Wednesday, August 4, 2010: 4:00 PM
320, David L Lawrence Convention Center
Paul Simonin1, Lars Rudstam2, Patrick Sullivan1, Donna Parrish3 and Bernard Pientka4, (1)Natural Resources, Cornell University, Ithaca, NY, (2)Department of Natural Resources, Cornell University, Ithaca, NY, (3)Vermont Cooperative Fish and Wildlife Research Unit, U.S. Geological Survey, Burlington, VT, (4)Vermont Department of Fish and Wildlife, Essex Junction, VT
Background/Question/Methods Intra-annual survival of larval and age-0 rainbow smelt (Osmerus mordax) in Lake Champlain was studied in relation to adult abundance and gradients in the physical aquatic environment. Spatial dynamics of rainbow smelt are key to rainbow smelt population dynamics because this species is cannibalistic and the rate of cannibalism is a function of spatial overlap and fish density. Thus, our objective was to determine how physical environmental gradients are related to rainbow smelt distribution then determine subsequent cannibalism rates and mortality of young fish. Using day and night hydroacoustic data from 2007 and 2008, we created generalized additive mixed effects models to predict rainbow smelt vertical distribution as a function of temperature and light. We compared predicted and observed cannibalism and subsequent mortality of age-0 fish as a function of fish distribution.Results/Conclusions
We found highest intra-annual mortality occurred during spring when no thermocline separated adult rainbow smelt from age-0 fish. However, the magnitude of mortality rates varied as a function of adult density, thus causing inter-annual variability. Comparisons with historic data suggested inter-annual variability in Lake Champlain was also related to changes in adult rainbow smelt mortality. This affect of physical gradients, which may change with climate changes, on rainbow smelt population dynamics is likely present in other systems, like the Great Lakes.
