An Investigation into the effects of boat proximity on the behaviour of bottlenose dolphins (Tursips truncatus) in Cardigan Bay by Sinead Martin

An investigation into the effects of boat proximity on the behaviour of bottlenose dolphins (Tursiops truncatus) in Cardigan Bay by Sinead Martin (CBMWC 2015)

Sinead volunteered with the Cardigan Bay Marine Wildlife Centre (CBMWC) during the field season in 2015. During her time as a Living Seas volunteer she collected data for her undergraduate dissertation project under the guidance of Sarah Perry our Living Seas Science officer.

Sinead used shore based observation data collected by CBMWC volunteers to investigate the effects of boat proximity on the behaviour of bottlenose dolphins in Cardigan Bay for her undergraduate dissertation project at the University of Derby.

Abstract

A constant challenge in marine conservation science is understanding how human activities impact marine species. For bottlenose dolphins, Tursiops truncatus, a frequent anthropogenic threat can occur through interactions with marine vessels. Boats commonly disrupt dolphin feeding, mating, and resting behaviours; that ultimately can lead to permanent changes in dolphin demography and habitat-usage. However, some dolphin populations become habituated and show no behavioural responses to boats. In Cardigan Bay, Wales, dolphins routinely interact with a variety of marine vessels. However, there is debate among local organisations about whether boat activities in the bay are negatively impacting the dolphins. The goal of this study was to determine whether boats influence the behaviour of dolphins in Cardigan Bay. Land based surveys were conducted during May and June in 2015 to quantify the frequency of dolphin behaviours in relation to boats. These data were combined with similar surveys conducted in 2005 and 2010 to determine if dolphins demonstrate positive or negative reactions to boats; whether, the variety of dolphin behaviours decreased when boats were present; and, whether boat traffic and dolphin abundance has changed since 2005. Overall, dolphins in Cardigan Bay did not appear to be affected by boat activity. An increase in dolphin sightings between 2005 and 2015 appeared to be independent of boat activity that did not show any predictable change during the same period. Further, the majority of dolphin responses to boats were neutral; and very few dolphins altered their behaviour before and during boat encounters. However, not all interactions were benign: motorboats and vessels operated in a negative manner elicited negative behaviour from dolphins. Hence, while dolphins in Cardigan Bay appear to be a strong population that are accustomed to boat activities, a small number of boats are a potential threat. Future research and management strategies may look to these specific dolphin-boat interactions to enhance the protection of the dolphins.

Sineads project is available to download here