NatureScot has published the results of the fifth full census of Scotland’s harbour seals (Phoca vitulina) over the last 25 years which reveals Scotland’s harbour seals are doing well overall but there remains a striking divide between east and west coast populations.

Estimates based on these surveys undertaken by the Sea Mammal Research Unit (SMRU) suggest total populations in Scotland of around 37,300 harbour seals and 106,300 grey seals.

The data show that for harbour seals, there remain striking differences in population trends between different regions.  Northern and eastern coasts have seen significant declines since the early 2000s, with the most dramatic changes occurring around Orkney, in Shetland, and in the Firth of Tay and Eden Estuary.

In contrast, numbers in the west have been either stable or increasing. The latest counts show that more than three-quarters (78%) of all harbour seals in Scotland are currently found in the west, a significant shift since the 1990s when Orkney and Shetland were the most important regions in Scotland for harbour seals.

Ongoing studies are attempting to identify the reasons behind the large regional declines.

Click here and, for the SMRU report, here.

SAMS: Also in Scottish waters, a recent Scottish Association for Marine Science (SAMS) study highlights the potential for ‘collateral damage’ from interventions to reduce human–wildlife conflicts with seals which may affect the long-term health and habitat use of non-target species especially, in this study’s case, for harbour porpoises protected under the EU and UK Habitats Regulations.

The Scottish aquaculture sector frequently report depredation by harbour and grey seals (Halichoerus grypus) at salmon farms).  Acoustic deterrent devices (ADDs), first introduced in the mid-1980s to counteract this issue and reduce the practice of shooting seals, produce loud sounds within the mid- to high-frequency range that are audible to marine mammals, both seals and small cetaceans, and are used globally in coastal areas, where aquaculture production can extend over large spatial scales, to reduce seal depredation.

The study reports on the “Auditory impairment from acoustic seal deterrents predicted for harbour porpoises in a marine protected area”. Click here (open access).