Inbreeding and Allele Retention for Lake Sturgeon Populations under Different Supplementation Strategies

Abstract

AbstractLake sturgeon Acipenser fulvescens once were abundant throughout the Great Lakes basin but have been reduced to less than 1% of historical levels because of habitat degradation and overexploitation. Current management plans suggest stocking as a tool to increase abundance, but stocking also has genetic implications. The objectives of this study were to determine the supplementation level that would maintain long‐term population persistence with the smallest genetic impact and to determine whether different supplementation strategies would be required for different starting conditions. An individual‐based model that incorporated demographics and genetics was used to explore scenarios that included three initial population sizes, two different supplementation time frames, varying sex ratios, variance in family size, and different percentages of the adult population contributing progeny for supplementation. As expected, all supplementation scenarios reduced extinction risk, increased population sizes, increased allele retention, and reduced inbreeding over time compared with scenarios involving no supplementation. Supplementation over long time frames was only necessary when supplementing large population sizes. Contrary to expectations, a skewed sex ratio and an unequal family size had little impact on the genetics of populations. When the percentage of adults contributing progeny for supplementation was reduced, allele retention decreased and inbreeding increased. Supplementing larger populations over longer time frames and capturing the greatest number of adults from the population for supplementation are the most important considerations for maintaining alleles and reducing inbreeding under the scenarios we explored.Received December 22, 2010; accepted July 28, 2011