Evaluate the post-release survival of silky sharks captured by longline fishing vessels in the equatorial EPO, using best handling practices

Project M.2.a - Evaluate the post-release survival of silky sharks captured by longline fishing vessels in the equatorial EPO, using best handling practices

01 Jan 2016 - 31 Dec 2018

Completed

Program(s) in charge: Life History and Behavior Group

Funded

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Theme 4. Ecological impacts of fishing: assessment and mitigation
Goal M. Mitigate the ecological impacts of tuna fisheries
Target M.2. In collaboration with the industry, conduct scientific experiments to develop best practices for the release of prioritized bycatch species

Objectives

Estimate the post-release survival of silky sharks captured by longline vessels in the equatorial EPO, using archival tags

Background

Apparent severe decline in the population of silky sharks in the EPO, based on trends in standardized catch-per-unit-of-effort indices
Domestic longline fleets from Latin America conduct multi-species fisheries including retaining silky sharks

Relevance for management

Resolution C-16-06 on conservation measures for silky sharks stipulates to improve handling practices for live sharks to maximize post-release survival

Duration

2016-2018

Workplan and status

2016-2017: 40 total silky sharks were tagged and released with satellite tags, and the resulting data have been analyzed to estimate a post-release survival rate, , and evaluate movements, dispersion, and potential entanglement in FADs
2017: A final report for this project was submitted to the EU (funding source)
2018: A manuscript is in progress and will be submitted to a scientific journal

External collaborators

INCOPESCA, Costa Rica; WWF, Ecuador; University of Hawaii

Deliverables

Silky shark post-release survival rate following capture by longline vessels, using best handling practices
Presentation of preliminary results at SAC-08
Manuscript for publication in a peer-reviewed scientific journal

Updated date: 01 Jun 2019
Progress summary for the reporting period: Manuscript accepted for publication in the Bulletin of Marine Science.
: Schaefer, K.M., Fuller, D.W., Aires-da-Silva, A., Carvajal, J.M., Martinez, J. and Hutchinson, M.R., 2019. Post-release survival of silky sharks (Carcharhinus falciformis) following capture by longline fishing vessels in the equatorial eastern Pacific Ocean. Bulletin of Marine Science.