Trophic Relationships among Lean and Siscowet Lake Trout in Lake Superior

Data for the Canadian fisheries system in Lake Superior were organized into monthly time series of catch and effort from January 1963 through December 1976 for six fish species. Multivariate, autoregressive (ARMA) models were identified for the system based on data for the first 140 mo. Forecasts were compared to data for the last 28 mo. The structure of the models indicate that (1) within the system, AR processes, as opposed to MA processes, were of overriding importance, (2) intraspecific interactions (inferred from data on catch-per-unit-effort, CPUE) were more prevalent than interspecific interactions, (3) interactions within the system occurred with lags of 1, 4, 12, 24, 25, 28, and 36 mo, (4) some of the trophic relationships among the fish species were revealed by the models, and (5) CPUE time series of lake trout (Salvelinus namaycush) affected, but was not affected by, the CPUE time series of other species. The models were used to forecast catch and CPUE for the last 28 mo, and the data were generally within one standard error of the forecasts. The models may help policy decision makers to explore the effects of inputs (e.g. quota regulations) and feedbacks within the fisheries' system on outputs (e.g. production, CPUE).

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A stable isotope evaluation of the structure and spatial heterogeneity of a Lake Superior food web

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-072 ◽

2000 ◽

Vol 57 (7) ◽

pp. 1395-1403 ◽

Cited By ~ 58

Author(s):

Chris J Harvey ◽

James F Kitchell

Keyword(s):

Stable Isotope ◽

Spatial Heterogeneity ◽

Food Web ◽

Lake Trout ◽

Trophic Position ◽

Lake Superior ◽

Salvelinus Namaycush ◽

Trophic Relationships ◽

Rainbow Smelt ◽

Western Lake

We used stable isotope analysis to derive trophic relationships and movement patterns for components of the western Lake Superior food web. Trophic linkages implied by previous gut content studies were only marginally supported by stable isotope data. Siscowet lake trout (Salvelinus namaycush siscowet) were the top predators, and trophic overlap between siscowet and lean lake trout (Salvelinus namaycush) was low. Exotic Pacific salmon (Oncorhynchus spp.) occupied a lower trophic position than native piscivores because the latter relied more on coregonids. To evaluate spatial heterogeneity of the food web, we assumed that the adjacent cities of Duluth and Superior (DS) were a point source of 15N, and we measured isotopes of organisms close to and far from DS. Slimy sculpin (Cottus cognatus) were enriched in the DS area relative to other sites, implying that they are relatively sedentary. Rainbow smelt (Osmerus mordax) showed no differences at any sites, implying high vagility. Other organisms showed differences that could not be attributed to DS, implying that other mechanisms, such as trophic ontogeny, were influencing their isotopic signatures.

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Declining Survival of Lake Trout Stocked during 1963–1986 in U.S. Waters of Lake Superior

North American Journal of Fisheries Management ◽

10.1577/1548-8675(1994)014<0395:dsolts>2.3.co;2 ◽

1994 ◽

Vol 14 (2) ◽

pp. 395-402 ◽

Cited By ~ 12

Author(s):

Michael J. Hansen ◽

Mark P. Ebener ◽

Richard G. Schorfhaar ◽

Stephen T. Schram ◽

Donald R. Schreiner ◽

...

Keyword(s):

Lake Trout ◽

Lake Superior

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Dynamics and Exploitation of Mature Walleyes, Stizostedion vitreum vitreum, in the Nipigon Bay Region of Lake Superior

Journal of the Fisheries Research Board of Canada ◽

10.1139/f68-121 ◽

1968 ◽

Vol 25 (7) ◽

pp. 1347-1376 ◽

Cited By ~ 11

Author(s):

R. A. Ryder

Keyword(s):

