Winter residency and site association in the Critically Endangered North East Atlantic spurdog Squalus acanthias

摘要

Identification and incorporation of residential behaviour into elasmobranch management plans has the potential to substantially increase their effectiveness by identifying sites where marine protected areas might be used to help conserve species with high migratory potential. There is evidence that the spurdog Squalus acanthias displays site association in some parts of its global distribution, but this has currently not been shown within the North East Atlantic where it is Critically Endangered. Here we investigated the movements of electronically tagged spurdog within Loch Etive, a sea loch on the west coast of Scotland. Archival data storage tags (DSTs) that recorded depth and temperature revealed that 2 mature female spurdog overwintered within the loch, restricting their movements to the upper basin, and remaining either in the loch or the local vicinity for the rest of the year. This finding was supported by evidence for limited movements from conventional mark-recapture data and from an acoustically tagged individual spurdog. Some of the movements between the loch basins appear to be associated with breeding and parturition events. This high level of site association suggests that spatial protection of the loch would aid the conservation of different age and sex classes of spurdog.