Challenges of estimating post-release mortality of istiophorid billfishes caught in the recreational fishery: A review

Istiophorid billfishes are targeted in recreational fisheries throughout the tropical and subtropical waters of the world's oceans. Over the past thirty years, changes in management regulations and increased angler conservation awareness have resulted in an increasing proportion of the billfish catch being released alive, and in many areas the fishery is principally catch-and-release. However, the fate of released fish, and thus the fishing mortality associated with the recreational fishery, is not well understood. Some insights into post-release mortality of billfishes caught in the recreational fishery have been gained from analyses of conventional tag data, hooking location information, and acoustic tracking data. Over the past 10 years pop-up satellite archival tags (PSATs) have been used to specifically estimate post-release mortality for a limited number billfish species. Extrapolation of the results of these limited studies throughout the various recreational billfish fisheries is not prudent due to potential influences of different species, areas, seasons, fishing styles, and hook types. The current high cost of PSATs presents a significant obstacle to evaluating the effect of these variables on rates of post-release survival. Nonetheless, the results of the few studies to date have had an important impact on fisheries management and the behavior of recreational anglers.