Mitigating sea turtle by-catch in coastal passive net fisheries

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

Research output: Contribution to journalReview articlepeer-review

102 Scopus citations

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.

Original languageEnglish
Pages (from-to)57-88
Number of pages32
JournalFish and Fisheries
Volume11
Issue number1
DOIs
StatePublished - Mar 2010

Keywords

  • By-catch
  • Gillnet
  • Passive net fisheries
  • Pound net
  • Sea turtle
  • Small-scale fisheries

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