Evaluating juvenile post-stocking survival and adult paddlefish spatial distribution for recreational fishery potential in a large reservoir

Angler interest in targeting Paddlefish Polyodon spathula is growing throughout the Missouri and Mississippi River basins. In response, state agencies are increasing management efforts (e.g., stocking) and evaluating whether restored or maintained populations are suitable candidates for recreational fisheries. However, there is little or no information about post-stocking survival of juvenile Paddlefish or adult Paddlefish accessibility to anglers. Here, we quantified apparent survival of stocked juvenile Paddlefish over 12 weeks and 1 year and described the spatial distribution of adult Paddlefish in areas that are accessible to recreational Paddlefish anglers in Lake Sharpe, South Dakota. Apparent weekly survival of two cohorts of telemetered juvenile Paddlefish and environmental factors (weekly means) influencing survival were estimated using a Cormack–Jolly–Seber open population model. We also quantified monthly adult Paddlefish residency among reservoir zones and modeled environmental influences (monthly means) on residency in areas most accessible to anglers during 2017 and 2018. Across the observed environmental conditions, two cohorts of juvenile Paddlefish post-stocking weekly apparent survival ranged from 0.80 to 0.99. Juvenile Paddlefish survival was positively associated with flow and negatively associated with mean weekly water temperature. In contrast to the early-spring upstream movements commonly reported in other systems, adult Paddlefish in our study moved upstream into areas accessible to anglers primarily from June through September. Residency in areas most accessible to anglers was best explained by day of year, mean monthly water temperature, and mean monthly flow. Our results suggest that stocking during favorable flow and water temperature may promote increased survival of juvenile Paddlefish post-stocking. Additionally, understanding the spatial distribution of adult Paddlefish in this system provides insights into when these individuals are most accessible to recreational anglers and can inform the timing of potential harvest seasons.