The Importance of Post Release Genetic Monitoring in Conservation Aquaculture Programs

Genetic monitoring programs for conservation aquaculture programs (CAPs) commonly examine genetic characteristics of parents to evaluate genetic diversity conservation and estimate effective population size (N_e). However, post-release mortality can lead to genetic diversity loss in released cohorts. Extensive genetic and abundance monitoring of the Kootenai River White Sturgeon population makes the Kootenai Tribe of Idaho White Sturgeon CAP a unique model in which to study the effects of post-release mortality on genetic diversity conservation. We combined data from genetic monitoring of broodstock and post-release monitoring of captive-reared juveniles to reveal high variability in recapture among families. Index of variability values for White Sturgeon families and male and female broodstock were high relative to values reported for salmonid fishes. We found that genetic monitoring of broodstock alone overestimated genetic diversity conservation within year classes due to differential post-release mortality among families although cumulative genetic diversity conservation across years did not change. Effective population size was reduced in most year classes due to limited parental representation in released cohorts. Although rarely performed, our results indicate that post-release genetic monitoring is necessary to accurately characterize the genetic composition of supplemented or reintroduced populations altered by post-release mortality.