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Marine Ecology Progress Series

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MEPS 396:161-164 (2009)  -  DOI:

Comparability of blue shark mortality estimates for the Atlantic and Pacific longline fisheries

Steven E. Campana1,*, Warren Joyce1, Malcolm P. Francis2, Michael J. Manning2,†

1Bedford Institute of Oceanography, PO Box 1006, Dartmouth, Nova Scotia, Canada B2Y 4A2
2National Institute of Water and Atmospheric Research (NIWA), Private Bag 14901, Kilbirnie, Wellington, New Zealand

ABSTRACT: Blue sharks Prionace glauca are among the most frequently caught and discarded fish species in pelagic longline fisheries of both the Atlantic and Pacific oceans. Fishery-specific differences between Atlantic and Pacific longliners lead to differences in both hooking and post-release mortality rates. However, the estimates of both hooking and post-release mortality reported by Moyes et al. (2006; Trans Am Fish Soc 135:1389–1397) around Hawaii are considerably lower than those reported elsewhere, both in the Atlantic and the Pacific. Our comparison of Campana et al. (2009; Mar Ecol Prog Ser 387:241–253) with Moyes et al. suggests that the difference in blue shark mortality estimates is explained by the partial use of J hooks in the Atlantic fishery, and by the shorter soak time, fewer hooks fished, and gentler handling practices by the scientific crew in the Pacific study by Moyes et al. The study by Moyes et al. is an important contribution to our understanding of blue shark mortality; nevertheless, we consider it inappropriate to use their low estimates of blue shark mortality as a proxy for bycatch mortality rates in the commercial fishery.

KEY WORDS: Pop-up satellite archival tag · Hooking mortality · Soak time · Discard mortality · Longline fishery

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Cite this article as: Campana SE, Joyce W, Francis MP, Manning MJ (2009) Comparability of blue shark mortality estimates for the Atlantic and Pacific longline fisheries. Mar Ecol Prog Ser 396:161-164.

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