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1

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

USGS Publications Warehouse

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

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

2003-01-01

2

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

3

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

4

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

5

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

6

Longevity of Lake Superior lake trout  

USGS Publications Warehouse

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

Schram, Stephen T.; Fabrizio, Mary C.

1998-01-01

7

Lake Trout Movements in Northwestern Lake Michigan  

Microsoft Academic Search

We quantified the distance that lake troutSalvelinus namaycushmoved in northwestern Lake Michigan and examined (1) the directional preference and (2) the effect of population density on movement. Lake trout were captured in spring and fall 1983-1996, tagged with Floy anchor tags, and recaptured during subsequent agency sampling and by commercial fishers and anglers during 1983-1997. Angler recaptures were used to

Patrick J. Schmalz; Michael J. Hansen; Mark E. Holey; Patrick C. McKee; Michael L. Toneys

2002-01-01

8

Food of lake trout in Lake Superior  

USGS Publications Warehouse

Stomachs were examined from 1,492 lake trout and 83 siscowets collected from Lake Superior. Data are given on the food of lake trout of legal size (17 inches or longer) by year, season, and depth of water, and on the relation between food and size among smaller lake trout. Fish contributed 96.7 to 99.9 per cent of the total volume of food in the annual samples. Ciscoes (Coregonus spp.) were most common (52.2 to 87.5 per cent of the volume) in 1950 to 1953 and American smelt ranked first (65.6 per cent of the volume) in 1963. Cottids were in 8.9 to 12.3 per cent of the stomachs in 1950 to 1953 but in only 4.3 per cent in 1963. Insects ranked second to fish in occurrence (9.6 per cent for the combined samples) and crustaceans followed at 3.9 per cent. The greatest seasonal changes in the food of lake trout were among fish caught at 35 fathoms and shallower. The occurrence of Coregonus increased from 34.6 per cent in February-March to 71.1 per cent in October-December. Smelt were in 76.9 per cent of the stomachs in February-March but in only 2.2 per cent in October-December. Cottids, Mysis relicta, and insects were most common in the July-September collections. Lake trout taken at depths greater than 35 fathoms had eaten a higher percentage of Cottidae and Coregonus than had those captured in shallower water. Smelt, ninespine sticklebacks, Mysis, and insects were more frequent in stomachs of lake trout from less than 35 fathoms. Crustaceans comprised more than 70 per cent of the total volume of food for 4.0- to 7.9-inch lake trout but their importance decreased as the lake trout grew larger. Pontoporeia affinis was the most common in the stomachs of 4.0- to 6.9-inch lake trout and Mysis held first rank at 7.0 to 12.9 inches. Ostracods were important only to 4.0- to 4.9-inch lake trout. As the lake trout became larger, the importance of fish grew from 4.4-per cent occurrence at 5.0 to 5.9 inches to 93.9 per cent at 16.0 to 16.9 inches. Smelt were most commonly eaten by undersize (less than 17 inches) lake trout.

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

1965-01-01

9

Lake Trout Rehabilitation in Lake Ontario  

Microsoft Academic Search

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

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

1995-01-01

10

Genetic Differentiation among Lake Trout Strains Stocked into Lake Ontario  

Microsoft Academic Search

The lake trout Salvelinus namaycush is the focus of an international effort by fishery management agencies to restore this once-native species to Lake Ontario. Evaluation of reproductive success and comparisons among stocked lake trout strains require genetic markers. We used allozyme variation to make genetic comparisons among strains of lake trout stocked into Lake Ontario. Forty-two proteins presumed to be

Charles C. Krueger; J. Ellen Marsden; Harold L. Kincaid; Bernie May

1989-01-01

11

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

12

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

13

Progress Toward Lake Trout Restoration in Lake Michigan  

Microsoft Academic Search

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

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

1995-01-01

14

Gamete Ripening and Hormonal Correlates in Three Strains of Lake Trout  

Microsoft Academic Search

In our 2-year laboratory study of hatchery-reared adult lake trout Salvelinus namaycush of the Seneca Lake, Marquette (Lake Superior Lean), and Jenny Lake strains, we compared gamete ripening times and changes in plasma concentrations of seven hormones. If interstrain differences in these traits were found, such differences might help explain the apparent failure of stocked fish of these strains to

Neal R. Foster; Daniel V. OConnor; Carl B. Schreck

1993-01-01

15

Spatial patterns in PCB concentrations of Lake Michigan lake trout  

USGS Publications Warehouse

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 (Coregonus hoyi), slimy sculpin (Cottus cognatus), and deepwater sculpin (Myoxocephalus thompsoni), five species of prey fish eaten by lake trout in Lake Michigan, at three nearshore sites in the lake. Despite the lack of significant differences in the PCB concentrations of alewife, rainbow smelt, bloater, slimy sculpin, and deepwater sculpin from the southeastern nearshore site near Saugatuck (Michigan) compared with the corresponding PCB concentrations from the northwestern nearshore site near Sturgeon Bay (Wisconsin), PCB concentrations in lake trout at Saugatuck were significantly higher than those at Sturgeon Bay. The difference in the lake trout PCB concentrations between Saugatuck and Sturgeon Bay could be explained by diet differences. The diet of lake trout at Saugatuck was more concentrated in PCBs than the diet of Sturgeon Bay lake trout, and therefore lake trout at Saugatuck were more contaminated in PCBs that Sturgeon Bay lake trout. These findings were useful in interpreting the long-term monitoring series for contaminants in lake trout at both Saugatuck and the Wisconsin side of the lake.

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

1999-01-01

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

Suitability of habitat for spawning lake trout  

Microsoft Academic Search

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

P. G. Sly; D. O. Evans

1996-01-01

18

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

19

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

20

Density-independent survival of wild lake trout in the Apostle Islands area of Lake Superior  

USGS Publications Warehouse

The lake trout (Salvelinus namaycush) stock at Gull Island Shoal in western Lake Superior was one of only a few stocks of lean lake trout in the Great Lakes that survived overfishing and predation by the sea lamprey (Petromyzon marinus). Since the mid 1960s, the abundance of wild recruits measured at age 0 and the number of age-7 to -11 wild fish recruited to the fishable stock have increased. We used the Varley-Gradwell method to test for density-dependent survival between these life stages. Survival from age-0 to ages 7-11 was not affected by increasing density, which suggests that further increases in recruitment and stock size are still possible. We suggest that testing for the existence of density-dependent survival can be used to indicate when lake trout populations are rehabilitated.

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

1995-01-01

21

Maturity schedules of lake trout in Lake Michigan  

USGS Publications Warehouse

We determined maturity schedules of male and female lake trout (Salvelinus namaycush) in Lake Michigan from nearshore populations and from an offshore population on Sheboygan Reef, which is located in midlake. Gill nets and bottom trawls were used to catch lake trout in fall 1994 and 1995 from two nearshore sites and Sheboygan Reef. Each lake trout was judged immature or mature, based on visual examination of gonads. Probit analysis, coupled with relative potency testing, revealed that age-at-maturity and length-at-maturity were similar at the two nearshore sites, but that lake trout from the nearshore sites matured at a significantly earlier age than lake trout from Sheboygan Reef. However, length at maturity for the nearshore populations was nearly identical to that for the offshore population, suggesting that rate of lake trout maturation in Lake Michigan was governed by growth rather than age. Half of the lake trout males reached maturity at a total length of 580 mm, whereas half of the females were mature at a length of 640 mm. Over half of nearshore males were mature by age 5, and over half the nearshore females matured by age 6. Due to a slower growth rate, maturity was delayed by 2 years on Sheboygan Reef compared with the nearshore populations. Documentation of this delay in maturation may be useful in deciding stocking allocations for lake trout rehabilitation in Lake Michigan.

Madenjian, Charles P.; DeSorcie, Timothy J.; Stedman, Ralph M.

1998-01-01

22

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

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

Lake Trout Surveillance in Michigan's Waters of Lake Michigan.  

National Technical Information Service (NTIS)

The completion report consists of progress reports for 1966, 1967, 1968, and for 1969. Programs to control sea lamprey and reestablish lake trout are reported. The lake trout restoration program started in 1965 with the planting of 1.2 million fin-clipped...

M. Keller

1969-01-01

25

Estimating Potential Yeild and Harvest of Lake Trout 'Salvelinus namaycush' in Minnesota's Lake Trout Lakes, Exclusive of Lake Superior.  

National Technical Information Service (NTIS)

Given that lake trout are highly sought-after and are a limited resource in Minnesota, lake trout populations that may be stressed should be identified. They should be considered for greater protection from over-exploitation by anglers, and greater protec...

G. D. Siesennop

2000-01-01

26

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

USGS Publications Warehouse

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

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

1997-01-01

27

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

28

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

29

Fecundity of hatchery lake trout in Lake Ontario  

USGS Publications Warehouse

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

Fitzsimons, John D.; O'Gorman, Robert

1996-01-01

30

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

31

Genetic Evaluation of a Great Lakes Lake Trout Hatchery Program  

Microsoft Academic Search

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

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

2005-01-01

32

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

USGS Publications Warehouse

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

Van Oosten, John; Eschmeyer, Paul H.

1956-01-01

33

Assessment of Lake Trout Spawning Habitat and Egg Deposition and Survival in Lake Ontario  

Microsoft Academic Search

Identification of the amount of lake trout spawning habitat and its actual use by lake trout in Lake Ontario is important for re-establishment of this species. From a combination of hydrographic field data, bathymetry measurements, and video observations, 20 reputed spawning sites, 14 of which were considered to be historically important, were evaluated for possible use by lake trout. Based

John D. Fitzsimons

1995-01-01

34

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

35

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

36

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

37

Survival of Lake Trout Eggs on Reputed Spawning Grounds in Lakes Huron and Superior: in situ Incubation, 1987–1988  

Microsoft Academic Search

Lake trout reproduce widely in Lake Superior but little in Lake Huron. We examined whether survival of lake trout eggs and fry in either lake was reduced by physical disturbances and swim-up mortality. Eggs were collected from feral lake trout in Lake Superior and placed in 108 plastic incubators. A total of 48 incubators was set at Partridge Island Reef

Bruce A. Manny; Thomas A. Edsall; James W. Peck; Gregory W. Kennedy; Anthony M. Frank

1995-01-01

38

Genetic Analysis of Wild Lake Trout Embryos Recovered from Lake Michigan  

Microsoft Academic Search

The Mid-Lake Reef Complex (MLRC) is a large area of deep reefs that separate the two main basins of Lake Michigan. In an attempt to evaluate which of several strains of lake trout Salvelinus namaycush stocked in Lake Michigan are actively spawning at the MLRC, eggs that had been deposited by spawning lake trout were collected at three sites on

Jenefer DeKoning; Kimberly Keatley; Ruth Phillips; James Rhydderch; John Janssen; Marc Noakes

2006-01-01

39

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

40

Factors affecting feeding behavior and survival of juvenile lake trout in the Great Lakes  

USGS Publications Warehouse

We explored the importance of experience with feeding on live prey, of cataracts, of strain, and of maternally transferred contaminants for the feeding rate and predator avoidance behavior of young lake trout, Salvelinus namaycush. Hatchery-reared and feral juvenile lake trout were tested separately as predators on lake trout fry in tanks with artificial cobble reefs. Feral fish captured more prey per day and more prey per strike than did hatchery lake trout. The predatory performance of hatchery and feral fish did not improve significantly with experience. Feeding rates did not differ between lake trout with unilateral cataracts and normal-eyed fish, but significantly diminished for lake trout with bilateral cataracts. Neither strain nor contaminant background affected the ability of fry to feed or to avoid predators. Of the factors studied, previous experience with live food under natural conditions (i.e., the experience of feral fish) was the most important factor affecting feeding behavior of young lake trout.

Savino, Jacqueline F.; Henry, Mary G.; Kincaid, Harold L.

1993-01-01

41

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

Microsoft Academic Search

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

Michael J. Mac; Carol C. Edsall

1991-01-01

42

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

43

Evaluation of offshore stocking of Lake Trout in Lake Ontario  

USGS Publications Warehouse

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

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

2011-01-01

44

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

USGS Publications Warehouse

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

Manny, Bruce A.; Edsall, Thomas A.

1989-01-01

45

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

46

Do Toxic Substances Pose a Threat to Rehabilitation of Lake Trout in the Great Lakes? A Review of the Literature  

Microsoft Academic Search

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

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

1995-01-01

47

Investigations into Recent Declines in Survival of Brown Trout Stocked in Lake Charlevoix and Thunder Bay, Lake Huron.  

National Technical Information Service (NTIS)

Sharp declines in the Thunder Bay, Lake Huron and Lake Charlevoix brown trout fisheries prompted investigations into the causes of brown trout failures in these waters and possible solutions. Both Thunder Bay and Lake Charlevoix are located in the norther...

J. E. Johnson G. P. Rakoczy

2004-01-01

48

Genetic Assessment of Strain-Specific Sources of Lake Trout Recruitment in the Great Lakes  

Microsoft Academic Search

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

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

2003-01-01

49

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

50

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

USGS Publications Warehouse

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

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

2000-01-01

51

The Effect of Lamprey Attacks upon Lake Trout in Seneca Lake, New York  

Microsoft Academic Search

During an investigation of the spawning habits of the lake trout in Seneca Lake, New York, in October, 1941, it was obvious that an abundant population of sea lampreys was attacking the lake trout. It seemed probable that the attacked fish would be affected by loss of weight. Length-weight data and counts of all lamprey scars were obtained on a

William F. Royce

1950-01-01

52

Growth and Survival of Stocked Lake Trout with Nuclear Cataracts in Lake Ontario  

Microsoft Academic Search

Four strains of yearling lake trout Salvelinus namaycush from the 1985 and 1986 year-classes at the Allegheny National Fish Hatchery were evaluated for nuclear cataracts prior to stocking in Lake Ontario in June 1986 and 1987. Lake trout recaptured by bottom trawling from April to August 1987 and 1988 were examined for cataracts. Cataract frequencies in three strains of yearling

Harold L. Kincaid; Joseph H. Elrod

1991-01-01

53

Lake Trout Population Dynamics at Drummond Island Refuge in Lake Huron: Implications for Future Rehabilitation  

Microsoft Academic Search

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

Charles P. Madenjian; Mark P. Ebener; Timothy J. Desorcie

2008-01-01

54

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

55

Lake trout demographics in relation to burbot and coregonine populations in the Algonquin Highlands, Ontario  

USGS Publications Warehouse

The objective of the study was to test the hypothesis that lake trout populations change in relation to cisco, lake whitefish, round whitefish and burbot populations in lakes in the Algonquin Highlands region of Ontario. Lake trout population change is greatest where cisco and lake whitefish are present. Lake trout populations in lakes without either coregonine tend to have small adults and many juveniles. Where cisco or lake whitefish are present, adult lake trout are large, juvenile abundance is low, and the stock-recruit relationship appears to be uncoupled likely due to a larval bottleneck. Lake trout populations in these lakes may be sensitive to overfishing and recruitment failure. Lake trout populations do not appear to change in relation to round whitefish. There appears to be an indirect positive change on juvenile lake trout abundance through reductions in the density of benthic coregonines in the presence of large, hypolimnetic burbot. ?? 2007 Springer Science+Business Media B.V.

Carl, L. M.

2008-01-01

56

Swimming endurance of bull trout, lake trout, arctic char, and rainbow trout following challenge with Renibacterium salmoninarum  

USGS Publications Warehouse

We tested the swimming endurance of juvenile bull trout Salvelinus confluentus, lake trout S. namaycush, Arctic char S. alpinus, and rainbow trout Oncorhynchus mykiss at 9??C and 15??C to determine whether sublethal infection from a moderate challenge of Renibacterium salmoninarum administered months before testing affected the length of time fish could maintain a swimming speed of 5-6 body lengths per second in an experimental flume. Rainbow trout and Arctic char swam longer in trials than did bull trout or lake trout, regardless of challenge treatment. When we tested fish 14-23 weeks postchallenge, we found no measurable effect of R. salmoninarum on the swimming endurance of the study species except for bull trout, which showed a mixed response. We conducted additional trials with bull trout 5-8 weeks postchallenge to determine whether increasing the challenge dose would affect swimming endurance and hematocrit. In those tests, bull trout with clinical signs of disease and those exposed to the highest challenge doses had significantly reduced swimming endurance compared with unchallenged control fish. Fish hematocrit levels measured at the end of all swimming endurance tests varied among species and between test temperatures, and patterns were not always consistent between challenged and control fish.

Jones, D. T.; Moffitt, C. M.

2004-01-01

57

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

USGS Publications Warehouse

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

Eck, Gary W.; Wells, LaRue

1983-01-01

58

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

59

Predation on lake trout eggs and fry: A modeling approach  

USGS Publications Warehouse

A general model was developed to examine the effects of multiple predators on survival of eggs and fry of lake trout, Salvelinus namaycush, associated with spawning reefs. Three kinds of predation were simulated: epibenthic egg predators consuming eggs on the substrate surface during spawning, interstitial egg predators that can move in rocky substrate and consume incubating eggs, and fry predators. Also simulated was the effect of water temperature on predation rates. The model predicted that interstitial predation on eggs accounted for most (76 to 81%) of the predation on early life history stages of lake trout; epibenthic egg predation (12 to 19%) and fry predation (0 to 12%) had less effect on lake trout survival. Initial predation conditions chosen for the model were: epibenthic egg predation peaked at 2 eggs/mA?/d over 30 d, insterstitial egg predation at 2 eggs/mA?/d over 180 d, and fry predation at 1 fry/mA?/d over 60 d. With a starting egg density of 100 eggs/mA? and initial predation conditions, no lake trout were estimated to survive to swim-up. At egg densities of 250 eggs/mA?, 36% of the lake trout survived. At the highest egg densities examined, 500 to 1,000 eggs/mA?, estimated survival increased to about 70 to 80%. Simulated survival rates of lake trout decreased dramatically as predation rate increased but were not as sensitive to increases in the duration of predation.

Savino, Jacqueline F.; Hudson, Patrick L.; Fabrizio, Mary C.; Bowen, Charles A., II

1999-01-01

60

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

Microsoft Academic Search

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

David L. Perkins; Charles C. Krueger

1995-01-01

61

Population Differences in Chromosome-Banding Polymorphisms in Lake Trout  

Microsoft Academic Search

We used quinacrine hydrochloride and chromomycin A3 staining techniques to examine chromosome-banding polymorphisms in lake trout Salvelinus namaycush from seven wild populations and two hatchery stocks from the Great Lakes region. Although considerable variation in the number of bands occurred among individuals examined by both staining techniques, banding patterns were constant for all cells of a given individual. The populations

Ruth B. Phillips; Kerry D. Zajicek; Peter E. Ihssen

1989-01-01

62

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

Microsoft Academic Search

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

Edward F. Roseman; Wendylee Stott; Timothy P. O'Brien; Stephen C. Riley; Jeffery S. Schaeffer

2009-01-01

63

Habitat Use and Movement Patterns of Brook Trout in Nipigon Bay, Lake Superior  

Microsoft Academic Search

Brook trout Salvelinus fontinalis are one of two salmonine species native to Lake Superior. Abundant and widely distributed a century ago, Lake Superior's brook trout (coasters) have been reduced to a few remnant stocks, probably as a result of exploitation and habitat loss. Twenty brook trout captured in Nipigon Bay, Lake Superior, were surgically implanted with radio transmitters and were

Jamie M. Mucha; Robert W. Mackereth

2008-01-01

64

Field Evaluation of Two Rainbow Trout Strains Introduced into Three British Columbia Lakes  

Microsoft Academic Search

Stocking of rainbow trout Oncorhynchus mykiss is one of the major tools used in the management of recreational fishing in small British Columbia lakes. These fish originate mainly from eggs of native trout in Pennask Lake and partly domesticated trout in Premier Lake, Using samples of the two strains collected with gill nets, we examined growth, survival, and early maturation

Jeremy M. B. Hume; Kanji Tsumura

1992-01-01

65

Status of Lake Trout Rehabilitation on Six Fathom Bank and Yankee Reef in Lake Huron  

Microsoft Academic Search

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

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

2004-01-01

66

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

Microsoft Academic Search

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

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

2005-01-01

67

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

68

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

USGS Publications Warehouse

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

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

2003-01-01

69

Seasonal food of juvenile lake trout in U.S. waters of Lake Ontario  

USGS Publications Warehouse

Stomach contents of 3,554 lake trout (Salvelinus namaycush), 100 to 449 mm in total length, captured with bottom trawls during April through October 1978-81 along the south shore of Lake Ontario were examined. Invertebrates appeared to be an important food of lake trout less than 200 mm long but were only occasionally eaten by larger fish. For all seasons and size groups of juvenile lake trout combined, the slimy sculpin (Cottus cognatus) was the principal forage fish, making up 42% (by weight) of identifiable fish remains. Young-of-the-year slimy sculpins were a major food of recently stocked yearling lake trout during July through October. Alewives (Alosa pseudoharengus) were the principal forage during April and May, and made up 28% (by weight) of the identifiable fish remains. They were rarely eaten during July and August, however, when lake trout remained in the hypolimnion and alewives were above it. Over 99% of the alewives eaten from April through August were yearlings and over 99% eaten during October were young-of-the-year. Rainbow smelt (Osmerus mordax) were the primary forage during July and August, but contributed only a small part of the diet during other seasons; overall, they made up 25% of identifiable fish remains. Johnny darters (Etheostoma nigrum) made up 4% of identifiable fish remains and were most common in stomachs of small lake trout during October.

