Impaired Reflexes As a Measure of Delayed Mortality in Recreationally Caught Yellowtail Snapper (Ocyurus chrysurus)

Yellowtail snapper (Ocyurus chrysurus) are an important part of the reef fish assemblage in the western, tropical Atlantic and are caught by both recreational and commercial fisheries in South Florida and the Bahamas. It is estimated that 80% of snapper caught within southeastern Florida waters are discarded due to minimum size restrictions. Neglecting to include information on delayed mortality of undersized fish has the potential for fishery managers to overestimate the abundance of smaller size classes and introduce bias into stock assessments. This study combines reflex impairment and traditional physiological parameters to assess the post-release mortality of undersized yellowtail snapper. Laboratory experiments exposed yellowtail snapper to varying degrees of stressors in the form of air exposure to construct a reflex action mortality predictor (RAMP) curve. Blood draws were obtained from a subsample of fish. There was a significant sigmoidal relationship between delayed mortality and the proportion of impaired reflexes (p=0.019). Base excess and pH were significantly correlated to impaired reflexes. Delayed mortality was significantly correlated to pH, base excess and lactate concentration. The RAMP curve obtained from this study suggests that discarded, undersized yellowtail with more than 26% of their reflexes impaired will not survive.