Evidence of Low Discard Mortality for a Deep-Water, Demersal IUCN Red List Fish Species Caught Via Hook-and-Line

Fishing regulations for demersal snapper-grouper species in southeast United States Atlantic coast (SEUS) waters have increased considerably over the last few decades, to an extent that for some species the number of individuals discarded annually is considerably greater than the number of individuals retained. Stock assessments for many of these species have therefore become sensitive to estimates of the discard mortality rate, but discard mortality rates remain challenging to estimate empirically. We used a long-term, angler-based tagging dataset to make inferences about the discard mortality rate of warsaw grouper (Epinephelus nigritus), a deep-water, demersal IUCN Red List reef fish species whose fishery has been closed in SEUS waters since 2011 due to conservation concerns. A total of 213 warsaw grouper were tagged between 1994 and 2009 in SEUS waters, and 90 of these fish (42%) were recaptured at least once, a higher return rate than has been documented for other deep-water species. Moreover, 41 (46%) of these fish were recaptured multiple times, including two fish recaptured five times and one recaptured six times. We applied standard quantitative approaches to analyzing the data and found that the discard mortality rate of warsaw grouper was lower than expected for a deep-water species.