Characterization of Species Specific Relationships Between Capture and Soak Time As a Means to Reduce Bycatch in the Gulf of Mexico Reef Fish Bottom Longline Fishery

A recent NMFS review of sea turtle interactions in the Gulf of Mexico reef fish fishery indicate the number of loggerhead sea turtle takes authorized in the 2005 Biological Opinion by the bottom longline component of the reef fish fishery in the Gulf of Mexico have been exceeded. Sea turtle mortality is known to have a significant relationship with respect to time of forced submergence resulting from fisheries interactions. The NOAA Fisheries, Harvesting Systems Unit conducted a pilot study to investigate the potential of reduced gear soak times as method of reducing sea turtle interactions and mortality. Experiments were carried out using hook timers and time depth recorders to assess factors that influence the capture time of reef fish and bycatch species on bottom longlines. Three vessels conducted 291 sets deploying up to 150 hook timers per set. The mean soak time for hooks deployed was 99 minutes. The 90th percentile capture time for red grouper was 43 minutes. The 90th percentile for shark bycatch was 67 minutes. The distribution of shark capture times was significantly different than the distribution for targeted reef fish species. The results indicate that a reduction in hook soak time in the bottom longline reef fish fishery has the potential to reduce shark bycatch with a minimal effect on the catch rate of targeted species.  Based on past research, a reduction in soak time is also likely to reduce the mortality of sea turtles caught in the fishery.