Dolphins and Boat Traffic in Cardigan Bay

You may have seen or heard in the media recently of claims that Cardigan Bay’s famous bottlenose dolphins are being driven away by increasing boat traffic but researchers at the Cardigan Bay Marine Wildlife Centre (CBMWC) question the basis of these claims.

The claims came from a another organisation - Sea Watch Foundation - who said that the animals are moving northwards and out of Cardigan Bay in the summer and that boat numbers may be affecting their social structures.

Dolphin by Sarah Perry CBMWC

Dolphin by Sarah Perry CBMWC

However, CBMWC volunteers log the frequency of boat traffic of all types as well as numbers of dolphins in New Quay bay on behalf of Ceredigion County Council’s Dolphin Watch project  which has been running since 1994. 

CBMWC’s science officer Sarah Perry has been looking at the data from 2010 to 2012 and this actually shows that boat traffic has declined by more than a third over the past three years. So far this year we have been seeing the dolphins on a regular basis in New Quay - as we would expect - and we haven't observed an obvious decline in numbers over the last few years.

As for boat traffic, the last few years the summer months have experienced poor weather conditions and therefore fewer people on the water, particularly in the summer holiday period when there is usually an increase in boat traffic. Any change in dolphin distribution would more likely be explained by changes in prey distribution as these animals are primarily motivated by food availability.

One of the main reasons for the Dolphin Watch project is to not only count the number of boats but monitor their behaviour around cetaceans. Data shows that the vast majority of skippers obey the Ceredigion code of conduct for boat users by not getting too close to the dolphins or chasing them. Ceredigion County Council also have a member of staff out on the water during the summer months, making sure boat owners are aware of the code of conduct.

Although we’ve no reason to believe that current levels of boat traffic are causing the dolphins to leave Cardigan Bay, research by scientists in Scotland shows that dolphins can compensate for even a six-fold increase in boat traffic, as long as that is the only man-made activity that changes.

Due to our photo-ID work we’ve been able to identify animals that normally frequent Cardigan Bay in areas as far away as the Isle of Man and Anglesey but this is not abnormal behaviour. Fishermen have seen dolphins in North Wales for many years. Some bottlenose dolphins identified in the Moray Firth on the east coast of Scotland have subsequently been reported off the Irish coast so it’s relatively normal behaviour to travel large distances. Dolphins are motivated basically by food availability and conditions suitable for breeding and so far at least, Cardigan Bay remains clean and unpolluted.