ABSTRACTS OF POSTERS –ABUNDANCE & DISTRIBUTION
aB 32 risso’s dolphin in Ireland: an inshore species of the continental shelf?
Nick Massett (1), Dave Wall (1), Simon Berrow (1) Irish Whale and Dolphin Group
Although Risso’s dolphin are commonly recorded in Ireland little is known of their ecology. During over 6198 hours of offshore line transect survey effort in Irish waters, between 2001 and 2011, 27 sightings of Risso’s dolphin were recorded. A significant finding of these surveys was the lack of Risso’s dolphin sightings in deep water and slope habitats. This was at variance with the reported preference for these habitat types exhibited by Risso’s dolphins elsewhere. Sightings data from Irish waters suggests that Risso’s Dolphins have a largely coastal distribution and regularly occur at inshore locations on the southeast and southwest coasts of Ireland and in the Irish Sea. Risso’s dolphins were recorded on 11 transects (38%) around the Blasket Islands, Co Kerry between 1/6/2009 and 17/8/2011. Group size varied from 5 to 50 with a mean of 14 animals. Photo-identification of individual dolphins taken from these surveys and commercial whale watch operators suggest there was some site fidelity with 1 individual recorded more than once 14 days apart within a season and two individuals recorded 14 and 32 months apart respectively.