PIFSC Sea Turtle Longline Research EA June 1, 2009
catch of target species decreases to the point where revenues are affected, the fishers will not incorporate the modifications into their operations (Gilman et al. 2006, Beverly and Chapman 2007).
PIFSC research originally focused on modification of fishing gear and identifying areas with high potential for fishing interactions with sea turtles. The program expanded over time to conduct research of effective modified gear and operations in additional domestic and foreign fleets and transfer of effective modifications to foreign fisheries. Results of the research conducted to date indicate that significant reductions in bycatch of sea turtles can be achieved using large circle hooks instead of traditional J hooks and using mackerel bait rather than squid bait (Largacha et al. 2005), especially in the shallow-set fisheries targeting swordfish at night when both sea turtles and swordfish are foraging in near-surface waters (Read 2007, Gilman et al. 2007). Many effective sea turtle bycatch reduction measures have been implemented by regulation in the Hawaii-based longline fishery in 2004, resulting in substantial reductions in sea turtle bycatch, while, generally, maintaining catch per unit effort (CPUE) of target species. Interactions of U.S. longline vessels with sea turtles represent only a small fraction of the total fishing effort by all fleets. Typical tests of modified gear and operations involve hook size and/or shape, type of bait or lure, branch line position, line materials, depth of set, daily time of set and/or other operational and gear parameters as they become available, and may be conducted anywhere in the oceans in participating fleets where sea turtles and pelagic longline fisheries interact.
All field-based research, both domestic and foreign, would typically use modified gear and/or operations that have been indicated to be effective at reducing bycatch in comparison with standard gear, deployed using unbiased protocols. However, experiments could involve testing gear or methods that have shown promise for reducing bycatch or injury and that have no known mechanism for causing additional harm to turtles or to the environment, but have not been proven to reduce sea turtle bycatch in pelagic longline fishing in a particular region with different fisheries. Since domestic and foreign field studies are coincidental to normal fishing operations, no additional bycatch of sea turtles compared to that experienced using standard gear and operations is anticipated.
This research is intended to evaluate the effectiveness of modified gear on the catchability of target species while reducing the bycatch per unit effort (BPUE) of sea turtles; it is not intended to directly catch or take sea turtles. While conducting this research, any interactions with turtles by contracted Hawaii-based longline vessels in the shallow-set fishery will count against the hard cap authorized in the Incidental Take Statements of the Biological Opinion pursuant to the Endangered Species Act – Section 7 Consultation (NMFS 2008a).
Need for Action
Introduction to Longline Gear and Fishing Methodologies
Vessels fishing with longline gear generally target bigeye tuna (Thunnus obesus), yellowfin tuna (T. albacares), albacore tuna (T. alalunga), or broadbill swordfish (Xiphias gladius). Fleets participating in PIFSC research also target bluefin tuna (T. thynnus) and mahimahi (dolphinfish, Coryphaena hippurus, C. equiselis). Pelagic longline gear, however, also catch a variety of other