Harbor Porpoise

The English word porpoise comes from the French (Old French , 12th century), which is from Medieval Latin , which is a compound of porcus (pig) and (fish). The old word is probably a loan-translation of a Germanic word, compare Danish and Middle Dutch (sea swine). Classical Latin had a similar name, porculus marinus. The species' taxonomic name, Phocoena phocoena, is the Latinized form of the Greek φώκαινα, phōkaina, "big seal", as described by Aristotle; this from φώκη, phōkē, "seal". The species is sometimes known as the common porpoise in texts originating in the United Kingdom. In parts of Atlantic Canada it is known colloquially as the puffing pig, and in Norway 'nise', derived from an Old Norse word for sneeze, both of which refer to the sound made when porpoises surface to breathe.

The harbour porpoise species is widespread in cooler coastal waters of the North Atlantic, North Pacific and the Black Sea. In the Atlantic, harbour porpoises may be present in a curved band of water running from the coast of West Africa to the coasts of Portugal, Spain, France, the United Kingdom, Ireland, Scandinavia, Iceland, Greenland, Nova Scotia and Newfoundland and the eastern seaboard of the United States.

The harbour porpoise has a global population of at least 700,000. Based on surveys in 1994, 2005 and 2016, the harbour porpoise population in this region is stable. As of 2022, the entire North Sea population (including the Danish waters of the Skagerrak) was about 339,000. In the Western Atlantic it is estimated that there are about 33,000 harbour porpoises along the mid-southwestern coast of Greenland (where increasing temperatures have aided them), In contrast, some subpopulations are seriously threatened. For example, there are less than 12,000 in the Black Sea,

Harbour porpoises prefer temperate and subarctic waters. capelin, and sprat. Almost all the fish they ate were very small, between long. Harbour porpoises tend to be solitary foragers, but they do sometimes hunt in packs and herd fish together. An alternative explanation is that the adult dolphins exhibit infanticidal behaviour and mistake the porpoises for juvenile dolphins which they are believed to kill. Grey seals are also known to attack harbour porpoises by biting off chunks of fat as a high energy source.

Some studies suggest porpoises are relatively sedentary and usually do not leave a certain area for long. A rarely occurring parabolic dive type has been hypothesized to represent a state of unihemispheric slow-wave sleep, during which the porpoise engages in largely automated swimming behavior and very little vocalization. These episodes make up only a small proportion of all dives, but the animal may also engage in periods of sleep during other undemanding manoeuvers, such as slow surfacing from depth.The social life of harbour porpoises is not well understood. They are generally seen as a solitary species. and in captivity up to 28 years. In a study of 239 dead harbour porpoises in the Gulf of Maine–Bay of Fundy, the vast majority were less than 12 years old and the oldest was 17.

Harbour porpoises were traditionally hunted for food, as well as for their blubber, which was used for lighting fuel. Among others, hunting occurred in the Black Sea, off Normandy, in the Bay of Biscay, off Flanders, in the Little Belt strait, off Iceland, western Norway, in Puget Sound, Bay of Fundy and Gulf of Saint Lawrence. The drive hunt in the Little Belt strait is the best documented example. Thousands of porpoises were caught there until the end of the 19th century (it was banned in 1899), and again in smaller scale during the shortages that occurred in World War I and World War II. A similar, short-lived re-emergence of hunting during the world wars happened in Poland and the Baltic countries. Currently, the species is only hunted as part of the traditional Inuit hunt in the Arctic, notably in Greenland. In prehistoric times, harbour porpoises were also hunted in many areas, for example by the Alby People of the east coast of Öland, Sweden.

The main threat to porpoises is static fishing techniques such as gill and tangle nets. Bycatch in bottom-set gill nets is considered the main anthropogenic mortality factor for harbour porpoises worldwide. Several thousand die each year in incidental bycatch, which has been reported from the Black Sea, the Baltic Sea, the North Sea, off California, and along the east coast of the United States and Canada. Porpoise-scaring devices, so-called pingers, have been developed to keep porpoises out of nets and numerous studies have demonstrated they are very effective at reducing entanglement. However, concern has been raised over the noise pollution created by the pingers and whether their efficiency will diminish over time due to porpoises habituating to the sounds. Mortality resulting from trawling bycatch seems to be less of an issue, probably because porpoises are not inclined to feed inside trawls, as dolphins are known to do.

Overfishing may reduce preferred prey availability for porpoises. Overfishing resulting in the collapse of herring in the North Sea caused porpoises to hunt for other prey species. Reduction of prey may result from climate change, overfishing, or both.

Noise from ship traffic and oil platforms is thought to affect the distribution of toothed whales, like the harbour porpoise, that use echolocation for communication and prey detection. Noise from shipping traffic, particularly busy sea lanes, appears to instigate evasive behavior, with predominantly lateral movements during the day and deeper dives during the night. The construction of thousands of offshore wind turbines, planned in different areas of North Sea, is known to cause short-term displacement of porpoises from the construction site, particularly if steel monopile foundations are installed by percussive piling, where reactions can occur at distances of more than . Noise levels from operating wind turbines are low and unlikely to affect porpoises, even at close range. Wind turbine locations may in fact attract porpoises by providing improved foraging on benthic fish that aggregate around pile foundations.

Marine top predators like porpoises and seals accumulate pollutants such as heavy metals, PCBs and pesticides in their fat tissue. Porpoises have a coastal distribution that potentially brings them close to sources of pollution. Porpoises may not experience any toxic effects until they draw on their fat reserves, such as in periods of food shortage, migration or reproduction.

An increase in the temperature of the sea water is likely to affect the distribution of porpoises and their prey, but has not been shown to occur. Reduced stocks of sand eel along the east coast of Scotland, a pattern linked to climate change, appears to be the main reason for the increase in malnutrition in porpoises in the area.

Overall, the harbour porpoise is not considered threatened and the total population is in the hundreds of thousands. In 2013, the two Baltic Sea subpopulations were listed as vulnerable and critically endangered respectively by HELCOM. Although the species overall is considered to be of Least Concern by the IUCN, In addition, the harbour porpoise is covered by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS), the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS) and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia (Western African Aquatic Mammals MoU).