The Harbor Porpoise (Phocoena phocoena) is one of six species of porpoise. It is one of the smallest ocean mammals. As its name implies, it stays close to coastal areas or river estuaries and as such is the most familiar porpoise to whale watchers. This porpoise often ventures up rivers and has been seen hundreds of miles from the sea.
The species is sometimes known as the Common Porpoise in texts originating in the United Kingdom, though this usage appears to be dying out.
Significant predators of Harbor Porpoises include white sharks and orcas. Researchers at the University of Aberdeen in Scotland have also discovered that the local Bottlenose Dolphins attack and kill Harbour Porpoises without eating them due to competition for a decreasing food supply.
Harbor Porpoises were traditionally hunted for food and especially fat used for lighting purposes in Denmark, especially in the Little Belt strait. Currently, however, this species is not subject to commercial whaling. The global population is in the hundreds of thousands and the Harbor Porpoise is not under threat of widespread extinction. 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 Harbor Porpoises in busy fishing seas such as the Black and Baltic. 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.