Predator responses to prey population dynamics: an empirical analysis based on lake trout growth rates

1995 ◽  
Vol 52 (7) ◽  
pp. 1564-1571 ◽  
Author(s):  
Lisa A. Eby ◽  
Lars G. Rudstam ◽  
James F. Kitchell
Keyword(s):  
Growth Rates ◽  
Prey Density ◽  
Lake Trout ◽  
Energy Content ◽  
Stock Assessment ◽  
Lake Superior ◽  
Average Density ◽  
Rainbow Smelt ◽  
Search Volume ◽  
Consumption Rates

Lake trout (Salvelinus namaycush) growth rates were lower in Lake Superior (with the lowest prey density) than in Lakes Michigan and Ontario. In contrast, consumption rates (estimated using bioenergetics models) of lake trout were similar in Lakes Superior, Michigan, and Ontario because the primary prey in Lake Superior, rainbow smelt (Osmerus mordax), have a lower energy content than the primary prey in Lakes Michigan and Ontario, alewife (Alosa pseudoharengus). Estimated consumption rates did not respond to three-to five-fold changes in prey density within lakes and were similar across a 100-fold difference in prey density among lakes. These results demonstrate that lake trout are able to sustain high predation rates at low prey densities and a type II functional response fitted to these data rises very steeply at low prey densities. Two factors are implicated: the large search volume of these predators and disparity between the average density estimates of prey stock assessment and the spatial and temporal scaling appropriate for understanding predator–prey interactions. If prey are highly aggregated or predators can search large areas, then a decrease in whole-lake prey abundance will not necessarily result in a lower predation rate until prey populations are severely reduced.

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

2000 ◽  
Vol 57 (7) ◽  
pp. 1395-1403 ◽  
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.

Lake Superior Revisited 1984

1987 ◽  
Vol 44 (S2) ◽  
pp. s23-s36 ◽  
Author(s):  
Wayne R. MacCallum ◽  
James H. Selgeby
Keyword(s):  
Fish Community ◽  
Lake Trout ◽  
Pacific Salmon ◽  
Lake Superior ◽  
Sea Lamprey ◽  
Osmerus Mordax ◽  
Coregonus Clupeaformis ◽  
Rainbow Smelt ◽  
Coregonus Artedii ◽  
Historical Levels

The Lake Superior fish community has changed substantially since the early 1960s, when control of the sea lamprey (Petromyzon marinus) became effective. Self-reproducing stocks of lake trout (Salvelinus namaycush) have been reestablished in many inshore areas, although they have not yet reached pre-sea lamprey abundance; offshore lake trout are probably at or near pre-sea lamprey abundance. Stocks of lake whitefish (Coregonus clupeaformis) appear to have fully recovered; commercial catches are at or above historical levels. Lake herring (Coregonus artedii) are recovering rapidly in U.S. waters and are abundant in western Canadian waters. The population of rainbow smelt (Osmerus mordax), which declined in the 1970s, is recovering. Pacific salmon (Oncorhynchus) are becoming more abundant as a result of increased stocking in U.S. waters and are reproducing in most suitable tributaries; they have become significant in anglers' creels.

Estimates of Skipped Spawning in Lean and Siscowet Lake Trout in Southern Lake Superior: Implications for Stock Assessment

2014 ◽  
Vol 143 (3) ◽  
pp. 660-672 ◽  
Author(s):  
Shawn P. Sitar ◽  
Andrew J. Jasonowicz ◽  
Cheryl A. Murphy ◽  
Frederick W. Goetz
Keyword(s):  
Lake Trout ◽  
Stock Assessment ◽  
Lake Superior ◽  
Skipped Spawning

Consequences of prey fish community dynamics on lake trout (Salvelinus namaycush) foraging efficiency in Lake Superior

1998 ◽  
Vol 55 (5) ◽  
pp. 1273-1284 ◽  
Author(s):  
Doran M Mason ◽  
Timothy B Johnson ◽  
James F Kitchell
Keyword(s):  
Fish Community ◽  
Community Dynamics ◽  
Lake Trout ◽  
Size Structure ◽  
Lake Superior ◽  
Salvelinus Namaycush ◽  
Foraging Efficiency ◽  
Prey Fish ◽  
Rainbow Smelt ◽  
Lake Herring

We used a size-structured model, indexed by age, that combines bioenergetics and foraging theory to evaluate the effects of prey fish community structure (species dominance, size structure, and density) on the diet and net foraging efficiency of lake trout (Salvelinus namaycush) in Lake Superior. Prey size structure was important for young lake trout but decreased in importance for older lake trout, especially with increasing prey density. The model predicted that rainbow smelt (Osmerus mordax) should dominate the diet of young lake trout due to the size-dependent capture limitations of larger prey. In contrast, lake herring (Coregonus artedi) should dominate the diet of oldest lake trout owing to a higher net energy return than rainbow smelt. Model results are consistent with age-specific diet and size-at-age of lake trout during the last 40 years. Diets of intermediate-sized lake trout do not reflect the recent resurgence of lake herring populations. Absence of a dietary switch is probably due to higher capture probability for rainbow smelt. Lake trout growth and production will likely be highest with a mixed prey species assemblage of young rainbow smelt and older lake herring.

