The Survival of Rajids Discarded in the New England Scallop Dredge Fisheries

Due primarily to regulatory factors, skates (family Rajidae) account for nearly half the total bycatch discarded during commercial fishing operations in the U.S. portion of the Northwest Atlantic Ocean. Although the New England scallop dredge fishery has the second highest skate discard rate, no information regarding their resiliency to interaction with this gear type exists. To gain insight into species-specific mortality rates, 295 tows were conducted across six research trips (2012-2013 fishing season), with a total of 4020 skates (little, Leucoraja erinacea, winter, Leucoraja ocellata, and barndoor, Dipturus laevis) evaluated and scored on vitality (i.e. reflex impairment) and condition (i.e. overt physical trauma) indexes. To quantify mortality rates associated with these indexes, 290 skates were maintained in a novel on-deck refrigerated flow-through seawater system for 72-hours. This study also assessed the effect of fishing conditions and practices on post-release mortality. Preliminary data based on condition and vitality indexes, suggests species-specific differences in post-release mortality exist. For example, highest mortality (up to 100%) was observed in barndoor skates while winter skates were most resilient (up to 23.5%). As such, a species-specific management plan may be more appropriate for skates in this fishery. A more extensive analysis of the data is underway.