Does Live Release Provide an Effective Means of Reducing Fishing Mortality on Istiophorid Billfishes?
61st Annual Tuna Conference, Lake Arrowhead, California, May 17-20, 2010
Many of the species targeted by the pelagic longline fishery in the Atlantic Ocean, such as bigeye tuna, yellowfin tuna, and swordfish, are estimated to have current biomasses at or near levels necessary for maximum sustainable yield. In contrast, stocks of most Atlantic istiophorid billfishes, which constitute a bycatch of the pelagic longline fishery, are severely depleted. Historically, the International Commission for the Conservation of Atlantic Tunas (ICCAT) has been reluctant to adopt management measures to protect stocks of Atlantic billfish, especially if such measures would impact fisheries for target species. Release of live billfish represents one means to reduce fishing mortality on overfished billfish stocks without impacting takes of target species, if released billfish survive. In general, more than 50% of istiophorid billfish are alive at the time of haulback; however, conventional tagging studies of billfish released from pelagic longline gear have reported very few tag recoveries, a result consistent with high post‐release mortality. Over the past several years we have deployed pop‐up satellite archival tags to estimate short term mortality of blue marlin, white marlin, and sailfish released from pelagic longline gear. Rates of post‐release survival for all three species exceeded 80%, suggesting that live release represents an effective means of reducing fishing mortality. At its 2000 Commission meeting, ICCAT adopted a binding management measure requiring release of live blue marlin and white marlin from longline gear. Although many countries required a few years to implement this measure and compliance has not been perfect, the most recent assessments of blue marlin and white marlin stocks suggest that live release has had a positive impact.
Graves, John E. and Kerstetter, David W., "Does Live Release Provide an Effective Means of Reducing Fishing Mortality on Istiophorid Billfishes?" (2010). Oceanography Faculty Proceedings, Presentations, Speeches, Lectures. 198.