Great Lakes Fishery Commission

Effective fisheries management and restoration requires reliable estimates of abundance and population trajectories through time. However, absolute population estimates are extremely difficult to obtain in large systems due to the prohibitively high sample sizes required by most approaches. Close-kin mark-recapture (CKMR) is a new technique that can obviate this hurdle by using the observed kinship within a sample to estimate the true adult population. Our project aimed to develop a CKMR model for lake trout (Salvelinus namaycush) and apply it understand the re-establishment of Lake Champlain’s wild population by estimating the abundance of individuals contributing to wild recruitment. We used a multi-year tissue dataset, in combination with a recently-designed genotyping panel and close-kin mark-recapture, to quantify the performance (i. e., survival and reproductive success) of stocking sources and strategies with an eye towards informing restoration programs in other systems. We also assessed the overall abundance of adult fish and parental dynamics associated with wild recruitment. Our results indicate that adult survival is remarkably high and overall abundance is low compared to other large lake systems in similar latitudes, with the vast majority of wild recruitment genetically traceable to the Seneca strain fish historically stocked by New York State. We observed little evidence of hybridization between the two strains and close-kin mark-recapture estimates indicated that approximately 20 % of the adult population was contributing to successful recruitment on a regular basis. Ultimately, our results point to a growing wild population that has the potential to become self-sustaining.\\\\r\\\\n

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