Fam.: Phocoenidae

Harbour porpoises are the most abundant cetacean species in the North Sea and the only native species inhabiting the Baltic Sea.
They are small animals with a blunt short-beaked head and a low wide-based triangular dorsal fin. Adults are usually less than 1.8m long and weigh from 45 to 70 kg. Generally, harbour porpoises occur singly or in small groups of less than eight individuals. Occasionally, larger schools of up to several hundred animals have been reported.

The species is inconspicuous compared to most dolphins. They rarely approach boats to ride on bow waves and seldom breach or leap from the water. Reproduction takes place from spring to mid-summer, and newborn calves measure 70 to 90 cm. Harbour porpoises feed opportunistically on a wide variety of pelagic and demersal fish as well as on marine invertebrates. Main prey items appear to be schooling fish species, such as herring, mackerel and sand.

The species exhibits a coastal circumpolar distribution in the Northern Hemisphere, including the North Sea and the Baltic.

Until the 1930s the range of the Baltic population extended northeastward to the xxxAland Islands (north of Stockholm) and to the coast of Finland, including the Gulf of Riga and the entrance to the Gulf of Finland. Since then a dramatic decline in the Baltic population has been accompanied by a steady retreat from large parts of its former distribution range in the eastem and central Baltic Sea.

Today, Baltic harbour porpoises are generally restricted to the Kattegat and Belt Sea, the westernmost section of their former range. Occasionally they are also found further East along the German and Polish coasts and in Swedish waters.

Illustrations: M. Camm