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Phocoena dioptrica Lahille,
1912 
English: Spectacled porpoise
German: Brillenschweinswal
Spanish: Marsopa de anteojos
French: Marsouin à lunettes
Family Phocoenidae
Phocoena dioptrica © Wurtz-Artescienza (see links)
1. Description
Most knowledge on the biology and ecology of the spectacled porpoise
was obtained from stranded specimens, with less than fifteen confirmed
sightings at sea. Published photographs of live animals in their
natural environment are also very rare (Sekiguchi et al. 2006).
The spectacled porpoise is highly distinctive with its unusual pigmentation,
small head and facial features and the large male dorsal fin. It
is a robust animal with a rounded head and beak. The flippers are
small and situated well forward. The dorsal fin is broadly triangular
and grows much larger and rounded in males than in females. The
flukes are small and have rounded tips. Adults are black dorsally,
sharply separated from the white belly. Size ranges to 204 cm in
females and 224 cm in males and mass to 85 kg in females and 115
kg in males (Goodall, 2002; 2009). Based on observations at sea
and new photographs of live animals, a pale saddle around the dorsal
fin is apparent (Sekiguchi et al. 2006).
Perrin et al. (2000) described osteological characteristics for
specimens from Argentina and other areas of the Southern Hemisphere:
tooth counts were16-26 and 17-23 in the upper and lower jaws, respectively.
Total number of vertebrae was 66-70. The rostrum may be relatively
smaller in the Auckland Islands than in other regions.
2. Distribution
There are records from widely separate locations; some of these
may involve strays, or cases of mistaken identity. Records from
offshore islands (mostly of dead animals and skulls), hint at a
circumpolar distribution and suggest that the range may also include
large areas of open sea. It is not known whether these represent
isolated populations, or whether they mix with mainland coastal
animals by migrating across the open sea (Carwardine, 1995).
Distribution of Phocoena dioptrica: coastal
waters of southeastern South America and offshore islands around
Antarctica (Hammond et al. 2008; © IUCN; enlarge
map).
According to Goodall (2002, 2009), P. dioptrica
is circumpolar in cool temperate, sub-Antarctic and low Antarctic
waters. It ranges in coastal waters of south-eastern South America,
from Santa Catarina in southern Brazil (32°S; Pinedo et al.
2002) south to Tierra del Fuego; Falkland Islands (Islas Malvinas);
South Georgia; Iles Kerguélen; Heard Island; Tasmania; Macquarie
Island; Auckland Islands; Antipodes Islands (Rice, 1998), South
Island, New Zealand (Baker, 1999) and South Australia (Kemper and
Hill 2001). The southernmost sighting was at 64°33'S (Goodall,
2009). The suggested circumpolar and offshore distribution of the
species was extended further south than previously thought, into
Antarctic waters south of the Antarctic Convergence (Brownell and
Clapham, 1999; Van Waerebeek et al, 2004; Sekiguchi et al. 2006).
3. Population size
Nothing is known on the abundance of this porpoise (Goodall, 2009;
Hammond et al. 2008). It was the most commonly encountered species
during preliminary beach surveys undertaken on Tierra del Fuego
by R.N.P. Goodall, but once the beaches had been cleared it was
exceeded in frequency of occurrence by Commerson's dolphin (Brownell
and Clapham, 1999).
4. Biology and Behaviour
Habitat: P. dioptrica is mainly an oceanic species
sighted in deep offshore waters. However, some have been sighted
in coastal habitat, including in channels and even river estuaries
(Goodall, 2009; Jefferson et al. 1993). Spectacled porpoises seem
to occur only in cold temperate waters and where recorded, water
temperatures associated with sightings ranged from 5.5°C to
9.5°C (Brownell and Clapham, 1999). However, this temperature
range has recently be extended to 0.9-10.3 °C, with most of
the sightings (52.0%) in waters of 4.9-6.2 °C (Sekiguchi et
al. 2006).
Behaviour: Spectacled porpoises are very inconspicuous when
surfacing (Jefferson et al. 1993). They generally show fast swimming
behaviour when approached by a vessel, resembling the swimming behaviour
of harbour porpoises (Sekiguchi et al. 2006).
Schooling: P. dioptrica appears to live mainly alone
(most of the strandings and sightings are of solitary animals),
but may also live in small groups (Carwardine, 1995; Jefferson et
al. 1993). In southern waters, group size was small, averaging 2
animals per group. A total of six cow-calf pairs were observed and
all such pairs were accompanied by one or two additional adults,
always including a mature male (Sekiguchi et al. 2006).
Reproduction: Births appear to occur in the southern spring
to summer (Jefferson et al. 1993). Nothing is known on pregnancy
rates, interbirth intervals or duration of lactation in this species
(Brownell and Clapham, 1999).
Food: Based upon its dentition, it is likely that, like other
phocoenids, this species feeds upon fish and squid. Records of prey
remains are scarce: anchovy (Engraulis sp.) and small crustaceans
(possibly stomatopods) as well as squid (Brownell and Clapham, 1999;
Goodall, 2009).
5. Migration
Nothing is known on the seasonal movements, if any, of this species
(Brownell and Clapham, 1999; Goodall, 2009). Most sightings were
pelagic, but strandings around Tierra del Fuego suggest at least
some neritic activity of the species.
6. Threats
Direct catch: In the past, spectacled porpoises were killed
deliberately for food. In Argentina and Chile, spectacled porpoises
are taken in gillnets, and they may have been taken deliberately
for crab (centolla; Lithodes santolla) bait off southern
Chile. The effects of these catches on spectacled porpoise populations
are not known (Jefferson et al. 1993).
