Critical evaluation of fish abdomen deflation as a means of enhancing survival of undersized catch in the reef fish fishery. Final report.

Abstract

This information constitutes the final report by Mote Marine Laboratory on reef fish venting from February 1, 1997 - June 30, 1999. Reef fish brought rapidly to the surface from any appreciable depth experience rapid expansion of swimbladder gases leading to ruptured swimbladders, bloating, protrusion of internal organs and eyes, and embolisms. Without some easy shipboard method of aiding the descent of these bloated, undersized fish, forced discard leads mostly to floating fish that are easy prey for birds and predatory fishes such as barracuda and sharks. The problem comes in deciding when abdomen deflation (venting) is necessary to assist the descent of the fish because some fish will be able to re-descend without it. Before widely encouraging the technique of venting as a means of enhancing survival of undersized catch caught from depth, it is necessary to determine whether venting actually improves the chances for post-release survival over that which would occur without it. With venting there is the possibility of further injury to the fish. The present study focuses on these issues. The study targeted six species to be tagged in three primary areas in Florida, according to local availability: red grouper and gag off the west coast, red snapper and vermilion snapper off Cocoa Beach/Daytona; and mangrove snapper and mutton snapper off Miami. Participants were also free to tag any of the six species in any locations. The objectives of the study were accomplished by integrating an appropriate experimental design into an existing and long-term tag-recapture study that was already in progress at Mote during this time. The results are discussed.