Effectiveness of Venting and Recompression for Increasing Postrelease Survival of Barotraumatized Black Sea Bass across a Range of Depths

Abstract

The effectiveness of venting and recompression for increasing postrelease survival for fish that experience barotrauma has rarely been tested across a range of depths. We conducted a field tag–recapture experiment to test how well venting and recompression each increased postrelease survival of Black Sea Bass Centropristis striata relative to untreated controls at three different depth ranges on the U.S. South Atlantic continental shelf: 24–26, 29–32, and 35–38 m. Venting and recompression were applied by researchers alongside untreated controls at all three depths, and venting by anglers who were inexperienced with this technique was an additional treatment at the intermediate depth. Tests of independence were used to evaluate the association between treatment type (venting versus controls) and postrelease submergence at each depth. Cox proportional hazards models were fit to the tag–recapture data that were collected at each depth to determine whether the experimental treatment influenced postrelease survival. Postrelease submergence was significantly higher in vented fish at the intermediate and deep depths but not at the shallow depth. The hazards rates were not significant for venting and recompression at the shallow and intermediate depths but were at the deepest depth, demonstrating that these techniques practiced at >35 m increased postrelease survival relative to untreated controls. Mean increases in absolute survival at the 35–38 m depth were calculated to be 6.8% and 8.1% relative to controls when using venting and recompression, respectively. The results further suggest that anglers who are unfamiliar with venting do not reduce postrelease survival compared with venting by experienced personnel. These results provide guidance to fishery managers who are tasked with seeking methods to reduce catch‐and‐release mortality for an important reef species. Taken together, the findings from submergence success and survival models suggest that both venting and recompression should be encouraged to increase the postrelease survival of Black Sea Bass that are caught from depths >29 m.