Impairment indicators for predicting delayed mortality in black sea bass (Centropristis striata) discards within the commercial trap fishery

Abstract

Harvest restrictions (e.g. size, sex or species limitations) that are implemented to maintain sustainable fisheries often result in by-catch, e.g. unwanted non-target catch. By-catch is frequently discarded back into the ocean and assumed to survive. However, discarded fishes can succumb to delayed mortality resulting from accumulated stress from fishing activity, and such mortality can impede sustainability efforts. Quantifying reflex and behavioural impairments is a quick and cost-effective method to predict discard-related mortality in some species. We developed and evaluated the effectiveness of a release condition index, based on a reflex-action mortality prediction (RAMP) model, for predicting delayed mortality of black sea bass (Centropristis striata) caught and discarded by the commercial trap fishery in the Mid-Atlantic Bight. Accumulation of impairments, and therefore release condition index, was strongly correlated with delayed mortality of black sea bass discarded and held in sea cages. This is the first release condition index validation study to predict mortality in black sea bass and could be a useful approach for predicting delayed mortality in the commercial fishery.