English: Commerson's dolphin
Spanish: Delfín de Commerson
French: Dauphin de Commerson
Cephalorhynchus commersonii © Wurtz-Artescienza (see "links")
Small, blunt-headed chunky dolphins without beak (and therefore
often wrongly called porpoises) with rounded, almost paddle-shaped
flippers. The dorsal fin is proportionally large and with a rounded,
convex trailing edge (Dawson, 2009). Body colour is muted grey on
black in the young, often appearing uniform. Later, this grey pales
into white in the South American Form (Jefferson et al. 2008).
The head is black, with a white throat. The dorsal area from the
fin backward is also black, and a black patch is located on the
undersides, linking the flippers, which are also dark. The rest
of the body is white apart from a black genital patch. Size ranges
to 1.4 m in South America and to 1.7 m in the Kerguélen Islands;
the heaviest animal recorded weighed 45 and 86 kg, respectively
There are two populations separated by 130° of longitude, or
8,500 km. The animals at Kerguélen differ markedly from those
in South America and merit designation as a separate subspecies
(Rice, 1998; Goodall, 1994; Robineau et al. 2007).
C. commersonii commersonii - Falkland Islands / Islas Malvinas
and the coastal waters of southern South America. The northernmost
reliably documented limit of the South America population is on
the Brazilian coast between 31 and 32°S (Pinedo et al. 2002).
Range extends south into Drake Passage (61°50'S) as far as the
South Shetland Islands, well within the range of C. eutropia (Rice,
1998). On the west coast of South America, specimens have been reported
from Isla Chiloé, Chile (42°45 'S; Rice, 1998).
C. commersonii kerguelenensis - Shallow coastal waters around
all of the Iles Kerguélen in the southern Indian Ocean (Rice,
1998; Robineau, 2007). No sightings or specimens have yet been reported
from islands between South America and Kerguélen, such as
Crozet, Heard, Amsterdam or St Paul (Goodal, 1994 and refs. therein).
However, de Bruyn et al. (2006) reported sighting of a single specimen
over the South African continental shelf in 2004. This is the first
record of this species in these waters, over 4000 km from the known
Distribution of Cephalorhynchus commersonii:
southern South America, including the
Falkland/Malvinas Islands, and Kerguélen Islands in the Indian
Ocean (Reeves et al. 2008;
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3. Population size
It seems that Commerson's dolphin, despite the impacts it suffers
(see below), is probably the most abundant member of the genus Cephalorhynchus
Single dolphins and groups of hundreds of animals have been sighted
in the late 1980's and early 1990's from shores along the north
coast of Tierra del Fuego. In other areas of Patagonia, concentrations
seem to be near towns, probably a reflection of research effort
rather than patchy distribution (Goodall, 1994 and refs. therein).
Leatherwood et al. (1988) conducted aerial surveys in the northern
Strait of Magellan and estimated a minimum of 3,221 dolphins for
that area. However, they did not observe Commerson 's dolphins in
some areas where they had previously been recorded. When Venegas
(1996) estimated the density of Commerson's dolphin during early
summer (1989-1990) in the eastern sector of the Strait of Magellan,
they estimated a population size of only 718 individuals, which
was attributed to methodological factors as well as to the time
of year. However, Lescrauwaet et al. (2000) et al. estimated population
size in the same sector in summer of 1996 to be 1,206 (95% CI 711
- 2,049) individuals.
Recent aerial surveys suggest that there are approximately 21,000
Commerson's dolphins along the entire South American coast, with
7,000 between 42-48ºS and 14,000 in Tierra del Fuego (Pedraza
et al., in review).
The status of the population at the Kerguélen Islands is
unknown, although Commerson's dolphins are now being reported frequently,
owing to recent emphasis on research. By 1985, over 100 sightings
were known, and the largest group seen near the edge of the shelf
contained about 100 dolphins (Goodall, 1994 and refs. therein; Robineau,
4. Biology and Behaviour
Habitat: Commerson's dolphins are found in cold in-shore
waters on open coasts and in sheltered fjords, bays, harbours and
river mouths, and they occasionally enter rivers. The offshore limit
of the species range is said to be the 100 m isobath (Reyes, 1991;
Carwardine, 1995; Dawson, 2009), however, Pedraza et al. (in rev.)
have sighted Commerson's dolphins in water over 1,000 m deep.
