Catch‐and‐Release Angling Effects on Lake Sturgeon in Wisconsin, USA

Abstract Discard mortality is an important factor to consider when managing catch‐and‐release fisheries. Even low levels of discard mortality can induce population‐level effects particularly in long‐lived, low‐productivity species like Lake Sturgeon Acipenser fulvescens . Unfortunately, little is known about the effects of catch‐and‐release angling on Lake Sturgeon physiology and probability of discard mortality. We used controlled angling events with standardized gear to capture 96 Lake Sturgeon from August to October 2019 from four regional locations in Wisconsin, USA. We evaluated the physiological effects of angling and activation of the stress response using whole blood concentrations of lactate and glucose as well as assessment of reflex impairment and postcapture monitoring of recovery time. Lactate levels were positively related to fight duration and the fight duration × total length interaction. Glucose level was related to the time a fish spent out of water postangling event. Water temperature had a positive effect on the probability of reflex impairment and the probability that a sturgeon required recovery time. The recovery duration was positively related to the amount of time that the fish was out of water. The movements of a subset of 15 individuals from one location were monitored using acoustic telemetry for approximately 2 weeks postangling. All individuals showed continuous up‐ and downstream movement during the postrelease monitoring period, and there was no evidence of mortality related to the angling events. Managers considering catch‐and‐release fisheries for Lake Sturgeon should consider population‐specific relative abundance and catch rates. They should exercise caution in scenarios when seasonal aggregations may lead populations to be susceptible to high catch rates, during times of elevated water temperatures, or the combination of these factors. The Lake Sturgeon in this study appeared to be robust to angling‐induced stress effects. Nevertheless, caution is still warranted, as low levels of discard mortality have the potential to influence low‐productivity species like Lake Sturgeon.