Harbour Porpoise
Mhug mhara – Phocoena phocoena
How to identify
The Harbour porpoise is much smaller than any other cetacean found in Irish waters. They only reach up to 2 metres in length and usually surface quickly in a rolling motion, not breaching in the way that other dolphins do. Their dorsal fin is also much less prominent and more triangular in shape. Sometimes they are referred to as ‘puffing pigs’, which originates from the sound of their blow (exhale). When they surface, that ‘puff’ can be heard from shore in very calm conditions.
Ecology, social dynamics and seasonality
Porpoises with their fast, rolling motion in Kenmare Bay, Iveragh – Christina Winkler
Unlike their larger relatives, the dolphins, porpoises live more of a solitary lifestyle and large pods are not a common sight. You are more likely to see them alone, in small groups of a few individuals, or as a mother and calf pairing. They prefer areas where different currents mix, such as around headlands. These areas are where a lot of their favoured prey items like sand eel and other smaller fish species congregate. During the summer months, they can be seen more frequently, as they tend to migrate with their food source, which moves to more open water in the colder months. Besides waters around Ireland and the UK, their mainly coastal distribution reaches as far north as Iceland, Greenland and Alaska and as far south as the north of the USA, the north-west of Africa and Japan. Being widely distributed through Europe, they however do not inhabit the Mediterranean Sea and are completely absent in the southern hemisphere.
Spot the porpoise! A pair of harbour porpoises, small and elusive, hard to spot even on a calm day – Christina Winkler
Harbour porpoises along the Iveragh coast
Although the harbour porpoise is the most frequently sighted cetacean in Irish waters, they can be hard to spot in rough weather which, of course, is very common on the west coast of Ireland. Harbour porpoises, therefore, are mostly seen in sheltered bays, such as Ballinskelligs and Kenmare Bay, but also off of Bolus Head and Bray Head.
