Research Document 2019/042

A Review of the Use of Recompression Devices as a Tool for Reducing the Effects of Barotrauma on Rockfishes in British Columbia

By D.R. Haggarty

Abstract

Pacific Rockfish (genus Sebastes) suffer high rates of barotrauma when they are brought to the ocean’s surface because they have a closed, or physoclistic, gas bladder. Although many jurisdictions recommend the use of descending devices that return recreationally caught fish with barotrauma to depth, little research on the use of these devices and the survival of recompressed fishes has been done in British Columbia. The purpose of this report is to review the literature regarding the effects of barotrauma on rockfishes and the ability of recompression devices to decrease mortality of released fish in the short- and long-term; document types of descending devices and what is known about each; synthesize study results for each species that occurs in BC; and characterize research gaps and uncertainty. Rockfish species are found to demonstrate a remarkable ability to recover from barotrauma and to survive after recompression in the short-term. However, the effects of barotrauma and variation in survival rates are complex in this diverse genus of fishes, and a number of uncertainties remain. Although recompression certainly increases the survival rates of discarded fish that would otherwise be unable to descend and therefore risk predation, keeping what you catch and moving fishing locations to avoid further capture or ceasing to fish once limits have been reached remain better recommendations. Incorporating the voluntary or mandatory use of descending devices in the management of recreational rockfish fisheries will require careful consideration because considerable uncertainty about their effectiveness to mitigate rockfish mortality on a scale that affects populations remains.

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