Off South America, Commerson's dolphins appear to prefer areas where
the continental shelf is wide and flat, the tidal range is great,
and temperatures are influenced by the cool Malvinas Current. Water
temperatures in areas frequented in these areas range from 4°C
to 16°C. Commerson's dolphins are often seen swimming in or
at the edge of kelp beds (Reyes, 1991 and refs. therein). Within
the Strait of Magellan, they prefer the areas with strongest currents,
such as the Primera and Segunda Angostura (First and Second Narrows),
where the current can reach or exceed 15 km/hr (Goodall, 1994, Lescrauwaet
et al. 2000).
Kerguélen sightings are most common within the Golfe du Morbihan,
where human activity is greatest and observation programmes are
under way. There, the dolphins inhabit open waters, kelp-ringed
coastlines and protected areas between islets (Goodall, 1994). Preferred
temperature range around Kerguélen is 1°C to 8°C
(Reyes, 1991 and refs. therein).
Reproduction: The breeding season is in the southern spring
and summer, September to February (Jefferson et al. 1993). Females
bear their first calf at between 6-9 years and gestation lasts 10-11
months. Males reach sexual maturity at between 5-9 years (Dawson,
2009). Calves were observed between mid-September and mid-March,
which suggests that calves are born in the austral spring and early
summer (Iniguez and Tossenberger, 2007).
Schooling: Groups are generally small, one to three animals
being most common, although the dolphins do some times aggregate
into groups of over 100. These are quick, active animals. They are
known to ride bow waves and to engage in various types of leaps.
Commerson's dolphins often swim upside down (Jefferson et al. 1993;
Goodall, 1994; pers. obs.).
Food: Feeding is on various species of fish, squid, and
shrimp. In South America, animals taken incidentally in shore nets
were coastal feeders on at least 25 food items: mysid shrimp (22.5%
of total diet), three species of small fish (20.4%), squid (14.1%),
17 species of other invertebrates, four species of algae, and miscellaneous
plant remains. At Kerguélen, specimens taken in January (summer)
were found to have been feeding mainly on 15 - 25 cm semipelagic
chaennichthyid fish (Champsocephalus gunnari) and to a lesser
extent on coastal benthic notothenids. Pelagic crustaceans (amphipods,
hyperiids and euphausiids), benthic crustaceans (Halicarcinus
planatus), and, in one specimen, numerous annelid tubes and
asciadians, were also found in stomachs (Goodall, 1994 and refs.
therein). Commerson's dolphins thus appear to be opportunistic,
feeding primarily near the bottom (Jefferson et al. 1993; Reyes,
1991; Goodall, 1994; Clarke and Goodall, 1994, Iniguez and Tossenberger,
South America: There are few data on movements or migrations.
Off Patagonia, the abundance of Commerson's dolphins is higher during
the colder months (May-December), when schools are larger, than
in the warmer months (Coscarella et al. 2003). There, dolphins are
seen throughout the year. Further South, fishermen claim that most
disappear during the winter to return in November. The dolphins
may follow the fish (róbalo, merluza) which move offshore
during winter. A low count of Commerson's dolphins in the Strait
of Magellan in late autumn may be accounted for by such movements.
Certainly the number observed is larger in summer (Goodall, 1994
and refs. therein; Venegas, 1996). The largest documented movements
are of about 300 km (Mora et al. 2001).
Kerguélen: Preliminary observations carried out throughout
the year indicate that although some dolphins stay, most move out
of the Golfe du Morbihan from June to December (winter and spring).
Nevertheless, as dolphins were seldom found over the adjacent continental
shelf, they may move to other parts of the archipelago (Goodall,
1994 and refs. therein).
Direct catch: In the past, various species of small cetaceans,
mainly Commerson's dolphins, have been harpooned and used as bait
in the southern king crab ("centolla"; Lithodes santolla)
fishery in both Argentina and Chile. Because the centolla is overfished
in the Magellan region, the fishing effort has shifted to the false
king crab, which is exploited principally farther west in the channels
where Commerson's dolphins are not found. However, in Argentina
the crab fishery operates in the Beagle Channel, which is also Commerson's
dolphin habitat. In addition, some animals have been killed for
sport (Reyes, 1991 and refs. therein). Some Commerson's dolphins
have been captured live in recent years, and the species appears
to have done relatively well in captivity (Jefferson et al. 1993).
