Harbour porpoisePhocoena phocoena — habitat, diet and reproduction

Grey harbour porpoise with a short snout and small triangular dorsal fin swimming in greenish water

Harbour porpoise (Phocoena phocoena) swimming underwater. · Erik Christensen / CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0). Cropped and resized.

The harbour porpoise is a small cetacean related to dolphins but with a short, rounded snout and no “beak”. It is the smallest of the three cetaceans of the Black Sea, alongside the common and bottlenose dolphins. It is rarely seen because it surfaces only briefly, without dramatic leaps.

Quick facts

Common name	Harbour porpoise
Scientific name	Phocoena phocoena
Lifespan	About 8–13 years; rarely over 20
Length	About 1.4–1.9 m
Weight	About 45–70 kg
Diet	Carnivore: small fish such as anchovy, sprat and gobies
Predators	Orcas and large sharks in other seas
Conservation status	Least Concern (LC) globally; Black Sea subspecies Endangered (EN)
Distribution	Cool coastal waters of the Northern Hemisphere and the Black Sea
Habitat	Coastal waters, bays, estuaries
Family	Phocoenidae
Navigation	Echolocation

Primary category:Mammals
Explore this animal's categories:
Animals of Asia Animals of Europe Animals of North America Animals of Romania Animals that live in groups Animals that use echolocation Aquatic animals Carnivores Cetaceans Fish-eating animals H Live-bearing animals Mammals Marine animals Marine mammals Ocean animals Protected animals of Romania Vertebrates Wild animals

Interesting facts

The porpoise must eat almost constantly because it loses heat quickly in water.
Its teeth are flattened like little spades, unlike the conical teeth of dolphins.
A distinct subspecies lives in the Black Sea, separated from Atlantic populations for thousands of years.
Many porpoises die accidentally caught in turbot nets.

Characteristics

The harbour porpoise has a stocky body, dark grey above and pale below. The head is small without a long beak, and the dorsal fin is small and triangular.

It is much smaller than the bottlenose dolphin, and females are slightly larger than males.

Behaviour

Porpoises live alone or in small groups of 2–5 animals. They are shy and avoid boats.

When breathing, they roll at the surface with barely visible movement and a short puff. They use echolocation, sending very high-frequency clicks and listening to echoes to find prey and navigate.

Habitat and distribution

The species lives in cool coastal waters of the North Atlantic, North Pacific and Baltic Sea. An isolated population lives in the Black Sea, the Sea of Azov and sometimes the Sea of Marmara.

In Romanian waters it occurs along the coast, especially in spring when following fish shoals.

Diet and feeding

The porpoise eats small fish. In the Black Sea its main prey are anchovy, sprat, gobies and red mullet.

Being small, it loses heat quickly in cold water, so it must eat a lot, almost all the time, to keep warm.

Reproduction and life cycle

The female gives birth to one calf after about 10–11 months. The calf is born tail first underwater, and the mother helps it to the surface for its first breath.

It suckles rich milk for several months. Females can become pregnant while still nursing the previous calf.

Name and history

The name “marsuin” comes from the French “marsouin”, roughly “sea pig”. Older Romanian sources also call it “porc de mare”.

The Black Sea subspecies, Phocoena phocoena relicta, is a relic of populations that entered this sea long ago.

Conservation and threats

The species is assessed globally as Least Concern, but the Black Sea porpoise is Endangered. In the twentieth century, tens of thousands of cetaceans were killed in the Black Sea for oil until hunting was banned in 1983 in the former USSR, Romania and Bulgaria.

Today the main danger is set nets for turbot, in which porpoises become trapped and drown. Pollution and underwater noise also harm them. In Romania all cetaceans are strictly protected.