Changes in the Multispecies, Winter Angling Fishery of Lake Simcoe, Ontario, 1961–83: Invasion by Rainbow Smelt, Osmerus mordax, and the Roles of Intra- and Interspecific Interactions

1987 ◽  
Vol 44 (S2) ◽  
pp. s182-s197 ◽  
Author(s):  
David O. Evans ◽  
Peter Waring

Winter creel surveys revealed major changes in the abundance of five fish species (lake trout, Salvelinus namaycush, lake whitefish, Coregonus clupeaformis, lake herring, Coregonus artedii, yellow perch, Perca flavescens, and rainbow smelt, Osmerus mordax) in Lake Simcoe (1961–83). Variations in abundance were in part caused by intra- and interspecific factors. Catches in alternate years for both lake herring and rainbow smelt were inversely correlated, suggesting negative interactions between their young-of-the-year and yearlings. Similarly an inverse relation between parental stock size and recruitment explained a significant component of the catch variation of lake herring and yellow perch. Natural recruitment of lake trout declined during the 1950s (associated with eutrophication effects), and in the early 1960s, rainbow smelt invaded the fake. Lake whitefish abundance declined in the early 1970s as smelt abundance increased; the decline in whitefish recruitment was probably caused by interaction between smelt and whitefish young-of-the-year. Catches of yellow perch were positively correlated with rainbow smelt and negatively correlated with lake whitefish. Lake herring also increased when lake whitefish density was low. Increased abundance of lake trout after 1975 (due to stocking) appears to have resulted in lower densities of lake herring, rainbow smelt, and yellow perch and the reestablishment of lake whitefish recruitment at a low level. These results suggest that a large predator (lake trout) can have a major influence on the structure of a fish community, by direct and indirect effects.

1987 ◽  
Vol 44 (S2) ◽  
pp. s10-s14 ◽  
Author(s):  
Bryan A. Henderson ◽  
F. E. J. Fry

Of the nine species caught in pound and gill nets in South Bay, Lake Huron (lake whitefish (Coregonus clupeaformis), rainbow smelt (Osmerus mordax), lake trout (Salvelinus namaycush), splake (S. namaycush × S. fontinalis), burbot (Lota lota), lake hering (Coregonus artedii), alewife (Alosa pseudoharengus), white sucker (Catostomus commersoni), and yellow perch (Perca flavescens)), only yellow perch, white sucker, and lake whitefish were significantly related to the abundances of all other fish species (multiple regression) from 1965 to 1984. For the longer period (pound nets 1949–84), all but smelt, burbot, and white sucker were dependent upon variations in the abundance of the nine other species. For the same period (1965–84) and species (nine), the abundances only of yellow perch and white suckers were significantly and positively related in two basins of the Bay. None of the inverse correlations between species abundances was significant in both basins. Within the Outer Basin, only the correlations between alewife and lake herring (r = −0.49, r = −0.45) and yellow perch and white sucker (r = +0.55, r = +0.47) were significant in the same direction for both time periods (1949–64 and 1965–84, respectively). We concluded that there was little evidence that the abundances of species were affected significantly by interspecific influences.


1981 ◽  
Vol 38 (6) ◽  
pp. 662-668 ◽  
Author(s):  
Larry B. Crowder ◽  
John J. Magnuson ◽  
Stephen B. Brandt

The potential for ecological segregation of Lake Michigan fishes was examined by comparing diets and thermal habitat use of common species. Samples were collected by bottom trawling (N = 68) off Grand Haven, Michigan, September 7–13, 1977. Five common species exhibited complementarity in the use of food and thermal habitat resources. During the day, adult alewife (Alosa pseudoharengus), and rainbow smelt (Osmerus mordax) had similar diets but occupied somewhat different thermal habitats. Young-of-the-year (YOY) alewives segregated from adult alewife and rainbow smelt on both habitat and food. Spottail shiner (Notropis hudsonius), YOY alewives, and yellow perch (Perca flavescens) used similar thermal habitats but fed on different prey. Trout-perch (Percopsis osmiscomaycus) tended to segregate from the others based on both food and thermal habitat but may experience diffuse competition. Adults of the three native species consume entirely different prey than exotic alewife and rainbow smelt. The native species which declined during the invasion of alewife and rainbow smelt were those with apparently similar habitat and food requirements to the exotics. These data suggest that competition is important in maintaining the structure of the Lake Michigan fish community.Key words: competition, fishes, food, habitat, Lake Michigan, predation, temperature