Elrod, Joseph H.

1983-01-01

70

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

71

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

72

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

73

Effect of Substrate Size on Lake Trout Egg Predation by Mottled Sculpin  

Microsoft Academic Search

Salmonines, including lake trout (Salvelinus namaycush), deposit their eggs in aggregates of rock. Eggs settle into interstitial spaces where they are safe from epibenthic predators, but vulnerable to interstitial predators such as sculpins. This study examined how rock size and mottled sculpin (Cottus bairdi) size affected predation by mottled sculpin on lake trout and rainbow trout (Oncorhynchus mykiss) eggs infield

Heather Biga; John Janssen; J. Ellen Marsden

1998-01-01

74

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

75

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

76

Polychlorinated Biphenyl Residues: Accumulation in Cayuga Lake Trout with Age  

Microsoft Academic Search

The concentration of polychlorinated biphenyls was shown to progressively increase with maturity in a series of lake trout. The presence of these compounds was determined by column chromatographic isolation, specific detector gas chromatography and mass spectrometry. The relation between fish age and the concentration of polychlorinated biphenyls was highly significant.

Carl A. Bache; James W. Serum; William D. Youngs; Donald J. Lisk

1972-01-01

77

Polychlorinated biphenyl residues: accumulation in Cayuga Lake trout with age.  

PubMed

The concentration of polychlorinated biphenyls was shown to progressively increase with maturity in a series of lake trout. The presence of these compounds was determined by column chromatographic isolation, specific detector gas chromatography and mass spectrometry. The relation between fish age and the concentration of polychlorinated biphenyls was highly significant. PMID:4626944

Bache, C A; Serum, J W; Youngs, W D; Lisk, D J

1972-09-29

78

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

79

Gamete ripening and hormonal correlates in three strains of lake trout  

USGS Publications Warehouse

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

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

1993-01-01

80

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

81

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

PubMed

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

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

2009-12-01

82

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

83

Reproductive Potential and Fecundity of Lake Trout Strains in Southern and Eastern Waters of Lake Ontario, 1977–1994  

Microsoft Academic Search

We assessed the reproductive potential of various genetic strains of hatchery lake trout (Salvelinus namaycush) in southern and eastern Lake Ontario from indices of fecundity and indices of male abundance. Indices were constructed from catches of mature lake trout in gill nets during September 1980 to 1994 after correcting for mortality from sea lampreys (Petromyzon marinus) which occurred between September

Robert O’Gorman; Joseph H. Elrod; Clifford P. Schneider

1998-01-01

84

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

85

Naturally Occurring Thiamine Deficiency Causing Reproductive Failure in Finger Lakes Atlantic Salmon and Great Lakes Lake Trout  

Microsoft Academic Search

A maternally transmitted, noninfectious disease known as the Cayuga syndrome caused 100% mortality in larval offspring of wild-caught landlocked Atlantic salmon Salmo salar from several of New York's Finger Lakes. Survival of lake trout Salvelinus namaycush from Lakes Erie and Ontario was also impaired, but not until yolk absorption was nearly complete; moreover, mortality was greatly reduced relative to that

Jeffrey P. Fisher; John D. Fitzsimons; Gerald F. Combs Jr; Jan M. Spitsbergen

1996-01-01

86

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

87

Comparison of Catch and Lake Trout Bycatch, in Commercial Trap Nets and Gill Nets Targeting Lake Whitefish in Northern Lake Huron.  

National Technical Information Service (NTIS)

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 fro...

J. E. Johnson M. P. Ebener K. Gebhardt R. Bergstedt

2004-01-01

88

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...

89

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

90

Performance of Two Strains of Lake Trout Stocked in the Midlake Refuge of Lake Michigan  

Microsoft Academic Search

To evaluate the performance of Seneca and Marquette strains of lake trout Salvelinus namaycush for restoring stocks in southern Lake Michigan, we compared relative abundance (fish per lift of 305 m of gill net), survival (slope of the decline in natural logarithms of relative abundance), growth (von Bertalanffy growth curves), and wounding rates by sea lamprey Petromyzon marinus of the

Patrick C. McKee; Michael L. Toneys; Michael J. Hansen; Mark E. Holey

2004-01-01

91

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

92

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

USGS Publications Warehouse

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

Sakagawa, Gary T.; Pycha, Richard L.

1971-01-01

93

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

94

Susceptibility and humoral response of brown trout X lake trout hybrids to infectious hematopoietic necrosis virus: a model for examining disease resistance mechanisms  

Microsoft Academic Search

A model system for examining resistance mechanisms of interspecific hybrids to a viral disease was designed and tested. Diploid rainbow trout Oncorhynchus mykiss and heat-induced triploid brown trout Salmo trutta female X lake trout Salvelinus namaycush male hybrids (or brake trout) were evaluated for susceptibility and humoral response to infectious hematopoietic necrosis virus (IHNV). The triploid hybrids exposed to waterborne

S. E. LaPatra; K. A. Lauda; G. R. Jones; W. D. Shewmaker; J. M. Groff; D. Routledge

1996-01-01

95

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

USGS Publications Warehouse

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

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

1953-01-01

96

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

97

Coaster Brook Trout Study in Lake Superior and Its North Shore Tributaries Above and Below Barriers. Completion Report.  

National Technical Information Service (NTIS)

Brook trout Salvelinus fontinalis which spend at least part of their life cycle in Lake Superior are termed 'coasters' (Newman and Dubois 1996). Coaster brook trout were once abundant along the Minnesota shoreline of Lake Superior and attracted many angle...

J. Tilma J. Ostazeski S. Morse

1999-01-01

98

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

USGS Publications Warehouse

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

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

2000-01-01

99

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

USGS Publications Warehouse

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

Kincaid, Harold L.; Elrod, Joseph H.

1991-01-01

100

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

USGS Publications Warehouse

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

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

1953-01-01

101

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

102

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

103

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

104

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

105

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

SciTech Connect

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

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

1991-08-01

106

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

USGS Publications Warehouse

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

Mac, Michael J.; Edsall, Carol C.

1991-01-01

107

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

108

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

USGS Publications Warehouse

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

Nester, Robert T.; Poe, Thomas P.

1987-01-01

109

Visualizing the geology of lake trout spawning sites; northern Lake Michigan  

USGS Publications Warehouse

Geologists and biologists are working together to understand the links between lake floor geology (composition and shape) and the distribution of lake trout throughout their life cycle. Lake floor geology is one of the main factors determining where lake trout spawn, feed, and hide. In support of ongoing research to study Lake Michigan trout habitats, the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers mapped the morphology of principle lake trout spawning sites. Using the Army Corps of Engineer's SHOALS airborne lidar (Light Detection and Ranging) system we mapped six regions in Northern Lake Michigan in order to identify ideal spawning regions composed of shallow, clean, gravel/cobble substrate, adjacent to deeper water. Lidar mapping systems, which use laser pulses to measure water depths from an airplane, are now available to map the nearshore lake morphology at meter-scale detail. Maps generated from the bathymetric data are used to define regions with smooth homogeneous substrate, regions with higher relief, and mixed regions with both smooth and rough relief. This morphologic information combined with sediment samples and direct bottom observations enable geologists to map areas with rougher relief composed of rock outcrop, boulders, and cobbles, as well as smooth regions covered with sand or mud. This information helps biologists, fishery managers, and ecologists visualize the lake floor in significant detail which promotes better fishery management, species protection, and habitat identification. These maps present the maps and discuss the geology of the six lake trout spawning sites mapped by the lidar system. Where the mapping approached land, aerial photography of the land is combined with the bathymetric data to help visualize the scale of the offshore features. Map and perspective views of Boulder Reef, Hog Island Reef, and Little Traverse Bay are shown on sheet 1, whereas map and perspective views of Trout and High Island Shoal, Gull Island Reef, and Dahlia Shoal are shown on sheet 2. Additional information, bathymetric data, imagery, and metadata are available online at http://geopubs.wr.usgs.gov/open-file/of03-120/.

Dartnell, Peter; Barnes, Peter; Gardner, James V.; Lee, Kristen

2006-01-01

110

Visualizing the geology of lake trout spawning sites, northern Lake Michigan  

USGS Publications Warehouse

Geologists and biologists are working together to understand the links between lake floor geology (composition and shape) and the distribution of lake trout throughout their life cycle. Lake floor geology is one of the main factors determining where lake trout spawn, feed, and hide. In support of ongoing research to study Lake Michigan trout habitats, the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers mapped the morphology of principle lake trout spawning sites. Using the Army Corps of Engineer's SHOALS airborne lidar (Light Detection and Ranging) system we mapped six regions in Northern Lake Michigan in order to identify ideal spawning regions composed of shallow, clean, gravel/cobble substrate, adjacent to deeper water. Lidar mapping systems, which use laser pulses to measure water depths from an airplane, are now available to map the nearshore lake morphology at meter-scale detail. Maps generated from the bathymetric data are used to define regions with smooth homogeneous substrate, regions with higher relief, and mixed regions with both smooth and rough relief. This morphologic information combined with sediment samples and direct bottom observations enable geologists to map areas with rougher relief composed of rock outcrop, boulders, and cobbles, as well as smooth regions covered with sand or mud. This information helps biologists, fishery managers, and ecologists visualize the lake floor in significant detail which promotes better fishery management, species protection, and habitat identification. These maps present the maps and discuss the geology of the six lake trout spawning sites mapped by the lidar system. Where the mapping approached land, aerial photography of the land is combined with the bathymetric data to help visualize the scale of the offshore features. Map and perspective views of Boulder Reef, Hog Island Reef, and Little Traverse Bay are shown on sheet 1, whereas map and perspective views of Trout and High Island Shoal, Gull Island Reef, and Dahlia Shoal are shown on sheet 2. Additional information, bathymetric data, imagery, and metadata are available online at http://geopubs.wr.usgs.gov/open-file/of03-120/.

Dartnell, Peter; Barnes, Peter; Gardner, James V.; Lee, Kristen

2004-01-01

111

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

USGS Publications Warehouse

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

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

1992-01-01

112

Observed and Calculated Lengths of Lake Trout (Salvelinus namaycush) in Cayuga Lake, New York  

Microsoft Academic Search

Back-calculated lengths of lake trout (Salvelinus namaycush) in Cayuga Lake, New York, were compared with empirical values. The body-scale relationship was sigmoid over a range of fish lengths of 6 to 26 inches; the method of back-calculation involved preparation of a body-scale ruler adapted for use on a conventional direct proportion calculating device. When compared graphically, calculated and observed mean

Dwight A. Webster; William A. Lund Jr; Richard W. Wahl; William D. Youngs

1960-01-01

113

Population Dynamics of Lake Ontario Lake Trout during 1985–2007  

Microsoft Academic Search

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

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

2011-01-01

114

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

115

Predation by sea lamprey (Petromyzon marinus) on lake trout (Salvelinus namaycush) in southern Lake Ontario, 1982-19921,2  

Microsoft Academic Search

Dead lake trout (Salvelinus namuycush) killed by sea lamprey (Petromyzon marinus) were collected from the bottom of Lake Ontario using bottom trawls. The number of dead lake trout per hectare could be predicted from the number of type A-l sea lamprey marks observed on live fish in September gillnet surveys (r2 = 0.60, P < 0.01) but not from the

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

116

Lake Trout Movements in U.S. Waters of Lake Huron Interpreted from Coded Wire Tag Recoveries in Recreational Fisheries  

Microsoft Academic Search

Lake trout management and restoration make use of age-structured population models that incorporate parameters to represent movement among management areas, and harvest quotas are based on proportions of stocked fish remaining in and moving out of areas of release. We investigated movements of lake trout in U.S. waters of Lake Huron based on spatial and temporal distributions of coded-wire-tag (CWT)

Sara A. Adlerstein; Edward S. Rutherford; John A. Clevenger; James E. Johnson; David F. Clapp; Aaron P. Woldt

2007-01-01

117

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

USGS Publications Warehouse

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

Johnson, J. H.

2008-01-01

118

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

119

Effects of Vitamin B1 (Thiamine) Deficiency in Lake Trout Alevins and Preventive Treatments  

Microsoft Academic Search

The objectives of this study were to examine the effect of thiamine immersion of fish from a population known for compromised survival as a result of early mortality syndrome (EMS) and to investigate the cause–response relationship between thiamine concentration and lesions in tissues in swim-up-stage lake trout Salvelinus namaycush alevins. Lake trout eggs from 14 fish from Lake Michigan were

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

2009-01-01

120

Residues of p,p? DDE and mercury in lake trout as a function of age  

Microsoft Academic Search

Lake trout (Salvelinus namaycush) of known age from 1 to 12 years were taken from Cayuga Lake in central New York State in 1991 and p,p'-DDE and mercury were determined in their flesh. The concentrations of p,p'-DDE and mercury increased significantly (pp,p'-DDE also increased significantly (pp,p'-DDE were much lower than those found in Cayuga Lake trout of similar age captured

Walter H. Gutenmann; Joseph G. Ebel; H. Thomas Kuntz; Kenneth S. Yourstone; Donald J. Lisk

1992-01-01

121

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

USGS Publications Warehouse

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

Elrod, Joseph H.

1987-01-01

122

Population recovery and natural recruitment of lake trout at Gull Island Shoal, Lake Superior, 1964-1992  

USGS Publications Warehouse

We documented an increase in the abundance of wild lake trout (Salvelinus namaycush) at Gull Island Shoal in western Lake Superior and examined the relationship between parental-stock size and recruitment of age-0 fish in 1964-1992. Abundance of adult wild female lake trout and densities of age-0 fish both increased during the 28-year period. A significant positive, linear relationship (p = 0.0002) was found between the abundance of wild females on the spawning reef in the fall and density of age-0 lake trout on adjacent nursery grounds in August and September of the following year. The abundance of hatchery-origin females did not explain significant amounts (p = 0.107) of variation in recruitment. We concluded that most recruitment in 1965-1992 was the result of natural reproduction of wild females. After 28 years of recovery the Gull Island Shoal lake trout population appears to have additional capacity to increase because the stock-recruitment relationship is still linear. Therefore, restoration periods on the order of 30 years may be needed for other lake trout populations in the Great Lakes. We recommend that the refuge established to protect this population be maintained to allow further study of the relationship between parental stock and recruitment, and to provide a major source of recruitment to the lake trout population in the surrounding waters.

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

1995-01-01

123

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

124

Differences in Reproduction among Hatchery Strains of Lake Trout at Eight Spawning Areas in Lake Ontario: Genetic Evidence from Mixed-Stock Analysis  

Microsoft Academic Search

The restoration of self-sustaining populations of lake trout to the Great Lakes has involved stocking multiple hatchery strains of lake trout. To determine whether reproductive success varied among strains, embryos and fry from three sites in the eastern basin and four sites in the western basin of Lake Ontario were genetically characterized with allozyme electrophoresis at 18 polymorphic loci. These

David L. Perkins; John D. Fitzsimons; J. Ellen Marsden; Charles C. Krueger; Bernie May

1995-01-01

125

Genetic Comparison of Naturally Spawned and Artificially Propagated Lake Ontario Lake Trout Fry: Evaluation of a Stocking Strategy for Species Rehabilitation  

Microsoft Academic Search

Two strategies have been used in the effort to restore lake trout Salvelinus namaycush to Lake Ontario. First, lake trout strains from multiple wild and hatchery sources have been stocked to maximize genetic variability in the lake, Second, a unique hatchery “strain” of fish to be stocked was created each year with gametes collected from adult, hatchery-origin fish that had

J. Ellen Marsden; Charles C. Krueger; Peter M. Grewe; Harold L. Kincaid; Bernie May

1993-01-01

126

Genetic Comparison of Naturally Spawned and Artificially Propagated Lake Ontario Lake Trout Fry: Evaluation of a Stocking Strategy for Species Rehabilitation  

Microsoft Academic Search

Two strategies have been used in the effort to restore lake trout Salvelinus namaycush to Lake Ontario. First, lake trout strains from multiple wild and hatchery sources have been stocked to maximize genetic variability in the lake. Second, a unique hatchery \\

J. ELLEN MARSDEN; CHARLES C. KRUEGER; PETER M. GREWE; HAROLD L. KINCAID; BERNIE MAY

1993-01-01

127

Hatchery Origins of Naturally Produced Lake Trout Fry Captured in Lake Ontario: Temporal and Spatial Variability Based on Allozyme and Mitochondrial DNA Data  

Microsoft Academic Search

Stocking of juvenile lake trout reared in hatcheries has been one of several management actions used to restore self-sustaining populations of lake trout Salvelinus namaycush in the Great Lakes. Since 1973, Lake Ontario has been stocked predominately with Clearwater, Jenny, Killala, Manitou, Seneca, and Superior strains. Reproductive success of these strains was assessed by using allozyme and mitochondrial DNA (mtDNA)

P. M. Grewe; C. C. Krueger; J. E. Marsden; C. F. Aquadro; B. May

1994-01-01

128

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

129

Comparison of the Growth of Lake Trout Fingerlings from Eggs Taken in Seneca, Saranac, and Raquette Lakes  

Microsoft Academic Search

1. In hatchery practice, the relative growth rates of the fingerling lake trout of the three strains reared in New York State are obscured by two circumstances. First, because of a difference In spawning times, the fingerlings from eggs of wild fish from Seneca Lake usually start to feed nearly a month earlier than those taken from Raquette Lake, and

David C. Haskell

1952-01-01

130

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

131

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

132

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

133

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

134

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

135

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

Microsoft Academic Search

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

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

2005-01-01

136

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

137

Food Interrelationships of Salmon, Trout, Alewives, and Smelt in a Maine Lake  

Microsoft Academic Search

Food habits of landlocked salmon (Salmo salar), brook trout (Salvelinus fontinalis), landlocked alewives (Alosa pseudoharengus), and American smelt (Osmerus mordax) were studied in Echo Lake, Mount Desert Island, Maine, from June, 1967, to May, 1968. Landlocked alewives were introduced into Echo Lake as adults taken from Cayuga Lake, New York, in 1966.Annual salmon diet consisted of invertebrates (mainly insects) and

Robert T. Lackey

1969-01-01

138

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...