Incidental catch: Off southern South America, this is the
odontocete species most frequently taken in gill nets, perhaps due
to its coastal habits and narrow-band sounds. It is taken most often
in fairly large-mesh nets and is apparently able to avoid nets with
fine mesh. Although the exact size of the by-catch is unknown, at
least 5-30 Commerson's dolphins die each year in nets set perpendicular
to the shore in eastern Tierra del Fuego alone. Dolphins are also
taken in this type of fishing in the Argentinean provinces north
of Tierra del Fuego and in the eastern Strait of Magellan and Bahía
Inútil in Chile. A few are taken by trawlers offshore in
northern Patagonia (Goodall, 1994 and refs. therein; Crespo et al.
1995), especially pelagic trawls in the anchovies fishery (Crespo
et al. 2007). Because the dolphins are used as bait, the fishers
have no motive to avoid areas where captures occur and may favour
them (Dawson, 2009).
Pollution: Low levels of chlorinated hydrocarbons (DDT, PCB
and HCB) were found in blubber of Kerguélen dolphins, confirming
the presence of contaminants in oceans far from the main sources
of pollution. However, these levels were 10-100 times lower than
those of cetaceans in the North Atlantic (Goodal, 1994).
Tourism: Dolphin-watching activities have increased in Patagonia;
the number of tourists increased from 532 in 1999 to 2,113 in 2001.
Dolphins showed a short-term reaction to the presence of the boat,
performing aerial displays which are otherwise rarely seen. (Coscarella
et al. 2003).
Range states (Reeves et al. 2008) :
Antarctica; Argentina; Chile; Falkland Islands (Islas Malvinas);
French Southern Territories (Kerguelen)
Cephalorhynchus commersonii is listed in the IUCN Red list
as "Data deficient" (Reeves et al. 2008) and it is listed
in Appendix II of CITES. The South American population is listed
in Appendix II of CMS.
Commerson 's dolphins may have been seriously affected by the illegal
take for bait in the crab fishery. It seems that the pressure on
this species has been reduced in the late 1980s. However, the incidental
mortality in gillnets and other fishing operations continues and
now represents the major threat to this dolphin (Reyes, 1991, Dawson,
Regulations for small cetaceans in Argentina and Chile date back
to 1974 and 1977, respectively. Permits are required for any taking,
but in practice enforcement applies only to live-captures. In particular,
enforcement is difficult in southern Chile, where the characteristics
of the area preclude appropriate control. There does not appear
to be any legislation protecting small cetaceans in the Falkland/Malvinas
Islands, although some proposed conservation areas may protect the
habitat. In the case of live-captures, Argentina banned this activity
until more information on the species would be available (Reyes,
1991 and ref. therein, Dawson, 2009).
The main reasons for a regional conservation agreement on southern
South-American small cetaceans including C. commersonii were
developed in a CMS-review (Hucke-Gaete, 2000; see Appendix
· Carwardine M (1995) Whales, dolphins and porpoises. Dorling
Kindersley, London, UK, 257 pp.
· Clarke M, Goodall N (1994) Cephalopods in the diets of
three odontocete cetacean species, stranded at Tierra del Fuego,
Globicephala melaena (Traill, 1809), Hyperoodon planifrons
Flower, 1882 and Cephalorhynchus commersonii (Lacepede, 1804).
Ant Sci 6(2): 149-154.
· Coscarella MA, Dans SL, Crespo EA, Pedraza SN (2003) Potential
impact of unregulated dolphin watching activities in Patagonia.
J Cetacean Res Manag 5: 77-84
· Crespo EA, Pedraza SN, Dans SL, Alonso MK, Reyes LM, Garcia
N, Coscarella M, Schiavini ACM (1995) Direct and indirect effects
of the high seas fisheries on the marine mammal populations in the
northern and central Patagonian coast. Nafo Sci Counc Res Doc 1995
no 95/88, 25 pp.
