View source for Spectacled porpoise

{{Short description|Species of mammal}}
{{Use dmy dates|date=December 2014}}
{{Speciesbox
| name = Spectacled porpoise
| image = Subadult female spectacled porpoise.png
| image_caption = Subadult female spectacled porpoise
| image2 = Spectacled porpoise size.svg
| image2_caption = Size compared to an average human
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 18 November 2021">{{cite iucn |author=Dellabianca, N. |author2=Pitman, R.L. |author3=Braulik, G. |date=2018 |title=''Phocoena dioptrica'' |volume=2018 |article-number=e.T41715A50381544 |doi=10.2305/IUCN.UK.2018-2.RLTS.T41715A50381544.en |access-date=18 November 2021}}</ref>
| status2 = CITES_A2 
| status2_system = CITES 
| status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref>
| genus = Phocoena
| species = dioptrica
| authority = [[Fernando Lahille|Lahille]], 1912
| range_map = cetacea_range_map_Spectacled_Porpoise.PNG
| range_map_caption = Spectacled porpoise range
| synonyms = Australophocaena dioptrica
}}

The '''spectacled porpoise''' ('''''Phocoena dioptrica''''') is a small to midsize [[porpoise]] indigenous to the [[Southern Ocean]]. It is one of the most poorly studied cetaceans, partly due to its remote range in the Southern Ocean. What little is known about this porpoise species has been gathered mainly from stranded individuals, and a few observations of living animals made at sea.<ref name="researchgate.net">{{cite journal |last1= Sekiguchi |first1= K|last2= Olavarria |first2= C|last3=Morse| first3= L| last4= Olson| first4= P| last5= Matsuoka | first5= K| last6= Pitman| first6= R| last7= Findlay| first7=K| last8= Gorter| first8= U| date= 2006 |title= The Spectacled porpoise (''Phocoena dioptrica'') in Antarctic waters|url= https://www.researchgate.net/publication/288842846|journal= Journal of Cetacean Research and Management|volume= 8|issue= 3|pages= 265–27 |doi= 10.47536/jcrm.v8i3.722|s2cid= 257454374|doi-access= free}}</ref>

The species was first described in 1912 by [[Fernando Lahille]].<ref>{{Cite web |title=Species ''Phocaena dioptrica'' Lahille, 1912 |url=https://biodiversity.org.au/afd/taxa/Phocaena_dioptrica |access-date=2024-07-28 |website=Australian Faunal Directory |publisher=Australian Government}}</ref><ref>{{Cite Q|Q128020754}}</ref>

==Description==
[[File:Stranded male spectacled porpoise.jpg|thumb|left|Stranded male spectacled porpoise nearby [[Dunedin]] in New Zealand]]

As with other porpoise species, the spectacled porpoise has no beak. It has small pectoral fins with rounded tips positioned far forward on the body, and a triangular dorsal fin. This porpoise species shows obvious [[sexual dimorphism]] between adult males and females, as the dorsal fins in males are much larger and more rounded than those of females.<ref name="Natalie 2018 912–916">{{cite book |last1= Natalie |first1= R | last2= Goodall| first2= P| last3= Brownell Jr.| first3= R.L. |editor-last1=Würsig |editor-first1=B |editor-last2=Thewissen |editor-first2=J.G.M.| editor-last3= Kovacs| editor-first3= K.M. |title=Encyclopedia of marine mammals,3rd Ed.|publisher=Academic Press |date=2018 |pages=912–916 |chapter=Spectacled Porpoise: Phocoena dioptrica |isbn= 978-0-12-804327-1 |chapter-url=https://www.sciencedirect.com/science/article/pii/B9780128043271002405}}</ref>
 
Records for female length range up to {{convert|204|cm|in}}, while males may reach {{convert|224|cm|in}}, which represents the largest specimen documented thus far. The maximum weight for a female was {{convert|85|kg|lb}}, while a male has been recorded at {{convert|110|kg|lb}}.<ref name="Natalie 2018 912–916"/>

The spectacled porpoise has a distinctive coloration. As an adult it is [[countershaded]], with a black dorsal region which is sharply delineated from a white belly. In some individuals, this line can be feathered.<ref name="Natalie 2018 912–916"/> An obvious dark eye patch is present in both juveniles and adults. A pale 'saddle-patch' around the dorsal fin and a dark line around the blowhole have also been documented.<ref name="onlinelibrary.wiley.com">{{cite journal |last1= Evans |first1= K|last2= Kemper |first2= C|last3=Hill| first3= M| date= 2001 |title= First records of the spectacled porpoise ''Phocoena dioptrica'' in continental Australian Waters |url= https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-7692.2001.tb00986.x|journal= Marine Mammal Science|volume= 17|issue= 1|pages= 161–170 |doi= 10.1111/j.1748-7692.2001.tb00986.x|bibcode= 2001MMamS..17..161E|url-access= subscription}}</ref> Females are described as lighter in coloration, while young animals may have a dorsal area that is grey rather than black, with a lighter grey on the belly, a clearly demarked line connecting the mouth and flipper.