139

Lake trout restoration in the Great Lakes: stock-size criteria for natural reproduction  

USGS Publications Warehouse

We examined the question of whether the lake trout restoration program in the Great Lakes has developed brood stocks of adequate size to sustain natural reproduction. Stock size criteria were developed from areas of the Great Lakes where natural reproduction has been successful (defined as detection of age-1 or older recruits by assessment fishing). We contrasted them with stocks in areas with no natural reproduction. Based on the relative abundance of spawners measured in the fall and the presence or absence of natural reproduction in 24 areas of the Great Lakes, we found three distinct sets of lake trout populations. In seven areas of successful natural reproduction, the catch-per-unit-effort (CPE) of spawners ranged from 17 to 135 fish/305 m of gillnet. Stock sizes in these areas were used as a gauge against which stocks in other areas were contrasted. We conclude that stock densities of 17-135 fish/305 m of gill net are adequate for natural reproduction, provided that all other requirements are met. No natural reproduction has been detected in seven other areas, where CPEs of spawners ranged from only 3 to 5 fish/305 m. We conclude that spawning stocks of only 3-5 fish/305 m of net are inadequate to develop measurable natural reproduction. Natural reproduction has also not been detected in ten areas where CPEs of spawners ranged from 43 to 195 fish/305 m of net. We conclude that spawning stocks in these ten areas were adequate to sustain natural reproduction, but that some factor other than parental stock size prevented recruitment of wild lake trout.

Selgeby, James H.; Bronte, Charles R.; Brown, Edward H.; Hansen, Michael J.; Holey, Mark E.; VanAmberg, Jan P.; Muth, Kenneth M.; Makauskas, Daniel B.; Mckee, Patrick; Anderson, David M.; Ferreri, C. Paola; Schram, Stephen T.

1995-01-01

140

Effect of size on lake trout survival after a single sea lamprey attack  

USGS Publications Warehouse

When lake trout Salvelinus namaycush were subjected to a single attack by a sea lamprey Petromyzon marinus in laboratory tests in 1986, percentage mortality was significantly higher in small fish (64%; 469-557 mm; N = 67) than in medium (44%; 559-643 mm; N = 45) or large fish (43%; 660-799 mm; N = 47). Additional studies conducted in 1987 with 55 medium (559-650 mm) and 52 large (660-825 mm) lake trout confirmed that there was no difference in mortality between the two larger size-groups. Mortality declined in lake trout over 559 mm, but was still greater than 43%. This level of mortality and the sea lampreys' apparently active selection of larger fish indicated that, contrary to previously published opinions, large size in lake trout (up to ?800 mm in length) might not allow better survival from single sea lamprey attacks.

Swink, William D.

1990-01-01

141

Growth chronologies of white sucker, Catostomus commersoni , and lake trout, Salvelinus namaycush : a comparison among lakes and between trophic levels  

Microsoft Academic Search

A growth chronology index was used to determine whether changes in ecosystem structure and function in lakes could be associated\\u000a with fish growth histories. Growth chronologies were compared for white suckers, Catostomus commersoni, from Little Moose (oligotrophic), Oneida (eutrophic), and Cayuga (mesotrophic) lakes (New York) from opercular bone growth\\u000a increments, and for lake trout, Salvelinus namaycush, from Little Moose Lake

Nathan G. Smith; Charles C. Krueger; John M. Casselman

2008-01-01

142

Behavior of Post-emergent Lake Trout Fry in the Presence of the Alewife, a Non-native Predator  

Microsoft Academic Search

Although predation by non-native alewife (Alosa pseudoharengus) on lake trout fry (Salvelinus namaycush) has been documented, whether or not emergent lake trout fry innately recognize alewives as predators is unknown. This study investigated the behavior of post-emergent, free-swimming lake trout fry in the presence of alewives. Study objectives were to determine (1) if fry respond to the presence of alewives

Timothy R. Strakosh; Charles C. Krueger

2005-01-01

143

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

144

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

USGS Publications Warehouse

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

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

1994-01-01

145

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

USGS Publications Warehouse

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

Swedberg, Donald V.; Peck, James W.

1984-01-01

146

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

PubMed Central

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

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

2003-01-01

147

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

USGS Publications Warehouse

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

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

2003-01-01

148

Occurrence of a Swim-up Syndrome in Lake Ontario Lake Trout in Relation to Contaminants and Cultural Practices  

Microsoft Academic Search

Collections of lake trout eggs were made from Lake Ontario adults to evaluate the occurrence of a swim-up mortality syndrome and determine its relationship to cultural practices and egg contaminant burdens (PCBs, pesticides, dioxins, furans, polynuclear aromatic hydrocarbons, and trace metals). The syndrome, characterized by hyperexcitability, anorexia, loss of equilibrium, and eventual death, was observed in fry hatched from eggs

John D. Fitzsimons; Susan Huestis; Bill Williston

1995-01-01

149

Acclimation in Simulated Lake Water Increases Survival of Lahontan Cutthroat Trout Challenged with Saline, Alkaline Water from Walker Lake, Nevada  

Microsoft Academic Search

We investigated the effect of acclimation and condition factor (K) on short-term survival of subyearling Lahontan cutthroat trout Oncorhynchus clarkii henshawi reared at Lahontan National Fish Hatchery, Gardnerville, Nevada, and challenged for 1 week with saline, alkaline water from Walker Lake, Nevada. The effect of acclimation and lake-water challenge on plasma osmolality was also investigated. Fish were acclimated for 0,

John P. Bigelow; Wendy M. Rauw; Luis Gomez-Raya

2010-01-01

150

Food Habits of Landlocked Salmon and Brook Trout in a Maine Lake after Introduction of Landlocked Alewives  

Microsoft Academic Search

Stomach analysis of landlocked Atlantic salmon and brook trout from Echo Lake, Maine, indicated that salmon relied more on open water prey (landlocked alewives, rainbow smelt and terrestrial insects) than did brook trout, which fed more on bottom and shoreline prey (sticklebacks, killifish and aquatic invertebrates). Most fish were eaten by salmon and trout in summer and few were eaten

Garrett D. Speirs

1974-01-01

151

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

PubMed

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

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

2008-10-01

152

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

153

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

USGS Publications Warehouse

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

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

2001-01-01

154

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

155

Using Diverse Data Types to Calibrate a Watershed Model of the Trout Lake Basin, Northern Wisconsin  

Microsoft Academic Search

As part of the USGS Water, Energy, and Biogeochemical Budgets project and NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and

R. J. Hunt; D. T. Feinstein; C. D. Pint; M. P. Anderson

2004-01-01

156

An Evaluation of Restoration Efforts in Fishless Lakes Stocked with Exotic Trout  

Microsoft Academic Search

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 paleo- limnological indicators (diatoms, invertebrates, and sediment characteristics) in eight 480-year-old sediment cores from eight lakes, we

Deanne C. Drake; Robert J. Naiman

2000-01-01

157

Residues of p,p'-DDE and mercury in lake trout as a function of age.  

PubMed

Lake trout (Salvelinus namaycush) of known age from 1 to 12 years were taken from Cayuga Lake in central New York State in 1991 and p,p'-DDE and mercury were determined in their flesh. The concentrations of p,p'-DDE and mercury increased significantly (p less than 0.001) with increasing age of the fish. The concentration of p,p'-DDE also increased significantly (p less than 0.001) with increasing fat content. The concentrations of p,p'-DDE were much lower than those found in Cayuga Lake trout of similar age captured in 1978. PMID:1586207

Gutenmann, W H; Ebel, J G; Kuntz, H T; Yourstone, K S; Lisk, D J

1992-05-01

158

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

PubMed

Eggs spawned from Lake Michigan lake trout contain a number of xenobiotic compounds, including polychlorinated biphenyls (PCBs). To assess whether this contamination is sufficient to induce hepatic cytochrome P-450-dependent monooxygenase (MO) activity during early development, the hepatic MO systems of laboratory-cultured offspring of Lake Michigan, Green Bay, and Marquette Hatchery lake trout were compared. Additionally, the induction of hepatic cytochrome P-450 systems in developing lake trout by the commercial PCB mixture, Aroclor 1254 (A1254), was characterized. During late embryonic development and at the swim-up stage, the hepatic MO systems of the feral lake trout offspring appeared induced, based on levels of aryl hydrocarbon hydroxylase (AHH) activity that were 3.5- to 8.6-fold higher than the hatchery control levels. Furthermore, at the swim-up stage the feral trout offspring resembled A1254-treated hatchery fry with regard to the degree of inhibition of hepatic AHH activity by alpha-naphthoflavone, and the presence of an inducible Mr = 58,000 polypeptide in hepatic microsomes. The levels of aminopyrine N-demethylase activity, which was relatively unresponsive to inducers, were moderately lower in the Lake Michigan and Green Bay swim-up fry compared to the hatchery control levels. After 7 months of posthatching laboratory culture, when residues of xenobiotics present at fertilization were greatly diluted by growth, the hepatic MO systems of the Lake Michigan and hatchery trout offspring appeared essentially indistinguishable with regard to a number of parameters. These results indicate that the differences observed between the hatchery and feral trout offspring at earlier stages were not likely to have a genetic basis, but rather were due to a xenobiotic-type induction. Dose-response experiments and residue analysis data indicated that residues of commercial PCB mixtures were at least partially responsible for the effects described here. Overall, these data provide very strong evidence that contamination of Lake Michigan lake trout gametes by PCBs and possibly other xenobiotics caused induction of hepatic MO activity in their progeny. Fish embryos and fry with induced MO systems may have an increased sensitivity to the toxicity of certain environmental contaminants that are metabolically activated by cytochrome P-450. PMID:6542891

Binder, R L; Lech, J J

1984-12-01

159

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

160

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

161

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

162

Fossil zooplankton and the historical status of westslope cutthroat trout in a headwater lake of Glacier National Park, Montana  

USGS Publications Warehouse

Surviving pure-strain populations of westslope cutthroat trout Oncorhynchus clarki lewisi in headwater lakes of Glacier National Park could play an important role in the managed recovery of regional cutthroat trout fisheries. However, uncertainty exists about whether native trout could have naturally invaded several park lakes where they now occur. This study used paleolimnological techniques to address the question of whether the population of native trout in Avalanche Lake is indigenous or became established through an undocumented introduction. The validity of using fossil diapause eggs (ephippia) of the fish-sensitive cladocerans Daphnia spp. as indicators for the historical presence of zooplanktivorous fish was tested with a survey of live zooplankton and corresponding surface-sediment fossil assemblages in eight Glacier Park lakes with or without trout. Analysis of a sediment core from Avalanche Lake dated by lead radioisotopes, historical wildfires, and a flood allowed reconstruction of zooplankton dynamics from about 1700 A.D. to the present. Fossil Daphnia ephippia were rare or absent in Avalanche Lake sediments deposited before 1910, suggesting intense zooplanktivory due to sustained presence of an indigenous population of native cutthroat trout. Fossil evidence for larger Daphnia populations in the 1930s and early 1940s revealed a temporary disturbance of the lake's normal food web interactions during which zooplanktivory was significantly reduced. This disturbance may have resulted from a collapse of the native trout population caused indirectly by failed attempts between 1915 and 1943 to stock Avalanche Lake with Yellowstone cutthroat trout O. clarki bouvieri.

Verschuren, D.; Marnell, L. F.

1997-01-01

163

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

Microsoft Academic Search

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

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

2005-01-01

164

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

165

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

166

Vulnerability of young lake trout to predation after chronic exposure to PCB's and DDE  

USGS Publications Warehouse

The vulnerability of fry of Lake Michigan lake trout (Salvelinus namaycush) to predation by rainbow trout (Salmo gairdneri) was tested after the fry had been exposed to PCB's, DDE, and a combination of these contaminants in both water and food at concentrations corresponding to ambient levels (1X) in water and plankton in Lake Michigan and at levels 5 and 25 times higher. Vulnerability of the fry, measured as the ratio of escapes to predator attacks, was not significantly increased by either 90 or 165 days of exposure to the contaminants at any of the concentrations tested, and no behavioral differences were observed between control and exposed fry in their reaction to predators. Exposure to PCB's and DDE at environmental and higher concentrations thus did not affect the vulnerability of lake trout fry to predation. This observation suggests that the failure of lake trout reproduction in Lake Michigan was not caused by contaminant-induced reductions in the ability of the fry to escape predators.

Mac, Michael J.

1981-01-01

167

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

168

Swimming performance of young lake trout after chronic exposure to PCBs and DDE  

USGS Publications Warehouse

Swimming performance was measured in fry of lake trout (Salvelinus namaycush) exposed to PCB's, DDE, and a combination of these two contaminants in both food and water at concentrations equal to, and 5 and 25 times higher than, levels found in Lake Michigan water and plankton. Fry were tested after about 50, 110, and 165 days of exposure. We measured swimming performance by forcing the fry to swim through a continuous series of incrementally increased velocities until the fish were exhausted. Although we observed significant differences in swimming performance between a few test groups, we detected no relation between swimming performance of the fry and exposure to PCB's or DDE, or both, at the concentrations tested. Inasmuch as swimming performance apparently was not affected by the levels of contamination by PCB's and DDE in Lake Michigan, impairment of swimming by these contaminants cannot account for the failure of lake trout reproduction in Lake Michigan.

Rottiers, Donald V.; Bergstedt, Roger A.

1981-01-01

169

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

170

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. Environ Toxicol Chem 2014;33:1792-1801. © 2014 SETAC. PMID:24764175

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

2014-08-01

171

A trophic position model of pelagic food webs: Impact on contaminant bioaccumulation in lake trout  

SciTech Connect

To test how well use of discrete trophic levels represents pelagic trophic structure, dietary data from > 200 lake trout and pelagic forage fish populations was compiled and calculated a continuous (fractional) measure of trophic position for each population. Lake trout trophic position, which ranged from 3.0 to 4.6, explained 85% of the between-lake variability in mean PCB levels in lake trout muscle tissue, providing a significant improvement over the use of discrete trophic levels as a predictor of contaminant levels. Having demonstrated the utility of trophic position, a generalized {open_quotes}trophic position model{close_quotes} of lake trout food webs was developed. This approach eliminates minor trophic linkages, calculates a fractional measure of each species` trophic position, and aggregates species of similar trophic position into trophic guilds. This {open_quotes}realized{close_quotes} model represents trophic structure in terms of mass transfer and accounts for the complexity and omnivory that characterize aquatic food webs. In our trophic position model, smelt (a species of pelagic forage fish) were designated a trophic guild separate from other pelagic forage fish, due to their elevated trophic position. Separate consideration of smelt was supported by elevated lake trout trophic position, PCB, and Hg levels in lakes containing smelt. Consideration of omnivory caused biomagnification factors (BMFs) to be many times higher than BMFs that ignored omnivory. These omnivory-corrected BMF estimates appeared to be more consistent with values calculated using stable nitrogen isotopes ({delta}{sup 15}N), an alternative continuous measure of trophic position. {delta}{sup 15}N, an alternative continuous measure of trophic position. {delta}{sup 15}N provided trophic position estimates that generally corresponded with our diet-derived estimates. 186 refs., 7 figs., 3 tabs.

Zanden, M.J.V.; Rasmussen, J.B. [McGill Univ., Montreal, Quebec (Canada)

1996-11-01

172

The Effect of B-Vitamins on a Swim-up Syndrome in Lake Ontario Lake Trout  

Microsoft Academic Search

Collect ions of lake trout spawners and eggs were made in Lake Ontario to assess the ameliorative effects of several B-vitamins (thiamine, riboflavin, folic acid, nicotinic acid, pyridoxine hydrochloride) on mortality associated with swim-up syndrome. Vitamins were administered either by water immersion (1 gm\\/L to eggs from one female) or intraperitoneal injection (30 ppm to eggs from five females) into

John D. Fitzsimons

1995-01-01

173

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

174

Relationship between Mercury Concentration and Growth Rates for Walleyes, Northern Pike, and Lake Trout from Quebec Lakes  

Microsoft Academic Search

The relationship between mercury (Hg) concentrations in fish muscle and fish growth rates was assessed for 54 walleye Sander vitreus, 52 northern pike Esox lucius, and 35 lake trout Salvelinus namaycush populations throughout the Province of Quebec, Canada. We used the von Bertalanffy growth model to estimate the ages of fish specimens for a given length, and Hg concentrations in

Mélyssa Lavigne; Marc Lucotte; Serge Paquet

2010-01-01

175

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

176

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

SciTech Connect

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

Ostergaard, D.E.

1987-04-01

177

Juvenile Rainbow Trout Production in New York Tributaries of Lake Ontario: Implications for Atlantic Salmon Restoration  

Microsoft Academic Search

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

James E. McKenna Jr; James H. Johnson

2005-01-01

178

Verifying Identification of Salmon and Trout by Boat Anglers in Lake Ontario  

Microsoft Academic Search

We estimated how well anglers with varying levels of fishing experience identified six salmonid species during creel surveys of the boat angler fishery in Canadian waters of Lake Ontario (1995 and 1996). Anglers were asked to identify the species of their harvested salmon and trout. Angler identifications were compared with identifications made by creel survey technicians. In total, 583 noncharter

James N. Bowlby; Paul J. Savoie

2011-01-01

179

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

Microsoft Academic Search

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

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

2008-01-01

180

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

EPA Science Inventory

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

181

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

182

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

183

Homing and Orientation of Cutthroat Trout (Salmo Clarki) in Yellowstone Lake, with Special Reference to Olfaction and Vision.  

National Technical Information Service (NTIS)

In-season homing was exhibited by mature cutthroat trout (Salmo clarki) displaced from spawning tributaries to Yellowstone Lake during late May to early August 1964, 1965, and 1966. Of 1908 trout tagged and displaced from Clear and Cub creeks to three rel...

J. D. McCleave

1967-01-01

184

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

PubMed

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

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

2010-12-01

185

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

186

Effects of High Levels of Total Dissolved Solids in Walker Lake, Nevada, on Survival and Growth of Lahontan Cutthroat Trout  

Microsoft Academic Search

Walker Lake, Nevada, is an endorheic terminal lake experiencing significant increases in total dissolved solids (TDS) because of culturally derived reductions in inflow and continued evaporative water losses. Maintenance of the Walker Lake fishery for native Lahontan cutthroat trout Oncorhynchus clarki henshawi requires artificial propagation because fish no longer have access to suitable spawning sites upstream in the Walker River.

Bobette R. Dickerson; Gary L. Vinyard

1999-01-01

187

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

188

Relationship between young brown trout density and water quality in tributary streams to lakes in three acidic watersheds.  

National Technical Information Service (NTIS)

This publication examines the relationship between young brown trout densities in lake tributaries, and water chemistry and habitat variables. The study was carried out during the autumn in three acidic, freshwater river systems in western and southwester...

T. Hesthagen B. M. Larsen H. M. Berger T. Forseth

1998-01-01

189

Bathythermal Distribution, Maturity, and Growth of Lake Trout Strains Stocked in U.S. Waters of Lake Ontario, 1978–1993  

Microsoft Academic Search

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

Joseph H. Elrod; Robert O’Gorman; Clifford P. Schneider

1996-01-01

190

Myxobolus cerebralis in native cutthroat trout of the Yellowstone Lake ecosystem  

USGS Publications Warehouse

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

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

2006-01-01

191

Shifts in depth distributions of alewives, rainbow smelt, and age-2 lake trout in southern Lake Ontario following establishment of Dreissenids  

USGS Publications Warehouse

In the mid-1990s, biologists conducting assessments of fish stocks in Lake Ontario reported finding alewives Alosa pseudoharengus, rainbow smelt Osmerus mordax, and juvenile lake trout Salvelinus namaycush at greater depths than in the mid-1980s. To determine if depth distributions shifted coincident with the early 1990s colonization of Lake Ontario by exotic Dreissena mussels, we calculated mean depth of capture for each of the three species during trawl surveys conducted annually during 1978-1997 and examined the means for significant deviations from established patterns. We found that mean capture depth of alewives, rainbow smelt, and age-2 lake trout shifted deeper during the build up of the dreissenid population in Lake Ontario but that timing of the shift varied among seasons and species. Depth shifts occurred first for rainbow smelt and age-2 lake trout in June 1991. In 1992, alewives shifted deeper in June followed by age-2 lake trout in July-August. Finally, in 1993 and 1994, the distribution of lake trout and alewives shifted in April-May. Reasons why the three fishes moved to deeper water are not clear, but changes in distribution were not linked to temperature. Mean temperature of capture after the depth shift was significantly lower than before the depth shift except for alewives in April-May. Movement of alewives, rainbow smelt, and age-2 lake trout to colder, deeper water has the potential to alter growth and reproduction schedules by exposing the fish to different temperature regimes and to alter the food chain, increasing predation on Mysis relicta in deep water and decreasing alewife predation on lake trout fry over nearshore spawning grounds in spring.

