Does Hook Choice Matter? Effects of Three Circle Hook Models on Postrelease Survival of White Marlin

Abstract

Throughout the Atlantic, the white marlin Kajika albida (formerly Tetrapturus albidus) is overfished but remains a major target species for offshore recreational anglers. The vast majority of white marlin taken in the U.S. fishery are caught on natural baits and subsequently released. A previous study demonstrated that the use of circle hooks with natural baits resulted in a highly significant increase in white marlin postrelease survival relative to the use of straight-shank (J-type) hooks with natural baits. However, several models of circle hooks, which vary in shape and the degree to which the point is offset from the shaft, are available to anglers. Survival estimates determined from experiments conducted using one model may not be transferable to other models. We evaluated postrelease survival of white marlin caught on three circle hook models commonly used in the recreational fishery. High-resolution pop-up satellite archival tags that were programmed to release from the fish after 10 d were deployed to follow the fates of 20 white marlin caught on each type of circle hook. Only one mortality was inferred from the 59 tags that provided useful data. No significant differences in the incidence of deep (internal) hooking, hook-induced trauma, or postrelease survival were found among fish caught on the different circle hook models. Incidences of white marlin deep hooking, hook-induced trauma, and postrelease mortality were significantly lower for the three circle hook models (combined) than for J hooks evaluated in a previous study. Current U.S. domestic management measures requiring the use of non-offset circle hooks with natural baits during registered tournaments for Atlantic billfishes (Istiophoridae) will provide some relief for white marlin; however, the use of circle hooks in recreational fisheries targeting this species throughout the Atlantic Ocean could substantially reduce fishing mortality on this overfished resource.