"Determining Post-Release Mortality for Atlantic Cod Discarded in the Gulf of Maine Lobster Fishery

Atlantic cod, Gadus morhua, has experienced heightened fishing-induced mortality since the 1990s leading to the lowest population abundances in recorded history. Although rigorous commercial and recreational limitations have been established in an attempt to restore this species, population levels remain at all-time lows. A potential issue affecting the recovery of cod populations is the unaccounted discard mortality experienced within Northwest Atlantic fisheries. With over 4 million fished traps, the lobster industry represents Maine’s largest fishery, and has recently been suggested as a major contributor towards the increased mortality rates of cod within this region. For example, preliminary data suggests that discard rates as high 1.32 cod/trip may exist. In order to address this issue, an active collaboration was established during the fall of 2015 with lobster fisherman to investigate the post release mortality of cod within commercial lobster gear. Captured individuals will be tagged with ultrasonic transmitters and released into an established 36 km² acoustic receiver array to monitor movement patterns after release. Discard mortality will be assessed by correlating vitality condition upon capture with the observed or absence of movement throughout the acoustic array. The preliminary data collected will be presented at this year’s conference.