Effects of Air Exposure on Postrelease Mortality Rates of White Marlin Caught in the U.S. Offshore Recreational Fishery

Abstract

White Marlin Kajikia albida are targeted by recreational fisheries in tropical and subtropical waters of the Atlantic Ocean. Off the U.S. East Coast, the vast majority of White Marlin are released after capture. Federal regulations prohibit anglers from removing a White Marlin from the water unless the fish is to be retained; however, numerous photographs of anglers holding White Marlin out of the water are posted on the Internet each summer, demonstrating that there is considerable noncompliance with this management measure. To better understand the effect of air exposure on postrelease survival of White Marlin, we attached pop-up satellite archival tags (PSATs; programmed to release after 30 d) to individuals that were caught on natural baits rigged with circle hooks and that were removed from the water for a period of 1 min (n = 6 fish), 3 min (n = 5 fish), or 5 min (n = 7 fish). We compared our results with those from a previous study in which PSATs were used to follow the fates of 59 White Marlin that were caught on circle hooks but not removed from the water. The proportion of postrelease mortalities increased with air exposure duration; the overall rate of postrelease mortality was significantly higher for White Marlin that were subjected to air exposure (33.3%) than for those that remained in the water (1.7%). These data provide strong support for the current U.S. regulation prohibiting the removal of a White Marlin from the water if the fish is to be released. Effective communication of the deleterious effects of air exposure on White Marlin should help to deter the practice of removing fish from the water among members of the recreational angling community, which has been supportive of other conservation measures for this species.

Received January 13, 2016; accepted June 15, 2016 Published online September 30, 2016

ACKNOWLEDGMENTS

We thank captains Ken Neill (FV Healthy Grin), Pete Manuel (FV Delta Dawn), and Bobby Whelan (FV Bay Custom) and their crews for graciously providing access to White Marlin. We are also grateful to Richard Brill and two anonymous reviewers, whose comments greatly improved this manuscript. Our research was supported by the National Marine Fisheries Service (Grant Number NA15NMF4270302). This is Contribution 3565 from the Virginia Institute of Marine Science.