November 18, 2020 — A new study reports that, for several species of oceanic sport fish, individual fish that are caught, released and recaught are more likely to be caught again than scientists anticipated. The findings raise some interesting questions for policy makers tasked with preserving sustainable fisheries.
The study makes use of data from tagging programs, in which researchers tag fish and release them into the wild. When those fish are caught, and the tag information is returned to the researchers, it can give scientists information that informs fishery policies.
“Fisheries researchers who work in tagging programs have long noticed that certain fish seem to get caught repeatedly, and we set out to determine the implications of this phenomenon,” says Jeff Buckel, co-author of the study and a professor of applied ecology at North Carolina State University.
To that end, researchers examined decades’ worth of Atlantic coast tagging datasets on four fish species: black sea bass (Centropristis striata), gray triggerfish (Balistes capriscus), red grouper (Epinephelus morio), and Warsaw grouper (Hyporthodus nigritus). Using a computational model, the researchers determined that—for the black sea bass and both types of grouper—survival was significantly higher after the second, third, and fourth release as compared to the first release.
“Think of it this way,” says Brendan Runde, first author of the study and a Ph.D. student at NC State. “Let’s say you tagged 1,000 fish and recaptured 100 of them for a first time. After re-releasing those 100 fish, you would only expect to recapture 10 of them a second time. But that’s not what we’re seeing. We’re seeing much higher numbers of fish getting recaptured after the second time.