Incidental catch: At least 34 animals were killed incidentally
between 1975 and 1990 in coastal gill nets set in Tierra del Fuego,
and there was a co-occurrence of strandings and fishing activity
in south-eastern Chile, suggesting additional undocumented mortalities
from this source. Some mortality of spectacled porpoises was also
reported from bottom and mid-water trawls off the coast of Chubut,
Argentina (Brownell and Clapham, 1999, and refs. therein). Jefferson
and Curry (1994) summarise that the effects of incidental takes
on the population are unknown.
Potential threats include also incidental captures in expanding
fisheries in the Southern Ocean, especially in areas adjacent to
subantarctic islands; disturbance and pollution resulting from coastal
and offshore oil and mineral exploration (Argentina); pollution
of preferred habitats, leading to accumulation of toxic substances
in body tissues (Klinowska 1991; Bannister et al. 1996).
7. Remarks
Range states:
Argentina; Australia (Macquarie Is., Tasmania); Brazil; Chile; Falkland
Islands (Malvinas); French Southern Territories (the) (Kerguelen);
Heard Island and McDonald Islands; New Zealand (Antipodean Is.);
South Georgia and the South Sandwich Islands; Uruguay
IUCN Status: "Data Deficient" (Hammond et al. 2008).
P. dioptrica is included in Appendix II of CMS. The species
is listed in Appendix II of CITES.
According to Jefferson and Curry (1994), gillnets represent the
single most important threat to porpoises as a group, and this may
be an example of a "no technical solution problem". They
conclude that better documentation of catches and new approaches
to dealing with porpoise/gillnet interaction problems are needed
in order to prevent the loss of several species and populations.
See further recommendations and conclusions on South American stocks
in Hucke-Gaete (2000) in Appendix
1.
8. Sources
· Baker, A.N. 1999. Whales and dolphins of New Zealand and
Australia: an Identification Guide. Victoria University Press, Wellington.
133 pp.
· Bannister JL, Kemper CM, Warneke RM (1996) The Action Plan
for Australian Cetaceans. Australian Nature Conservation Agency:
Canberra vii 242 pp.
· Brownell RL, Clapham PJ (1999) Spectacled porpoise - Phocoena
dioptrica Lahille, 1912. In: Handbook of Marine Mammals (Ridgway
SH, Harrison SR, eds.) Vol. 6: The second book of dolphins and porpoises,
pp.379-392.
· Carwardine M (1995) Whales, Dolphins and Porpoises. Dorling
Kindersley, London, UK, 257 pp.
· Goodall RNP (2002) Spectacled porpoise - Phocoena dioptrica.
In: Encyclopedia of marine mammals (Perrin WF, Würsig B, Thewissen
JGM, eds.) Academic Press, San Diego, pp. 1158-1161.
· Goodall RNP (2009) Spectacled porpoise - Phocoena dioptrica.
In: Encyclopedia of marine mammals (Perrin WF, Würsig B, Thewissen
JGM, eds.) Academic Press, San Diego, pp. 1087-1091.
· Hammond PS, Bearzi G, Bjørge A, Forney K, Karczmarski
L, Kasuya T, Perrin WF, Scott MD, Wang JY, Wells RS, Wilson B (2008)
Phocoena dioptrica. In: IUCN 2009. IUCN Red List of Threatened
Species. Version 2009.2.
· Hucke-Gaete R ed. (2000) Review on the conservation status
of small cetaceans in southern South America. UNEP/CMS Secretariat,
Bonn, Germany, 24 pp.
· Jefferson TA, Curry BE (1994) A global review of porpoise
(Cetacea: Phocoenidae) mortality in gillnets. Biol Conserv 67: 167-183.
· Jefferson TA, Leatherwood S, Webber MA (1993) FAO Species
identification guide. Marine mammals of the world. UNEP/FAO, Rome,
320 pp.
· Kemper C, Hill M (2001) First records of the spectacled
porpoise Phocoena dioptrica in continental australian waters.
Mar Mamm Sci 17: 161-170.
· Klinowska M (1991). Dolphins, Porpoises and Whales of the
World: The IUCN Red Data Book. IUCN, Gland and Cambridge vii 429
pp.
· Perrin WF, Goodall RNP, Cozzuol MA (2000) Osteological
variation in the spectacled porpoise (Phocoena dioptrica).
J Cetacean Res Manag 2: 211-215
· Pinedo MC, Barreto AS, Lammardo MP, Andrade ALV, Geracitano
L (2002) Northernmost records of the spectacled porpoise, Layard's
beaked whale, Commerson's dolphin, and Peale's dolphin in the southwestern
Atlantic Ocean. Aquat Mamm 28: 32-37
· Rice DW (1998) Marine mammals of the world: systematics
and distribution. Society for Marine Mammalogy, Special Publication
Number 4 (Wartzok D, ed.), Lawrence, KS. USA.
· Sekiguchi I, Olavarria C, Morse L, Olson P, Ensor P, Matsuoka
K, Pitman R, Findlay K, Gorter U (2006) The spectacled porpoise
(Phocoena dioptrica) in Antarctic waters. J Cetacean Res Manag 8:
265-271
· Van Waerebeek K, Leaper R, Baker AN, Papastavrou V, Thiele
D (2004) Odontocetes of the Southern Ocean Sanctuary. IWC Scientific
Committee Document SC/56/SOS1. 25pp.
© Boris Culik (2010) Odontocetes.
The toothed whales: "Phocoena dioptrica". UNEP/CMS
Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.
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