Coupling age-structured stock assessment and fish bioenergetics models: a system of time-varying models for quantifying piscivory patterns during the rapid trophic shift in the main basin of Lake Huron

2015 ◽  
Vol 72 (1) ◽  
pp. 7-23 ◽  
Author(s):  
Ji X. He ◽  
James R. Bence ◽  
Charles P. Madenjian ◽  
Steven A. Pothoven ◽  
Norine E. Dobiesz ◽  
...  
Keyword(s):  
Alternative Energy ◽  
Lake Trout ◽  
Stock Assessment ◽  
Time Varying ◽  
Rainbow Smelt ◽  
Trophic Shift ◽  
Fish Bioenergetics ◽  
Age Structured ◽  
Time Varying Models ◽  
Energy Pathways

We quantified piscivory patterns in the main basin of Lake Huron during 1984–2010 and found that the biomass transfer from prey fish to piscivores remained consistently high despite the rapid major trophic shift in the food webs. We coupled age-structured stock assessment models and fish bioenergetics models for lake trout (Salvelinus namaycush), Chinook salmon (Oncorhynchus tshawytscha), walleye (Sander vitreus), and lake whitefish (Coregonus clupeaformis). The model system also included time-varying parameters or variables of growth, length–mass relations, maturity schedules, energy density, and diets. These time-varying models reflected the dynamic connections that a fish cohort responded to year-to-year ecosystem changes at different ages and body sizes. We found that the ratio of annual predation by lake trout, Chinook salmon, and walleye combined with the biomass indices of age-1 and older alewives (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) increased more than tenfold during 1987–2010, and such increases in predation pressure were structured by relatively stable biomass of the three piscivores and stepwise declines in the biomass of alewives and rainbow smelt. The piscivore stability was supported by the use of alternative energy pathways and changes in relative composition of the three piscivores. In addition, lake whitefish became a new piscivore by feeding on round goby (Neogobius melanostomus). Their total fish consumption rivaled that of the other piscivores combined, although fish were still a modest proportion of their diet. Overall, the use of alternative energy pathways by piscivores allowed the increases in predation pressure on dominant diet species.

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

1994 ◽  
Vol 14 (2) ◽  
pp. 395-402 ◽  
Author(s):  
Michael J. Hansen ◽  
Mark P. Ebener ◽  
Richard G. Schorfhaar ◽  
Stephen T. Schram ◽  
Donald R. Schreiner ◽  
...  
Keyword(s):  
Lake Trout ◽  
Lake Superior

Effects of turbidity on prey consumption and growth in brook trout and implications for bioenergetics modeling

2001 ◽  
Vol 58 (2) ◽  
pp. 386-393 ◽  
Author(s):  
John A Sweka ◽  
Kyle J Hartman
Keyword(s):  
Growth Rates ◽  
Brook Trout ◽  
Specific Growth ◽  
Abiotic Factors ◽  
Foraging Strategies ◽  
Turbid Water ◽  
Daily Consumption ◽  
Consumption Rates ◽  
The Difference ◽  
Specific Growth Rates

Brook trout (Salvelinus fontinalis) were held in an artificial stream to observe the influence of turbidity on mean daily consumption and specific growth rates. Treatment turbidity levels ranged from clear (<3.0 nephelometric turbidity units (NTU)) to very turbid water (> 40 NTU). Observed mean daily specific consumption rates were standardized to the mean weight of all brook trout tested. Turbidity had no significant effect on mean daily consumption, but specific growth rates decreased significantly as turbidity increased. Brook trout in turbid water became more active and switched foraging strategies from drift feeding to active searching. This switch was energetically costly and resulted in lower specific growth rates in turbid water as compared with clear water. Bioenergetics simulations were run to compare observed growth with that predicted by the model. Observed growth values fell below those predicted by the model and the difference increased as turbidity increased. Abiotic factors, such as turbidity, which bring about changes in the activity rates of fish, can have implications for the accuracy of predicted growth by bioenergetics models.

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

1968 ◽  
Vol 25 (7) ◽  
pp. 1347-1376 ◽  
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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