Mitigating sea turtle by-catch in coastal passive net fisheries |
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| Authors: | Eric Gilman Jeff Gearhart Blake Price Scott Eckert Henry Milliken John Wang Yonat Swimmer Daisuke Shiode Osamu Abe S Hoyt Peckham Milani Chaloupka Martin Hall Jeff Mangel Joanna Alfaro-Shigueto Paul Dalzell & Asuka Ishizaki |
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| Institution: | IUCN (International Union for the Conservation of Nature) and University of Tasmania;;U.S. National Marine Fisheries Service, Southeast Fisheries Science Center, 3209 Frederic Street, Pascagoula MS 39567, USA;;North Carolina Division of Marine Fisheries, 3441 Arendell Street, Morehead City, NC 28557, USA;;WIDECAST and Duke University Marine Laboratory, 135 Duke Marine Lab Road, Beaufort, North Carolina 28516-9721, USA;;U.S. National Marine Fisheries Service, Northeast Fisheries Science Center, 166 Water Street, Woods Hole, MA 02543, USA;;Joint Institute of Marine and Atmospheric Research, University of Hawaii at Manoa NOAA-Kewalo Research Facility, 1125B Ala Moana Blvd., Honolulu, HI 96814, USA;;U.S. National Marine Fisheries Service, Pacific Islands Fisheries Science Center, 501 W. Ocean Blvd., Long Beach, CA 90802, USA;;Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato, Tokyo, 108-8477, Japan;;Southeast Asian Fisheries Development Center, Fisheries Garden, Chendering, Kuala Terengganu, 21080, Malaysia;;ProPeninsula and University of California at Santa Cruz, Dept. of Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA;;Ecological Modeling Services, PO Box 6150, University of Queensland, St Lucia, Queensland, 4067, Australia;;Inter-American Tropical Tuna Commission, 8604 La Jolla Shores Dr., La Jolla, CA 92037, USA;;ProDelphinus and University of Exeter, School of Biosciences, Jose Galvez 1136, Miraflores, Lima 18, Peru;;Western Pacific Fishery Management Council, 1164 Bishop St, Suite 1400, Honolulu, HI 96813, USA |
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| Abstract: | There is growing evidence that small-scale, coastal, passive net fisheries may be the largest single threat to some sea turtle populations. We review assessments of turtle interactions in these fisheries, and experiments on gear-technology approaches (modifying gear designs, materials and fishing methods) to mitigate turtle by-catch, available from a small number of studies and fisheries. Additional assessments are needed to improve the limited understanding of the relative degree of risk coastal net fisheries pose to turtle populations, to prioritize limited conservation resources and identify suitable mitigation opportunities. Whether gear technology provides effective and commercially viable solutions, alone or in combination with other approaches, is not well-understood. Fishery-specific assessments and trials are needed, as differences between fisheries, including in gear designs; turtle and target species, sizes and abundance; socioeconomic context; and practicality affect efficacy and suitability of by-catch mitigation methods. Promising gear-technology approaches for gillnets and trammel nets include: increasing gear visibility to turtles but not target species, through illumination and line materials; reducing net vertical height; increasing tiedown length or eliminating tiedowns; incorporating shark-shaped silhouettes; and modifying float characteristics, the number of floats or eliminating floats. Promising gear-technology approaches for pound nets and other trap gear include: replacing mesh with ropes in the upper portion of leaders; incorporating a turtle releasing device into traps; modifying the shape of the trap roof to direct turtles towards the location of an escapement device; using an open trap; and incorporating a device to prevent sea turtle entrance into traps. |
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| Keywords: | By-catch gillnet passive net fisheries pound net sea turtle small-scale fisheries |
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