Evaluating Survivability of Cod Discarded in the Gulf of Maine Lobster Fishery

The Atlantic cod (Gadus morhua) is one of the most iconic and historically plentiful species of commercialized fish. In the Gulf of Maine (GOM), the most recent stock assessment suggests that cod are overfished, and are experiencing overfishing. It is thus critical to improve understanding of mortality sources. Based on the Maine Department of Marine Resources sea sampling program, a potential mortality source is discarded cod in the GOM lobster (Homarus americanus) fishery. During ascent in a trap, cod experience barotrauma from the sudden change in ambient pressure. Because barotrauma is not well understood in cod, we only have a limited understanding of survival rates for discarded cod, and discards from the lobster fishery are not included in the stock assessment. This study evaluates the capacity of cod to survive release, despite the effects of barotrauma and handling stress. A reflex action mortality predictor approach is used in conjunction with video recompression to evaluate whether cod recompression in the commercial fishery is a feasible method to improve survivability of cod. An improved understanding of discard survivability can yield a better estimate of the total mortality, improve the stock assessment, and promote rebuilding efforts of the GOM Atlantic cod stock.