakes associated with vegetation and bare sediments, whereas limnetic sticklebacks spend most of their lives in the pelagic zone. The cutthroat trout (Oncorhynchus clarki) is a major predator of sticklebacks and the only other fish species native to lakes containing both benthic and limnetic species. In pond experiments we found that the addition of these predators primarily impacted the survival of limnetics. By contrast, benthic survival was unaffected by trout addition. The result was that relative survival of benthics and limnetics was reversed in the presence of trout. The presence of trout had no effect on the rank order of parent species growth rates, with benthics always growing faster than limnetics. F(1) hybrids survived poorly relative to benthics and limnetics and their growth rates were intermediate regardless of treatment. The results implicate predation by trout in the divergence of the species but not through increased vulnerability of F(1) hybrids. PMID:12028775

Vamosi, Steven M; Schluter, Dolph

2002-01-01

406

Wat is Lean Six Sigma? Lean Six Sigma is een standaard-  

E-print Network

Wat is Lean Six Sigma? Lean Six Sigma is een standaard- aanpak voor het organiseren van kwaliteits standaardmodellen voor programmamanagement en de organisatiestructuur, schrijft de Lean Six Sigma aanpak een uitvoering van hun projecten en faciliteren project- tracking. Tot slot biedt Lean Six Sigma een uitgebreide

van Rooij, Robert

407

Wat is Lean Six Sigma? Lean Six Sigma is een standaard-  

E-print Network

Wat is Lean Six Sigma? Lean Six Sigma is een standaard- aanpak voor het organiseren van kwaliteits standaardmodellen voor programmamanagement en de organisatiestructuur, schrijft de Lean Six Sigma aanpak een uitvoering van hun projecten en faciliteren project- tracking.Tot slot biedt Lean Six Sigma een uitgebreide

van Rooij, Robert

408

The Leaning Tower of Pisa  

NSDL National Science Digital Library

The official site of the Leaning Tower of Pisa offers users a comprehensive tour of this historic landmark with 6,400 images and two QTVR films. In addition to the exhaustive photographic tour, which illuminates almost every conceivable detail of the Tower's eight floors (help on navigating the photos is available), the site includes a nice history of the Tower from 1173 to the present, and a fourteen-part exhibit on the building's construction and efforts to conserve the Tower. Simply put, this is THE site for anyone interested in the Leaning Tower of Pisa. Naturally, the site is also available in Italian.

409

Congenital onychogryphosis: Leaning Tower nail.  

PubMed

A 45-year-old man presented with a thickened and raised nail of his left fifth finger since birth. He was otherwise healthy. On examination, the nail of the left little finger was markedly thickened, hyperkeratotic, and situated at an angle of approximately 45 degrees to the long axis of the distal phalanx. There was prominent subungual hyperkeratosis. A diagnosis of congenital onychogryphosis of the little finger of idiopathic nature was considered. Visual analogy to the leaning tower of Pisa encouraged us to describe it as congenital leaning tower nail. PMID:22136865

Nath, Amiya Kumar; Udayashankar, Carounanidy

2011-01-01

410

The missing arguments of lean construction  

Microsoft Academic Search

The emerging concept of lean construction is concerned with the application of lean thinking to the construction industry. The ideas of lean thinking seem set to dominate the UK construction industry's quest to improve quality and efficiency. However, the current debate is based on a highly selective interpretation of the available literature. The extent to which the Japanese model of

S. D. Green

1999-01-01

411

Classification scheme for lean manufacturing tools  

Microsoft Academic Search

For the past few years almost every manufacturing industry has been trying to get 'lean'. A headlong rush to become lean also resulted in many misapplications of existing lean manufacturing tools often due to inadequate understanding of the purpose of tools. While tool descriptions abound, there is no way systematically to link a manufacturing organization to its problems and to

S. J. Pavnaskar; J. K. Gershenson; A. B. Jambekar

2003-01-01

412

Computer simulation to manage lean manufacturing systems  

Microsoft Academic Search

There is a difference between a lean manufacturing system and a manufacturing system that just applies lean techniques. This paper addresses the previous statement through using computer simulation to explore the impact of applying just in time lean policy on a traditional inventory based production system. A system dynamics model is introduced to capture the different components of the production

Ahmed Deif

2010-01-01

413

Pollution Prevention and Lean Manufacturing Paper # 360  

E-print Network

Pollution Prevention and Lean Manufacturing Paper # 360 Harry W. Edwards and Jason M. Jonkman in lean manufacturing is elimination of non-value-added activities through continuous process improvement and reduction of wastes can enhance lean manufacturing. INTRODUCTION The Colorado State University Industrial

414

Squaring lean supply with supply chain management  

Microsoft Academic Search

Lean supply - the system of purchasing and supply chain management required to underpin lean production - has been characterized as “beyond partnership”. Re-examines this idea, comparing the techniques which constitute lean supply with those contained in supply chain management, partnership sourcing, and strategic purchasing. The observations and conclusions are based on research principally in the automotive and electronics industries

Richard Lamming

1996-01-01

415

Implementing Lean into a Servicing Environment  

E-print Network

a change program? RQ3: Is implementation of Lean servicing consistent across role types? 2 LiteratureImplementing Lean into a Servicing Environment Ross Ritchie and Jannis Angelis Warwick Business benchmarking and Kaizen