Demographic and Genetic Evaluations of Lake Sturgeon Stocking in the Cheboygan River Watershed, Michigan

Release of hatchery produced juvenile lake sturgeon (Acipenser fulvescens) is increasingly used to restore extirpated or numerically depressed populations in Great Lakes tributaries.  The success of stocking prescriptions is difficult to document due to delayed sexual maturity and occupancy of expansive lake environments during non-spawning periods.  We conducted gillnet surveys to collect demographic and genetic data to assess the success of stocking during 1984-1987 and 2001-2013 in the closed Black Lake Michigan population. Based on the presence and location of coded wire tags and pectoral fin ray age determinations we determined individual age and stocking year.  Cohort survival was estimated based on known number stocked, compositional age estimates and estimated abundance from gillnet mark-recapture data. Genetic pedigree analyses were used to establish parental contributions and effective numbers of breeding adults.  Rates of survival varied significantly by cohort, largely due to body size at release.  Pedigree analyses revealed that the genetic diversity of each year’s cohort differed and differed from the expectations based on compositional estimates of the progeny stocked from each family cross each year.  Data can be used to establish guidelines for ongoing and future stocking programs to increase post-stocking survival and genetic diversity.