UC Davis

Conservation aquaculture programs that release fish to supplement wild populations can potentially capture greater genetic diversity by collecting offspring as embryos and larvae from wild spawning events than by producing them conventionally from broodstock. A conservation aquaculture program for the endangered white sturgeon population of the Upper Columbia River initially utilized wild broodstock for 14 years before fully transitioning to rearing wild-origin offspring in 2014. Here we evaluated the performance of this program in capturing the wild population’s genetic diversity since transitioning to wild-origin offspring. We analyzed genotypes of 325 tetrasomic single nucleotide polymorphism (SNP) markers in more than 5,000 offspring reared from 2014 to 2020 and over 1,000 wild adults from the population. Genetic diversity statistics were highly similar between each offspring year class and the wild adult population. We inferred sibship structure to estimate the total number of spawners (Ns) and effective number of breeders (Nb) represented within each year class and found values as high as 932.5 (95% CI 876–989) and 146.3 (95% CI 144–149), respectively, far surpassing the numbers included as broodstock. We further estimated Ns and Nb for three year classes with their individuals that died in aquaculture and found that on average, the mortality rate of 33.2% decreased Ns by 21.5% and Nb by 7.9%. Finally, we analyzed relationship coefficients to identify full-sibships spanning collection sites and found them in one year class, comprising 0.27% of all full-sibling pairs that year, demonstrating that the separate sites display negligible redundancy with respect to sibling families collected. Our results illustrate a robust performance by this program in representing the wild population’s diversity compared to broodstock approaches and support the adoption of utilizing wild-origin offspring in other conservation aquaculture programs when feasible.