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Title: Effects of marine recreation on bottlenose dolphins in Cardigan Bay
Author: Vergara Peña, Alejandra
ISNI:       0000 0004 9353 1985
Awarding Body: Bangor University
Current Institution: Bangor University
Date of Award: 2020
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Anthropogenic activities are markedly increasing in the oceans, causing widespread concern about potential effects on marine mammals and ecosystems. In the UK, a large population of bottlenose dolphins inhabits the coastal waters of Wales, where it has experienced an increase in disturbance from human activities. The importance of the region for the species has been recognised in EU legislation through the establishment of two Special Areas of Conservation (SAC) within Cardigan Bay. Cardigan Bay SAC is located in the southern part of Cardigan Bay and Pen Llŷna’r Sarnau SAC is located in the north of the Bay and around the Llŷn Peninsula. Conservation strategies in the area include a boating code of conduct with respect to marine mammal encounters: the southern SAC has had a code of conduct in place for several years now, with good compliance, whilst the northern SAC implemented the code of conduct for the first time in the summer of 2016, to reduce disturbance or pressure upon marine mammals in Cardigan Bay. Sea Watch Foundation has been monitoring the bottlenose dolphin population in the area since 2001. Over that period, a marked increase in human pressure has been observed, as well as a decline in bottlenose dolphin usage within the Cardigan Bay SAC. Some individuals have been found to be particularly vulnerable to local human activities, and therefore the population may no longer be at Favourable Conservation Status within the SAC. Since the Welsh bottlenose dolphin population is a central attraction for visitors, generating millions of pounds of income annually, careful management is needed in order to conserve the species whilst safeguarding its socio-economic value. The present study aimed to evaluate effects of recreational boating and dolphin-watching activities on the bottlenose dolphins inhabiting Cardigan Bay, in order to build scientific evidence that can be used towards a better management plan. Boat-based surveys, theodolite tracking using land-watches, passive acoustic monitoring, as well as social science surveys were used to examine dolphin presence and behavioural responses during boat encounters, together with marine users’ perceptions about these activities and their potential impacts, to help shape future conservation strategies. The probability of encountering dolphins was related to the type of boat as well as the temporal scale at which this was explored. In the short-term, dolphin density decreased in relation to speed craft only. In the long-term, the probability of encountering dolphins varied in relation to the presence of all type of boats, with an increase in dolphin density in relation to fishing boats in Cardigan Bay SAC. This shows that the presence of fishing vessels may be beneficial to dolphins, potentially by offering additional feeding opportunities. Nonetheless, the fact that dolphin density decreased in relation to the presence of most boat types, shows that frequent boat activity disrupts dolphin numbers in the area, with certain boat types triggering a more significant decrease in density. This indicates the need for further management assessments and recommendations focused on minimising harassment and potential effects of vessel disturbance, avoiding a reduction in dolphin usage of certain areas (Pierpoint et al., 2009), with particular focus on speed craft, their travel speed and numbers permitted around dolphins during an encounter. When looking at short-term responses of bottlenose dolphins to boat encounters in Cardigan Bay, dolphin avoidance responses were found to be caused by high travel speed and close approaches by boats, but not by distance between dolphin and boat. It was evidenced that during a boat encounter, dolphins increased their swim speeds at Abersoch, where the code of conduct has been in place since 2016, but reduced it at New Quay, where the code of conduct has been in place since 2004. At Abersoch, dolphin abundance was highest during the boat encounter, whereas in New Quay dolphin numbers increased after the encounter, perhaps as an avoidance mechanism in which, to swim away from the threat source, dolphins swim faster and cluster together (covering a reduced area) to protect more individuals within the group. Dolphins maintain occupancy despite vessel presence but alter their behaviour, with greater negative responses to boats at Abersoch, which can be linked to the time that codes of conduct have been running in the SACs. This suggests that codes of conduct could have both conservation and socio-economic benefits by allowing people to encounter dolphins without causing excessive disturbance to animals and therefore compliance should be promoted across Cardigan Bay. Evaluation of dolphin presence and foraging activity in Cardigan Bay SAC, where the boating code of conduct has been in place since 2004, suggested an increase in both when boats were in the vicinity. Bottlenose dolphins appear able to sustain the present level of boat activity, perhaps due to its constant low intensity. However, further studies at a finer scale should be implemented, because the length of time of a boat-dolphin encounter is important to characterise disruption to dolphin presence and foraging by boat activities. Further acoustic and visual-based surveys could help to predict the effects of noise disturbance, as well as the presence of different numbers and types of boat, upon bottlenose dolphin responses. Bearing in mind that the bottlenose dolphin population in Cardigan Bay provides important economic benefits to local human communities, it is important for users to adhere to management regulations such as a boating code of conduct in order to maintain those benefits. Results from social surveys of recreational users, commercial operators, and dolphin-watching trip clients in Cardigan Bay highlighted the importance of the bottlenose dolphin population to all of them. Nonetheless, data suggested differences in knowledge of a local boating code of conduct between recreational users in both SACs, with fewer people knowing about it at Pen Llŷn a’r Sarnau SAC than at Cardigan Bay SAC. This evidences the need for further environmental education of users to improve their responses during a dolphin encounter, minimising harassment and disturbance whilst ensuring the dolphins remain in Cardigan Bay. In conclusion, bottlenose dolphin responses to boats are different in both SACs. More neutral or positive reactions were seen in the long-standing code of conduct area (Cardigan Bay SAC), with the guidelines in place in New Quay (i.e. minimum 100 metres boat-dolphin distance, no direct approach to dolphins, and maximum 8 knots travel speed) appearing to be working. Similar management guidelines should be established on a wider scale, perhaps implementing an area-based management scheme, but with particular emphasis upon restricting the number of boats during a dolphin encounter, reducing boat speeds and modifying boat behaviour (avoiding direct approach to dolphins). Results highlight that codes of conduct can be effective if they are monitored and complied with, but education is important, particularly for recreational users. If followed, codes of conduct will not only help the bottlenose dolphin population but also facilitate a sustainable wildlife watching industry.
Supervisor: Cordes, Line ; Waggitt, James ; Turner, John Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Bottlenose dolphin ; Cardigan Bay ; Special Area of Conservation ; Marine recreation