PIFSC Sea Turtle Longline Research EA June 1, 2009
Descriptions of Actions Included
1) Evaluate modifications to gear and/or operational factors on fishing boats in domestic and foreign fleets. Conduct operations using modified longline gear or modified timing or logistics of operations, along with instrumentation for gear monitoring and oceanographic sampling, to investigate variables which may alter the vulnerability of sea turtles and target fish species to being captured by the gear. In addition to sea turtles, particular interest would be in maintaining or increasing the CPUE of target tunas, sharks, marlins, other billfishes, dolphinfish (mahi mahi), and associated species.
The protocol for assisting foreign fishermen in conducting tests of fishing gear to reduce sea turtle bycatch under this action is to modify fishing effort that would have been conducted in any case. However, to consider the worst case where unforeseen circumstances might curtail fishing operations had these not been financially-assisted (contracted) by NOAA Fisheries, the magnitude of financially-assisted fishing effort is compared to background levels of fishing effort. Financially-assisted gear testing in foreign fisheries would never exceed a maximum of about 200,000 hooks in any year, throughout the world.
Methods for effectively reducing sea turtle bycatch while maintaining economic viability in particular circumstances appears to include a variety of alternatives (Boggs and Swimmer 2007):
1A) Modified gear could include different types of hooks, lines, weights, floats, lights, baits, lures, fishing depths, and deterrent devices such as galvanic metals, flavors, and odors. Specific examples of anticipated work include, but are not limited to, testing:
Hooks without barbs for efficacy in catch retention and bycatch release
Larger circle hooks
Hooks with appendages
Replacement of lightweight flexible polyfilament cord main line with less flexible monofilament line to reduce sea turtle entanglement
Increasing gear depth to reduce epipelagic bycatch and increase target catch, such as fishing for swordfish at much deeper depths than currently practiced by commercial fisheries (for example, Figure 7)
Altered frequencies, flickering rates, intensities, and directionality of light stick lures to determine their attractiveness to target species and sea turtles
1B) Modified timing or logistics of operations could include earlier or later setting, longer or shorter soaks, and targeting or avoiding specific localities.
1C) Utilization of oceanographic sampling could include observing the structure of the water column with respect to temperature, salinity, dissolved gases, nutrients, plankton, and nekton, to determine characteristics favoring the aggregation or sparsity of target catch and nontarget bycatch species, respectively. Specific examples of anticipated work include, but are not limited to finding: