Genetic Family Reconstruction Characterizes Lake Sturgeon Use of Newly Constructed Spawning Habitat and Larval Dispersal

Abstract

AbstractSince 2004, seven spawning reefs have been constructed in the St. Clair–Detroit River system to remediate lost spawning habitat and increase recruitment of Lake Sturgeon Acipenser fulvescens. Assessment of management actions by collecting and enumerating eggs and larvae provided evidence of spawning Lake Sturgeon and survival of eggs until larval dispersal at constructed reef sites. However, the number of spawners contributing sampled offspring (Ns), effective number of breeders (Nb), and extent of larval dispersal was unknown. Genetic reconstruction of familial relationships assigned eggs and larvae (n = 725) collected in 2015 and 2016 to full‐ and half‐sibling groups and estimated Ns, Nb, and genetic connectivity. We used a modified COLONY simulation module to simulate and convert 18 microsatellite loci (13 disomic and 5 polysomic) to 205 dominant present/absent markers to increase marker number and familial assignment accuracy in family reconstruction analysis. We assessed COLONY's ability to accurately infer familial relationships across small (n = 50), moderate (n = 125), and large (n = 750) larval sample sizes using two assumed allele frequency distributions for polysomic loci. We found that with fewer offspring sampled, COLONY underestimated Ns and with large sample sizes overestimated Ns. However, estimates were usually within 12–16% of the simulated true Ns. Across reefs, estimates of Ns were 151 in 2015 and 208 in 2016, and Nb was similar (158 in 2015 and 198 in 2016). Evidence of full‐ and half‐sibling larvae collected at multiple locations indicated that individual Lake Sturgeon spawned at multiple locations within years and larvae dispersed considerable distances. Estimating Ns, Nb, larval dispersal, and inferred genetic connectivity between locations provides managers with population demographic parameters to assess habitat remediation projects. Continued monitoring, including genetic family reconstruction, may provide insight into the long‐term effects of constructed spawning habitat on recruitment and population‐level genetic diversity.