MEPS 521:143-154 (2015)  -  DOI: https://doi.org/10.3354/meps11073

Post-release survival of juvenile silky sharks  captured in a tropical tuna purse seine fishery

Melanie Rhiannon Hutchinson1,*, David George Itano2,3,4, Jeffrey Allen Muir2,3,5, Kim Nicholas Holland1

1Department of Zoology, University of Hawaii, Hawaii Institute of Marine Biology, PO Box 1346 Kaneohe, Hawaii 96744, USA
2International Seafood Sustainability Foundation, 805 15th Street NW, Suite 650, Washington D.C. 20005, USA
3Pelagic Fisheries Research Program, University of Hawaii, Marine Science Building 312, Honolulu, Hawaii 96822, USA
4Present address: NOAA Inouye Regional Center, NMFS/PIR/PIRO/SFD, 1845 Wasp Blvd. Bldg. 176 Honolulu, Hawaii 96818, USA
5Present address: Hawaii Institute of Marine Biology, PO Box 1346 Kaneohe, Hawaii 96744, USA
*Corresponding author:

ABSTRACT: Juvenile silky sharks Carcharhinus falciformis comprise the largest component of the incidental elasmobranch catch taken in tropical tuna purse seine fisheries. During a chartered cruise on board a tuna purse seine vessel conducting typical fishing operations we investigated the post-release survival and rates of interaction with fishing gear of incidentally captured silky sharks using a combination of satellite linked pop-up tags and blood chemistry analysis. To identify trends in survival probability and the point in the fishing interaction when sharks sustain the injuries that lead to mortality, sharks were sampled during every stage of the fishing procedure. The total mortality rates of silky sharks captured in purse seine gear was found to exceed 84%. We found survival to precipitously decline once the silky sharks had been confined in the sack portion of the net just prior to loading. Additionally, shark interactions recorded by the scientists were markedly higher than those recorded by vessel officers and the fishery observer. Future efforts to reduce the impact of purse seine fishing on silky shark populations should be focused on avoidance or releasing sharks while they are still free swimming.


KEY WORDS: Post-release survival · Bycatch · Silky shark · Fish aggregating device


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Cite this article as: Hutchinson MR, Itano DG, Muir JA, Holland KN (2015) Post-release survival of juvenile silky sharks  captured in a tropical tuna purse seine fishery. Mar Ecol Prog Ser 521:143-154. https://doi.org/10.3354/meps11073

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