Postrelease Survival of Sailfish Caught by Commercial Pelagic Longline Gear in the Southern Gulf of Mexico

The biomass levels of several target species of the Atlantic pelagic longline fishery, including various tunas of the genus Thunnus and swordfish Xiphias gladius , are estimated to be close to those required to support the maximum sustainable yield. In contrast, several species captured incidentally are severely depleted. Live release of incidental catch is one means of reducing the fishing mortality of these species without sacrificing the target catch, but the efficacy of such a measure is predicated on the assumption that postrelease survival is relatively high. Prior work has evaluated postrelease survival from pelagic longline gear for the larger istiophorid billfishes, such as blue marlin Makaira nigricans and white marlin Kajikia albida , but survival rates are unknown for sailfish Istiophorus platypterus . To estimate the postrelease survival of sailfish caught on pelagic longline gear in the southern Gulf of Mexico, short-duration pop-up satellite archival tags (PSATs) were deployed on captured sailfish for 10-d periods. Of the 29 sailfish captured, 20 (68.9%) were alive at the time of longline haulback, and the first 17 encountered alive were tagged. All tags transmitted at the preprogrammed times, and data from 15 of the 17 PSATs (88.2%) were consistent with the survival of the tagged sailfish for the 10-d tag deployment. Our results clearly demonstrate that sailfish can survive the trauma from interaction with pelagic longline gear and that management measures promoting the release of live individuals from this fishery can significantly reduce sailfish mortality without reducing the catches of target species.