Project co-financed by the EEA Financial Mechanism 2009-2014



The harbor porpoise is one of the smallest species of cetaceans. An adult body length in the Baltic Sea is about 180 cm and the weight does not exceed 60 kg. Females are slightly larger than males. Porpoises are characterized by fusiform and stocky body with a strong construction. The front of the head is rounded, and their teeth have a “spatulate” shape, unique for the porpoise family. Porpoises are covered with flexible, naked skin with delicate epidermis. The colors on the side of the body pass gradually from the black of the back towards the white belly. The dorsal fin is similar to the shape of an equilateral triangle. The caudal fin with rounded ends, cut in its middle part, is located horizontally on the shaft of laterally flattened tail.

They live mostly alone or in groups of 2-3 individuals. They usually reside in the coastal zone of the seas while leading a very secretive lifestyle. In search for food they dive even to a depth of 90 m. They normally swim near the water surface, while preying at the bottom, and rarely jumping out of the water. They swim at a speed of 17-22 km/h.

Porpoises eat mainly fish, mostly herring and sprat. They enrich their diet with algae and crustaceans. Males reach the reproductive maturity at the age of 5, and females a little later. The mating season covers the period from May to September. After 11 months of pregnancy a single calf is born, usually in coastal areas in the period from May to August. Porpoises live up to 15 years – the majority of the population is 7-8 years old. The main threat for the harbor porpoise population is the use of large amounts of gill-nets in the Baltic fishery. Suspended in the water are invisible to animals which fall into them while pursuing fish. Also, acoustic sounds that scare animals away from their habitat are very dangerous for the harbor porpoise, as well as rapid growth of maritime transport in the Baltic Sea, detonations on marine ranges, and the aggressive development of the motorboat tourism.

Historically, the porpoise was called by Polish fishermen „morsun”, or „sea-pig” or a Baltic dolphin. This very numerous species has been depleted in the early twentieth century and now it is critically endangered with extinction. It is estimated that there are about 100 individuals today in the Baltic Sea. Historically speaking, porpoises have been regularly caught for their meat and fat since the fourteenth century. Even in the eighteenth and the nineteenth century there were many hunters associated in guilds. The porpoise hunting also engaged residents of the southern Baltic coasts. Even in the first half of the twentieth century, porpoises were so numerous that the Polish authorities in the 1920's introduced bonuses for catching or killing a porpoise, treating the species as a cause of net destruction and constituting competition for the fishermen. In the years 1922-1933 at least 600 individuals were caught. Since 1936, there is no information about the presence of harbor porpoises in the Polish Baltic waters. In the years 1950-1990 there were reports about 1-2 individuals a year, and in the years 1990-2008, thanks to the research activities of the UG Marine Station in Hel, there were 102 reports about by-caught, found or seen harbor porpoises in the Polish zone of the Baltic Sea.

Based on information from the Institute of Marine Station of Oceanography on the University of Gdańsk (IMSOUG) and WWF Poland.

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