O'Gorman, Robert; Elrod, Joseph H.; Owens, Randall W.; Schneider, Clifford P.; Eckert, Thomas H.; Lantry, Brian F.

2000-01-01

192

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

SciTech Connect

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

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

1993-11-01

193

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

USGS Publications Warehouse

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

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

2005-01-01

194

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

195

Effects of Water Temperature on Survival of Eggs and Fry of Lake Trout  

Microsoft Academic Search

Eggs of lake trout (Salvelinus namaycush) were incubated during 1984-1985 and 1985-1986 in chilled water that decreased in temperature from 41.5°F in November to 38.7°F in January and then increased to 45.9°F in February. Ambient water temperatures varied from 51°F in November to 47°F in February. The mean survival (range in parentheses) from fertilization through hatching to a size of

David E. Ostergaard

1987-01-01

196

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

197

The importance of diverse data types to calibrate a watershed model of the Trout Lake Basin, Northern Wisconsin, USA  

Microsoft Academic Search

As part of the USGS Water, Energy, and Biogeochemical Budgets project and the NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to

Randall J. Hunt; Daniel T. Feinstein; Christine D. Pint; Mary P. Anderson

2006-01-01

198

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

199

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

200

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

201

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

202

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

203

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 Jr; Erik J. Olsen

2007-01-01

204

Identification of Parental Origins of Naturally Produced Lake Trout in Lake Ontario: Application of Mixed-Stock Analysis to a Second Generation  

Microsoft Academic Search

Management decisions related to the restoration of a self-perpetuating population of lake trout Salvelinus namaycush in Lake Ontario would be improved with information about differences in the reproductive success of stocked strains. Assessment of differential reproductive success of naturally spawning mixed-stock fish populations requires the use of genetic markers that are transmitted between generations. This paper describes the identification of

J. Ellen Marsden; Charles C. Krueger; Beanie May

1989-01-01

205

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

206

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

SciTech Connect

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

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

1991-02-01

207

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

208

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

209

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

210

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

211

Shifts in Depth Distributions of Alewives, Rainbow Smelt, and Age2 Lake Trout in Southern Lake Ontario following Establishment of Dreissenids  

Microsoft Academic Search

In the mid-1990s, biologists conducting assessments of fish stocks in Lake Ontario reported finding alewives Alosa pseudoharengus, rainbow smelt Osmerus mordax, and juvenile lake trout Salvelinus namaycush at greater depths than in the mid-1980s. To determine if depth distributions shifted coincident with the early 1990s colonization of Lake Ontario by exotic Dreissena mussels, we calculated mean depth of capture for

Robert OGorman; Joseph H. Elrod; Randall W. Owens; Clifford P. Schneider; Thomas H. Eckert; Brian F. Lantry

2000-01-01

212

Temperature selection by young lake trout after chronic exposure to PCB's and DDE  

USGS Publications Warehouse

Temperature selection tests were conducted with fry of Lake Michigan lake trout (Salvelinus namaycush) exposed to PCB's, DDE and a combination of these contaminants in food and water at levels 25 times the ambient levels in plankton and water in Lake Michigan. The observed effect of the contaminants was a lowering of the preferred temperature. After 98 days of exposure, mean preferred temperatures were 10.3A?C for fry exposed to PCB's, 9.8A?C for those exposed to DDE, and 8.7A?C for those exposed to PCB's + DDE, as compared with 11.2A?C for control fry. Frequency distributions of residence temperatures were significantly (P < 0.01) different among all treatments. Such a change in the preferred temperature caused by a contaminant could reduce the energetic efficiency of a fish and thereby reduce growth and survival.

Mac, Michael J.; Bergstedt, Roger A.

1981-01-01

213

Using Diverse Data Types to Calibrate a Watershed Model of the Trout Lake Basin, Northern Wisconsin  

NASA Astrophysics Data System (ADS)

As part of the USGS Water, Energy, and Biogeochemical Budgets project and NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more parameterized model. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance, and the depth of the lake plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target, however, was a conventional regional baseflow target that was important for correctly distributing flow between sub-basins and the regional system. The use of parameter estimation: 1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and 2) provided a best fit for the particular model conceptualization. The model calibration required the use of a "universal" parameter estimation code in order to include all types of observations in the objective function. The methods described here help address issues of watershed complexity and non-uniqueness common to deterministic watershed models.

Hunt, R. J.; Feinstein, D. T.; Pint, C. D.; Anderson, M. P.

2004-12-01

214

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

Microsoft Academic Search

Eggs of lake trout (Salvelinus namaycush) were incubated during 1984-1985 and 1985-1986 in chilled, water that decreased in temperature from 41.5°F in November to 38.7°F in January and then increased to 45.9°F in February. Ambient water temperatures varied from 51°F in November to 47°F in February. The mean survival (range in parentheses) from fertilization through hatching to a size of

Ostergaard

1987-01-01

215

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

PubMed

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

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

2014-05-01

216

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

217

Stability of Allozyme and Mitochondrial DNA Markers among Three Year-Classes of Lake Trout Propagated from Seneca Lake, New York  

Microsoft Academic Search

Lake trout Salvelinus namaycush representing three year-classes (1988, 1989, and 1990) of gametes collected from adults captured in Seneca Lake, New York, were examined for allelic variation at 18 polymorphic loci and for mitochondrial DNA (mtDNA) haplotype variation, mtDNA was digested with the four restriction endonucleases Ava I, Bam H I, Hin f I, and Taq I. Analysis of allelic

Peter M. Grewe; Charles C. Krueger; Charles F. Aquadro; Bernie May

1994-01-01

218

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

EPA Science Inventory

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

219

Trends of chlorinated organic contaminants in Great Lakes trout and walleye from 1970-1998  

USGS Publications Warehouse

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

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

2006-01-01

220

Perfluoroalkyl contaminants in Lake Ontario Lake Trout: detailed examination of current status and long-term trends.  

PubMed

Perfluoroalkyl contaminants (PFCs) were determined in Lake Ontario Lake Trout sampled annually between 1997 and 2008 in order to assess how current trends are responding to recent regulatory bans and voluntary phase-outs. We also combined our measurements with those of a previous study to provide an updated assessment of long-term trends. Concentrations of PFCs generally increased from the late 1970s until the mid-1980s to mid-1990s, after which concentrations either remained unchanged (perfluorooctane sulfonate (PFOS) and perfluorocarboxylates) or declined (perfluorodecanesulfonate (PFDS)). The temporal trends were assessed using three models, quadratic, exponential rise to maximum, and two-segment linear piecewise function, and then evaluated for best fit using Akaike Information Criteria. For PFOS and perfluorocarboxylates, the exponential rise to maximum function had the best fit. This is particularly interesting for PFOS as it suggests that although concentrations in Lake Ontario Lake Trout may have stopped increasing in response to voluntary phase-outs in 2000-2002, declines have yet to be observed. This may be due to continuing input of PFOS from products still in use and/or slow degradation of larger precursor molecules. A power analysis of PFOS suggested that 15 years of data with a within-year sample size of 10 is required to obtain sufficient power (80%) to detect a 5% decreasing trend. However, the length of the monitoring program had a greater influence on the ability to detect a trend compared to within-year sample size. This provides evidence that additional sampling years are required to detect a response to bans and phase-outs, given the variability in the fish data. The lack of observed declines of perfluorocarboxylate residues in fish may be expected as regulations for these compounds were only recently enacted. In contrast to the other compounds, the quadratic model had the best fit for PFDS. The results of this study emphasize the importance of long-term monitoring for assessing the effectiveness of bans and phase-outs on PFCs in the environment. PMID:22553902

Gewurtz, Sarah B; De Silva, Amila O; Backus, Sean M; McGoldrick, Daryl J; Keir, Michael J; Small, Jeff; Melymuk, Lisa; Muir, Derek C G

2012-06-01

221

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

222

Total and Methyl Mercury in 1994-5 Lake Michigan Lake Trout and Forage Fish  

EPA Science Inventory

Total and methyl mercury were analyzed in Lake Michigan fish collected in 1994 and 1995 as part of the Lake Michigan Mass Balance project (LMMB). One predator fish species and five forage fish species were analyzed to determine the bioaccumulative nature of mercury. These data ...

223

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

SciTech Connect

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

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

1994-09-01

224

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

USGS Publications Warehouse

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

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

1999-01-01

225

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

226

Lake trout reproductive behavior: influence of chemosensory cues from young-of-the-year by-products  

USGS Publications Warehouse

Chemosensory cues, particularly those emanating from substrate areas occupied by previously hatched young, may play an important role in the reproductive behavior of lake trout Salvelinus namaycush. Support for this hypothesis was obtained in laboratory experiments. Adults were placed in a large circular pool with four experimental reefs. Egg membranes and feces obtained from young that had hatched earlier were placed in polyester fiber in screen envelopes and positioned on selected reefs. Females approached and males contacted ('cleaned') the treated reefs but not the untreated reefs. Of 6,858 eggs recovered, 92% were from treated reefs. Some of these eggs had been fertilized and provide the first record of volitional spawning by lake trout under artificial conditions. A second experiment was less definitive, because no spawning occurred, but visual observations and analysis of videotaped behavior sequences showed that, again, adults were attracted more to reefs treated with feces of young of the year than to untreated reefs.

Foster, Neal R.

1985-01-01

227

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

228

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

USGS Publications Warehouse

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

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

1990-01-01

229

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

USGS Publications Warehouse

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

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

1990-01-01

230

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

231

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

232

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

233

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

234

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

235

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

236

Sample size requirements and analysis of tag recoveries for paired releases of lake trout  

USGS Publications Warehouse

A simple chi-square test can be used to analyze recoveries from a paired-release experiment to determine whether differential survival occurs between two groups of fish. The sample size required for analysis is a function of (1) the proportion of fish stocked, (2) the expected proportion at recovery, (3) the level of significance (a) at which the null hypothesis is tested, and (4) the power (1-I?) of the statistical test. Detection of a 20% change from a stocking ratio of 50:50 requires a sample of 172 (I?=0.10; 1-I?=0.80) to 459 (I?=0.01; 1-I?=0.95) fish. Pooling samples from replicate pairs is sometimes an appropriate way to increase statistical precision without increasing numbers stocked or sampling intensity. Summing over time is appropriate if catchability or survival of the two groups of fish does not change relative to each other through time. Twelve pairs of identical groups of yearling lake trout Salvelinus namaycush were marked with coded wire tags and stocked into Lake Ontario. Recoveries of fish at ages 2-8 showed differences of 1-14% from the initial stocking ratios. Mean tag recovery rates were 0.217%, 0.156%, 0.128%, 0.121%, 0.093%, 0.042%, and 0.016% for ages 2-8, respectively. At these rates, stocking 12,100-29,700 fish per group would yield samples of 172-459 fish at ages 2-8 combined.

Elrod, Joseph H.; Frank, Anthony

1990-01-01

237

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

238

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

239

The importance of diverse data types to calibrate a watershed model of the Trout Lake Basin, Northern Wisconsin, USA  

NASA Astrophysics Data System (ADS)

As part of the USGS Water, Energy, and Biogeochemical Budgets project and the NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake water plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more detailed parameterization capable of resolving model objectives with well-constrained parameter values. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance and the depth of the lake water plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target overall, however, was a conventional regional baseflow target that led to correct distribution of flow between sub-basins and the regional system during model calibration. The use of an automated parameter estimation code: (1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and (2) allowed assessment of the influence of observed targets on the calibration process. The model calibration required the use of a 'universal' parameter estimation code in order to include all types of observations in the objective function. The methods described in this paper help address issues of watershed complexity and non-uniqueness common to deterministic watershed models.

Hunt, Randall J.; Feinstein, Daniel T.; Pint, Christine D.; Anderson, Mary P.

2006-04-01

240

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

241

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

242

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...

243

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

244

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

245

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

246

METHODOLOGY USED FOR A LABORATORY DETERMINATION OF RELATIVE CONTRIBUTIONS OF WATER, SEDIMENT, AND FOOD CHAIN ROUTES OF UPTAKE FOR 2,3,7,8-TCDD BIOACCUMULATION BY LAKE TROUT IN LAKE ONTARIO  

EPA Science Inventory

A long-term laboratory exposure of lake trout to eke Ontario sediment and smelt (food chain) provided comprehensive bioaccumulation relationships for 2,3,7,8-TCDD. he laboratory exposure was designed to investigate the rates of TCDD uptake via water, sediment, and food under simu...

247

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

248

Genetic differentiation and hybridization in two naturally occurring sympatric trout Salmo spp. forms from a small karstic lake.  

PubMed

In this study, multiple molecular markers [genotyping of 12 nuclear microsatellite loci and the protein-coding gene ldh-c1* plus sequencing of the mitochondrial DNA (mtDNA) control region] were employed to investigate the genetic structure of the two trout forms, Salmo cettii and Salmo fibreni, inhabiting Lake Posta Fibreno, central Italy. The two forms were found to share a unique mtDNA haplotype, belonging to a widespread Mediterranean haplogroup (AD). Bayesian clustering analyses showed that these two forms correspond to well-defined autochthonous gene pools. Genetic introgression between the two gene pools, however, was observed, whose frequency appears to correlate with the environmental features of the spawning sites. The interplay of selection for the spawning sites, philopatry and natural selection can be argued to maintain genetic differentiation despite the lack of complete reproductive isolation. PMID:23398073

Gratton, P; Allegrucci, G; Gandolfi, A; Sbordoni, V

2013-02-01

249

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

250

The Impacts of Atlantic Salmon Stocking on Rainbow Trout in Barnum House Creek, Lake Ontario  

Microsoft Academic Search

We compared the impacts of stocking age-0 Atlantic salmon (Salmo salar) at high and low densities, and no stocking on abundance and growth of age-0 rainbow trout (Oncorhyncus mykiss) in Barnum House Creek, Ontario during 1993 to 2005. A similar stream, Shelter Valley Creek, was chosen as an appropriate reference stream where age-0 Atlantic salmon were not stocked. The catches

Jason P. Dietrich; James N. Bowlby; Bruce J. Morrison; Nicholas E. Jones

2008-01-01

251

Evaluation of Stocked Rainbow Trout Populations in Interior Alaska, 2006.  

National Technical Information Service (NTIS)

Stocked rainbow trout populations were sampled in 10 lakes in the Tanana River and Copper River drainages during 2006 to determine if the stocked fisheries program was meeting management objectives. Rainbow trout populations in nine lakes had regional man...

A. Behr C. Skaugstad D. Reed

2010-01-01

252

Evaluation of temporal and age-related trends of chemically and biologically generated 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in Lake Ontario lake trout, 1977 to 1993  

SciTech Connect

Levels of selected non-, mono-, and di-ortho-substituted polychlorinated biphenyl (PCB) congeners, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) were determined in 4-year-old lake trout from the eastern basin of Lake Ontario, collected from 1977 to 1993. Results confirm that overall levels of contaminants have decreased steadily in lake trout since 1977, and that coplanar PCB levels do not appear to be increasing over time in relation to levels of other PCBs. Contaminant levels in lake trout from 3 to 9 years old, collected in 1988 from the western end of Lake Ontario, show the body burden of contaminants increases with age. Relative levels of coplanar PCBs to other PCBs for the age study samples showed no change, except for PCB 77, which exhibited a slight decrease in relation to total PCB levels. Toxic equivalents (TEQs) were calculated from fish contaminant concentrations measured for the time study using toxic equivalence factors (TEFs) from both mammalian and teleost studies. The relative contributions of PCBs, PCDDs, and PCDFs to total TEQs were examined. When TEFs used for risk assessment are applied to temporal trend data, 15 to 20% of the total TEQs were due to mono-ortho-substituted PCBs; 40 to 50% to non-ortho coplanar PCBs; and 20 to 30% to 2,3,7,8-substituted PCDD and PCDFs. The TEQs determined from lake trout extracts by an H4IIE cell bioassay technique are compared to those determined by chemical analyses, using a variety of TEFs.

Huestis, S.Y.; Servos, M.R.; Whittle, D.M. [Department of Fisheries and Oceans, Burlington, Ontario (Canada). Great Lakes Lab. for Fisheries and Aquatic Sciences; Heuvel, M. van den; Dixon, D.G. [Univ. of Waterloo, Ontario (Canada). Dept. of Biology

1997-02-01

253

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.

Cline, Timothy J.; Bennington, Val; Kitchell, James F.

2013-01-01

254

Loss of genetic integrity in wild lake trout populations following stocking: insights from an exhaustive study of 72 lakes from Qu?bec, 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.

Valiquette, Eliane; Perrier, Charles; Thibault, Isabel; Bernatchez, Louis

2014-01-01

255

CONDITIONS FOR REESTABLISHMENT OF BROOK TROUT SALVELINUS FONTINALIS) POPULATIONS IN ACIDIC LAKES FOLLOWING BASE ADDITION  

Microsoft Academic Search

Some lakes with an historical record of fish populations have undergone acidification and fish no longer exist in these systems. Toxicity data suggest that the inability of fish to survive in these acidic environments is due to increased concentrations of hydrogen ion (H) and aluminum (Al) in the water column. To reestablish fish populations in lakes of this kind it

Steven P. Gloss; Carl L. Schofield; Robert L. Spateholts

1987-01-01

256

Seasonally dynamic diel vertical migrations of Mysis diluviana, coregonine fishes, and siscowet lake trout in the pelagia of western Lake Superior  

USGS Publications Warehouse

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 pelagic food web and (2) examine the mechanisms underlying the observed variability by using models of foraging, growth, and ?. Our results suggest that the opossum shrimp Mysis diluviana, kiyi Coregonus kiyi, and siscowet lake trout Salvelinus namaycush migrate concurrently during each season, but spring migrations are less extensive than summer and fall migrations. In comparison with M. diluviana, kiyis, and siscowets, the migrations by ciscoes C. artedi were not as deep in the water column during the day, regardless of season. Foraging potential and ? probably drive the movement patterns of M. diluviana, while our modeling results indicate that movements by kiyis and ciscoes are related to foraging opportunity and growth potential and receive a lesser influence from ?. The siscowet is an abundant apex predator in the pelagia of Lake Superior and probably undertakes vertical migrations in the water column to optimize foraging efficiency and growth. The concurrent vertical movement patterns of most species are likely to facilitate nutrient transport in this exceedingly oligotrophic ecosystem, and they demonstrate strong linkages between predators and prey. Fishery management strategies should use an ecosystem approach and should consider how altering the densities of long-lived top predators produces cascading effects on the nutrient cycling and energy flow in lower trophic levels.

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

2011-01-01

257

Mammalian and teleost cell line bioassay and chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent concentrations in lake trout (Salvelinus namaycush) from Lake Superior and Lake Ontario, North America  

SciTech Connect

For livers of lake trout from three Great Lakes sites, the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent concentrations (TEQs) were determined in four ways. Bioassay-derived (BD) TEQs were measured with rat (H4IIE) and rainbow trout (RTL-W1) cell lines, and chemistry-derived (CD) TEQs were calculated with TCDD equivalency factors (TEFs) derived with H4IIE and RTL-W1. Generally, BD-TEQs and CD-TEQs for individual samples did not differ significantly for either H4IIE or RTL-W1, indicating that all of the AhR-active compounds in a sample were accounted for by the congener analysis and that these compounds acted in an additive fashion in both mammalian and piscine systems. However, contributions of individual chemicals to overall CD-TEQs differed with H4IIE and RTL-W1 TEFs, and for some individual samples. TEQs did depend on the method used. Hepatic TEQs and ethoxyresorufin-O-deethylase (EROD) levels differed significantly between sites. For TEQs, the order was Glenora > Jackfish Bay > Black Bay; for EROD activity, the order was Jackfish Bay > Glenora = Black Bay. No correlation was found between hepatic TEQs and EROD activity, which suggests that the two measurements are evaluating different but related consequences of contaminant exposure.