· Crespo EA, Dans SL, Koen Alonso M, Pedraza SN (2007) Interactions
between marine mammals and fisheries. The Argentine Sea and its
fisheries resources. Vol. 5. The marine ecosystem. pp. 151-169
· Dawson SM (2009) Cephylorhynchus dolphins. In: Encyclopedia
of marine mammals (Perrin WF, Würsig B, Thewissen JGM, eds.)
Academic Press, Amsterdam, pp. 191-196.
· de Bruyn PJN, Hofmeyr GJG, de Villiers MS (2006) First
record of a vagrant Commerson's dolphin, Cephalorhynchus commersonii,
at the southern African continental shelf. Afr Zool 41: 131-133
· Goodall RNP (1994) Commerson's dolphin - Cephalorhynchus
commersonii (Lacépède, 1804). In: Hand-book of
Marine Mammals (Ridgway SH, Harrison SR, eds.) Vol. 5: The first
book of dolphins. Academic Press, London, pp. 241-268.
· Hucke-Gaete R ed. (2000) Review on the conservation status
of small cetaceans in southern South America. UNEP/CMS Secretariat,
Bonn, Germany, 24 pp.
· Iniguez MA, Tossenberger VP (2007) Commerson's Dolphins
(Cephalorhynchus commersonii) off Ria Deseado, Patagonia,
Argentina. Aquat Mamm 33: 276-285
· Jefferson TA, Leatherwood S, Webber MA (1993) FAO Species
identification guide. Marine mammals of the world. UNEP/FAO, Rome,
· Jefferson TA, Webber MA Pitman RL (2008) Marine mammals
of the world. Elsevier, Amsterdam, 573 pp.
· Leatherwood S, Kastelein RA, Hammond PS (1988) Estimate
of numbers of Commerson's dolphins in a portion of the northeastern
Strait of Magellan, January-February 1984. Biology of the Genus
Cephalorhynchus. (Brownell, R L, Jr; Donovan, G P, eds.) 93-102.
Rep Int Whal Comm (SI 9).
· Lescrauwaet A-C, Gibbons J, Guzman L, Schiavini A (2000)
Abundance estimation of Commerson's dolphin in the eastern area
of the Strait of Magallan-Chile. Rev Chil Hist Nat 73: 473-478
· Mora NJ, Pedraza SN,Coscarella MA, Crespo, E (2001) Resultados
preliminares de la evaluación de la técnica de fotoidentificación
en tonina overa (Cephalorhynchus commersonii). IX Congreso
Latonoamericano sobre Ciencias del Mar. Isla San Andrés,
Colombia Septiembre 16 - 20, 2001
· Pedraza SN, Schiavini ACM, Crespo EA, Dans SL, Coscarella
MA (In review). Abundance of Commerson´s dolphins (Cephalorhynchus
commersonii) in the coasts of Patagonia (Argentina). Journal
of Cetacean Research and Management.
· 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
· Reyes JC (1991) The conservation of small cetaceans: a
review. Report prepared for the Secretariat of the Convention on
the Conservation of Migratory Species of Wild Animals. UNEP/CMS
· Reeves RR, Crespo EA, Dans Jefferson TA, Karczmarski L,
Laidre K, O'Corry-Crowe G, Pedraza S, Rojas-Bracho L, Secchi ER,
Slooten E, Smith BD, Wang JY, Zhou K (2008) Cephalorhynchus commersonii.
In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2.
· Rice DW (1998) Marine mammals of the world: systematics
and distribution. Society for Marine Mammalogy, Spec Publ 4, Lawrence,
· Robineau D (1989) The cetacean species of the Kerguelen
Islands. Mammalia 53: 265-278.
· Robineau D, Goodall RNP, Pichler F, Baker CS (2007) Description
of a new subspecies of Commerson's dolphin, Cephalorhynchus commersonii
(Lacepede, 1804), inhabiting the coastal waters of the Kerguelen
Islands. Mammalia. 71: 172-180
· Venegas CC (1996) Estimation of population density by aerial
line transects of Commerson's dolphin Cephalorhynchus commersonii
in the Strait of Magellan, Chile. An Inst Patagonia Ser Cien Nat
© Boris Culik (2010) Odontocetes.
The toothed whales: "Cephalorhynchus commersonii".
UNEP/CMS Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.