Habitat modification including barriers to migration, poor water quality, and modification of benthic habitat has contributed to the decline of lake sturgeon (Acipenser fulvescens) abundances in the Great Lakes. Lack of habitat was identified as a limiting factor for lake sturgeon recovery in the St. Clair-Detroit River System (SCDRS). To increase habitat availability in the SCDRS with the intent of increasing lake sturgeon populations, seven spawning reefs were constructed. Using 741 eggs and larvae collected during traditional assessments, genetic pedigree analysis was used to further quantify spawning habitat use. In 2015 and 2016, 339-349 spawners were estimated to have contributed offspring across all sites. The effective number of breeders was estimated at 295-314 spawners, with mean (4.26-4.37 larvae) and variance (6.26-7.20) in individual reproductive success across all reefs and in 2015 and 2016. Evidence of adults spawning at multiple reefs within and between rivers was revealed by shared sib-ship of offspring collected at multiple locations. Comparison between gear types revealed that differences in the way individuals are collected can affect estimates generated from genetic pedigree analysis. Finally, species richness estimators were combined with genetic pedigree analysis to estimate the total number of spawners contributing offspring at constructed reefs (11-92 spawners per reef per year). Detailed information regarding lake sturgeon spawning behavior associated with spawning habitat construction in the SCDRS informs future assessment and management action for conservation of lake sturgeon throughout their range.
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