Effects of 2D Seismic on Snow Crab Movement Behavior

Sound is an environmental feature that is used by a variety of marine taxa for feeding, reproduction, navigation and predator avoidance. Consequently, alterations to the soundscape have the potential to alter an individual’s behaviour, physiology and ultimately fitness. Furthermore, such responses have the potential to negatively influence commercial fishing interests. In Atlantic Canada, snow crab fishing and hydrocarbon extraction are billion dollar industries. Snow crab harvesters contend that seismic noise from hydrocarbon exploration has strong negative effects on catch rates; an issue that is likely to become more acute given that the species is currently in decline. As part of a collaborative, multi-disciplinary study conducted offshore on the continental slope, positioning telemetry was used from 2015-2017 in a Before-After-Control-Impact (BACI) study design to assess the behavioral responses of snow crab to exposure from industry seismic vessels. While effects of seismic exposure on snow crab movement could not be ruled out completely, effects were at most quite small relative to natural variation. In contrast, snow crab exhibited much clearer responses to handling, temperature and time of day. Overall, our results suggest that seismic effects, specific to the behavior of adult male snow crab, are at most subtle and are not likely to be a prominent threat to the fishery.