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Spatio-temporal variation in total lipid content of stocked and wild juvenile lake trout (Salvelinus namaycush) in Lake Champlain
Sorrentino, Madelyn Gene
Sorrentino, Madelyn Gene
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Abstract
After more than 40 years of stocking, lake trout (Salvelinus namaycush) in Lake Champlain have started to exhibit strong, natural recruitment which suggests a change in limiting factors such as the prey base or overwinter survival. The distribution of juvenile wild lake trout shows variation in abundance and condition factor among regions of Lake Champlain. These differences suggest the prey base, or foraging success, may vary geographically within the lake. Stocked and wild lake trout may differ in their ability to utilize resources and in overwinter survival. One metric that may indicate differences in resources across regions is lipid content, which reflects the quality of available food and acts as an important energy reserve for overwinter survival. We quantified total lipid content of stocked and wild juvenile lake trout across spatial (lake regions) and temporal (seasonal) scales. No spatial differences in lipid content were apparent. Wild fish were significantly greater in lipid content than stocked fish. Seasonally, stocked fish showed a drop in lipid content from pre-winter levels to the following spring, and lipids continued to drop through autumn. Wild fish showed a cyclical summer increase in lipids following replenishment from winter depletion, which plateaued by autumn. Results suggest that hatchery conditions cause stocked juvenile lake trout to be less competitive in the Lake Champlain environment than wild juveniles, evidenced by their lower lipid content and seasonal depletion. Hatchery practices could be modified to produce more competitive juvenile lake trout and support the goal of restoring a self-sustaining population.
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Date
2019-01-01