By Sue Burton (Pembrokeshire Marine SAC Officer)
Harbour porpoise (Phocoena phocoena) may be considered by some to be a poor cousin to dolphins, but they are the cetacean that is most likely to be seen off the Pembrokeshire coast. In fact in some areas, pick the right state of tide and you are almost guaranteed to see them! They are small and dark brown to grey in colour with a lighter belly. They have a small triangular fin. They regularly break the surface of the water but are difficult to spot as they don’t jump out of the water like dolphins. A good indicator of possible porpoise presence is feeding gannets as both species will be after the same prey species.
A summary of the work done over the last 8 years within Ramsey Sound, with recommendations for future management has been funded by Biodiversity Solutions for the Pembrokeshire Marine Special Area of Conservation (SAC) Relevant Authorities Group, a partnership of organisations working to enhance and protect the SAC for the future. The summary has been drawn together by Malcolm Barradell (Pembrokeshire Marine Environmental) who has studied Harbour porpoise in Ramsey Sound for many years. Malcolm made the porpoises in Ramsey Sound the topic of his B.Sc. (hons) thesis in 2008 and in subsequent years continued to monitor their movements and behaviour whenever opportunity allowed. He has worked over the last couple of years as a marine mammal observer for Tidal Energy Ltd. where he documents porpoise sightings within areas of tidal energy interest. Even though there has been a lot of porpoise research in Ramsey Sound, it was felt that a wider look at the ‘story’ of the whole sound and the porpoises use of it was needed.
The Harbour porpoise is associated with the shallow inlets and bays feature of the SAC but can be found throughout the site, particularly at high energy tidal sites around headlands and off shore islands, in wakes, tidal eddies and upwelling’s where the water movement enables rich feeding sites.
Research into harbour porpoise within Ramsey Sound concludes with certainty that Harbour porpoise are present in Ramsey Sound all year round, with indications of seasonal variation in abundance. The abundance, frequency of activity, and presence in a particular area of the Sound is related both to the tidal cycle and prey availability. There is also evidence to suggest that a local pocket population of porpoise favour the use of Ramsey Sound as a foraging area.
This has been a small but vital piece of work to draw together a wealth of knowledge and data into an easily digestible summary that can then be utilised for multiple purposes to benefit the future conservation of this charismatic but little understood species. Ramsey Sound porpoise management recommendations have been given to help future conservation of porpoise in the area. These include recommendations for use of the area by wildlife tour operators and recreational vessels that will be fed into Pembrokeshire Marine Code work. This summary has also been fed into the recent porpoise SAC consultation. Regardless of whether or not a porpoise specific SAC is designated off the Pembrokeshire coast, it is clear that porpoise are happy here and likely to stay as long as prey is abundant and their activity undisturbed.