Whyte, J.J.; Heuvel, M.R. van den; Clemons, J.H.; Dixon, D.G.; Bols, N.C. [Univ. of Waterloo, Ontario (Canada). Dept. of Biology; Huestis, S.Y. [Dept. of Fisheries and Oceans, Burlington, Ontario (Canada); Servos, M.R. [Environment Canada, Burlington, Ontario (Canada). National Water Research Inst.

1998-11-01

258

Surface- and ground-water characteristics in the Upper Truckee River and Trout Creek watersheds, South Lake Tahoe, California and Nevada, July-December 1996  

USGS Publications Warehouse

The Upper Truckee River and Trout Creek watersheds, South Lake Tahoe, California and Nevada, were studied from July to December 1996 to develop a better understanding of the relation between surface water and ground water. Base flows at 63 streamflow sites were measured in late September 1996 in the Upper Truckee River and Trout Creek watersheds. Most reaches of the main stem of the Upper Truckee River and Trout Creek had gaining or steady flows, with one losing reach in the mid-section of each stream. Twenty-seven of the streamflow sites measured in the Upper Truckee River watershed were on 14 tributaries to the main stem of the Upper Truckee River. Sixteen of the 40 streamflow sites measured in the Upper Truckee River watershed had no measurable flow. Streamflow in Upper Truckee River watershed ranged from 0 to 11.6 cubic feet per second (ft3/s). The discharge into Lake Tahoe from the Upper Truckee River was 11.6 ft3/s, of which, 40 percent of the flow was from ground-water discharge into the main stem, 40 percent was from tributary inflows, and the remaining 20 percent was the beginning flow. Gains from or losses to ground water along streams ranged from a 1.4 cubic feet per second per mile (ft3/s/mi) gain to a 0.5 ft3/s/mi loss along the main stem. Fourteen of the streamflow sites measured in the Trout Creek watershed were on eight tributaries to the main stem of Trout Creek. Of the 23 streamflow sites measured in the Trout Creek watershed, only one site had no flow. Flows in the Trout Creek watershed ranged from zero to 23.0 ft3/s. Discharge into Lake Tahoe from Trout Creek was 23.0 ft3/s, of which, about 5 percent of the flow was from ground-water discharge into the main stem, 75 percent was from tributary inflows, and the remaining 20 percent was the beginning flow. Ground-water seepage rates ranged from a 1.4 ft3/s/mi gain to a 0.9 ft3/s/mi loss along the main stem. Specific conductances measured during the seepage run in September 1996 increased in a downstream direction in the main stem of the Upper Truckee River and remained relatively constant in the main stem of Trout Creek. Water temperatures measured during the seepage run also increased in a downstream direction in both watersheds. Depths to ground water measured at 62 wells in the study area were used with the results of the seepage run to produce a water-level map in the Upper Truckee River and Trout Creek watersheds. Ground-water levels ranged from 1.3 to 69.8 feet below land surface. In the upper sections of the watersheds ground-water flow is generally toward the main stems of Upper Truckee River and Trout Creek, whereas in the lower sections, ground-water flow generally parallels the two streams and flows toward Lake Tahoe. The altitude of ground water between Lake Tahoe and Highway 50 was nearly the same as the lake-surface altitude from July to November 1996. This suggests ground-water discharge beneath the Upper Truckee River and Trout Creek drainages directly to Lake Tahoe was minimal and that much of the ground-water discharge was to the channels of the Upper Truckee River and Trout Creek upstream from Highway 50. Hydraulic gradients ranged from near zero to 1,400 feet per mile. Samples were collected at six surface-water-quality and eight ground-water-quality sites from July through mid-December 1996. Specific conductance of the ground-water-quality sites was higher than that of the surface-water-quality sites. Water temperature and pH median values were similar between ground-water-quality and surface-water-quality sites but ground water had greater variation in pH and surface water had greater variation in water temperature. Ground-water nutrient concentrations were generally higher than those in streams except for bioreactive iron.

Rowe, T. G.; Allander, Kip K.

2000-01-01

259

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...

260

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...

261

Detecting contaminant-induced apoptosis and necrosis in lake trout thymocytes via flow cytometry.  

USGS Publications Warehouse

This chapter details the cytofluorometric techniques employed to assess levels of active (apoptosis) and passive (necrotic) cell death in untreated and contaminant-treated fish thymocytes. The thymus is believed to be a central component of hematopoiesis and immune function in teleosts (Abelli et al., 1996). Hence, chemically-elicited adverse effects to the thymus may result in immunomodulation and organ dysfunction. However, it is not well documented that environmental contaminants induce apoptosis, or programmed cell death. There is some evidence suggesting that low level exposure to waterborne contaminants can specifically induce cell death in the olfactory epithelium of rainbow trout (Julliard et al., 1996). Presently, only limited information is available in the literature regarding apoptotic death in piscine immune cells (Alford et al., 1994; Greenlee et al., 1991).

Sweet, Leonard I.; Passino-Reader, Dora R.; Meier, Peter G.; Omann, Geneva M.

1997-01-01

262

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

263

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

264

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.

2013-07-29

265

Methodology used for a laboratory determination of relative contributions of water, sediment and food-chain routes of uptake for 2,3,7,8-TCDD bioaccumulation by lake trout in Lake Ontario  

SciTech Connect

A long-term laboratory exposure of lake trout to Lake Ontario sediment and smelt (food chain) provided comprehensive bioaccumulation relationships for 2,3,7,8-TCDD. The laboratory exposure was designed to investigate the rates of TCDD uptake via water, sediment, and food under simulated Lake Ontario conditions. Innovative methods of preparing sediment, dosing sediment, preparing food and feeding the fish were developed. Results indicated that bioaccumulation of 2,3,7,8-TCDD occurs primarily through the food chain and secondarily through contact with contaminated sediment. The water exposure route, even under simulated equilibrium conditions, and low suspended solids concentrations did not appear to make a significant contribution to 2,3,7,8-TCDD bioaccumulation.

Batterman, A.R.; Cook, P.M.; Lodge, K.B.; Lothenbach, D.B.; Butterworth, B.C.

1989-01-01

266

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

267

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

268

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

269

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

270

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

271

Lean healthcare.  

PubMed

As healthcare organizations look for new and improved ways to reduce costs and still offer quality healthcare, many are turning to the Toyota Production System of doing business. Rather than focusing on cutting personnel and assets, "lean healthcare" looks to improve patient satisfaction through improved actions and processes. PMID:18615998

Weinstock, Donna

2008-01-01

272

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

273

An Attempt to Rehabilitate a Collapsed Brook Trout Population by Introducing F1 Splake to Control Yellow Perch  

Microsoft Academic Search

Historically, brook trout Salvelinus fontinalis provided an outstanding sport fishery and lived sympatrically with yellow perch Perca flavescens in East Lake, a 30-ha water body in central Ontario. The fishery collapsed when lake access was improved and cottages were built around the shore in the early 1960s. Annual stocking of brook trout did not improve the brook trout fishery. During

Charles R. Rumsey Retired; Nicholas E. Jones; Hugh H. Banks

2007-01-01

274

Food of salmonine predators in Lake Superior, 1981-87  

USGS Publications Warehouse

Diets of ten species of Lake Superior salmonines are described. Rainbow smelt (Osmerus mordax) were the primary prey during all seasons and years for inshore lake trout (Salvelinus namaycush), Pacific salmon (Oncorhynchus spp.), Atlantic salmon (Salmo salar), brown trout (S. trutta), brook trout (Salvelinus fontinalis), and splake (lake trout x brook trout hybrid). Coregonines were the second most-important prey for chinook salmon (O. tshawytscha), siscowet trout (S. namaycush siscowet), and splake. Invertebrates were important to rainbow trout (O. mykiss), coho salmon (O. kisutch), and pink salmon (O. gorbuscha), especially during the summer. Diets of lake trout from inshore and offshore locations differed markedly. Rainbow smelt were the primary food of inshore lake trout, and coregonines were the main food of offshore lake trout. Chinook salmon and inshore lake trout had the most similar diets because they ate similar proportions of rainbow smelt and coregonines. Salmonines generally ate more rainbow smelt and less coregonines in proportion to the abundance of these prey in the lake. If rainbow smelt populations collapse, the ability of salmonines to convert to a diet based on lake herring (Coregonus artedi) could be important to the stability of predator populations.

Conner, David J.; Bronte, Charles R.; Selgeby, James H.; Collins, Hollie L.

1993-01-01

275

Measuring groundwater-surface water interaction and its effect on wetland stream benthic productivity, Trout Lake watershed, northern Wisconsin, USA  

USGS Publications Warehouse

Measurements of groundwater-surface water exchange at three wetland stream sites were related to patterns in benthic productivity as part of the US Geological Survey's Northern Temperate Lakes-Water, Energy and Biogeochemical Budgets (NTL-WEBB) project. The three sites included one high groundwater discharge (HGD) site, one weak groundwater discharge (WGD) site, and one groundwater recharge (GR) site. Large upward vertical gradients at the HGD site were associated with smallest variation in head below the stream and fewest gradient reversals between the stream and the groundwater beneath the stream, and the stream and the adjacent streambank. The WGD site had the highest number of gradient reversals reflecting the average condition being closest to zero vertical gradient. The duration of groundwater discharge events was related to the amount of discharge, where the HGD site had the longest strong-gradient durations for both horizontal and vertical groundwater flow. Strong groundwater discharge also controlled transient temperature and chemical hyporheic conditions by limiting the infiltration of surface water. Groundwater-surface water interactions were related to highly significant patterns in benthic invertebrate abundance, taxonomic richness, and periphyton respiration. The HGD site abundance was 35% greater than in the WGD site and 53% greater than the GR site; richness and periphyton respiration were also significantly greater (p???0.001, 31 and 44%, respectively) in the HGD site than in the GR site. The WGD site had greater abundance (27%), richness (19%) and periphyton respiration (39%) than the GR site. This work suggests groundwater-surface water interactions can strongly influence benthic productivity, thus emphasizing the importance of quantitative hydrology for management of wetland-stream ecosystems in the northern temperate regions. ?? 2005 Elsevier B.V. All rights reserved.

Hunt, R. J.; Strand, M.; Walker, J. F.

2006-01-01

276

Flathead Basin Case History for Bull Trout ('Salvelinus confluentus').  

National Technical Information Service (NTIS)

The following case history for the Flathead Lake and river system (Flathead Complex) has been developed to provide some background and context for exploring bull trout monitoring and evaluation issues. The document provides information on the geography of...

2005-01-01

277

Mercury in Fishes and Their Diet Items from Flathead Lake, Montana  

Microsoft Academic Search

Mercury levels in lake trout Salvelinus namaycush, lake whitefish Coregonus clupeaformis, and benthic invertebrates were investigated in Flathead Lake, Montana. For both fish species, mercury increased with size and age and showed a negative relationship with growth rate. No gender-based differences in mercury levels were observed for either lake trout or lake whitefish. A positive relationship between mercury concentration and

Craig P. Stafford; Barry Hansen; Jack A. Stanford

2004-01-01

278

Computer Simulation of Trophic Level Interrelationships in Cayuga Lake.  

National Technical Information Service (NTIS)

An attempt is described to simulate a particular trophic chain in Cayuga Lake. The chain, consisting of phytoplankton, zooplankton, alewives and lake trout, was selected primarily because it is largely independent of other inhabitants of the lake, and rep...

R. Plant

1973-01-01

279

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

280

The Effects of Increasing Salinity on the Pyramid Lake Fishery.  

National Technical Information Service (NTIS)

Groups of Lahontan Cutthroat Trout were tested in Pyramid Lake water which was altered with the addition of the sodium salts of sulfate, chloride, carbonate and bicarbonate, to simulate conditions in the lake as the lake volume decreases. Trout tested at ...

R. E. L. Taylor

1972-01-01

281

Habitat use by fishes of Lake Superior. I. Diel patterns of habitat use in nearshore and offshore waters of the Apostle Islands region  

USGS Publications Warehouse

Diel patterns of distribution of fishes in nearshore (15–80 m depth) and offshore (>80 m) waters of the Apostle Islands region of Lake Superior were described using bottom trawls, mid-water trawls, and acoustic gear during day and night sampling. These data revealed three types of diel migration: diel vertical migration (DVM), diel bank migration (DBM), and no migration. DVM was expressed by fishes migrating from benthopelagic to pelagic strata and DBM was expressed by fishes migrating horizontally from deeper waters in the day to shallower waters at night while remaining within the benthopelagic stratum. Most fishes that did not exhibit diel migration showed increased nighttime densities as a result of increased activity and movement from benthic to benthopelagic strata. Rainbow Smelt (Osmerus mordax), Cisco (Coregonus artedi), Bloater (C. hoyi), Kiyi (C. kiyi), juvenile Trout-Perch (Percopsis omiscomaycus), and adult siscowet (Salvelinus namaycush siscowet) exhibited DVM. Lake Whitefish (C. clupeaformis), lean Lake Trout (Salvelinus namaycush namaycush), and juvenile siscowet exhibited DBM. Adult Trout-Perch and adult Pygmy Whitefish (Prosopium coulteri) exhibited a mixture of DBM and DVM. Burbot (Lota lota), Slimy Sculpin (Cottus cognatus), Spoonhead Sculpin (C. ricei), and Deepwater Sculpin (Myoxocephalus thompsonii) did not exhibit diel migration, but showed evidence of increased nocturnal activity. Ninespine Stickleback (Pungitius pungitius) exhibited a mixture of DVM and non-migration. Juvenile Pygmy Whitefish did not show a diel change in density or depth distribution. Species showing ontogenetic shifts in depth distribution with larger, adult life stages occupying deeper waters included, Rainbow Smelt, lean and siscowet Lake Trout, Lake Whitefish, Pygmy Whitefish, Ninespine Stickleback and Trout-Perch. Of these species, siscowet also showed an ontogenetic shift from primarily DBM as juveniles to primarily DVM as adults. Across all depths, fishes expressing DVM accounted for 73% of the total estimated community areal biomass (kg ha?1) while those expressing DBM accounted for 25% and non-migratory species represented 2% of the biomass. The proportion of total community biomass exhibiting DVM increased with depth, from 59% to 95% across ?30 m to >90 m depth zones. Along the same depth gradient, the proportion of total community biomass exhibiting DBM declined from 40% to 1%, while non-migrators increased from 1% to 4%. These results indicate that DVM and DBM behaviors are pervasive in the Lake Superior fish community and potentially provide strong linkages that effect coupling of benthic and pelagic and nearshore and offshore habitats.

Gorman, O. T.; Yule, D. L.; Stockwell, J. D.

2012-01-01

282

Polychlorinated biphenyl congeners and selected organochlorines in Lake Superior fish, USA  

Microsoft Academic Search

Walleye, whitefish and whitefish livers, lake trout, and siscowet lake trout were collected from the Apostle Islands Region of Lake Superior. Carp were obtained from a Lake Michigan tributary near Oshkosh, Wisconsin, USA. Each fish species was analyzed for 89 polychlorinated biphenyl congeners, 12 selected organochlorines, and total lipids. Congener profiles varied greatly between the fish species. Carp and whitefish

Shawn L. Gerstenberger; J. A. Dellinger; M. P. Gallinat

1997-01-01

283

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

284

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....

285

Lean health care.  

PubMed

Principles of Lean management are being adopted more widely in health care as a way of improving quality and safety while controlling costs. The authors, who are chief executive officers of rural North Carolina hospitals, explain how their organizations are using Lean principles to improve quality and safety of health care delivery. PMID:23802475

Hawthorne, Henry C; Masterson, David J

2013-01-01

286

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

287

Population dynamics of daphnia pulex and utilization by the rainbow trout (salmo gairdneri)  

Microsoft Academic Search

The effect of rainbow trout (Salmo gairdneri) predation on the population dynamics of the water flea,Daphnia pulex, was examined during 1976 and 1977 in Becker Lake, a small, shallow, productive reservoir in northeastern Arizona.\\u000a \\u000a \\u000a Rainbow trout were size-biased feeders, utilizing daphnids which were 1.3 mm in size or larger. Trout predation uponDaphnia pulex occurred mainly during winter and early spring

William W. Taylor; Shelby D. Gerking

1980-01-01

288

Water Quality (2000-08) and Historical Phosphorus Concentrations from Palelimnological Studies of Swamp and Speckled Trout Lakes, Grand Portage Reservation, Northeastern Minnesota.  

National Technical Information Service (NTIS)

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 In...

J. M. Ramstack M. B. Edlund P. M. Jones V. G. Christensen

2006-01-01

289

Results from the U.S. Great Lakes Fish Monitoring Program and Effects of Lake Processes on Bioaccumulative Contaminant Concentrations  

Microsoft Academic Search

An analysis of composite samples of 820 lake trout, walleye, steelhead, Chinook, and coho from the Laurentian Great Lakes reveals differences in contaminant processing among and between lakes which results in differing concentrations of bioaccumulative contaminants. Generally, contaminants are most concentrated in fish from Lake Michigan and least concentrated in fish from Lake Superior, with the notable exceptions of toxaphene

Daniel L. Carlson; Deborah L. Swackhamer

2006-01-01

290

Genetic diversity of infectious hematopoietic necrosis virus from Feather River and Lake Oroville, California, and virulence of selected isolates for Chinook salmon and rainbow trout  

USGS Publications Warehouse

Infectious hematopoietic necrosis virus (IHNV) is a significant pathogen of young salmonid fishes worldwide but particularly within the historical range of the Pacific Northwest and California. In the Sacramento and San Joaquin River drainages of California, IHNV outbreaks in juvenile Chinook salmon Oncorhynchus tshawytscha have been observed regularly at large production hatcheries, including Coleman National Fish Hatchery (established in 1941) and Feather River State Fish Hatchery (FRH; established in 1967), since facility operations began. Recent severe epidemics at the FRH in 1998 and 2000-2002 prompted investigations into the characteristics and potential sources of virus at this facility. Both phylogenetic analyses of a variable portion of the glycoprotein gene and serologic comparisons based on neutralization with three polyclonal rabbit sera were used to characterize 82 IHNV isolates from the Feather River watershed between 1969 and 2004. All isolates examined were in the L genogroup and belonged to one of three serologic groups typical of IHNV from California. The IHNV isolates from the Feather River area demonstrated a maximum nucleotide sequence divergence of 4.0%, and new isolates appeared to emerge from previous isolates rather than by the introduction of more diverse subgroups from exogenous sources. The earliest isolates examined from the watershed formed the subgroup LI, which disappeared coincidently with a temporal shift to new genetic and serologic types of the larger subgroup LII. Experimental challenges demonstrated no significant differences in the virulence for juvenile Chinook salmon and rainbow trout O. mykiss from selected isolates representing the principal types of IHNV found historically and from recent epidemics at FRH. While most isolates were equally virulent for both host species, one isolate was found to be more virulent for Chinook salmon than for rainbow trout. ?? Copyright by the American Fisheries Society 2007.

Bendorf, C. M.; Kelley, G. O.; Yun, S. C.; Kurath, G.; Andree, K. B.; Hedrick, R. P.

2007-01-01

291

Genetic diversity of infectious hematopoietic necrosis virus from Feather River and Lake Oroville, California, and virulence of selected isolates for Chinook salmon and rainbow trout.  