<em>Abstract</em>.—Lake trout <em>Salvelinus namaycush </em>eggs were collected from 18 separate locations in the Great Lakes and inland lakes to evaluate the relationship between diet and egg thiamine content. Thiamine concentrations in the eggs of lake trout whose diet consisted primarily of rainbow smelt <em>Osmerus mordax </em>and alewife <em>Alosa pseudoharengus </em>were one-ninth to one-seventeenth those of eggs of lake trout whose diet lacked either of these two species and was composed of lake herring <em>Coregonus artedi</em>, yellow perch <em>Perca flavescens</em>, cyprinids, or invertebrates. Within the Great Lakes, concentrations of thiamine in the eggs of lake trout increased in the order Ontario, Erie, Michigan, Huron < Superior and reflected the proportion of smelt, alewives, or both in the diet. Of the three forms of thiamine found in eggs, free thiamine was the most important and the form most affected by a diet of alewives or smelt. Collections from inland lakes were similar in terms of thiamine content and its relationship to diet composition. Average free thiamine concentrations in lake trout from Lakes Ontario, Erie, Michigan, and Huron were 1.5 to 4 times a threshold of 0.8 nmol/g that has been associated with the development of a thiamine-responsive early mortality syndrome. In contrast, the concentration of free thiamine in Lake Superior lake trout eggs was 26 times the threshold. We concluded that the reduction in egg thiamine concentrations in lake trout whose diet was primarily smelt or alewives was the result of their high thiaminase content, because published thiamine contents could not explain the patterns observed. Egg thiamine concentrations in lake trout were unaffected by maternal age.


1986 ◽  
Vol 43 (4) ◽  
pp. 812-818 ◽  
Author(s):  
D. H. Loftus ◽  
P. F. Hulsman

Rainbow smelt (Osmerus mordax) predation on larval lake whitefish (Coregonus clupeaformis) and lake herring (C. artedii) in Twelve Mile Lake, Ontario, was intense in 1984. Coregonid larvae hatched in early April as smelt spawning was ending. Predation was continuous for a 7-wk period, beginning at the onset of hatching. Numbers of coregonid larvae observed in smelt stomachs were directly proportional (p ≤ 0.005) to their abundance in the lake. During the week when the larvae were most abundant, they occurred in 93% of the smelt stomachs containing food. The corresponding average daily consumption was 8.4 larvae per smelt. Simulation of the combined effects of smelt predation and "natural" mortality indicated that mortality of lake whitefish may be 100%. Survival of herring larvae must be greatly reduced as well. Rainbow smelt became established in Twelve Mile Lake in the 1950's; their effect on larval whitefish survival may have been aggravated by intensified dipnetting of spawning lake whitefish during the 1960's. There has been little or no recruitment of young whitefish to the population since 1975, although dipnetting for adults ceased in about 1970. Our results support the hypothesis that the primary cause of recruitment failure of this whitefish population is predation by smelt.


2003 ◽  
Vol 60 (12) ◽  
pp. 1552-1574 ◽  
Author(s):  
Charles R Bronte ◽  
Mark P Ebener ◽  
Donald R Schreiner ◽  
David S DeVault ◽  
Michael M Petzold ◽  
...  

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.


1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.


<em>Abstract</em>.—Thiamine concentrations in representative Great Lakes prey fish, including alewives <em>Alosa pseudoharengus</em>, rainbow smelt <em>Osmerus mordax</em>, slimy sculpin <em>Cottus cognatus</em>, bloater chub <em>Coregonus hoyi</em>, and lake herring <em>Coregonus artedi</em>, and their major dietary items, including mysids <em>Mysis relicta</em>, amphipods <em>Diporeia hoyi</em>, and net macroplankton, were measured to assess their potential involvement in depressed thiamine concentrations in lake trout <em>Salvelinus namaycush </em>of the Great Lakes. Mean thiamine concentrations in all biota were greater than the recommended dietary intake of 3.3 nmol/g for prevention of effects on growth, although the adequacy of these concentrations for reproduction is not known. Mean thiamine concentrations decreased in the order alewives > bloater chub, herring > smelt and differed from the order of associated egg thiamine concentrations published for lake trout feeding on these species (herring > alewives, smelt). As a result, these data strongly implicate the high thiaminase content, rather than the low thiamine content, of alewives and smelt as being responsible for the low egg thiamine concentrations of Great Lakes lake trout stocks that feed heavily on these species. Variations in thiamine content among prey species did not appear to be related to levels in their diet, because thiamine concentrations in <em>Mysis</em>, <em>Diporeia</em>, and macroplankton showed little consistency between group or between lake variation. There was no lake to lake variation in mean thiamine concentrations of prey species, but considerable within species variation occurred that was unrelated to size.


