Sebastes fasciatus abundance and associated seabed environmental conditions in a Vazella pourtalesii sponge ground in the Sambro Bank (Scotian Shelf)

The genus Sebastes is a morphologically and ecologically diverse genus of rockfish characterized by high longevity, late-maturity, and low natural mortality. On the northwest Atlantic continental shelf, the Acadian redfish (Sebastes fasciatus) is the most common rockfish species above 300 m depth. This species has been widely exploited resulting in the depletion or collapse of most of its stocks. Management of long-lived species with intricate life-history characteristics is challenging and requires highly integrated biological and oceanographic monitoring, which allow the identification of environmental drivers and demographic and behavioural trends. The present study uses high temporal resolution imaging and environmental data, acquired with an autonomous lander deployed for 10-months at the Sambro Bank Sponge Conservation Area (Scotian Shelf) to elucidate S. fasciatus temporal dynamics and behavioural trends in response to near-bed environmental conditions. S. fasciatus, mostly displayed passive locomotion and static behaviours, in common with other shelf-dwelling Sebastes species. Hydrodynamics appear to act as a synchronizing factor conditioning its swimming behaviour. S. fasciatus total counts exhibited a seasonal shift in rhythm's phase likely reflecting changes in lifestyle requirements.