Using Acoustic Telemetry and Hyperbaric Experimentation to Estimate Discard Mortality in the Red Snapper Fishery

Red snapper (Lutjanus campechanus) is the most economically important reef fish species in the Gulf of Mexico. Overfished stocks are recovering but may be hindered to due to barotrauma related post-release mortality. Barotrauma afflicted fish may not only experience immediate surface mortality but also delayed mortality upon returning to depth.  Using a combination of field acoustic tagging and hyperbaric laboratory experiments, we estimated survival rates and delayed mortality events in a series of temperature, depth, and release treatments. We also examined the use of rapid recompression and venting tools to determine post-release survival and recovery potential. Field trials showed that chances of survival decreased with increasing water temperature. Field and lab trials both showed strong depth effects resulting in increased barotrauma injuries, more impaired reflexes, and greater mortality as depth increased. Venting and rapid recompression strategies showed greater survival than non-vented, surface released fish. These data support venting or rapid recompression as effective tools for alleviating barotrauma symptoms and increasing overall post-release survival. Estimates from this study can be integrated into stock assessment models to achieve better determination of overall mortality and ultimately increase survival.