Spatial and Temporal Patterns in Trawl Survey Catches Reflect Stock-Specific Dispersal of Age-0 Fishes and Individual Spawning Stock Production in Lake Erie

Large aquatic ecosystems often support spatially discrete spawning stocks that allow spatial coherence during dispersal of early life stages.  Therefore, it is possible to develop stock specific information on recruitment.  We used data from monthly bottom-trawl sampling in western Lake Erie to determine: 1) dispersal patterns of age-0 fishes from individual spawning stocks; and 2) index the success and contribution of individual spawning stocks to Lake Erie’s fish populations.  A hotspot analysis revealed dispersal and distribution patterns of fish species, such as Walleye (Sander vitreus), Yellow Perch (Perca flavescens), and Gizzard Shad (Dorosoma cepedianum), that spawn in rivers or distinct areas of the lake.  In contrast, Emerald Shiners (Notropis atherinoides), a pelagic species, did not reveal patterns of dispersal.  The hotpot analysis also revealed bottom trawl locations near known spawning areas could be used to index the contributions of individual spawning stocks to Lake Erie populations with minimal overlap of individual stocks.  We found the contribution of individual spawning stocks can vary considerably across years and among stocks.  This study further contributes to the knowledge of fisheries population dynamics in Lake Erie by demonstrating patterns in dispersal and distributions of fishes and providing measurements of the contributions of spawning stocks.