==Geographic distribution ==
The distribution of the spectacled porpoise is thought to be circumpolar, and it is considered a predominately oceanic species, however occasional sightings and specimens are documented in coastal regions.<ref name="A global review of porpoise Cetace">{{cite journal |last1= Jefferson |first1= T.A.|last2= Curry|first2= B.E.| date= 1993 |title= A global review of porpoise (Cetacea: Phocoenidae) mortality in gillnets|url= https://www.researchgate.net/publication/222488716|journal= Biological Conservation|volume= 67|issue= 2|pages= 197–183 }}</ref> Evidence from sightings and strandings suggest that the species can be found within cool temperate, sub-Antarctic and Antarctic waters, where water temperatures range between {{convert|0.9|and|10.3|°C|°F}}.<ref name="Natalie 2018 912–916"/>

Stranded individuals have been found across the southern hemisphere. In the south-western Atlantic records have been made at Santa Catarina in Southern Brazil,<ref name="Northernmost records of the spectac">{{cite journal |last1= Pinedo |first1= M.C.|last2= Barreto |first2= A.S.|last3=Lammardo| first3= M.P.| last4= Andrade| first4= A.L.V.| last5= Geracitano | first5= L| date= 2002 |title= Northernmost records of the spectacled porpoise, Layard's beaked whale, Commerson's dolphin, and Peale's dolphin in the southwestern Atlantic Ocean |journal= Aquatic Mammals|volume= 28|pages= 32–37 }}</ref> [[Uruguay]], from [[Buenos Aires]] to [[Tierra del Fuego]], and the [[Falkland Islands]] and [[South Georgia Island|South Georgia]]. Records exist from the south-western South Pacific (Auckland and Maquarie Islands) to the southern Indian Ocean (Heard and Kerguelen), and also from [[New Zealand]],<ref>{{Cite web|url=https://www.stuff.co.nz/science/10515524/Little-known-about-rare-porpoise|title = Little known about rare porpoise|date = 18 September 2014}}</ref> [[Burney Island]], [[Tasmania]] and South Australia. This widespread distribution is evidence of a circumpolar range, and possible association with the [[Falkland Current]] and [[Antarctic Circumpolar Current]] (ACC) which transports cold water along the Atlantic coast of South America, and around Antarctica respectively.<ref name="Natalie 2018 912–916"/>

Sightings of spectacled porpoise at sea are similarly widespread, and include waters off [[Patagonia]], [[South Georgia Island|South Georgia]], Kerguelen, south of New Zealand, Tasmania and Heard Island. Nine sightings have been made south of 64°, in Antarctic waters.<ref name="researchgate.net"/>

==Foraging==
Little dietary information is available for the spectacled porpoise, but it is thought to forage on fish and squid. No observations of foraging behaviour at sea have been made. Stomach contents from a small number of stranded specimens included [[anchovy]] (''[[Engraulis]] sp.''), [[stomatopod]]s, [[cephalopod beak]]s (''[[Sepia (cephalopod)|Sepia]] sp.'') and a half digested ornate cowfish (''[[Aracana ornata]]'').<ref name="researchgate.net"/><ref name="Northernmost records of the spectac"/>

==Reproduction==
Little is known about the reproduction of the spectacled porpoise. In the Tierra del Fuego region, studies estimate that young porpoises are born at {{convert|100|cm|in}} long in late spring or summer (November to February).<ref name="On the biology of the spectacled po">{{cite journal |last1= Goodall |first1= R.N.P.|last2= Schiavini |first2= A.C.M. | date= 1995 |title= On the biology of the spectacled porpoise, Australophocoaena dioptrica |journal= Report of the International Whaling Commission}}</ref> No information is available on gestation, lactation, or inter-birth intervals.

