Depth Distribution, Diet, and Overwinter Growth of Lake Trout (Salvelinus Namaycush) in Southeastern Lake Michigan Sampled in December 1981 and March 1982

1986 ◽  
Vol 12 (4) ◽  
pp. 263-269 ◽  
Author(s):  
Gary W. Eck ◽  
LaRue Wells
Keyword(s):  
Lake Michigan ◽  
Depth Distribution ◽  
Lake Trout ◽  
Salvelinus Namaycush

An examination of the PCB: lipid relationship among individual fish

1997 ◽  
Vol 54 (5) ◽  
pp. 1031-1038
Author(s):  
C A Stow ◽  
L J Jackson ◽  
J F Amrhein
Keyword(s):  
Salmo Trutta ◽  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Salvelinus Namaycush ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Strong Linear Correlation ◽  
Brown Trout Salmo Trutta ◽  
The Relationship

We examined data from 1984 to 1994 for five species of Lake Michigan salmonids to explore the relationship between total PCB concentration and percent lipid. When we compared mean species lipid and PCB values, we found a strong linear correlation. When we compared values among individuals, we found modest positive PCB:lipid associations in brown trout (Salmo trutta), chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), and rainbow trout (Oncorhynchus mykiss) collected during spawning, but positive associations were not apparent among nonspawning individuals. Lake trout (Salvelinus namaycush) exhibited no discernible PCB:lipid relationship. Our results are not incompatible with previous observations that contaminants are differentially partitioned into lipids within a fish, but these results do suggest that lipids are not a major factor influencing contaminant uptake.

An Energetics Model for Lake Trout, Salvelinus namaycush: Application to the Lake Michigan Population

1983 ◽  
Vol 40 (6) ◽  
pp. 681-698 ◽  
Author(s):  
Donald J. Stewart ◽  
David Weininger ◽  
Donald V. Rottiers ◽  
Thomas A. Edsall
Keyword(s):  
Lake Michigan ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
High Energy ◽  
Alosa Pseudoharengus ◽  
Fishing Mortality ◽  
Age Classes ◽  
Short Term ◽  
Conversion Efficiencies

An energetics model is implemented for lake trout, Salvelinus namaycush, and applied to the Lake Michigan population. It includes an egestion function allowing any proportional mix of fish and invertebrates in the diet, a growth model accounting for both ontogenetic and seasonal changes in energy-density of predator and prey, a model for typical in situ swimming speed, and reproductive energy losses due to gametes shed. Gross conversion efficiency of energy by lake trout over their life (21.8%) is about twice the efficiency of converting biomass to growth because they store large amounts of high-energy fats. Highest conversion efficiencies are obtained by relatively fast-growing individuals, and over half the annual energy assimilated by older age-classes may be shed as gametes. Sensitivity analysis indicates a general robustness of the model, especially for estimating consumption by fitting a known growth curve. Largest sensitivities were for the intercept and weight dependence coefficients of metabolism. Population biomass and associated predatory impact of a given cohort increase steadily for about 3.5 yr then decline steadily after fishing mortality becomes important in the fourth year in the lake. This slow response time precludes manipulation of lake trout stocking densities as a means to control short-term prey fluctuations. Predation by lake trout on alewife, Alosa pseudoharengus, has been increasing steadily since 1965 to about 8 400 t∙yr−1, and is projected to rise to almost 12 000 t∙yr−1 by 1990.

Genetic Differences in Retention of Swimbladder Gas Between Two Populations of Lake Trout (Salvelinus namaycush)

1974 ◽  
Vol 31 (8) ◽  
pp. 1351-1354 ◽  
Author(s):  
P. Ihssen ◽  
J. S. Tait
Keyword(s):  
Brook Trout ◽  
Depth Distribution ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Genetic Differences ◽  
Trout Population ◽  
Two Populations

Lake trout (Salvelinus namaycush) derived from two populations differed in retention of swimbladder gas. The two reciprocal interpopulation crosses were intermediate to the parent populations. The two F1 hybrids obtained by crossing fish from each lake trout population with brook trout (S. fontinalis) were also found different in retention. Gas retention was correlated with depth distribution of the parent populations, high retention being associated with deeper distribution.