PubMed

Infectious hematopoietic necrosis virus (IHNV) is a significant pathogen of young salmonid fishes worldwide but particularly within the historical range of the Pacific Northwest and California. In the Sacramento and San Joaquin River drainages of California, IHNV outbreaks in juvenile Chinook salmon Oncorhynchus tshawytscha have been observed regularly at large production hatcheries, including Coleman National Fish Hatchery (established in 1941) and Feather River State Fish Hatchery (FRH; established in 1967), since facility operations began. Recent severe epidemics at the FRH in 1998 and 2000-2002 prompted investigations into the characteristics and potential sources of virus at this facility. Both phylogenetic analyses of a variable portion of the glycoprotein gene and serologic comparisons based on neutralization with three polyclonal rabbit sera were used to characterize 82 IHNV isolates from the Feather River watershed between 1969 and 2004. All isolates examined were in the L genogroup and belonged to one of three serologic groups typical of IHNV from California. The IHNV isolates from the Feather River area demonstrated a maximum nucleotide sequence divergence of 4.0%, and new isolates appeared to emerge from previous isolates rather than by the introduction of more diverse subgroups from exogenous sources. The earliest isolates examined from the watershed formed the subgroup LI, which disappeared coincidently with a temporal shift to new genetic and serologic types of the larger subgroup LII. Experimental challenges demonstrated no significant differences in the virulence for juvenile Chinook salmon and rainbow trout O. mykiss from selected isolates representing the principal types of IHNV found historically and from recent epidemics at FRH. While most isolates were equally virulent for both host species, one isolate was found to be more virulent for Chinook salmon than for rainbow trout. PMID:18333482

Bendorf, Christin M; Kelley, Garry O; Yun, Susan C; Kurath, Gael; Andree, Karl B; Hedrick, Ronald P

2007-12-01

292

Management of Lake Taneycomo, Missouri. Job 3: Management Evaluation. Sport Fish Restoration Project F-1-R-51.  

National Technical Information Service (NTIS)

Lake Taneycomo is Missouri's largest body of coldwater habitat and supports a popular fishery for both rainbow and brown trout. A decline in the put-grow-and-take rainbow fishery prompted numerous studies that concluded rainbow trout experienced degraded ...

1991-01-01

293

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

Federal Register 2010, 2011, 2012, 2013

...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

294

Seasonal Patterns in Growth, Blood Consumption, and Effects on Hosts by Parasitic-Phase Sea Lampreys in the Great Lakes: An Individual-Based Model Approach  

Microsoft Academic Search

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 Marquettestrain lake trout. Modeling results indicated

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

2003-01-01

295

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

296

Rethinking Lean Service  

NASA Astrophysics Data System (ADS)

Ever since Levitt's influential Harvard Business Review article 'Production-Line Approach to Service' was published in 1972, it has been common for services to be treated like production lines in both the academic literature and more widely in management practice. The belief that achieving economies of scale will reduce unit costs is a common feature of management decision-making. As technological advancement has produced ever more sophisticated IT and telephony, it has become increasingly easier for firms to standardise and off-shore services. The development of the 'lean' literature has only helped to emphasise the same underlying management assumptions: by managing cost and workers' activity, organisational performance is expected to improve. This chapter argues that through misinterpretation of the core paradigm 'lean' has become subsumed into the 'business as usual' of conventional service management. As a result, 'lean' has become synonymous with 'process efficiency' and the opportunity for significant performance improvement - as exemplified by Toyota - has been missed.

Seddon, John; O'Donovan, Brendan; Zokaei, Keivan

297

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

298

LEAN LANDING GEAR DESIGN  

Microsoft Academic Search

Lean design involves carefully establishing the functionality required in a mechanism or structure and then embodying only that functionality and nothing else, in the design. This approach is applied to the design of the torque links in the main landing gear system of the Airbus family of aircraft. Different possible mechanism arrangements are explored and for each, the optimum material

M J Platts

2000-01-01

299

Lean to Health  

Microsoft Academic Search

LEARNING OUTCOME: To define the four levels of intervention of the Lowfat Chinese Cuisine Campaign in San FranciscoThe goal of the Lean to Health: Lowfat Chinese Cuisine Campaign is to help people identify healthy food choices and learn new and creative ways to cook Chinese food. The campaign includes 4 levels of interventions: 1)enhancing individual knowledge and skills via the

C. Wong; G. Lam

1997-01-01

300

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

301

The Lean Woman  

Microsoft Academic Search

Objective: In the current obesity epidemic, the ability to remain lean is beginning to be uncommon. Therefore, it was considered of interest to characterize such subjects.Research Methods and Procedures: From a population of premenopausal women (n = 270), all 40 years of age, those with a similar body mass index (BMI) as women at the age of 21 years, born

Fariba Baghaei; Roland Rosmond; Lars Westberg; Monica Hellstrand; Mikael Landén; Elias Eriksson; Göran Holm; Per Björntorp

2002-01-01

302

A Comparison of Susceptibility to Myxobolus cerebralis among Strains of Rainbow Trout and Steelhead in Field and Laboratory Trials  

Microsoft Academic Search

Three strains of rainbow trout and steelhead Oncorhynchus mykiss were evaluated for the presence of whirling disease in field and laboratory trials. In the field exposures, fingerling Salmon River steelhead and Cayuga Lake and Randolph strains of rainbow trout were placed in wire cages in an earthen, stream-fed pond in New York State that was known to harbor Myxobolus cerebralis.

C. L. Densmore; V. S. Blazer; D. D. Cartwright; W. B. Schill; J. H. Schachte; C. J. Petrie; M. V. Batur; T. B. Waldrop; A. Mack; P. S. Pooler

2001-01-01

303

The origin of introduced rainbow trout ( Oncorhynchus mykiss ) in the Santa Cruz River, Patagonia, Argentina, as inferred from mitochondrial DNA  

Microsoft Academic Search

Rainbow trout (Oncorhynchus mykiss) was first introduced into Argentinean Patagonia, the southernmost region of South America, from the United States in 1904 and at present constitutes the most conspicuous freshwater fish in lakes and rivers of the region. The Santa Cruz River in Southern Patagonia is the only river in the world where a self-sustained population of introduced rainbow trout

Carla M. Riva Rossi; Enrique P. Lessa; Miguel A. Pascual

2004-01-01

304

Use of naturally occurring mercury to determine the importance of cutthroat trout to Yellowstone grizzly bears  

USGS Publications Warehouse

Spawning cutthroat trout (Oncorhynchus clarki (Richardson, 1836)) are a potentially important food resource for grizzly bears (Ursus arctos horribilis Ord, 1815) in the Greater Yellowstone Ecosystem. We developed a method to estimate the amount of cutthroat trout ingested by grizzly bears living in the Yellowstone Lake area. The method utilized (i) the relatively high, naturally occurring concentration of mercury in Yellowstone Lake cutthroat trout (508 ?? 93 ppb) and its virtual absence in all other bear foods (???6 ppb), (ii) hair snares to remotely collect hair from bears visiting spawning cutthroat trout streams between 1997 and 2000, (iii) DNA analyses to identify the individual and sex of grizzly bears leaving a hair sample, (iv) feeding trials with captive bears to develop relationships between fish and mercury intake and hair mercury concentrations, and (v) mercury analyses of hair collected from wild bears to estimate the amount of trout consumed by each bear. Male grizzly bears consumed an average of 5 times more trout/kg bear than did female grizzly bears. Estimated cutthroat trout intake per year by the grizzly bear population was only a small fraction of that estimated by previous investigators, and males consumed 92% of all trout ingested by grizzly bears.

Felicetti, L. A.; Schwartz, C. C.; Rye, R. O.; Gunther, K. A.; Crock, J. G.; Haroldson, M. A.; Waits, L.; Robbins, C. T.

2004-01-01

305

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

306

COMBINING PREDICTION AND MONITORING FOR REDUCTION OF TOXICS: THE LAKE MICHIGAN MASS BALANCE STUDY  

EPA Science Inventory

This presentation will focus on PCBs and the primary findings of mathematical modeling including the mass balance of PCBs for Lake Michigan and forecasts of future concentrations of PCBs in lake trout....

307

Mortality and physiological stress of year-classes of landlocked and migratory Atlantic salmon, brown trout and brook trout in acidic aluminium-rich soft water  

Microsoft Academic Search

Physiological stress, measured as changes in plasma chloride, and mortality were measured on different year-classes of landlocked and migratory Atlantic salmon, two strains of brown trout, and brook trout, in a flow-through system with acidic Al-rich soft water. The oldest year-classes of salmon were smolts. Water from Lake Byglandsfjord (pH = 5.9), was enriched 1 th inorganic Al (as AlCl3)

B. O. Rosselind; O. K. Skogheim; F. Kroglund; E. Hoell

1986-01-01

308

Ecology and Life History of Coaster Brook Trout and Potential Bottlenecks in Their Rehabilitation  

Microsoft Academic Search

Lake Superior once supported abundant lake-dwelling brook trout Salvelinus fontinalis called coasters; however, only scattered remnant populations remained by the early 20th century. Owing to their early decline, there is little information about their ecology and life history, yet such information is vital for the ecologically based rehabilitation and management of coasters. This study reviews the ecology of coaster brook

Casey J. Huckins; Edward A. Baker; Kurt D. Fausch; Jill B. K. Leonard

2008-01-01

309

Resource Partitioning in Summer by Salmonids in South-Central Lake Ontario  

Microsoft Academic Search

During the summers of 1981 and 1982, we studied resource partitioning by stocked lake trout Salvelinus namaycush, brown trout Salmo trutta, and chinook salmon Oncorhynchus tshawytscha by fishing vertical gill nets at six distances from shore in south-central Lake Ontario. The nets were set at depths of approximately 15-45 m (nearshore stations, <4 km offshore) and more than 55 m

ROBERT A. OLSON; JIMMY D. WINTER; DAVID C. NETTLES; James M. Haynes

1988-01-01

310

Sea growth of anadromous brown trout ( Salmo trutta)  

NASA Astrophysics Data System (ADS)

Sea growth rates were studied in anadromous brown trout caught in Lake IJsselmeer, The Netherlands. Growth in the first year at sea was estimated at 26 cm from length-frequency distributions, and at 21 cm from back-calculated growth rates from scale readings. These estimates are considerably higher than sea growth rates observed in populations at higher latitudes (Norway, Sweden), but compare well with the limited information on sea growth rates estimated for anadromous trout in the River Rhine and rivers in Normandy (France).

de Leeuw, J. J.; ter Hofstede, R.; Winter, H. V.

2007-08-01

311

Long-term impacts of invasive species on a native top predator in a large lake system  

USGS Publications Warehouse

1.?Declining abundances of forage fish and the introduction and establishment of non-indigenous species have the potential to substantially alter resource and habitat exploitation by top predators in large lakes. 2.?We measured stable isotopes of carbon (?13C) and nitrogen (?15N) in field-collected and archived samples of Lake Ontario lake trout (Salvelinus namaycush) and five species of prey fish and compared current trophic relationships of this top predator with historical samples. 3.?Relationships between ?15N and lake trout age were temporally consistent throughout Lake Ontario and confirmed the role of lake trout as a top predator in this food web. However, ?13C values for age classes of lake trout collected in 2008 ranged from 1.0 to 3.9‰ higher than those reported for the population sampled in 1992. 4.?Isotope mixing models predicted that these changes in resource assimilation were owing to the replacement of rainbow smelt (Osmerus mordax) by round goby (Neogobius melanostomus) in lake trout diet and increased reliance on carbon resources derived from nearshore production. This contrasts with the historical situation in Lake Ontario where ?13C values of the lake trout population were dominated by a reliance on offshore carbon production. 5.?These results indicate a reduced capacity of the Lake Ontario offshore food web to support the energetic requirements of lake trout and that this top predator has become increasingly reliant on prey resources that are derived from nearshore carbon pathways.

Rush, Scott A.; Paterson, Gordon;Johnson, Tim B.; Drouillard, Ken G.; Haffner, Gordon D.; Hebert, Craig E.; Arts, Michael T.; McGoldrick, Daryl J.; Backus, Sean M.; Lantry, Brian F.; Lantry, Jana R.; Schaner, Ted; Fisk, Aaron T.

2012-01-01

312

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

313

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

314

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

315

Lean Implementation in Service Companies  

Microsoft Academic Search

\\u000a Service companies have been implementing Lean only in recent years. In this research three third party logistic companies\\u000a and seven companies of the financial sector have been thoroughly interviewed and showed a few interesting aspects on the way\\u000a they implemented Lean. They are implementing Lean in high volume low variety processes and focus on back office activities,\\u000a which are most

Alberto Portioli-Staudacher

2009-01-01

316

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

317

Effect of damming on distribution of rainbow trout in Hokkaido, Japan  

Microsoft Academic Search

Rainbow trout introduced into Hokkaido in 1920 have become widely distributed due to extensive release into many reservoirs\\u000a and lakes for sport-fishing; their presence often results in reductions of native fish populations. We analyzed and predicted\\u000a the relationship between the probability of occurrence of rainbow trout and the proximity of dams (or attributed reservoirs),\\u000a using a database of the presence

Mideok Han; Takehiko Fukushima; Michio Fukushima

2009-01-01

318

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

319

Application of a Dichotomous Key to the Classification of Sea Lamprey Petromyzon Marinus Marks on Lake Sturgeon Acipenser Fulvescens.  

National Technical Information Service (NTIS)

The current sea lamprey (Petromyzon marinus) mark classification system used for Great Lakes fishes was originally developed based on lake trout (Salvelinus namaycush) (King 1980). This scheme recognizes two basic types of sea lamprey marks (Types A and B...

H. K. Patrick T. M. Sutton W. D. Swink

2007-01-01

320

Ares Launch Vehicles Lean Practices Case Study  

NASA Technical Reports Server (NTRS)

This viewgraph presentation describes test strategies and lean philisophies and practices that are applied to Ares Launch Vehicles. The topics include: 1) Testing strategy; 2) Lean Practices in Ares I-X; 3) Lean Practices Applied to Ares I-X Schedule; 4) Lean Event Results; 5) Lean, Six Sigma, and Kaizen Practices in the Ares Projects Office; 6) Lean and Kaizen Success Stories; and 7) Ares Six Sigma Practices.

Doreswamy, Rajiv, N.; Self, Timothy A.

2008-01-01

321

The Economics of Lean Programing  

ERIC Educational Resources Information Center

Examples of "lean" programs are contrasted with examples of small-step programs. An analysis of cost data for 11 programs shows that trainees' wages are the major source of training costs. Lean programing cuts training time by a third or a half and thus reduces a major element in training costs. (Author)

Rummler, Geary A.

1973-01-01

322

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

323

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; Holloway, Lawrence

2009-09-11

324

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

325

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

326

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.

Society, American C.

2001-01-01

327

Triploidy in rainbow trout  

Microsoft Academic Search

An analysis of the chromosomes of the rainbow trout, Salmo gairdneri, revealed one triploid individual among 18 specimens examined. The diploid specimens possessed 60 chromosomes, whereas the single triploid possessed approximately 90. Suppression of the second meiotic division followed by fertilization of the unreduced oocyte is the most likely mechanism by which triploidy was achieved in this fish.Copyright © 1972

O. Cuellar; T. Uyeno

1972-01-01

328

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

329

Effects of Partially Anadromous Arctic Charr ( Salvelinus alpinus ) Populations on Ecology of Coastal Arctic Lakes  

Microsoft Academic Search

Little research has been conducted on effects of iteroparous anadromous fishes on Arctic lakes. We investigated trophic ecology,\\u000a fish growth, and food web structure in six lakes located in Nunavut, Canada; three lakes contained anadromous Arctic charr\\u000a (Salvelinus alpinus) whereas three lakes did not contain Arctic charr. All lakes contained forage fishes and lake trout (Salvelinus namaycush; top predator). Isotope

Heidi K. Swanson; Karen A. Kidd; James D. Reist

2010-01-01

330

Lean Spacecraft Avionics Trade Study.  

National Technical Information Service (NTIS)

Spacecraft design is generally an exercise in design trade-offs: fuel vs. weight, power vs. solar cell area, radiation exposure vs. shield weight, etc. Proper analysis of these trades is critical in the development of lightweight, efficient, 'lean' satell...

J. A. Main

1994-01-01

331

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

332

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.

2014-01-01

333

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

334

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

335

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

336

Effect of Sea-run Alewives on Rainbow Trout and Brown Trout in Reclaimed Ponds  

Microsoft Academic Search

Investigators combined yearling and fingerling rainbow trout (Salmo gairdneri) and brown trout (Salmo trutta) with adult and young sea-run alewives (Alosa pseudoharengus) in ponds cleared of other fish species. Fish recovery by chemical reclamation showed that, when alewives were present, trout numbers and biomass were lower, trout released as yearlings were larger after 18 months, and trout released as fingerlings

Robert S. McCaig

1980-01-01

337

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

338

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

339

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

340

Trout Production Dynamics and Water Quality in  

Microsoft Academic Search

We sampled fish assemblages and quantified production dynamics of brook trout Salvelinus fontinalis, brown trout Salmo trutta, and rainbow trout Oncorhynchus mykiss in 13 southeastern Minnesota streams during 1988-1990 to examine the influence of water quality on fish populations in fertile trout streams. Fish assemblages in 15 stream reaches were abundant, but low in diversity; 13 species were collected. Parameter

THOMAS J. KWAK; THOMAS F. WATERS

1997-01-01

341

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

342

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

343

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

344

Modeling Brook Trout Presence and Absence from Landscape Variables Using Four Different Analytical Methods  

Microsoft Academic Search

As a part of the Great Lakes Regional Aquatic Gap Analysis Project, we evaluated methodologies for modeling associations between fish species and habitat characteristics at a landscape scale. To do this, we created brook trout Salvelinus fontinalis presence and absence models based on four different techniques: multiple linear regression, logistic regression, neu- ral networks, and classification trees. The models were

Paul J. Steen; Dora R. Passino-Reader; Michael J. Wiley

2006-01-01

345

'Lean' approach gives greater efficiency.  

PubMed

Adapting the 'Lean' methodologies used for many years by many manufacturers on the production line - such as in the automotive industry - and deploying them in healthcare 'spaces' can, Roger Call, an architect at Herman Miller Healthcare in the US, argues, 'easily remedy many of the inefficiencies' found within a healthcare facility. In an article that first appeared in the September 2013 issue of The Australian Hospital Engineer, he explains how 'Lean' approaches such as the 'Toyota production system', and 'Six Sigma', can be harnessed to good effect in the healthcare sphere. PMID:24620487

Call, Roger

2014-02-01

346

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.

347

Learning Lean: A Survey of Industry Lean Needs  

ERIC Educational Resources Information Center

The authors examined business practitioners' preferences for higher education curricula design in general and for what graduates should know about Lean, or waste-reduction efforts. The authors conducted a Web-based survey and found that practitioners are not as concerned about graduates' possessing specific technical skills as they are about them…

Fliedner, Gene; Mathieson, Kieran

2009-01-01

348

77 FR 73650 - Peabody Trout Creek Reservoir LLC;  

Federal Register 2010, 2011, 2012, 2013

...No. 14446-001] Peabody Trout Creek Reservoir LLC; Notice of Preliminary Permit Application...November 30, 2012, Peabody Trout Creek Reservoir LLC (Peabody) filed an application...feasibility of the Peabody Trout Creek Reservoir Hydroelectric Project (Trout Creek...

2012-12-11

349

Learning to be lean: the influence of external information sources in lean improvements  

Microsoft Academic Search

Purpose – The purpose of this paper is to examine the role of management exposure to external information sources, such as training sessions, plant visits, and conferences, in helping manufacturing organizations achieve lean goals. Design\\/methodology\\/approach – A model is proposed highlighting the relationship between various key drivers of lean, external information sources, management commitment to lean, and lean thinking. To

Todd A. Boyle; Maike Scherrer-Rathje; Ian Stuart

2011-01-01

350

Comparison and evaluation of maintenance operations in lean versus non-lean production systems  

Microsoft Academic Search

Purpose – Previous studies have found general differences between non-lean and lean production systems, but none of them have identified the major factors in supporting operations such as maintenance which are important in shifting the production from a non-lean to a lean system. The purpose of this paper is to determine the major factors and parameters of maintenance operations that

Farman A. Moayed; Richard L. Shell

2009-01-01

351

Keeping pristine lakes clean: Loughs Conn and Mask, western Ireland  

Microsoft Academic Search

The large western Irish lakes are natural salmonid lakes and a unique ecological resource. Lough Mask (82 km2) and Lough Conn (50 km2), Co. Mayo, are among the finest, natural, wild brown trout fisheries in Europe. Recently, however, threats have arisen to water quality in Lough Conn as a result of agricultural intensification. A doubling of phosphorus (P) inputs to

M. L. McGarrigle; W. S. T. Champ

1999-01-01

352

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...

353

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...

