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

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.

Abstract

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.

Helen M. Hiley, Sarah Perry, Steve Hartley & Stephanie L. King (2016): What’s occurring? Ultrasonic signature whistle use in Welsh bottlenose dolphins (Tursiops truncatus), Bioacoustics DOI: 10.1080/09524622.2016.1174885

ABSTRACT

Animal communication signals are diverse. The types of sounds that animals produce, and the way that information is encoded in those sounds, not only varies between species but can also vary geographically within a species. Therefore, an understanding of the vocal repertoire at the population level is important for providing insight into regional differences in vocal communication signals. One species whose vocal repertoire has received considerable attention is the bottlenose dolphin. This species is well known for its use of individually distinctive identity signals, known as signature whistles. Bottlenose dolphins use their signature whistles to broadcast their identity and to maintain contact with social companions. Signature whistles are not innate, but are learnt signals that develop within the first few months of an animal’s life. It is therefore unsurprising that studies, which have characterized signature whistles in wild populations of bottlenose dolphins, have provided evidence of geographic variation in signature whistle structure. Here, we describe the occurrence of signature whistles in a previously unexplored wild population of bottlenose dolphins in Cardigan Bay, Wales. We present the first occurrence of a signature whistle with an ultrasonic fundamental frequency component (>30 kHz), a frequency band that was not thought to be utilized by this species for whistle communication. We also describe the occurrence of an ultrasonic non-signature whistle. Our findings highlight the importance of conducting regional studies in order to fully quantify a species’ vocal repertoire, and call into question the efficacy of those studies that use restricted sampling rates.

You can access the paper here: http://www.tandfonline.com/doi/full/10.1080/09524622.2016.1174885