2002 ◽  
Vol 59 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Chris J Harvey ◽  
Paul C Hanson ◽  
Timothy E Essington ◽  
Paul B Brown ◽  
James F Kitchell

To describe temporal dynamics of stable isotope ratios in fishes, we developed a bioenergetics-based model that links isotope ratios to growth, as influenced by fish size, temperature, diet, and prey quality. The model includes error terms for isotope ratios, diet proportions, and fractionation. The model accurately predicted temporal δ15N dynamics of lake trout (Salvelinus namaycush) in a diet-switch experiment but was less successful for δ13C, possibly because of variable fractionation. The model was then used in three heuristic applications. In a diet-validation scenario, a model derived from limited knowledge of rainbow smelt (Osmerus mordax) diet reasonably estimated δ13C and δ15N compared with a null model but inaccurately estimated prey consumption. In a scenario where adult lake trout briefly cannibalized stocked lake trout fingerlings, the detectability of a cannibalism-induced δ15N increase depended on predator size, duration of cannibalism, and sample size. In a scenario where seasonal isotopic variability occurred at the base of a food web, variation propagated to higher trophic levels depended on consumer size and diet. Our approach is most valuable when used to examine multiple diet combinations that produce observed stable isotope ratios; one can then identify the most reasonable diets through field tests or other observations.


1979 ◽  
Vol 36 (1) ◽  
pp. 37-41 ◽  
Author(s):  
John R. M. Kelso ◽  
John K. Leslie

Larval fish were sampled by net in Lake Huron and the Douglas Point generating station throughout spring, summer, and early fall 1975. Dominance shifted from fourhorn sculpin (Myoxocephalus quadricornis) to rainbow smelt (Osmerus mordax) then to ale-wife (Alosa pseudoharengus) from late April to late September. Entrainment of the major species paralleled dominance and abundance observed in the lake, but yellow perch (Perca flavescens), brook stickleback (Eucalia inconstans), and slimy sculpin (Cottus cognatus) caught in the lake — each ranging from 5 to 25% of the total catch — were not entrained. Conversely, white sucker (Catostomus commersoni) was entrained but not captured in the lake. Size of individuals entrained, upper limit approx. 40 mm, paralleled size of individuals in the lake. Vertical distribution, and thus proximity to the submerged intake, greatly influenced entrainment rate. Key words: larval fish, entrainment, power plant, distribution, abundance.


1998 ◽  
Vol 55 (2) ◽  
pp. 307-317 ◽  
Author(s):  
Peter S Rand ◽  
Donald J Stewart

We tested the hypotheses that (1) reductions in individual size and energy density of adult alewife (Alosa pseudoharengus) in Lake Ontario over the past decade have caused reductions in mean size of consumed alewife and compensatory increases in frequency of feeding by salmonines and (2) perceived recent reductions in the alewife and rainbow smelt (Osmerus mordax) prey base in recent years have resulted in shifts in diets of salmonines to less preferred prey items. Data from a diet survey conducted on sport-caught salmonines during 1983-1988 and 1993 indicated significant reductions in the mean size of consumed alewife across all predator species over time and an increased frequency of feeding among some predators (reflected by a decline in the proportion of empty stomachs observed). We found evidence of increased ration levels in coho salmon (Oncorhynchus kisutch) and lake trout (Salvelinus namaycush) and an increase in the number of adult alewife in stomachs of all predator species that was accurately predicted by an earlier bioenergetic model analysis. We found evidence of a shift in diet across years away from rainbow smelt and other fishes to adult alewife. Results point toward possible sources of bioenergetic stress on salmonines in Lake Ontario.


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