354

LEAN VALUE CREATION METRICS FOR NETWORKED ORGANISATIONS  

Microsoft Academic Search

Research about lean has been mainly focused on process or product innovation. Innovation should not on ly be applied on product level but also on the way the va lue chain and system are organised. This research t akes the lean principles to a higher aggregation; to an orga nisation level. Adoption of lean principles and the 3C model -

Wouter W. A. Beelaerts; Sakyi O. B. Amo; Sicco C. Santema

355

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

356

GOLDEN TROUT WILDERNESS, CALIFORNIA.  

USGS Publications Warehouse

A mineral survey of the Golden Trout Wilderness, California revealed that four areas in the wilderness have resource potential for tungsten and base and precious metals. One, the Mineral King pendant, has substantiated potential for tungsten deposits; the others are designated as having probable resource potential for tungsten and base and precious metals. Demonstrated tungsten resources exist at the Pine Tree mine, a skarn deposit in the Mineral King pendant. There is no evidence for the existence of large undiscovered deposits within the wilderness. The geologic terrane precludes the occurrence of organic fuel resources.

Dellinger, David, A.; Zilka, Nicholas, T.

1984-01-01

357

Exploring the impact of lean management on innovation capability  

Microsoft Academic Search

Lean management and innovation are two driving forces of today's business success. However, with fundamentally different concepts, some aspects of lean management may negatively affect a company's capability to be successful with certain types of innovations. This paper develops a framework to analyze such impacts. With comparisons between the lean culture, lean design, lean supply chain management and lean human

Hongyi Chen; Ryan Taylor

2009-01-01

358

Dynamics of CFCs in northern temperate lakes and adjacent groundwater  

USGS Publications Warehouse

[1] Three dimictic lakes and one meromictic lake in and near the Trout Lake, Wisconsin, watershed were sampled to determine the variation of chlorofluorocarbon (CFC) concentrations within the lakes. The lakes were sampled during stratified conditions, during fall turnover, and during ice cover. The results demonstrate a considerable variation in CFC concentrations and corresponding atmospheric mixing ratios in the lakes sampled, both with depth and season within a given lake, and across different lakes. CFC profiles and observed degradation were not related to the groundwater inflow rate and hence are likely the result of in-lake processes influenced by CFC degradation in the (lake) water column, CFC degradation in the lake-bed sediments, and gas exchange rates and the duration of turnover (turnover efficiency).

Walker, J. F.; Saad, D. A.; Hunt, R. J.

2007-01-01

359

The Leaning Tower of Pisa  

Microsoft Academic Search

THE photograph of the ``Leaning'' Tower of Pisa in NATURE of August 4 shows clearly that the top tier is not square with the rest. From a rough alignment with the edge of a postcard, the photograph appears as if the tower was of the order of 25 mm.\\/metre out of plumb when the top tier was put on presumably

Edward G. Brown

1910-01-01

360

Cooperation of Lean Enterprises - Techniques used for Lean Supply Chain  

Microsoft Academic Search

The paper presents the problems with integration of the companies within the supply chain. Usually the separate actions are\\u000a undertaken by the companies to implement lean tools for production systems and external logistics processes. This situation\\u000a leads to minor results or moving the costs between production and logistics processes instead of reduction. The purpose of\\u000a the paper is to present

Marek Eisler; Remigiusz Horbal; Tomasz Koch

2007-01-01

361

Genetic Studies of Rainbow Trout.  

National Technical Information Service (NTIS)

Polymorphic lactate dehydrogenase (LDH) loci exist in the serum and tissues of rainbow trout. Electrophoretic distinction of three phenotypes involving the B2LDH subunit are presented. Paternal gene activation and inheritance of the LDH phenotypes are des...

C. B. Stalnaker G. A. Stillings G. T. Klar

1973-01-01

362

Intra-strain dioxin sensitivity and morphometric effects in swim-up rainbow trout (Oncorhynchus mykiss)  

USGS Publications Warehouse

Inter and intra-specific differences in sensitivity of early life stage salmonids to 2,3,7,8-TCDD exposure have been reported, but intra-strain differences have not been found in the literature. Our results indicate that intra-strain variability in terms of embryo mortality (LD50) is small in Eagle Lake strain of rainbow trout, LD50 values ranging from 285 to 457 pg TCDD egg g-1. These results confirm Eagle Lake as a less sensitive strain within rainbow trout, and do not indicate overlap with reported LD50 values for brook or lake trout. Our results also demonstrate that although generalized edema in regions including the yolk-sac are frequently associated with mortality following dioxin exposure, not all edematous fish die. We detected dose-dependent decreases in cranial length, eye diameter, mass, and total length (P<0.05) in viable swim-up rainbow trout. These effects are presumed to indicate more subtle dose-dependent disruptions of the viteline vein vasculature and, therefore, in access to energy sources. A tendency for dose-dependent decrease in liver glycogen reserves concurred with previous results on salmonids and with the well described TCDD-induced alterations in intermediate metabolism of rats and chicken embryos (wasting syndrome). This syndrome could be contributing to the reduced growth that we observed. ?? 2004 Elsevier Inc. All rights reserved.

Carvalho, P. S. M.; Noltie, D. B.; Tillitt, D. E.

2004-01-01

363

Changes in a population of exotic rainbow smelt in Lake Superior: Boom to bust, 1974-2005  

USGS Publications Warehouse

Changes in a population of rainbow smelt (Osmerus mordax) in the Apostle Islands region of Lake Superior were chronicled over a 32-yr time series, 1974-2005. At the beginning of the time series, rainbow smelt was the predominant prey species, abundance of lake herring (Coregonis artedi) was very low, and the dominant predator was stocked lake trout (Salvelinus namaycush). Following a period of successful lake trout stocking in the 1970s, the rainbow smelt population declined sharply in 1980, largely through mortality of adult fish and subsequent poor recruitment. In the succeeding 4 years, rainbow smelt populations reached historic low levels, resulting in reduced food resources for both wild and stocked lake trout. During 1985-1990 lake herring stocks began a spectacular recovery following the appearance of a very strong 1984 year class and subsequent 1988, 1989, and 1990 year classes. Rainbow smelt benefited from the high abundance of young lake herring as an alternate prey source for lake trout and showed a partial recovery in the late 1980s. However, a growing lake trout population coupled with an 8-yr period of low herring reproduction after 1990 resulted in a diminished rainbow smelt population dominated by age-1 and 2 fish and showing a pattern of alternating recruitment attributed to cannibalism. Low productivity of rainbow smelt and intermittent production of herring over the past decade has left lake trout populations with a diminished prey base. Although lake trout recovery benefited from the presence of rainbow smelt as a prey resource, the Lake Superior fish community was fundamentally altered by the introduction of rainbow smelt.

Gorman, O. T.

2007-01-01

364

Laboratory studies of lean combustion  

NASA Technical Reports Server (NTRS)

The fundamental processes controlling lean combustion were observed for better understanding, with particular emphasis on the formation and measurement of gas-phase pollutants, the stability of the combustion process (blowout limits), methods of improving stability, and the application of probe and optical diagnostics for flow field characterization, temperature mapping, and composition measurements. The following areas of investigation are described in detail: (1) axisymmetric, opposed-reacting-jet-stabilized combustor studies; (2) stabilization through heat recirculation; (3) two dimensional combustor studies; and (4) spectroscopic methods. A departure from conventional combustor design to a premixed/prevaporized, lean combustion configuration is attractive for the control of oxides of nitrogen and smoke emissions, the promotion of uniform turbine inlet temperatures, and, possibly, the reduction of carbon monoxide and hydrocarbons at idle.

Sawyer, R. F.; Schefer, R. W.; Ganji, A. R.; Daily, J. W.; Pitz, R. W.; Oppenheim, A. K.; Angeli, J. W.

1977-01-01

365

Lean six sigma in healthcare.  

PubMed

Healthcare, as with any other service operation, requires systematic innovation efforts to remain competitive, cost efficient, and up-to-date. This article outlines a methodology and presents examples to illustrate how principles of Lean Thinking and Six Sigma can be combined to provide an effective framework for producing systematic innovation efforts in healthcare. Controlling healthcare cost increases, improving quality, and providing better healthcare are some of the benefits of this approach. PMID:16749293

de Koning, Henk; Verver, John P S; van den Heuvel, Jaap; Bisgaard, Soren; Does, Ronald J M M

2006-01-01

366

Chemical and biological recovery from acid deposition within the Honnedaga Lake watershed, New York, USA.  

PubMed

Honnedaga Lake in the Adirondack region of New York has sustained a heritage brook trout population despite decades of atmospheric acid deposition. Detrimental impacts from acid deposition were observed from 1920 to 1960 with the sequential loss of acid-sensitive fishes, leaving only brook trout extant in the lake. Open-lake trap net catches of brook trout declined for two decades into the late 1970s, when brook trout were considered extirpated from the lake but persisted in tributary refuges. Amendments to the Clean Air Act in 1990 mandated reductions in sulfate and nitrogen oxide emissions. By 2000, brook trout had re-colonized the lake coincident with reductions in surface-water sulfate, nitrate, and inorganic monomeric aluminum. No changes have been observed in surface-water acid-neutralizing capacity (ANC) or calcium concentration. Observed increases in chlorophyll a and decreases in water clarity reflect an increase in phytoplankton abundance. The zooplankton community exhibits low species richness, with a scarcity of acid-sensitive Daphnia and dominance by acid-tolerant copepods. Trap net surveys indicate that relative abundance of adult brook trout population has significantly increased since the 1970s. Brook trout are absent in 65 % of tributaries that are chronically acidified with ANC of <0 ?eq/L and toxic aluminum levels (>2 ?mol/L). Given the current conditions, a slow recovery of chemistry and biota is expected in Honnedaga Lake and its tributaries. We are exploring the potential to accelerate the recovery of brook trout abundance in Honnedaga Lake through lime applications to chronically and episodically acidified tributaries. PMID:24671614

Josephson, Daniel C; Robinson, Jason M; Chiotti, Justin; Jirka, Kurt J; Kraft, Clifford E

2014-07-01

367

Fish community change in Lake Superior, 1970-2000  

USGS Publications Warehouse

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 lamprey (Petromyzon marinus) control, harvest limits, and stocking fostered recoveries of lake trout and allowed establishment of small nonnative salmonine populations. Natural reproduction supports most salmonine populations, therefore further stocking is not required. Nonnative salmonines will likely remain minor components of the fish community. Forage biomass has shifted from exotic rainbow smelt (Osmerus mordax) to native species, and high predation may prevent their recovery. Introductions of exotics have increased and threaten the recovering fish community. Agencies have little influence on the abundance of forage fish or the major predator, siscowet lake trout, and must now focus on habitat protection and enhancement in nearshore areas and prevent additional species introductions to further restoration. Persistence of Lake Superior's native deepwater species is in contrast to other Great Lakes where restoration will be difficult in the absence of these ecologically important fishes.

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

2003-01-01

368

Further Observations on Ulcer Disease of Trout  

Microsoft Academic Search

Brook trout were fed various meat and meal mixtures to which vitamins A, B1, C, D, G, and PP were added. None of these diets or vitamins affected the resistance of the trout to ulcer disease. Trout on a “natural” diet of insects, minnows, etc., succumbed to the disease. Infected fish planted in a small stream plentifully supplied with food

Louis E. Wolf

1941-01-01

369

ERP and Lean: How Lean Manufacturing Makes ERP Credible  

NSDL National Science Digital Library

This website discusses how Lean principles can improve Enterprise Resource Planning (ERP). As is explained on the site, the problem is often not the fault of software- an Enterprise Resource Planning (ERP) system can be an extremely powerful tool for management. The system plans future resource requirements through its scheduling algorithms. It then uses these schedules to predict the amount and timing for each of these resources. Manpower, materials, and cash flow are all readily predicted based upon the planning done within the system.

2010-08-03

370

Bull Trout Life History, Genetics, Habitat Needs, and Limiting Factors in Central and Northeast Oregon, Annual Report 2001.  

SciTech Connect

Bull trout Salvelinus confluentus exhibit a number of life history strategies. Stream-resident bull trout complete their life cycle in their natal tributaries. Migratory bull trout spawn in tributary streams where juvenile fish usually spend from one to four years before migrating to either a larger river (fluvial) or lake (adfluvial) where they rear before returning to the tributary stream to spawn (Fraley and Shepard 1989). These migratory forms occur where conditions allow movement from spawning locations to downstream waters that provide greater foraging opportunities (Dunham and Rieman 1999). Resident and migratory forms may occur together, and either form can produce resident or migratory offspring (Rieman and McIntyre 1993). The ability to migrate is important to the persistence of local bull trout populations (Rieman and McIntyre 1993). The identification of migratory corridors can help focus habitat protection efforts. Determining the life history form(s) that comprise local populations, the timing of seasonal movements, and the geographic extent of these movements are critical to bull trout protection and recovery efforts. This section describes work accomplished in 2001 that continued to address two objectives of this project. These objectives are (1) determine the distribution of juvenile and adult bull trout and habitats associated with that distribution, and (2) determine fluvial and resident bull trout life history patterns. Completion of these objectives is intended through studies of bull trout in the Grande Ronde, Walla Walla, and John Day basins. These basins were selected because they provide a variety of habitats, from relatively degraded to pristine, and bull trout populations were thought to vary from relatively depressed to robust. In the Grande Ronde and Walla Walla basins, we continued to monitor the movements of bull trout with radio transmitters applied in 1998 (Hemmingsen, Bellerud, Gunckel and Howell 2001) and 1999 (Hemmingsen, Gunckel and Howell 2001). No new radio transmitters were applied to bull trout of the upper John Day River subbasin, Mill Creek (Walla Walla Basin), or the Grande Ronde Basin in 2001. In Mill Creek, we used traps for the fourth consecutive year to obtain data on migrant bull trout. With these traps, we intended to determine the timing of bull trout movements both upstream and downstream, and to determine the relative abundance and size of migrant fish. No traps were operated in the John Day Basin in 2001.

Hemmingsen, Alan R.; Gunckel, Stephanie L.; Sankovich, Paul M.; Howell, Philip J.

2002-12-01

371

ACUTE TOXICITY OF KELTHANE, DURSBAN, DISULFOTON, PYDRIN, AND PERMETHRIN TO FATHEAD MINNOWS 'PIMEPHALES PROMELAS' AND RAINBOW TROUT 'SALMO GAIRDNERI'  

EPA Science Inventory

Flow-through acute lethal toxicity tests were conducted with kelthane, dursban, disulfoton, pydrin and permethrin using rainbow trout Salmo gairdneri and fathead minnows Pimephales promelas in Lake Superior water. Pydrin was the most toxic pesticide tested to both species of fish...

372

Explore it! Fish  

NSDL National Science Digital Library

Species profiles of 10 common, and often less-publicized, Great Lakes fishes. Each profile describes the fish's length, weight, coloring, common names, and preferred habitat. Site also discusses its creator, Cliff Kraft, and why he selected these 10 particular species. Profiles include: the lake sturgeon, lake herring, brook stickleback, brook trout, longnose sucker, deepwater sculpin, spottail shiner, siscowet, logperch, and lean lake trout.

373

Myxobolus cerebralis infection patterns in Yellowstone cutthroat trout after natural exposure.  

PubMed

Salmonid species and sub-species exhibit a range of susceptibility to Myxobolus cerebralis infection. Little is known about lesion severity and location, or time required for M. cerebralis myxospores to develop in Yellowstone cutthroat trout Oncorhynchus clarki bouvieri. In 2002 we performed three 10 d exposures of Yellowstone cutthroat trout fry in Pelican Creek, an M. cerebralis-positive tributary to Yellowstone Lake. At 90 and 150 d post-exposure we examined the fish for clinical signs, for infection prevalence, and by histology to determine M. cerebralis infection location and severity of lesions. The most prevalent clinical signs in Yellowstone cutthroat were whirling behavior and skeletal deformities, especially at 90 d post-exposure. Prevalence of infection and severity of cartilage lesions were not statistically different between fish held for 90 or 150 d post-exposure. Histopathology was most severe in cartilage of the cranium and the lower jaw, whereas cartilage of the nares and gill arches was seldom damaged. This study suggests that Yellowstone cutthroat trout are highly vulnerable to M. cerebralis and that current population declines in the Yellowstone Lake basin may, in part, result from whirling disease. Our results answer important questions in fish health and will aid in the development of diagnostic tools and management efforts against this pathogen in native cutthroat trout and other vulnerable salmonids. PMID:17058600

Murcia, Silvia; Kerans, Billie L; MacConnell, Elizabeth; Koel, Todd M

2006-08-30

374

Impact of forest harvesting on trophic structure of eastern canadian boreal shield lakes: insights from stable isotope analyses.  

PubMed

Perturbations on ecosystems can have profound immediate effects and can, accordingly, greatly alter the natural community. Land-use such as forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. The objective of this study was to evaluate the impact of forest harvesting on trophic structure in eastern Canadian Boreal Shield lakes. We measured carbon and nitrogen stable isotopes values for aquatic primary producers, terrestrial detritus, benthic macroinvertebrates, zooplankton and brook trout (Salvelinus fontinalis) over a three-year period in eight eastern Boreal Shield lakes. Four lakes were studied before, one and two years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. Stable isotope mixing models showed leaf-litter to be the main food source for benthic primary consumers in both perturbed and unperturbed lakes, suggesting no logging impact on allochthonous subsidies to the littoral food web. Brook trout derived their food mainly from benthic predatory macroinvertebrates in unperturbed lakes. However, in perturbed lakes one year after harvesting, zooplankton appeared to be the main contributor to brook trout diet. This change in brook trout diet was mitigated two years after harvesting. Size-related diet shift were also observed for brook trout, indicating a diet shift related to size. Our study suggests that carbon from terrestrial habitat may be a significant contribution to the food web of oligotrophic Canadian Boreal Shield lakes. Forest harvesting did not have an impact on the diet of benthic primary consumers. On the other hand, brook trout diet composition was affected by logging with greater zooplankton contribution in perturbed lakes, possibly induced by darker-colored environment in these lakes one year after logging. PMID:24763366

Glaz, Patricia; Sirois, Pascal; Archambault, Philippe; Nozais, Christian

2014-01-01

375

Impact of Forest Harvesting on Trophic Structure of Eastern Canadian Boreal Shield Lakes: Insights from Stable Isotope Analyses  

PubMed Central

Perturbations on ecosystems can have profound immediate effects and can, accordingly, greatly alter the natural community. Land-use such as forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. The objective of this study was to evaluate the impact of forest harvesting on trophic structure in eastern Canadian Boreal Shield lakes. We measured carbon and nitrogen stable isotopes values for aquatic primary producers, terrestrial detritus, benthic macroinvertebrates, zooplankton and brook trout (Salvelinus fontinalis) over a three-year period in eight eastern Boreal Shield lakes. Four lakes were studied before, one and two years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. Stable isotope mixing models showed leaf-litter to be the main food source for benthic primary consumers in both perturbed and unperturbed lakes, suggesting no logging impact on allochthonous subsidies to the littoral food web. Brook trout derived their food mainly from benthic predatory macroinvertebrates in unperturbed lakes. However, in perturbed lakes one year after harvesting, zooplankton appeared to be the main contributor to brook trout diet. This change in brook trout diet was mitigated two years after harvesting. Size-related diet shift were also observed for brook trout, indicating a diet shift related to size. Our study suggests that carbon from terrestrial habitat may be a significant contribution to the food web of oligotrophic Canadian Boreal Shield lakes. Forest harvesting did not have an impact on the diet of benthic primary consumers. On the other hand, brook trout diet composition was affected by logging with greater zooplankton contribution in perturbed lakes, possibly induced by darker-colored environment in these lakes one year after logging.

