English: Chilean dolphin
Spanish: Delfín Chileno
French: Dauphin du Chili
Cephalorhynchus eutropia © Wurtz-Artescienza (see links).
Small, chunky and blunt-headed dolphins without beak (and therefore
often wrongly called porpoises). The flippers are rounded and almost
paddle-shaped. The dorsal fin is proportionally large and with a
rounded, convex trailing edge, like a "Mickey Mouse" ear
(Dawson, 2009). Basically grey, with a lighter grey 'cap' over the
melon. The lips are white, as is the throat and belly, and behind
each flipper there is a white 'armpit'.
The flippers are linked by a grey band across the throat, which
is often shaped like a rhombus in the centre. Around 1.67 m long;
mass reaches 63 kg (Dawson, 2009).
Chilean dolphins occur in coastal waters of the west coast of southern
South America from Valparaiso, Chile (33°S), south to Isla Navarino,
Beagle Channel, and Cape Horn, Argentina (55° 15'S; Rice, 1998).
C. eutropia is restricted to cold, shallow, coastal waters.
Its distribution seems to be continuous, though there seem to be
areas of local abundance, such as off Playa Frailes, Valdivia, Golfo
de Arauco, and near Isla de Chiloé (Dawson, 2009). The species
is known to enter Rio Valdivia and other rivers (Carwardine, 1995).
Distribution of Cephalorhynchus
eutropia: coastal waters of Chile and southern Argentina
(Reeves et al. 2008; © IUCN; Click
here for large map).
The easternmost sighting of C. eutropia was near the eastern
mouth of the Strait of Magellan. Although it is mostly allopatric
with Commerson's dolphin, C. commersonii, the ranges of the
two species may overlap slightly in the Strait of Magellan and Beagle
Channel, on the border with Argentina (Goodall, 1994).
3. Population size
The total population appears to be very small (low thousands at
most). Suggestions that the species is becoming very rare are worrying
and impossible to refute without dedicated survey work (Dawson,
2009). C.eutropia has been called a rare dolphin, but perhaps
it has been seen rarely because of the lack of boat traffic and
of trained observers in the channels and because of its shy, evasive
Chilean dolphins represented 16% of the cetacean sightings, captures,
and strandings in an 8-year study between Coquimbo (30°S) and
Tome (36°37'S). However, most sightings occurred on an opportunistic
basis, as few ship surveys and no aerial surveys have been carried
out (Goodall, 1994). Overlapping with this area, and north of the
Maule River (36 °N), a zone more influenced by the estuarine
system, Perez-Alvarez et al. (2007) saw Chilean dolphins in 83%
of the surveys . The relative abundance was significantly higher
than to the south (13.6 dolphins/h versus 3.5 dolphins/h, respectively).
While it may appear to be locally abundant in areas such as Valdivia,
the Golfo de Arauco and near Chiloé, where groups of 20-50
or more animals have been seen (Goodall, 1994), a recent study (Heinrich,
2006) showed that local populations may be very small; at southern
Chiloé, the size of the local population amounted to only
Finally, a boat survey conducted between the southern tip of Chiloe
and Ushuaia made only few sightings of Chilean dolphins (Dawson
2009), confirming the general decrease in abundance from north to
4. Biology and Behaviour
Habitat: The Chilean dolphin inhabit two distinct areas:
(1) the channels from Cape Horn to Isla Chiloé and (2) open
coasts, bays and river mouths north of Chiloé, such as waters
near Valdivia and Concepción. It seems to prefer areas with
rapid tidal flow, tide rips, and shallow waters over banks at the
entrance to fjords. The dolphins readily enter estuaries and rivers
(Goodall, 1994). In Yaldad Bay, southern Chile, shallow waters (5-10
m) near the coast and rivers were the most significant environmental
features determining fine-scale dolphin distribution patterns(Ribeiro
et al. 2007).Although most sightings have been near shore and therefore
it is considered a coastal species, little scientific survey effort
has been made in offshore waters (Goodall, 1994).
Schooling: The usual group size is from two to 10 dolphins;
most observers have reported sighting only two or three animals
at one time. Nevertheless, groups of 20-50 or more dolphins are
seen at times, especially in the northern part of the range, and
early investigators wrote of "great numbers". Such observations
may represent occasional aggregations of smaller groups. The largest
concentration ever reported was 15 miles long, possibly 4,000 animals,
which moved north past Queule (39°22'S), hugging the shore (Goodall,
1994). The species may associate with Lagenorhynchus australis
(Goodall, 1994; Jefferson et al. 1993).
Food: C. eutropia feeds on crustaceans (Munida
subrugosa), cephalopods (Loligo gahi), and fish, such
as sardines (Strangomera bentincki), anchoveta (Engraulis
ringens), róbalo (Eteginops macrovinus) and the
green alga Ulva lactuca. Dolphins near a salmon hatchery
on Chiloé played with salmon and may have eaten young released
salmon (Goodall, 1994 and refs. therein).
Behaviour: Off central Chile, three behaviour categories
were recorded (feeding, socialising, and travelling) in both areas
(Perez-Alvarez et al. 2007). Foraging was the most frequently observed
activity. Aquaculture activities in the area were observed to affect
dolphin habitat use patterns by restricting space available for
biologically important dolphin behaviours (Ribeiro et al. 2007).
In the southern part of the range the dolphins tend to be more wary
of boats and difficult to approach; in the north, they have been
known to swim over to boats and may bow-ride Carwardine (1995).
The Chilean dolphin is thought to occur more or less continuously
throughout its range, and nothing is known of its movements or migration.
Numerous observations in the Valdivia area suggest that there is
at least one resident pod, but individual animals have not been
identified to confirm this. Sightings occur throughout the year
in the northern part of the range (north of Chiloé) (Perez-Alvarez
et al. 2007) and during most months in the central and southern
section have been reported (Goodall, 1994).
