Porpoise
Harbour Porpoise
Phocoena phocoena (Linnaeus, 1758)
Phocaena communis Cuv.: Kovachev, 1925: 7-8.
Order Cetacea
Family Phocoenidae
Conservation status: in Bulgaria: Vulnerable VU [A1acde + 2ce], BDA; International: IUCN-VU, BeC; BoC, HD.
General distribution. The coastal regions of the Arctic Ocean, the coasts of the northern parts of the Atlantic and the Pacific Ocean, the Mediterranean (including the Aegean Sea), the Black Sea and the Sea of Azov (the Black Sea individuals are smaller than the Mediterranean ones and represent a genetically independent population [1].
Distribution and abundance in Bulgaria. The coastal Black Sea waters. The data are rather scarce. More systemic observations were made along the northern coast – cape Emine, Galata, Zelenka, Duran-Kulak, etc. The numbers are understudied, with a tendency for a decrease. In 1967-1971 the Black Sea population numbered, according to some observations, about 18 300 individuals, and the species had much less numbers than the common dolphin. In the 1992-1995 period, from cape Galata to cape Emine only about 20 individuals were counted every year [2].
Habitats. The coasts, most often up to 2-3 sea miles from the shore (at depths of 30 – 35 m) [2].
Biology. It lives in small groups (4-6 individuals at the average). Larger groups are formed in mass gatherings of fish. It swims slowly, near the surface, rarely jumping over the water [3; 4; 2]. Food: mainly fish (predominantly benthic; in the spring and in the autumn also shoal, pelagic fish); also crayfish, molluscs, even algae. Mating season from June to September, giving birth (1 young) in May-August, preganancy lasts 11 months [5].
Similar species. It differs from the other two Black Sea dolphins, the common dolphin and the bottle-nosed dolphin, by the lack of a fold between the upper jaw and the frontal region; the small size (140 cm at the average); the low, triangular back fin.
Negative factors. Until 1983, industrial dolphin fishing. Nowdays, the abrupt worsening of the habitats (pollution of the coastal waters), the reduction of the nutrition base, the stationary fishing with modern synthetic nets, very robust and transparent (invisible for the dolphin): carcasses of dolphins washed ashore and suffocated were systematically observed in the last years along the coast between Kavarna – Durankulak and Pomorie – Sinemorets [6].
Conservation measures taken. Protected by the Biological Diversity Act. Included in the Bulgarian Red Data Book of 1985.
Conservation measures needed. Monitoring and study of the biology of the species in the Black Sea and of the causes for its declining. Control of coastal pollution and of the methods of coastal fishing.
References. 1. Rosel et al., 2003; 2. Stanev, 1996; 3. Kleinenberg, 1956; 4. Masi, 2000; 5. Nowak, 1999; 6. Peshev et al., 2005.
Author: Nikolai Spassov
