The Harbour Porpoise (Phocoena phocoena) is one of six species of porpoise. It is one of the smallest ocean mammals in the sea. As its name implies, it stays close to coastal areas or river estuaries and as such is the most familiar porpoise to whale watchers. The Harbour Porpoise often ventures up rivers and has been seen hundreds of miles from the sea.
The Harbour Porpoise is sometimes known as the Common Porpoise, though this usage appears to be dying out.
The Harbour Porpoise is a little smaller than the other porpoises. It is about 67 – 85 centimetres (26 – 33 inches) long at birth. Both male and female grow up to be 1.4 metres to 1.9 metres (4.6 – 6.2 feet). The females are heavier than the males, with a maximum weight of around 76 kilograms (167 pounds) compared with the males’ 61 kilograms (134 pounds).
The body of the Harbour Porpoise is robust and they have a triangular dorsal fin. Their flippers, dorsal fin, tail fin and back are a dark grey. Their sides are a slightly speckled lighter grey. Their underside is much whiter, though there are usually grey stripes running along the throat from the underside of the mouth to the flippers. Harbour Porpoises can live up to 25 years.
The Harbour Porpoise is widespread in cooler coastal waters in the Northern Hemisphere, largely in areas with a mean temperature of about 15°C including the coasts of Spain, France, the United Kingdom, Ireland, Norway, Iceland, Greenland and Newfoundland.
Harbour Porpoises feed mostly on small fish, particularly herring, capelin, and sprat. The deepest dive recorded was 224 metres (735 feet) deep. Young porpoises need to consume about 7% to 8% of their body weight each day in order to survive.
Harbour Porpoises are not and never have been actively hunted by whalers because they are too small to be of interest. However a key concern is the large number of porpoises caught each year in gill nets and other fishery equipment. This problem has led to a documented decrease in the number of Harbour Porpoises in busy fishing seas. It is known that the porpoises echolocation is sufficiently discriminating to detect the presence of the nets, but this does not stop porpoises from becoming trapped.
Scientists have developed beacons to attach to the nets to try to deter curious porpoises. These are not yet widespread and there is some controversy regarding their use some concerns have been raised about the value of adding more noise pollution to the seas.