Reducing Bycatch and Discard Mortality
Discard mortality has become a serious issue in many recreational and commercial fisheries across the globe.This issue is extremely pertinent to deep-dwelling reef fishes (snappers, groupers, rockfishes), which experience a suite of physiological problems collectively known as barotrauma during rapid ascent to the surface from fishing activities. These events either cause direct mortality (via barotrauma), or increase predation risk of discarded fish to several scavenging predators.
Two major techniques have been developed to mitigate barotrauma effects: 1) rapidly recompressing a fish by returning it to depth (i.e., forced descent); and 2) puncturing the swim bladder with a hollow needle (i.e., venting ) to release the pressure resulting from overexpansion. Previous research on forced descent recompression has concentrated on rockfishes (Sebastes sp.) and other deepwater species in the Pacific as a method of combating the effects of barotrauma caused by catch-and-release fishing. The method of resolving barotrauma issues in rockfishes has been use of descender hooks (e.g., Shelton Descender Hook) which drag fish back to depth and release them when the weight hits bottom. More recently, technological developments have created pressure-sensitive release devices (e.g. The SeaqualizerTM) to avoid premature release of discarded fishes. However, this new technology remains to be tested experimentally against other release techniques in recreational fisheries.