Impacts of boat activity on Cardigan Bay bottlenose dolphin (Tursiops truncatus) behaviour and their implications for the future by Emma Lowe

Impacts of boat activity on Cardigan Bay bottlenose dolphin (Tursiops truncatus) behaviour and their implications for the future by Emma Lowe (CBMWC 2015)

Emma volunteered with the Cardigan Bay Marine Wildlife Centre (CBMWC) during the field season in 2015. During her time volunteering as a Living Seas volunteer she collected data for her undergraduate dissertation project under the guidance of Sarah Perry our Living Seas Science officer. Her study focused on the behaviour of bottlenose dolphins; investigating possible relationships between dolphin behaviour and vessel activity in New Quay Bay. Emma's study investigated whether there was a link between dolphin presence and absence when boats are in the area, if dolphins respond differently to different boats and if they behave differently when boats are and aren’t present in the bay. Her study aimed to assess whether the Special Area of Conservation (SAC) status of Cardigan Bay and the local codes of conduct are effectively protecting these dolphins, or if heavy boat traffic may be causing negative impacts on their wellbeing.


Tursiops truncatus are a characteristic, social species that prefer coastal habitats, consequently come into contact with human activity. Cardigan Bay is subject to high levels of boat traffic during the summer months as tourism peaks, and there is increasing demand for dolphin watching trips. New Quay Bay is a small bay located on the Southern end of Cardigan Bay, and is a site often frequented by dolphins as feeding and nursing grounds. It is therefore questioned whether this intense vessel activity in New Quay bay is impacting the dolphins in terms of their behaviour. It was discovered that dolphins showed more staying behaviours, involving long dives and irregular surfacing when boats were present compared to when boats were absent (X2 = 17.1, d.f. = 6, p = 0.00876). These findings suggest that boat occurrence significantly affects dolphin behaviour. Other studies have reported similar results, with boat traffic causing short-term behavioural changes. The longer term implications of these behaviours would merit further study; however may involve site avoidance, reductions in biological fitness and lower breeding rates. Furthermore these impacts may be detrimental to the population of T. truncatus in Cardigan Bay, which are protected by the implementation of a Special Area of Conservation (SAC). This study suggests that further work is carried out to estimate the extent of damage being done to bottlenose dolphin populations via behavioural changes instigated by boat presence, and that stricter regulations are implemented in the code of conduct of the SAC to ensure effective protection of the species.

Emma's project is available to download here.