Harbour porpoise
Harbour porpoise Temporal range:
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Harbour porpoise in Ecomare, Netherlands | |
Size compared to an average human | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Infraorder: | Cetacea |
Family: | Phocoenidae |
Genus: | Phocoena |
Species: | P. phocoena
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Binomial name | |
Phocoena phocoena | |
Subspecies | |
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Harbour porpoise range.[3] | |
Synonyms | |
Delphinus phocoena Linnaeus, 1758 |
The harbour porpoise (Phocoena phocoena) is one of eight extant
Taxonomy
The English word porpoise comes from the French pourpois (
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.
Description
The harbour porpoise is a little smaller than the other porpoises, at about 67–85 cm (26+1⁄2–33+1⁄2 in) long at birth, weighing 6.4–10 kg. Adults of both sexes grow to 1.4 to 1.9 m (4 ft 7 in to 6 ft 3 in). The females are heavier, with a maximum weight of around 76 kg (168 lb) compared with the males' 61 kg (134 lb). The body is robust, and the animal is at its maximum girth just in front of its triangular dorsal fin. The beak is poorly demarcated. The flippers, dorsal fin, tail fin and back are a dark grey. The sides are a slightly speckled, lighter grey. The underside is much whiter, though there are usually grey stripes running along the throat from the underside of the body.
Many anomalously white coloured individuals have been confirmed, mostly in the North Atlantic, but also notably around Turkish and British coasts, and in the Wadden Sea, Bay of Fundy and around the coast of Cornwall.[5][6][7]
Although conjoined twins are rarely seen in wild mammals, the first known case of a two-headed harbour porpoise was documented in May 2017 when Dutch fishermen in the North Sea caught them by chance.[8] A study published by the online journal of the Natural History Museum Rotterdam points out that conjoined twins in whales and dolphins are extremely rare.[9]
The vocalizations of the harbour porpoise is made up of short clicks from 0.5 to 5 milliseconds in bursts up to two seconds long. Each click has a frequency between 1000 and 2200 hertz. Aside from communication, the clicks are used for echolocation.[10]
Distribution
The harbour porpoise species is widespread in cooler coastal waters of the North Atlantic, North Pacific and the Black Sea.[11] 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.[12][11] The population in the Baltic Sea is limited in winter due to sea freezing, and is most common in the southwest parts of the sea. There is another band in the Pacific Ocean running from the Sea of Japan, Vladivostok, the Bering Strait, Alaska, British Columbia, and California.[12][11]
The populations in these regions are not continuous[12] and are classified as separate subspecies with P. p. phocoena in the North Atlantic and West Africa, P. p. relicta in the Black Sea and Sea of Azov, an unnamed population in the northwest Pacific and P. p. vomerina in the northeast Pacific.[4][11]
Concerning the North Atlantic, an international workshop co-organised by the North Atlantic Marine Mammal Commission and the Norwegian Institute of Marine Research reviewed the status of the species in 2018. It concluded that the harbour porpoise population structure is more complex than previously thought, with at least three genetically distinct subspecies in the North Atlantic. Given the structure of the harbour porpoise population, the workshop delineated 18 assessment areas for the North Atlantic.[13]
Population status
The harbour porpoise has a global population of at least 700,000.
Natural history
Ecology
Harbour porpoises prefer temperate and subarctic waters.
Harbour porpoises tend to be solitary foragers, but they do sometimes hunt in packs and herd fish together.
Behaviour, reproduction and life-span
Some studies suggest porpoises are relatively sedentary and usually do not leave a certain area for long.[11] Nevertheless, they have been recorded to move from onshore to offshore waters along coast.[11] Dives of 220 metres (120 fathoms) by harbour porpoises have been recorded.[11] Dives can last five minutes but typically last one minute.[26]
The social life of harbour porpoises is not well understood. They are generally seen as a solitary species.[12] Most of the time, porpoises are either alone or in groups of no more than five animals.[12] Porpoises mate promiscuously.[11] Males produce large amounts of sperm, perhaps for sperm competition.[11] Females become sexually mature by their third or fourth year and can calve each year for several consecutive years, being pregnant and lactating at the same time. The gestation of the porpoise is typically 10–11 months.[12] Most births occur in late spring and summer.[11] Calves are weaned after 8–12 months.[12] Their average life-span in the wild is 8–13 years, although exceptionally individuals have reached up to 20,[11][27] and in captivity up to 28 years.[28] 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.[29]
Threats
Hunting
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
.Interactions with fisheries
The main threat to porpoises is static fishing techniques such as gill and tangle nets.
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
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.[41] Reduction of prey may result from climate change, overfishing, or both.
Noise pollution
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. The construction of thousands of offshore wind turbines, planned in different areas of North Sea, is known to cause displacement of porpoises from the construction site,[42] particularly if steel monopile foundations are installed by percussive piling, where reactions can occur at distances of more than 20 km (11 nmi).[43] Noise levels from operating wind turbines are low and unlikely to affect porpoises, even at close range.[44][45]
Pollution
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.
Climate change
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.[46]
Conservation status
Overall, the harbour porpoise is not considered threatened and the total population is in the hundreds of thousands.[1]
The harbour porpoise populations of the North Sea, Baltic Sea, western North Atlantic, Black Sea and North West Africa are protected under Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (
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 (
See also
References
- ^ . Retrieved 12 November 2021.
- ^ Group, Species account by IUCN SSC Cetacean Specialist; Team, regional assessment by European Mammal Assessment (26 January 2007). "IUCN Red List of Threatened Species: Phocoena phocoena". IUCN Red List of Threatened Species.