Glaz, Patricia; Sirois, Pascal; Archambault, Philippe; Nozais, Christian

2014-01-01

376

Lean spacecraft avionics trade study  

NASA Technical Reports Server (NTRS)

Spacecraft design is generally an exercise in design trade-offs: fuel vs. weight, power vs. solar cell area, radiation exposure vs. shield weight, etc. Proper analysis of these trades is critical in the development of lightweight, efficient, 'lean' satellites. The modification of the launch plans for the Magnetosphere Imager (MI) to a Taurus launcher from the much more powerful Delta has forced a reduction in spacecraft weight availability into the mission orbit from 1300 kg to less than 500 kg. With weight now a driving factor it is imperative that the satellite design be extremely efficient and lean. The accuracy of engineering trades now takes on an added importance. An understanding of spacecraft subsystem interactions is critical in the development of a good spacecraft design, yet it is a challenge to define these interactions while the design is immature. This is currently an issue in the development of the preliminary design of the MI. The interaction and interfaces between this spacecraft and the instruments it carries are currently unclear since the mission instruments are still under development. It is imperative, however, to define these interfaces so that avionics requirements ideally suited to the mission's needs can be determined.

Main, John A.

1994-01-01

377

The LEAN Payload Integration Process  

NASA Technical Reports Server (NTRS)

It is recognized that payload development and integration with the International Space Station (ISS) can be complex. This streamlined integration approach is a first step toward simplifying payload integration; making it easier to fly payloads on ISS, thereby increasing feasibility and interest for more research and commercial organizations to sponsor ISS payloads and take advantage of the ISS as a National Laboratory asset. The streamlined integration approach was addressed from the perspective of highly likely initial payload types to evolve from the National Lab Pathfinder program. Payloads to be accommodated by the Expedite the Processing of Experiments for Space Station (EXPRESS) Racks and Microgravity Sciences Glovebox (MSG) pressurized facilities have been addressed. It is hoped that the streamlined principles applied to these types of payloads will be analyzed and implemented in the future for other host facilities as well as unpressurized payloads to be accommodated by the EXPRESS Logistics Carrier (ELC). Further, a payload does not have to be classified as a National Lab payload in order to be processed according to the lean payload integration process; any payload that meets certain criteria can follow the lean payload integration process.

Jordan, Lee P.; Young, Yancy; Rice, Amanda

2011-01-01

378

Monitor and Protect Wigwam River Bull Trout for Koocanusa Reservoir; White River Bull Trout Enumeration Project Summary, Progress Report 2003.  

SciTech Connect

This report summarizes the first year of a three-year bull trout (Salvelinus confluentus) enumeration project on the White River and is a co-operative initiative of the British Columbia Ministry of Water, Land, and Air Protection and Bonneville Power Administration. The White River has been identified as an important bull trout spawning tributary of the upper Kootenay River in southeastern British Columbia. The objective was to collect information on the returning adult spawning population to the White River through the use of a fish fence and traps, and to conduct redd surveys at the conclusion of spawning to provide an index of spawning escapement and distribution. The fence was installed on September 9th, 2003 and was operated continuously (i.e. no high-water or breaching events) until the fence was removed on October 9th, 2003. Estimation of the spawning population of White River bull trout was incomplete. This was due to a larger and more protracted out-migration than expected. As a result, the bull trout spawning population of the White River was estimated to be somewhere above 899 fish. In comparison, this represents approximately one third the population estimate of the 2003 Wigwam River bull trout spawning population. Based on redd index data, the number of bull trout per redd was over twice that of the Wigwam River or Skookumchuck Creek. This was expected as the index sites on the Wigwam River and Skookumchuck Creek cover the majority of the spawning area. This is not true on the White River. From previous redd counts, it is known that there are approximately twice as many redds in Blackfoot Creek as there are in the index site. Additionally, given the large size of the White River watershed and in particular, the large number of tributaries, there is a high likelihood that important bull trout spawning areas remain unidentified. Both floy tag and radio-telemetry data for the White River bull trout have identified extensive life history migrations. Similar data for the Wigwam River and Skookumchuck Creek populations illustrate there is considerable overlap and mixing among these three local populations within their over-wintering and feeding habitat. The upper Kootenay River, Lake Koocanusa and the lower Bull River provide overwintering and feeding habitat for the White River, Skookumchuck Creek and Wigwam River bull trout. Recommendations to improve escapement estimates and spawning distribution are provided. An accurate population estimate is especially important to provide baseline for any potential impacts due to wildfire and subsequent salvage logging that is currently underway immediately adjacent to and upstream of important spawning and rearing habitat in the Middlefork of the White River. Identification of important spawning habitat is important to meet management objectives for the White River.

Cope, R.

2004-02-01

379

A simulation-enhanced lean design process  

Microsoft Academic Search

A traditional lean transformation process does not validate the future state before implementation, relying instead on a series of iterations to modify the system until performance is satisfactory. An enhanced lean process that includes future state validation before implementation is presented. Simulation modeling and experimentation is proposed as the primary validation tool. Simulation modeling and experimentation extends value stream mapping

Jon H. Marvel; Charles R. Standridge

1970-01-01

380

Lean production and sustainable competitive advantage  

Microsoft Academic Search

Today, “lean” may no longer be fashionable but its core principles (flow, value, pull, minimizing waste etc.) have become the paradigm for many manufacturing (and service) operations. Given this pre-eminence, the paper seeks to establish what impact it has had on the overall competitive positions of adopter firms. Combining normative and critical theory (from lean production and resource-based view of

Michael A. Lewis

2000-01-01

381

TRIZ as a Lean Thinking Tool  

Microsoft Academic Search

Lean Thinking is a highly evolved method of managing an organization to improve the productivity, efficiency and quality of its products or services. The core principle it uses is that no work should be done unless it is going to create customer value. Traditionally Lean tools were Value Stream mapping, Quick Changeover\\/Setup Reduction, Single Minute Exchange of Dies (SMED), Kaizen,

Sergei Ikovenko; Jim Bradley

382

Bioaccumulation of toxaphene congeners in the lake superior food web  

USGS Publications Warehouse

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 (±SD) 889 ± 896 ng/g wet wt and 60 ± 34 ng/g wet wt in Siskiwit Lake. Major congeners in lake trout were B8-789 (P38), B8-2226 (P44), B9-1679 (P50), and B9-1025 (P62). Toxaphene concentrations were found to vary seasonally, especially in lower food web organisms in Lake Superior and to a lesser extent in Siskiwit Lake. Toxaphene concentrations declined significantly in lake herring (Coregonus artedii), rainbow smelt (Omerus mordax), and slimy sculpin (Cottus cognatus) as well as in zooplankton (> 102 &mn;m) and Mysis (Mysis relicta) between May and October. The seasonal variation may reflect seasonal shifts in the species abundance within the zooplankton community. Trophic magnification factors (TMF) derived from regressions of toxaphene congener concentrations versus ?15N were > 1 for most octa- and nonachlorobornanes in Lake Superior except B8-1413 (P26) and B9-715. Log bioaccumulation factors (BAFs) for toxaphene congeners in lake trout (ng/g lipid/ng/L dissolved) ranged from 4.54 to 9.7 and were significantly correlated with log octanol-water partition coefficients. TMFs observed for total toxaphene and congener B9-1679 in Lake Superior were similar to those in Arctic lakes, as well as to previous studies in the Great Lakes, which suggests that the bioaccumulation behavior of toxaphene is similar in pelagic food webs of large, cold water systems. However, toxaphene concentrations were lower in lake trout from Siskiwit Lake and lakes in northwestern Ontario than in Lake Superior possibly because of shorter food chains and greater reliance on zooplankton or other pelagic invertebrates.

Muir, D. C. G.; Whittle, D. M.; De Vault, D. S.; Bronte, C. R.; Karlsson, H.; Backus, S.; Teixeira, C.

2004-01-01

383

Genetic Diversity and Conservation of the Prespa Trout in the Balkans  

PubMed Central

The Balkans are known to have a high level of biodiversity and endemism. No less than 15 taxa have been recorded in salmonids of the Salmo genus. Among them, the Prespa trout is found in only four river systems flowing into Lake Macro Prespa, three in the Former Yugoslav Republic of Macedonia and one in Greece. This is the first comprehensive survey of all streams located within the Macro Prespa Basin, encompassing the whole taxon range. A large genetic sample of 536 Prespa trout was collected mainly between 2005 and 2007. The sampling included 59 individuals from the Golema river system, 93 from the Kranska, 260 from the Brajcinska, 119 from the Agios Germanos, and five individuals from the lake itself. These specimens were analyzed with six microsatellite markers and by sequencing the mitochondrial control region. Nuclear data were examined through multidimensional analysis and assignment tests. Five clusters were detected by assignment: Golema, Kranska, Brajcinska upstream, Rzanska Brajcinska tributary and Brajcinska downstream. Most of these river systems thus hosted differentiated Prespa trout populations (with past gene flows likely dating before the construction of dams), except Agios Germanos, which was found to be composed of 5% to 32% of each cluster. Among the five trout individuals from the lake, four originated from Kranska River and one was admixed. Supported parsimonious hypotheses are proposed to explain these specificities. Conservation of this endemic taxon should take these results into account. No translocation should be performed between different tributaries of the lake and preservation of the Brajcinska populations should address the upstream-downstream differentiation described.

Berrebi, Patrick; Tougard, Christelle; Dubois, Sophie; Shao, Zhaojun; Koutseri, Irene; Petkovski, Svetozar; Crivelli, Alain J.

2013-01-01

384

Retention and Nonlethal External Detection of Calcein Marks in Rainbow Trout and Chinook Salmon  

Microsoft Academic Search

An osmotic induction method was used to apply calcein marks to Chinook salmon Oncorhynchus tshawytscha and the Kamloops strain of rainbow trout O. mykiss (both migratory strains used for stocking into tributaries of Lake Superior). Preliminary exposure to a saline solution followed by immersion in a 0.5% calcein solution encouraged rapid infusion of calcein into fish tissues. Four-month-old Chinook salmon

Mary T. Negus; Fred T. Tureson

2004-01-01

385

Population Biology of Steelhead Spawning Runs in Three Pennsylvania Tributaries to Lake Erie  

Microsoft Academic Search

Little is currently known about the population biology of steelhead (Oncorhynchus mykiss) that spawn in Pennsylvania's Lake Erie tributaries or the role of natural reproduction in supporting this fishery despite its popularity and importance. The goal of this study was to describe the population characteristics of steelhead spawning runs in Crooked Creek, Godfrey Run, and Trout Run, three Pennsylvania Lake

Bradley E. Thompson; C. Paola Ferreri

2002-01-01

386

An Ecosystem Perspective on Re-establishing Native Deepwater Fishes in the Laurentian Great Lakes  

Microsoft Academic Search

Herein we examine scientific questions related to successful re-establishment of native deepwater fish communities in the Laurentian Great Lakes, and we (1) propose a conceptual model for native deepwater fish communities; (2) review current research and identify research hypotheses for lake trout Salvelinus namaycush, pelagic ciscoes Coregonus spp., and sculpins (Cottus spp. and Myoxocephalus spp.); (3) pose research questions emerging

Mara S. Zimmerman; Charles C. Krueger

2009-01-01

387

Investigation of Total and Methyl Mercury in Fish and Sediment of Lake Michigan  

EPA Science Inventory

Sediment cores and fish collected between 1994 and 1996 as part of the Lake Michigan Mass Balance Project were analyzed for total and methyl mercury. Results of the fish analyses are being used to describe total and methyl mercury concentrations in forage fish and lake trout, re...

388

Feeding by Arizona trout ( Salmo apache ) and brown trout ( Salmo trutta ) at different light intensities  

Microsoft Academic Search

Synopsis Brown trout (Salmo trutta) were more efficient than Arizona trout (Salmo apache) in eating brine shrimp at starlight (10?4 fL) light levels. Arizona trout required light levels ? moonlight (10?3 fL) to feed. In bright light (50 fL), brown trout utilized cover to a much greater extent in both field and laboratory. Our study indicates that factors other than

Fredric W. Robinson; Jerry C. Tash

1979-01-01

389

Growth, morphology, and developmental instability of rainbow trout, Yellowstone cutthroat trout, and four hybrid generations  

USGS Publications Warehouse

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 cutthroat trout F1 hybrids as parents to construct seven different line crosses: F1 hybrids (both reciprocal crosses), F2 hybrids, first-generation backcrosses (both rainbow trout and Yellowstone cutthroat trout), and both parental taxa. We compared growth, morphology, and developmental instability among these seven crosses reared at two different temperatures. Growth was related to the proportion of rainbow trout genome present within the crosses. Meristic traits were influenced by maternal, additive, dominant, overdominant, and (probably) epistatic genetic effects. Developmental stability, however, was not disturbed in F1 hybrids, F2 hybrids, or backcrosses. Backcrosses were morphologically similar to their recurrent parent. The lack of developmental instability in hybrids suggests that there are few genetic incompatibilities preventing introgression. Our findings suggest that hybrids are not equal: that is, growth, development, character traits, and morphology differ depending on the genomic contribution from each parental species as well as the hybrid generation.

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

2011-01-01

390

Tissue carboxylesterase activity of rainbow trout  

SciTech Connect

The activity of carboxylesterase (CaE), a class of nonspecific serine hydrolases, was evaluated in vitro in tissues and microsomes of rainbow trout and compared to esterase activity in rats, other fish species, and embryo to adult life stages of trout. Trout gill and liver microsomes exhibited substantial CaE activity and limited variation over the range of 2 to 40 C, with a temperature optimum of approximately 22 C. Trout sera and rat liver microsomes exhibited a temperature optimum of approximately 35 to 40 C. The CaE of trout liver (maximum reaction rate [V{sub max}] = 672 nmol/min/mg microsomal protein) was four times less than in rats. Apparent Michaelis constant (K{sub m}) values ranged from 28 (trout liver) to 214 (trout sera) {micro}M. Values of V{sub max}/K{sub m} suggested that in vivo CaE activity of trout liver would be about three times higher than serum, 135 times higher than gill, and three times lower than rat liver. The CaE activity in whole rainbow trout homogenates significantly increased 300% per gram of tissue to 1,200% per milligram of protein between the yolk-sac and juvenile stages. The CaE activity of whole fish homogenates was not significantly different in juvenile rainbow trout, channel catfish, fathead minnows, and bluegill. The results demonstrate that rainbow trout had high esterase activity over a broad range of temperatures, the CaE activity significantly increased between the yolk-sac and juvenile life stages, and that variation between the CaE activity in trout and three other families of freshwater fish was limited. The CaE activity in fish is expected to substantially influence the accumulation and toxicity of pesticides and other esters entering the aquatic environment.

Barron, M.G.; Charron, K.A.; Stott, W.T.; Duvall, S.E.

1999-11-01

391

Toxaphene in Great Lakes biota and air  

NASA Astrophysics Data System (ADS)

Toxaphene is a complex mixture of at least 600 hexa- through decachlorinated bornanes and bornenes, which was used as an insecticide in the United States from the 1950's until 1982, when it was banned. Toxaphene is ubiquitous in the environment, probably because of its atmospheric transport away from areas of use. Toxaphene's complex nature makes accurate quantitation difficult. I have developed a computer program to automate quantitation, thus decreasing the time required for analysis while maintaining precise quantitation. I have shown that toxaphene in lake trout (Salvelinus namaycush) and rainbow smelt (Osmerus mordax) taken from Lake Superior have not decreased as they have in the four other Great Lakes from the time of the ban though 1992. This result could be due to three possibilities: ( a) There had been a food chain perturbation that made the 1982 concentrations unusually low. (b) The physical properties of Lake Superior make the loss rate significantly lower than the other Great Lakes. (c) There are current sources of toxaphene entering the Lake Superior basin. I analyzed an extended time series of lake trout from Lake Superior and from northern Lake Michigan to test the first two hypotheses. The concentrations of toxaphene have been constant in trout from Lake Superior since the late 1970's, so hypothesis a can be negated. The northern Lake Michigan samples did not decline as greatly as the southern basin samples, so hypothesis b can not be disproved. To determine the atmospheric deposition of toxaphene to Lake Superior, I analyzed air samples collected every twelve days for sixteen months at Eagle Harbor, Michigan. The concentrations of toxaphene in these samples are similar to those found in recent studies of air collected at Traverse City, MI., but significantly lower than samples taken at a land based site in southern Ontario in 1988 and 1989. This difference in concentration may (or may not) be due to differences in sampling times or locations or in quantitation protocols. These finding imply that Lake Superior is not receiving a unique atmospheric burden, but, because I have not explored terrestrial inputs, I cannot fully nullify hypothesis c.

Glassmeyer, Susan Theresa

1998-11-01

392

Microsatellite diversity and conservation of a relic trout population: McCloud River redband trout.  

PubMed

Rainbow trout native to the McCloud River, California, USA (Oncorhynchus mykiss stonei) are thought to represent a relic, nonanadromous trout adapted to harsh, fragmented environments. These fish, commonly named McCloud River 'redband' trout, survive in their most primitive form in a small, spring-fed stream, Sheepheaven Creek, in the upper McCloud River drainage. Turn-of-the-century fisheries records document both coastal anadromous steelhead and freshwater resident trout within the McCloud River drainage. The phylogenetic position of the McCloud River redband trout within O. mykiss has been debated for over 50 years. Based on phenotypic evidence, these fish were first reported as 'southern Sierra golden trout' by Wales in 1939. Behnke (1970) considered them a relic subspecies of nonanadromous, fine-scaled trout. Allozyme and mitochondrial DNA evidence suggested a coastal lineage. In this study, we examined within- and among-basin genetic associations for Sheepheaven Creek redband trout using 11 microsatellite loci. Within-basin analyses supported unique genetic characteristics in Sheepheaven Creek's trout in comparisons with other McCloud River rainbow trout. Microsatellite data supported significant independence between Sheepheaven Creek fish and hatchery rainbow trout. Inter-basin genetic distance analyses positioned Sheepheaven Creek fish with samples collected from Lassen Creek, a geographically proximate stream containing inland redband trout. California's redband trout shared a close genetic association with Little Kern River golden trout (O.m. whitei) and isolated rainbow trout from Rio Santo Domingo, Baja, Mexico (O.m. nelsoni), suggesting a vicariant distribution of microsatellite diversity throughout the southern range of this species. PMID:10703556

Nielsen, J L; Crow, K D; Fountain, M C

1999-12-01

393

A modified FMEA approach to enhance reliability of lean systems  

Microsoft Academic Search

Purpose – The purpose of this paper is to encourage the integration of Lean principles with reliability models to sustain Lean efforts on a long-term basis. It seeks to present a modified FMEA that will allow Lean practitioners to understand and improve the reliability of Lean systems. The modified FMEA approach is developed based on the four critical resources required

Rapinder Sawhney; Karthik Subburaman; Christian Sonntag; Prasanna Rao Venkateswara Rao; Clayton Capizzi

2010-01-01

394

Survey-based spreadsheet model on lean implementation  

Microsoft Academic Search

Purpose – This research was conducted to study benefits of a concept, known as lean manufacturing, which elicits organizations to do more with less effort, time, space, and equipment by eliminating waste. Because lean implementation involves finances, dedication, and cultural change in business, there is a need to assess a company's lean initiative. Design\\/methodology\\/approach – A comprehensive lean assessment tool

Devdas Shetty; Ahad Ali; Robert Cummings

2010-01-01

395

Lean Sigma and simulation, so what's the correlation? V2  

Microsoft Academic Search

This paper explores the fundamental relationships between Lean Sigma and simulation. A basic overview of Lean Sigma includes: 1) Lean Sigma philosophy, 2) basic tools, 3) theory of variation, 4) SPC, 5) process capability, 6) Lean Sigma infrastructure, and 7) DMAIC and DFSS processes. Simulation is applied to the appropriate areas of the overview. Improvement in the robustness of the

D. M. Ferrin; M. J. Miller; D. Muthler

2005-01-01

396

Dynamic analysis of a lean cell under uncertainty  

Microsoft Academic Search

One of the ultimate targets of lean manufacturing paradigm is to balance production and produce at takt time in production cells. This paper investigates the performance of a lean cell that implements the previous lean goals under uncertainty. The investigation is based on a system dynamics approach to model a dynamic lean cell. Backlog is used as a performance metric

Ahmed M. Deif

2012-01-01

397

Dynamic analysis of a lean cell under uncertainty  

Microsoft Academic Search

One of the ultimate targets of lean manufacturing paradigm is to balance production and produce at takt time in product