Quantification of historic lake trout (Salvelinus namaycush) spawning aggregations in Lake Michigan

1997 ◽  
Vol 54 (10) ◽  
pp. 2290-2302 ◽  
Author(s):  
K A Dawson ◽  
R L Eshenroder ◽  
M E Holey ◽  
C Ward
Keyword(s):  
Lake Michigan ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Catch Per Unit Effort ◽  
Spawning Activity ◽  
Commercial Catch ◽  
Northeast Section ◽  
Site Specific ◽  
Spawning Aggregations ◽  
Made In

We used commercial catch reports to determine site-specific characteristics of lake trout (Salvelinus namaycush) spawning aggregations in Michigan's and Wisconsin's waters of Lake Michigan before reproduction ceased in the 1950s. One hundred sites where annual catches exceeded 25 kg/year were identified. Two thirds of the catch was made in offshore waters and nearly half was made in the northeast sector of the lake. Catch was a better descriptor of the size of spawning aggregations than catch per unit effort (CPUE). CPUEs were not significantly different among onshore, offshore, and southern deepwater reefs. Spawning activity as measured by CPUE had peaked by the week beginning 29 October at all locations. Spawning aggregations were strongly clustered in the northeast section of the lake where Devonian rocks were subject to brecciation, i.e., fracturing and recementing following slumping. Areas zoned as refuges in the current lake trout rehabilitation plan account for 36% of the historical catch targeted at spawning aggregations. We recommend a refocusing of rehabilitation efforts in northern waters from sites where historical catches were modest to sites that produced the largest catches of lake trout aggregated for spawning.

Changes in Mortality of Lake Trout (Salvelinus namaycush) in Relation to Increased Sea Lamprey (Petromyzon marinus) Abundance in Green Bay, 1974–78

1980 ◽  
Vol 37 (11) ◽  
pp. 2052-2056 ◽  
Author(s):  
J. D. Moore ◽  
T. J. Lychwick
Keyword(s):  
Lake Michigan ◽  
Lake Trout ◽  
Petromyzon Marinus ◽  
Sea Lamprey ◽  
Salvelinus Namaycush ◽  
Green Bay ◽  
Methods Of Measurement

Increased sea lamprey (Petromyzon marinus) abundance in Green Bay during 1977 is documented utilizing sea lamprey counts and lake trout (Salvelinus namaycush) wounding as methods of measurement. Since lake trout rehabilitation began in 1965, sea lamprey predation has been consistently higher in Green Bay and Northern Lake Michigan than other areas of the lake. It appears that increased sea lamprey predation in Green Bay, above the former high levels, resulted in decreased abundance and increased mortality of lake trout. The increase in lampreys is related to the colonization of the Peshtigo River, Marinette County, Wisconsin.Key words: Green Bay, sea lamprey increases, Peshtigo River, lake trout, increased mortality

Endohelminths of salmonids from two localities in eastern Lake Michigan, with emphasis on Echinorhynchus salmonis

1989 ◽  
Vol 67 (6) ◽  
pp. 1604-1607 ◽  
Author(s):  
Patrick M. Muzzall
Keyword(s):  
Chinook Salmon ◽  
Salmo Trutta ◽  
Lake Michigan ◽  
Oncorhynchus Tshawytscha ◽  
Lake Trout ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Salvelinus Namaycush ◽  
Salmo Gairdneri ◽  
Brown Trout Salmo Trutta

Adult salmonids (101 chinook salmon, Oncorhynchus tshawytscha; 7 coho salmon, Oncorhynchus kisutch; 56 lake trout, Salvelinus namaycush; 6 steelhead, Salmo gairdneri; and 2 brown trout, Salmo trutta) were collected from eastern Lake Michigan (Ludington and Manistee, Michigan) in July–September 1986, and examined for helminths. Eight species (three Cestoda, three Nematoda, two Acanthocephala) were found in the digestive tract and other viscera. Echinorhynchus salmonis and Eubothrium salvelini were the most common helminths found. The intensity of E. salmonis significantly increased as chinook salmon became older and longer.

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