Relating angling-dependent fish impairment to immediate release mortality of red snapper ( Lutjanus campechanus)

Abstract

Catch-and-release (CAR) fishing of deep-water physoclistous species can lead to increased stress and impairment often resulting in immediate release mortality. We made use of a condition index (BtR score) to evaluate the relationship between CAR-related impairment and immediate release mortality in the recreational red snapper ( Lutjanus campechanus) fishery. Symptoms of barotrauma and impairment showed positive relationships with capture depth and occurred more frequently during the summer sampling than the fall. Impairment, as measured by BtR score, showed significant logistic relationships with immediate release mortality proxies such as floating and erratic swimming at release. Logistic curves had inflection points at BtR scores of 0.3–0.4 (on a scale of 0–1), above which fish experienced high immediate release mortality regardless of season (60–100%). Mean BtR scores were lower than the inflection point of the logistic curve, resulting in immediate release mortality estimates ranging from 20% to 28%. Recaptured fish showed significantly lower impairment than non-recaptured fish. The BtR score is a proficient method to estimate both impairment and immediate release mortality of red snapper in field settings.