Catch-and-release Survivability for Common Thresher Sharks in the Southern California Recreational Fishery

Project support provided by the NOAA Bycatch Reduction Engineering Program

PIER Research Staff:

Chugey Sepulveda, Ph.D.
Scott Aalbers, M.S.

Collaborative Researchers:

Diego Bernal, Ph.D. (University of Massachusetts)
Craig Heberer, NOAA Southwest Region Sustainable Fisheries Division
Suzy Kohin, Ph.D., NOAA Southwest Fisheries Science Center

Timeline:

March 2007; on-going.

Objectives:

1. Estimate a catch-and-release mortality rate for thresher sharks in the Southern California recreational fishery.

2. Analyze the physiological indicators of capture stress (e.g., blood and tissue biochemistry, stress proteins).

3. Investigate alternative gear types and methods (e.g., circle hooks, teasers, break-away tackle) to reduce capture stress and mortality.

4. Develop a strong outreach program that uses public educational seminars and popular literature to discuss best fishing practices.

Background

This research will implement pop-up archival transmitting (PAT) tags to estimate the post-release survivorship of large foul-hooked thresher sharks caught on recreational fishing gear. Since thresher sharks use their elongate upper caudal lobe to stun prey before it is consumed, anglers typically hook sharks by the tail. However, like most pelagic species, thresher sharks rely upon forward momentum to extract oxygen from the water. The fate of foul-hooked sharks following release is unknown and raises concern over the long-term sustainability of the fishery. Public forums involving fishermen are being held to discuss project findings and collectively develop better fishing tactics. We value your input so please join us at the thresher shark fishing seminars in April, 2008.

More information on 2008 shark fishing seminars

Read more about other ongoing thresher shark studies at PIER

Scott Aalbers with a large female thresher shark tagged and ready for release.