- ^ IUCN (International Union for Conservation of Nature) 2008. Phocoena phocoena. In: IUCN 2015. The IUCN Red List of Threatened Species. Version 2015.2. http://www.iucnredlist.org. Downloaded on 25 July 2015.
- ^ ISBN 978-0-7136-7037-0.
- doi:10.4404/hystrix-23.2-4792. Archived from the originalon 4 March 2016. Retrieved 8 July 2014.
- ^ Smallcombe, Mike (19 August 2018). "Incredibly rare white harbour porpoise spotted off the coast of Cornwall". Cornwall Live. Retrieved 20 August 2018.
- ^ "Rare white porpoise spotted off the coast of Cornwall in Mounts Bay". ITV News. ITV. 20 August 2018. Retrieved 20 August 2018.
- ^ Two-Headed Porpoise Found For First Time - Retrieved from National Geographic website - June 14, 2017
- ^ The first case of conjoined twin harbour porpoises Phocoena phocoena
- JSTOR 1378247.
- ^ ISBN 978-0-12-804327-1.
- ^ ISBN 0-375-41141-0.
- ^ Report of Joint IMR/NAMMCO International Workshop on the Status of Harbour Porpoises in the North Atlantic. North Atlantic Marine Mammal Commission and the Norwegian Institute of Marine Research 2019: 7-13
- ^ a b c "New study: 1.5 million whales, dolphins and porpoises in European Atlantic". University of St. Andrews. 2 May 2017. Retrieved 1 June 2017.
- ^ "Marsvin og delfiner boltrer sig i danske farvande" (in Danish). Fyens Stiftstidende. 2 May 2017. Retrieved 1 June 2017.
- ^ "Marsvin". Naturhistorisk Museum. Retrieved 17 September 2021.
- S2CID 59474268.
- ^ "Sound seeing increase in harbor porpoise numbers". Kitsap Sun. 17 March 2016. Retrieved 29 May 2018.
- ^ "St Andrews researchers help secure survival of the Baltic Sea harbour porpoise". University of St. Andrews. 8 March 2017. Retrieved 1 June 2017.
- ^ "Phocoena phocoena (Harbor porpoise)". Animal Diversity Web.
- ^ a b Zielinski, Sarah (12 June 2016). "For harbor porpoises, the ocean is a 24-hour buffet". Science News. Retrieved 18 March 2017.
- ^ S2CID 3923189.
- ISBN 978-0-89658-420-4.
- PMID 9699310.
- .
- doi:10.1139/f95-104.
- ^ "Phocoena phocoena, harbor porpoise". animaldiversity.org. Retrieved 3 July 2018.
- ^ "Marsvinet Freja bliver optaget i Guinness rekordbog". avisendanmark.dk. 1 August 2023. Retrieved 21 August 2023.
- .
- ^ Kinze, Carl C. "Marsvin i Danmark" (PDF). Hvaler.dk. Retrieved 22 October 2016.
- ISBN 9780416832402.
- ^ Petersen, Åge (1969). Marsvin og marsvinjægere (in Danish). Middelfart By- og Egnshistoriske Museum.
- ^ a b "Harbour porpoise". North Atlantic Marine Mammal Commission. Retrieved 21 August 2023.
- ^ "Fjord & Bælt". Ceta Base. 4 July 2018. Retrieved 4 July 2018.
- ^ .
- PMID 11285736.
- S2CID 6184532.
- S2CID 4412647.
- ^ Larsen, F (1999). The effect of acoustic alarms on the by-catch of harbour porpoises in the Danish North Sea gill net fishery. Paper SC/51/SM41 presented to the IWC Scientific Committee
- .
- ^ Santos, M.; Pierce, G. (1 January 2003). "The diet of harbour porpoise (Phocoena phocoena) in the Northeast Atlantic". Oceanogr Mar Biol Annu Rev. 41: 355–390.
- .
- PMID 19603857.
- hdl:10023/3847.
- PMID 19507958.
- PMID 17251125.
- ^ "Appendix II Archived 21 February 2012 at the Wayback Machine" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009.
- ^ HELCOM (2013). "HELCOM Red List of Baltic Sea species in danger of becoming extinct" (PDF). Baltic Sea Environmental Proceedings (140): 92. Archived from the original (PDF) on 7 October 2014. Retrieved 3 August 2014.
- ^ Hammond, P.S.; Bearzi, G.; Bjørge, A.; Forney, K.; Karczmarski, L.; Kasuya, T.; Perrin, W.F.; Scott, M.D.; Wang, J.Y.; Wells, R.S.; et al. (2008). "Phocoena phocoena (Baltic Sea subpopulation)". IUCN Red List of Threatened Species. 2008. Retrieved 1 June 2017.
- . Retrieved 12 November 2021.
- ^ "Phocoena phocoena". Convention on the Conservation of Migratory Species of Wild Animals. Retrieved 1 June 2017.
Further reading
- Friel, D.; Sleeman, D.P. (2010). "A neonate harbour porpoise (Phocoena phocoena (L.)) with damaged skin". Ir. Nat. J. 31: 55.
- "Phocoena phocoena". Integrated Taxonomic Information System. Retrieved 18 March 2006.
External links
- ARKive - images and movies of the harbour porpoise (Phocoena phocoena)
- Whale & Dolphin Conservation Society (WDCS)
- Convention on Migratory Species page on the Harbour porpoise
- Official website of the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area
- Official website of the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas
- Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia
- Voices in the Sea - Sounds of the Harbour Porpoise