Our collaborative paper on the importance of the waters around north-east Lewis (Scotland) for Risso’s dolphins (Grampus griseus) has just been published. Whale and Dolphin Conservation (WDC) are advocating for this area to be designated as a Marine Protected Area (MPA) for Risso’s dolphins.
Weir, C.R., Hodgins, N.K., Dolman, S.J. and Walters, A.E.M. (2019). Risso’s dolphins (Grampus griseus) in a proposed Marine Protected Area off east Lewis (Scotland, UK), 2010–2017. Journal of the Marine Biological Association of the United Kingdom, 99: 703–714.
The full paper is available to download at the Journal of the Marine Biological Association of the United Kingdom website or as a PDF by email request.
The coastal waters of east Lewis from the Butt of Lewis to Loch Erisort are a proposed Marine Protected Area (MPA) for Risso’s dolphins (Grampus griseus). A total of 100.4 hr (2006.4 km) of active search effort (Beaufort sea states ≤3) was collected during 72 dedicated boat surveys between 2010 and 2017 (primarily in August and September) in the southern part of the MPA and south to the Shiant Isles. Forty Risso’s dolphin sightings and 24.1 hr of encounter effort were recorded, predominantly along the southern and eastern Eye Peninsula in 20–40 m water depths and at distances <1 km from shore. Group size ranged from 1 to 50 animals (mean = 11.8 dolphins) and calves occurred in 37.5% of sightings. A total of 2,404 shore-based scans (Beaufort sea states ≤3) carried out from Tiumpan Head between September 2011 and December 2017 resulted in 271 (11.3%) “dolphin-present” scans. Dolphins were present year-round, with a seasonal increase between May and October. “Calf-present” scans only occurred between April and October. Photo-identification images from 28 boat surveys produced a minimum population size of 117 animals. There was evidence of high inter- and intra-annual site fidelity, with individual dolphins photographically-captured in up to six of the eight survey years, and between two and seven capture dates being recorded for over 45% of individuals within most years. The combined datasets support the importance of east Lewis for Risso’s dolphins, and recommendations are made for ongoing monitoring of dolphin occurrence throughout the wider MPA.