This shark family contains three species that use their long caudal fin for feeding and stunning prey. Off California, the bigeye and common thresher sharks are typically the most prevalent, but in some years we can also find pelagic threshers here as well. Below you can find areas in PIER has worked on this group of pelagic sharks and links to additional pages that describe the studies in more detail.
Survivorship in Commercial Fisheries
Recently, the PIER team conducted a tagging project assessing the post-release survivorship of bigeye thresher sharks, a frequent incidental catch in the developing deep-set buoy gear fishery. Because bigeye threshers do not have a comparable market value to swordfish, it is common for them to be released in an attempt to save hold space for more valuable product. The funding for this work was provided through the NOAA Bycatch Reducion and Engineering Program.
Bigeye thresher sharks caught during gear testing were outfitted with electronic satellite tags that can detect the animal’s movement throughout the water column. If these movements cease for a prescribed period of time, the shark is presumed deceased and the tag releases from the animal and pops up to the ocean surface, transmitting information on the mortality event to overhead satellites. Of 28 Bigeye thresher sharks tagged from 2016 to 2019, 25 survived the effects of capture and release, at least for the 30 day tag period which is the time determined to be most critical for the onset of adverse capture effects. This high likelihood of catch and release survival can be attributed to the many design features of Deep Set Buoy Gear and Linked Buoy Gear that allow for the rapid release of non-target species such as thresher sharks.
Survivorship studies are an important component in commercial gear development as it gives researchers, fishers, and managers insight into potential mitigation strategies to reduce bycatch mortality and, in cases such as deep set gear where survivorship is high, allows fishers to demand a price premium for their low-impact harvest techniques.
Survivorship in Recreational Fisheries
Past work by the PIER team has focused on documenting post release survivorship in the California recreational fishery for the common thresher shark. This species is a popular game fish that provides anglers with a challenge during the spring and fall months. This PIER-NOAA collaboration resulted in several outreach products including the production of a short video segment on catch and release survivorship studies by the NOAA Ocean Media Center.
Sustainable Sport Fishing for Thresher Sharks from NOAA Fisheries on Vimeo.
Additional studies at PIER include work on the Feeding Behavior and Ecology of the common thresher as well as NSF sponsored studies that focused on thresher shark muscle physiology.
As with most studies at PIER, the thresher work has been possible through the productive collaboration with researchers from several organizations including NOAA, University of Massachusetts, Dartmouth, MiraCosta College and the University of Calgary, Canada.