Use of Pop-up Satellite Archival Tags to Estimate Survival and Habitat Preferences of Sailfish (Istiophorus platypterus) from Commercial Pelagic Longline Gear in the Southern Gulf of Mexico

To estimate post-release survival of sailfish caught incidentally to regular commercial pelagic longline fishing operations in the southern Gulf of Mexico targeting mixed swordfish and tunas, 18 pop-up satellite archival tags were deployed on incidentally captured animals. A total of 17 tags transmitted following the full 10-day deployment period, transmitting 25-82% of the archived data. (Three tags were returned, allowing for 100% recovery of the archived data.) Repeated, short-duration movements to depth throughout the tag deployment duration and horizontal displacement data were consistent with survival for 15 of 17 animals (88.2%) for the ten-day deployment period. The short-duration behavior recorded by the tags also showed repeated movements to depths well below the measured effective fishing depths of the common types of pelagic longline fishing gear used in this geographic area. The results of this study clearly indicate that a large percentage of sailfish can survive the trauma resulting from interaction with pelagic longline gear, and that current domestic and international management measures promoting the release of sailfish from pelagic longline fisheries will reduce fishing mortality on the Atlantic sailfish stocks.