Effect of pelagic longline bait type on species selectivity: a global synthesis of evidence

Eric Gilman, Milani Chaloupka, Pascal Bach, Hannah Fennell, Martin Hall, Michael Musyl, Susanna Piovano, Francois Poisson, Liming Song

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Abstract

Fisheries can profoundly affect bycatch species with ‘slow’ life history traits. Managing bait type offers one tool to control species selectivity. Different species and sizes of marine predators have different prey, and hence bait, preferences. This preference is a function of a bait’s chemical, visual, acoustic and textural characteristics and size, and for seabirds the effect on hook sink rate is also important. We conducted a global meta-analysis of existing estimates of the relative risk of capture on different pelagic longline baits. We applied a Bayesian random effects meta-analytic regression modelling approach to estimate overall expected bait-specific catch rates. For blue shark and marine turtles, there were 34% (95% HDI: 4–59%) and 60% (95% HDI: 44–76%) significantly lower relative risks of capture on forage fish bait than squid bait, respectively. Overall estimates of bait-specific relative risk were not significantly different for seven other assessed taxa. The lack of a significant overall estimate of relative capture risk for pelagic shark species combined but significant effect for blue sharks suggests there is species-specific variability in bait-specific catch risk within this group. A qualitative literature review suggests that tunas and istiophorid billfishes may have higher catch rates on squid than fish bait, which conflicts with reducing marine turtle and blue shark catch rates. The findings from this synthesis of quantitative and qualitative evidence support identifying economically viable bycatch management measures with acceptable tradeoffs when multispecies conflicts are unavoidable, and highlight research priorities for global pelagic longline fisheries.

Original languageEnglish
Pages (from-to)535–551
Number of pages17
JournalReviews in Fish Biology and Fisheries
Volume30
Issue number3
Early online date3 Aug 2020
DOIs
Publication statusPublished - Sep 2020

Keywords

  • Bait
  • Bycatch
  • Longline
  • Mitigation
  • Selectivity
  • Tuna

ASJC Scopus subject areas

  • Aquatic Science

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    Gilman, E., Chaloupka, M., Bach, P., Fennell, H., Hall, M., Musyl, M., Piovano, S., Poisson, F., & Song, L. (2020). Effect of pelagic longline bait type on species selectivity: a global synthesis of evidence. Reviews in Fish Biology and Fisheries, 30(3), 535–551. https://doi.org/10.1007/s11160-020-09612-0