Direct catch: Although killing of dolphins is prohibited
by law, they are taken for bait, and it has been claimed that they
were also used for human consumption. Fishermen in coastal areas
north of Chiloe harpooned them or used those taken incidentally
in their nets, as bait for fish caught on long lines with many hooks,
for swordfish fished with individual hooks, or for crab ring nets.
From Chiloé south, and especially in the Magellan region,
dolphins are taken along with penguins, sheep, seals, sealions,
other marine birds, and fish for bait for the lucrative "centolla"
(southern king crab, Lithodes santolla) and "centolion"
(false king crab, Paralomis granulosa) fishery. The larger
crab-processing companies provide bait (in insufficient quantities)
for their fishermen, but independent fishermen who supply smaller
companies harpoon or shoot their own bait and claim that the crab
prefer dolphins over other animals and birds. It has been estimated
for the 1980's that two Chilean dolphins were taken per week per
boat, and that as many as 1,300-1,500 dolphins were harpooned per
year in the area near the western Strait of Magellan in the early
1980s. Fishing areas since then have moved farther north and south,
but the captures of dolphins for bait continue (Goodall, 1994).
Although hunting is now illegal, fishermen in the area are poor
and enforcement of the law in remote areas is practically impossible.
A dependable alternative supply of inexpensive bait is needed. (Dawson,
2009). The actual numbers taken remain unknown.
Incidental catch: Incidental catch probably occurs throughout
its range, especially in the north, where dolphins can become entangled
in several kinds of nets. No calculation has been made of the extent
of incidental catch in Chile, but at Queule, near Valdivia, Chilean
dolphins account for 45.8% of the dolphins taken in gill nets set
from some 30 boats. This implies a catch of some 65-70 animals per
year at this one port alone (Goodall, 1994, and refs. therein).
Around Chiloe, where gillnets are employed to catch escaped salmon,
bycatch may cause a significant population decline (Dawson, 2009).
Mariculture: Aquaculture farms for salmon and shellfish
also may have negative effects on Chilean dolphins, e.g. by restricting
their movements and eliminating important habitat along the east
coast of Isla Grande de Chiloé. Finally, there is evidence
that Chilean dolphins are sometimes caught incidentally in anti-sea
lion nets set up around salmon farms in the fjords and channels
(Reeves et al. 2008). Dolphins also react negatively to boat presence,
emphasizing the need to consider boat traffic disturbance on cetaceans
in coastal management plans (Ribeiro et al. 2005).
Range states (Reeves et al. 2008) : Argentina, Chile
C. eutropia is included in Appendix II of the CMS: the range
of this species may extend beyond the Chilean border into Argentinean
waters in the Beagle channel and at the entrance of the Strait of
Magellan near Cabo Virgenes and Cabo Espiritu Santo. The species
is listed in Appendix II of CITES.
The species is listed as "Near Threatened" by the IUCN:
Total population size appears to be low (in the low thousands) and
decline via catches and bycatch seems to be continuing, although
the decline rate is unknown. Collection of by-catch and sighting
data is therefore strongly needed. In a small population of slow
breeding animals, even a very low level of incidental catch can
be enough to continue the decline (Dawson, 2002; 2009).
In a recent CMS review (Hucke-Gaete, 2000; see Appendix
1) the main reasons for a regional conservation agreement on
southern South-American small cetaceans including C. eutropia
· Carwardine M (1995) Whales, dolphins and porpoises. Dorling
Kindersley, London, UK, 257 pp.
· Dawson SM (2009) Cephylorhynchus dolphins. In: Encyclopedia
of marine mammals, 2nd Ed. (Perrin WF, Würsig B, Thewissen
JGM, eds.) Academic Press, Amsterdam, pp. 191-196.
· Goodall RNP (1994) Chilean dolphin - Cephalorhynchus
eutropia (Gray, 1846). In: Handbook of marine mammals (Ridgway
SH, Harrison SR eds.) Vol. 5: The first book of dolphins. Academic
Press, London, pp. 269-288.
· Heinrich S (2006) Ecology of Chilean dolphins and Peales
dolphins at Isla Chiloé, Southern Chile. Ph D Thesis, U.
St. Andrews, UK.
· 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, Leatherwood S, Webber MA (1993) FAO Species
identification guide. Marine mammals of the world. UNEP/FAO, Rome,
· Perez-Alvarez MJ, Alvarez E, Aguayo-Lobo A, Olavarria C
(2007) Occurrence and distribution of Chilean dolphin (Cephalorhynchus
eutropia) in coastal waters of central Chile. N Z J Mar Freshw
Res 41: 405-409
· 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
eutropia. In: IUCN 2009. IUCN Red List of Threatened Species.
Version 2009.2. <www.iucnredlist.org>.
· Ribeiro S, Viddi FA, Freitas TRO (2005) Behavioural responses
of Chilean dolphins (Cephalorhynchus eutropia) to boats in
Yaldad Bay, Southern Chile. Aquat Mamm 31: 234-242
· Ribeiro S, Viddi FA, Cordeiro JL, Freitas TRO (2007) Fine-scale
habitat selection of Chilean dolphins (Cephalorhynchus eutropia):
Interactions with aquaculture activities in southern Chiloe Island,
Chile. J Mar Biol Assoc UK 87: 119-128
· Rice DW (1998) Marine mammals of the world: systematics
and distribution. Society for Marine Mammalogy, Spec Publ 4 , Lawrence,
© Boris Culik (2010) Odontocetes.
The toothed whales: "Cephalorhynchus eutropia".
UNEP/CMS Secretariat, Bonn, Germany.http://www.cms.int/small-cetaceans
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.