==Taxonomy==
The species was named by the French-born Argentinian zoologist [[Fernando Lahille]] in 1912 for its two distinctive black eye patches, with the latin dioptrica meaning 'spectacled'. In Spanish, the spectacled porpoise is known as 'marsopa de anteojos', a literal translation of the English common name.<ref name=audubon>{{cite book|title=Guide to Marine Mammals of the World|author=Reeves, R.|author2=Stewart, B.|author3=Clapham, P.|author4=Powell, J.|name-list-style=amp|page=[https://archive.org/details/guidetomarinemam00folk/page/292 292]|year=2002|isbn=978-0-375-41141-0|publisher=A.A. Knopf|location=New York|url-access=registration|url=https://archive.org/details/guidetomarinemam00folk/page/292}}</ref> Recent analyses of mitochondrial DNA from 50 porpoises indicated high levels of genetic diversity that would indicate a large and stable population, or one with a wide distribution. The study also revealed evidence for a recent expansion in population.<ref>{{cite journal |last1= Pimper|first1= L.E.|last2= Goodall |first2= R.N.P.|last3=Remis| first3= M.I.| date= 2012|title= First mitochondrial DNA analysis of the spectacled porpoise ( ' 'Phocoena dioptrica ' ') from Tierra del Fuego, Argentina |journal= Mammalian Biology|volume= 77|issue= 6|pages= 459–462|doi= 10.1016/j.mambio.2012.02.002|bibcode= 2012MamBi..77..459P|hdl= 11336/68238|hdl-access= free}}</ref>

Phylogenetic tree analyses found that spectacled porpoises are more closely related to [[Burmeister's porpoise]] (''Phocoena spinipinnis'') <ref>{{cite journal |last1=Rosel|first1= P.E.|last2= Haygood |first2= M.G.|last3=Perrin| first3= W.F.| date= 1995|title= Phylogenetic Relationships among the True Porpoises (Cetacea: Phocoenidae) |journal= Molecular Phylogenetics and Evolution|volume= 4| issue= 4|pages= 463–474|doi= 10.1006/mpev.1995.1043|pmid= 8747302|bibcode= 1995MolPE...4..463R}}</ref> than to the [[vaquita]] (''Phocoena sinus'') which appeared to diverge from Burmeister's and spectacled porpoises in the [[Pliocene]] era.<ref name="chehida">{{cite web|last1=Chehida|first1= Y.B.|last2= Thumloup|first2= J.|last3=Schumacher| first3= C.| last4= Harkins| first4= T.| last5= Aguilar| first5= A.| last6= Borrell|first6=A.|last7=Ferreira|first7=M |last8=Rojas-Bracho|first8=L|last9=Robertson|first9=K.M.|last10=Taylor|first10=B.L.|last11=Vikingsson |first11=G.A.|last12=Weyna|first12=A.|last13=Romiguier|first13=J.|last14=Morin|first14=P.A|last15=Fontaine |first15=M.C.|year= 2019|title= Evolutionary history of the porpoises (''Phocoenidae'') across the speciation continuum: a mitogenome phylogeographic perspective |url= https://www.biorxiv.org/content/10.1101/851469v1 |doi= 10.1101/851469|s2cid= 213500150}}</ref> These three species diverged from the [[harbour porpoise]] (''Phocoena phocoena'') and [[Dall's porpoise]] ( ''Phocoenoides dalli'') around 4 million years ago, while the split between Burmeister's and spectacled porpoises occurred 2.3 million years ago.<ref name="chehida"/>

==Population status==
The population size and its inter-connectedness across the Southern Ocean is unknown. Research cruises conducted between 1978 and 2004 in the Antarctic resulted in 28 sightings, however these were made in fair weather conditions and porpoises may have been missed during poorer conditions.<ref name="researchgate.net"/> It is possible that Passive Acoustic Monitoring (PAM) for spectacled porpoises may shed more light on their range and habitat use, however no studies have been conducted to date.

