Cost of predation avoidance in young-of-year lake trout (Salvelinus namaycush): growth differential in sub-optimal habitats
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Selection of habitat to avoid predation may affect the diet of young-of-year (YOY) lake trout (Salvelinus namaycush). YOY lake trout may use inshore habitat to avoid predation; this habitat may be sub-optimal for growth. To test this, YOY lake trout were penned in nearshore and offshore pelagic areas of two arctic lakes. Toolik Lake had a lake trout population, the other lake, S6, did not. YOY lake trout in Toolik Lake lost weight, but those offshore lost less weight. The YOY lake trout in Lake S6 gained weight and those offshore gained more weight.
The primary diet item of the YOY lake trout in both lakes during this experiment was the zooplankter Diaptomis probilofensis; it was also one of the most abundant species. However, its density inshore in Lake S6 was similar to inshore and offshore densities in Toolik Lake. The increased availability of alternative zooplankton prey in Lake S6 may account for the growth differential of YOY lake trout in Lake S6 relative to Toolik Lake.
Bioenergetic modeling of YOY lake trout suggests that growth similar to that in the offshore of Lake S6 would be necessary for successful recruitment. If the reduced zooplankton availability in Toolik Lake leads to the reduced growth of YOY in the inshore and offshore pelagic areas, then these fish will be more susceptable to winter predation/starvation. For YOY lake trout to survive in Toolik Lake they most likely shift to feeding on benthic prey before the end of their first summer.
Key wordslake trout predation risk zooplankton diet bioenergetics habitat lake
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- Cummins, K. W. & J. C. Wuycheck, 1971. Caloric equivalents for investigations in ecological energetics. Mitt. int. Ver. Limnol. 18: 158 pp.Google Scholar
- Hanson, K. L., A. E. Hershey & M. E. McDonald, 1992. A comparison of slimy sculpin (Cottus cognatus) populations in arctic lakes with and without piscivorous predators. Hydrobiologia 240: 189–201.Google Scholar
- Hewitt, S. W. & B. L. Johnson, 1987. A generalized bioenergetics model of fish growth for microcomputers. University of Wisconsin Sea Grant Institute, Madison, WIS-SG-87–245. 47 pp.Google Scholar
- Johnson, L., 1972. Keller Lake: characteristics of a culturally unstressed salmonid community. J. Fish. Res. Bd Can. 29: 731–740.Google Scholar
- Johnson, L., 1976. Ecology of arctic populations of lake trout, Salvelinus namaycush, lake whitefish, Coregonus clupeaformis, arctic char, S. alpinus, and associated species in unexploited lakes of the Canadian Northwest Territories. J. Fish. Res. Bd Can. 33: 2459–2488.Google Scholar
- Kettle, D. & W. J. O'Brien, 1978. Vulnerability of arctic zooplankton species to predation by small lake trout (Salvelinus namaycush). J. Fish. Res. Bd Can. 35: 1495–1500.Google Scholar
- Martin, N. V. & C. H. Olver, 1980. The lake charr, Salvelinus namaycush. In E. K. Balon (ed), Charrs. Dr W. Junk Publishers, The Hague, Netherlands: 205–277.Google Scholar
- McDonald, M. E. & A.E. Hershey, 1992 Shifts in abundance and growth of slimy sculpin in response to changes in the predator population in an arctic Alaskan lake. Hydrobiologia 240: 219–223.Google Scholar
- Merrick, G. W., A. E. Hershey & M. E. McDonald, 1991. Lake trout (Salvelinus namaycush) control of snail density and size distribution in an arctic lake. Can. J. Fish. aquat. Sci. 48: 498–502.Google Scholar
- Merrick, G. W., A. E. Hershey & M. E. McDonald, 1992. Salmonid diet and the size, distribution, and density of benthic invertebrates. Hydrobiologia 240: 225–233.Google Scholar
- Mittelbach, G. G. & P. L. Chesson, 1987. Predation risk: indirect effects on fish populations. In W. C. Kerfoot & A. Sih (eds), Predation. University Press of New England, Hanover, NH: 315–332.Google Scholar
- O'Brien, W. J., C. Buchanon & J. Haney, 1979. Arctic zooplankton community structure: exceptions to some general rules. Arctic 32: 237–247.Google Scholar
- Snedecor, G. W. & W. G. Cochran, 1967. Statistical methods, 6th edn. Iowa State Press, Ames, IA. 593 pp.Google Scholar