PHOTO-IDENTIFICATION OF BOTTLENOSE DOLPHINS (TURSIOPS TRUNCATUS) IN TRALEE BAY AND BRANDON BAY, CO. KERRY: A CASE FOR SAC BOUNDARY EXTENSION

Abstract

The Lower River Shannon is a Special Area of Conservation (SAC) with bottlenose dolphins (Tursiops truncatus) as a qualifying interest, and is one of only two SACs for this species in Ireland. Bottlenose dolphins in the Shannon Estuary are present year-round and genetically discrete from other populations in Ireland. They have regularly been reported from Tralee Bay and Brandon Bay, Co. Kerry, adjacent to the Lower River Shannon SAC boundary. In order to determine the provenance of these dolphins, photo-identification data collected between 2008 and 2016 from both bays were used to identify individuals and match them to existing bottlenose dolphin catalogues in Ireland. Bottlenose dolphins were observed on over 90% of the 13 trips carried out,with photo-identification data collected on 11 of these trips. A total of 70 individual dolphins were identified, of which 67 have been regularly recorded within the Lower River Shannon SAC, confirming them to be from this population. Shannon dolphins represented an average of 98% of dolphins photographed during each survey. Of the estimated 108 individual adult dolphins extant in the Shannon population, 62% were identified in Brandon Bay and/ or Tralee Bay during the study period. A discovery curve of individuals identified did not reach a plateau, suggesting that not all dolphins occurring in these bays were photographed during the study. Results suggest that these areas are of high importance to the Shannon dolphin population and support the need to extend the current boundary of the Lower River Shannon SAC to include Brandon Bay and Tralee Bay.