==Threats==
The spectacled porpoise is likely prey for [[sharks]], [[leopard seals]] (''Hydrurga leptonyx'') and [[killer whales]] (''Orcinus orca''). In Tierra del Fuego, it has been observed that scavenging birds such as kelp gulls will target stranded spectacled porpoise carcasses over other cetacean species. Such scavenging can result in a carcass becoming skeletonised rapidly, within one to two hours.<ref>{{cite book |last1= Natalie |first1= R | last2= Goodall| first2= P| last3= Brownell Jr.| first3= R.L.|editor-last1=Würsig |editor-first1=B |editor-last2=Thewissen |editor-first2=J.G.M.| editor-last3= Kovacs| editor-first3= K.M. |title=Encyclopedia of marine mammals,3rd Ed.|publisher=Academic Press |date=2018 |pages=912–916 |chapter=Spectacled Porpoise: Phocoena dioptrica |isbn= 978-0-12-804327-1 |chapter-url=https://www.sciencedirect.com/science/article/pii/B9780128043271002405}}</ref>

Researchers have uncovered spectacled porpoise remains within the kitchen middens of the canoe people who lived in Tierra del Fuego between 6000 and 1400 years ago.<ref>{{cite journal |last1= Piana|first1= W.F.|last2= Goodall |first2= R.N.P.|last3=Galeazzi| first3= A.R.| last4= Sobral| first4= A.P. | date= 1985 |title= Cetacean remains in Beagle Channel shell middens. | journal= Sixth Biennial Conference on the Biology of Marine Mammals}}</ref> It is possible the species was once a common food source for peoples in the region. More recently, porpoises may be caught and used as bait for the crab fishery industry, however the frequency of this activity and its impact on porpoise population status is unknown.<ref name="A global review of porpoise Cetace"/>

Bycatch and incidental capture are most likely the greatest anthropogenic threat to the spectacled porpoise.<ref name="iucn status 18 November 2021"/> Porpoises and other small cetaceans are particularly at risk of entanglement and drowning in gillnets, as the thin filaments are not easily detected by their echolocation clicks.<ref name="A global review of porpoise Cetace"/> The extent of incidental bycatch is unknown, however strandings and fishing ground locations often coincide.<ref name="On the biology of the spectacled po"/>

==Conservation status==

While previously listed by the [[IUCN]] in 2008 as 'Data Deficient' the species was upgraded to 'Least Concern' in 2018. While it is widely accepted that spectacled porpoises are threatened by fishery bycatch and entanglement, and stranding rates in Tierra del Fuego may be unsustainable for the population, the category of Least Concern has been applied provisionally until more data is available.<ref name="iucn status 18 November 2021"/>

==Captivity==

At least two incidents have been documented where a living spectacled porpoise was taken into captivity, in both cases for medical treatment and rehabilitation following stranding. The first individual was a very young 127&nbsp;cm long female calf that stranded in Port Elliot, Southern Australia, on 24 March 1997.<ref name="onlinelibrary.wiley.com"/> The calf was disorientated and exhausted, preventing refloating attempts, and rescuers subsequently transported the calf to the Royal Society for the Prevention of Cruelty to Animals (RSPCA) marine rescue unit in Adelaide. The porpoise died five days later on 29 March 1997, and a necropsy revealed damage to the oesophagus and first stomach caused by intubation during force-feeding. However, other organs were normal and no direct cause of death was determined.

The second incident occurred on 26 January 2019, where an adult male live stranded 30&nbsp;km up a river estuary in Argentina. The porpoise was emaciated and dehydrated, and was taken to the Marine Fauna Rescue and Rehabilitation Centre. The animal died four days later on 30 January 2019.<ref>{{cite web |url= http://derangedhyena-delphinidae.tumblr.com/post/182800222830/flukeprintphotography-spectacled-porpoise.com/|title= Spectacled Porpoise Rescued in Argentina|date= 14 February 2019 |access-date= 10 October 2020}}</ref>

== See also ==
{{Portal|Cetaceans|Mammals|Marine life}}
*[[List of cetaceans]]
*[[Marine biology]]

==References==
{{Reflist}}

==External links==
{{Commons category|Phocoena dioptrica}}
{{Wikispecies|Phocoena dioptrica}}

*[http://uk.whales.org/species-guide/spectacled-porpoise Whale & Dolphin Conservation (WDC)]
*[http://www.cms.int/reports/small_cetaceans/data/P_dioptrica/p_dioptrica.htm Convention on Migratory Species page on the Spectacled porpoise] {{Webarchive|url=https://web.archive.org/web/20130203212753/http://www.cms.int/reports/small_cetaceans/data/P_dioptrica/p_dioptrica.htm |date=3 February 2013 }}

{{Cetacea|O.}}

{{Taxonbar|from=Q749548}}

{{DEFAULTSORT:Spectacled Porpoise}}
[[Category:Phocoena]]
[[Category:Mammals of Argentina]]
[[Category:Mammals of Chile]]
[[Category:Fauna of the Auckland Islands]]
[[Category:Mammals described in 1912]]
[[Category:Taxa named by Fernando Lahille]]