Lake Trout ◽

Lake Superior ◽

Total Mortality ◽

Inland Waters ◽

Commercial Fishery ◽

Sea Lampreys ◽

Wood Fibres ◽

High Concentrations ◽

Trout Fishery ◽

Hexagenia Limbata

Walleye stocks in Nipigon Bay of Lake Superior were homogeneous with those in tributary inland waters but were discrete from Black Bay stocks. Returns from 2200 tagged walleyes in Lake Superior and tributary inland waters between 1955 and 1958 varied from 7.8 to 31.0% for 2 years after release. The commercial fishery in Lake Superior recovered 64.9% of the tags, the sports fishery in inland waters captured 27.6%. Fish tagged in the Nipigon River travelled a mean distance of 11.8 miles from the point of release and were recovered in 191 days (average). Total mortality rates for Nipigon Bay walleyes were 55.0% (1955–57). Mature walleyes on the spawning grounds in the Nipigon River in 1957 were estimated at 22,000, and fish in Nipigon Bay over 14 inches (total length) the same year at 41,000. All male walleyes were mature at 15 inches and females at 18 inches. Walleyes exploitation rates increased with the decline of the lake trout fishery. Wounding and scarring rates by sea lampreys increased during 1955–57 but never exceeded 1.0% on adult walleyes. Severe pollution on the west side of Nipigon Bay originated from a kraft mill. High concentrations of total solids and dense sedimentation of wood fibres created an environment unfavourable to Hexagenia limbata and Pontoporeia affinis. The recent elimination of the walleye fishery in Nipigon Bay is most likely attributable to industrial pollution rather than to overexploitation or sea lamprey predation.

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Survey of the Genetic Variation Among Eastern Lake Superior Lake Trout (Salvelinus namaycush)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f81-222 ◽

1981 ◽

Vol 38 (12) ◽

pp. 1738-1746 ◽

Cited By ~ 24

Author(s):

Terrence R. Dehring ◽

Anne F. Brown ◽

Charles H. Daugherty ◽

Stevan R. Phelps

Keyword(s):

Genetic Variation ◽

Gel Electrophoresis ◽

Lake Trout ◽

Lake Superior ◽

Salvelinus Namaycush ◽

Starch Gel Electrophoresis ◽

Average Heterozygosity ◽

Management Implications ◽

Salmonid Species ◽

Starch Gel

Patterns of genetic variation among lake trout (Salvelinus namaycush) of eastern Lake Superior were examined using starch gel electrophoresis. We used 484 individuals sampled from three areas, representing three morphological types (leans, humpers, and siscowets). Of 50 loci examined, 44 were monomorphic in all groups sampled. Genetic variation occurs at six loci AAT-1,2, MDH-3,4, ME-1, and SOD-1. The average heterozygosity found (H = 0.015) is low relative to other salmonid species. A significant amount of heterogeneity exists among the 10 lake trout samples. These differences are due to variation within as well as between morphological types. The significance and management implications of these data are discussed.Key words: genetic variation, lake trout, Salvelinus namaycush, Lake Superior

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Temporal Trends and Spatial Variabilities of PCB concentrations in Lake Trout from Lake Superior from 1995 to 2013

10.37099/mtu.dc.etdr/189 ◽

2016 ◽

Author(s):

Hongyi Lin

Keyword(s):

Lake Trout ◽

Lake Superior ◽

Temporal Trends

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Sea lamprey (Petromyzon marinus) size trends in a salmonid stocking context in Lake Superior

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f05-145 ◽

2005 ◽

Vol 62 (10) ◽

pp. 2354-2361 ◽

Cited By ~ 4

Author(s):

Jeffrey C Jorgensen ◽

James F Kitchell

Keyword(s):

Bayesian Model ◽

Fish Community ◽

Bayesian Model Averaging ◽

Lake Trout ◽

Pacific Salmon ◽

Lake Superior ◽

Petromyzon Marinus ◽

Control Period ◽

Model Averaging ◽

Sea Lamprey

Fish community objectives for Lake Superior call for restoration such that it resembles its historical species composition, to the extent possible, yet allow for supplementation of naturalized Pacific salmonids (Oncorhynchus spp.). To achieve these goals, managers strive to control the sea lamprey (Petromyzon marinus) to levels that cause insignificant (<5%) mortality to host species. While control efforts have been successful, sea lamprey size has increased during the control period. We analyzed long-term sea lamprey size trends and found a significant increase from 1961 to 2003 (F = 36.76, p < 0.001, R2 = 0.473). A local regression revealed two significant size increase periods. We used Bayesian model averaging to find the relationship between sea lamprey size and the stocking of salmonids (lean lake trout (Salvelinus namaycush) and Pacific salmon). Bayesian model averaging identified 91 models, and several regressors were common features in many of the models. Sea lamprey weight was related to stocked lake trout lagged 3, 9, 11, and 13 years, and stocked Pacific salmon lagged 4 years. If sea lampreys can achieve larger sizes attached to Pacific salmonid hosts, and thus inflict more damage, there may be a trade-off for managers in achieving the fish community objectives for Lake Superior.

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