The population of bottlenose dolphins off the east coast of Scotland has been studied since 1989 as part of a collaborative project between the University of Aberdeen Lighthouse Field Station and the Sea Mammal Research Unit at the University of St Andrews. The main distributional range of this population extends from the Moray Firth to the Firth of Forth, with around 50% of the estimated total population regularly using the waters of St Andrews Bay and Tayside every summer. This project, supported by the European Offshore Wind Deployment Centre (EOWDC), aims to improve the understanding of movement patterns of bottlenose dolphins across the main population range by combining new photo-identification data collected during the years 2017 to 2019 around the Tay Estuary, with equivalent data collected in the Moray Firth by the University of Aberdeen’s Lighthouse Field Station as part of a separate project. This report provides the estimate of the number of bottlenose dolphins using St Andrews Bay and the Firth of Tay in 2017, based on the data obtained during the field trips in 2017, and a summary of the photo-identification survey trips in that area conducted by the Sea Mammal Research Unit in 2018 .
The total number of bottlenose dolphins using the Firth of Tay and St Andrews Bay area in 2017 is estimated to be 130 (95% CI = 109-154). In 2018, twenty-one trips were conducted between May and September, resulting in a total of 47 bottlenose dolphin encounters with an average group size of 10 animals. Most of the encounters occurred between Broughty Ferry and the entrance to the Firth of Tay, and between Arbroath and Lunan Bay, with fewer encounters in St Andrews Bay and around Montrose. During the encounters, a total of 7,802 photographs containing one or multiple dorsal fins were taken. Each of these photographs were graded for their photographic quality, and the 1,880 best quality photographs have been preliminarily matched to the catalogue of known bottlenose dolphins in the east coast of Scotland population. A total of 92 different individuals has been positively identified so far; however, this number might change once the processing and dolphin identification is finalised as part of the annual protocol applied to all photo-ID data that are part of the Aberdeen/St Andrews Scottish east coast bottlenose dolphin project.