Bottlenose dolphins use Aberystwyth harbour
As part of a collaboration between Friends of Cardigan Bay and Aberystwyth University, a team of students and members of the public volunteered to participate in a shore-based bottlenose dolphin survey examining when and how bottlenose dolphins use the coastal waters of Aberystwyth. Previous reports from Ceredigion County Council had led to conclusions that in the past, the lack of sightings of dolphins at Aberystwyth highlighted the importance of other areas to this species.
These surveys were only run one day a week however, and anecdotal reports from local residents of frequent dolphin activity in the area did not support this conclusion. Therefore, a more thorough investigation into the use of Aberystwyth waters by bottlenose dolphins was considered to be a priority. The survey was carried out in June and July, for six hours each day from Aberystwyth’s South Beach. Each trained volunteer observer completed 2-hr watches where they recorded weather conditions, boat traffic and dolphin sightings and behaviour.
Observers collecting data at the survey site.
RESULTS: Observers achieved a total of 141 complete two hour watches over the two months. Dolphin sightings were recorded more frequently during conditions when the sea was calmer and the visibility good. Dolphins were sighted on 46% of watches completed in June, and 27% in July.
Although dolphins were sighted less frequently in July, when they did appear, they tended to stay within the harbour area for as much time as in June (on average between 15-20 mins but sometimes as long as 2 hours).
Mothers with baby dolphins (calves) were reported on 40% of watches in June and 31% in July. Indeed, one mother and calf repeatedly occupied the harbour area close to shore much to the delight of onlookers.
Therefore, dolphin sightings were significantly more frequent than previously reported and are consistent with the anecdotal reports. Although direct comparisons between studies are hard to make due to the different methods used, these results are similar to results obtained by other studies for areas within the Cardigan Bay SAC such as Aberporth, New Quay Bird’s Rock and Ynys Lochtyn.
Bottlenose dolphin leaping at Tan-Y Bwlch, Aberystwyth.
Other findings from this survey indicated a ‘hotspot’ within the harbour area where sightings of bottlenose dolphins were more concentrated. Within this hotspot, foraging behaviour was recorded frequently suggesting this is an area that may provide an important habitat for feeding. An investigation into the landscape of the seabed here revealed that this hotspot is located in a funnel shaped region which is flanked by shallow Castle Rocks to the north and the Trap to the south, and gently slopes upwards towards the beach.
Topography of the seabed with contours at 1 m interval.
Suggestions of the importance of sandy, gently sloping, shallow habitats for bottlenose dolphins and their offspring are increasingly supported in research literature. One explanation for this may be that these areas offer good conditions for protecting and rearing young as well as for foraging and catching prey. Underwater surveys of the hotspot by trained volunteer divers, revealed a predominantly sandy seabed with patches of boulders to the south.
These habitats provide opportunities to feed off prey such as worms, flatfish and crabs on the sand, as well as sand eels, mullet, salmon, sewin and garfish in the water column. In terms of management strategies for this species, protecting the habitat features of interest to dolphins is equally as significant as protecting the dolphins themselves. Therefore, if bottlenose dolphins are sighted as frequently in Aberystwyth and other regions of Cardigan Bay as they are in areas of the SAC, then surely, a protective and monitoring strategy for this species and the habitats that they utilise should encompass all of Cardigan Bay rather than one small part.
The Ceredigion Code of Conduct leaflet
For example, the Ceredigion Code of Conduct for Boat Users is widely publicised in New Quay and surrounding areas of the SAC. This Code advises boat users on the appropriate behaviour expected of them when in close proximity to marine mammals. Within Aberystwyth however, no posters or signs advertise this Code and information leaflets were not available from obvious points of contact such as the marina and harbourmaster.
Indeed, when asked, visitors to Aberystwyth especially, were unaware of the Code’s existence and that marine mammals such as dolphins even visited local waters. This lack of information leads to disturbance of marine wildlife and possible injury due to speeding vessels. Therefore, raising awareness to the presence of marine wildlife and educating the public in ways to co-exist harmoniously with marine wildlife is paramount. The subsequent issue of effective monitoring and enforcement of non-compliant behaviour to the Code is also a primary concern. However, the public need to be informed of these issues first before they can change their behaviour.