| |
Delphinus capensis (Gray,
1828)
English: Long-beaked common dolphin
German: Cape-Delphin, Gewöhnlicher Delphin mit langem Schnabel
Spanish: Delfín común a pico largo
French: Dauphin commun a bec large
Family: Delphinidae
Delphinus capensis © Wurtz-Artescienza (see links).
1. Description
Until 1994 all common dolphins were classified as a single species,
D. delphis, but research by Heyning and Perrin (1994), later
confirmed by Kingston and Rosel (2004), led to the recognition of
two distinct species: the long-beaked and the short-beaked common
dolphins.
The taxonomic status of D. capensis has been further clarified
in a morphometric study (Jefferson and Van Waerebeek 2002) The authors
suggest that the Indian Ocean form called by some Delphinus tropicalis
(as reviewed in van Bree and Gallagher, 1978) is actually a long-beaked
subspecies of D. capensis, which may hybridize or intergrade
with the standard capensis-form in Southeast Asia and possibly along
the east coast of Africa. The appropriate name is Delphinus capensis
tropicalis (van Bree, 1971).
D. capensis may be difficult to distinguish from D.
delphis, especially at sea. Its body is more slender and
it has a longer beak than the short-beaked common dolphin. The beak
is sharply demarcated from the melon, which is somewhat flat in
appearance. The coloration is somewhat muted and the chin-to-flipper
stripe, which often merges with the lip patch, thus darkening the
lower jaw, is broader. In addition, white is absent from the dorsal
fin and flippers (occurs in some short-beaked common dolphins).
There are 47-67 sharp pointed teeth in each tooth row, more than
in any other delphinid. Body size reaches 2.54 m and body mass 235
kg (Jefferson et al. 2008).
Detail of Delphinus capensis ©
Michelle Berman, Santa Barbara
2. Distribution
Disjunct populations of D. capensis are found in warm temperate
and tropical coastal waters around the world. The overall distribution
remains imperfectly known because of past confusion with D. delphis
(Rice, 1998; Sanino et al., 2003).
D. c. capensis -occurs in the Atlantic and Pacific Oceans
on the east coast of South America, West Africa, southern Japan,
Korea and northern Taiwan (and possibly China), central California
to southern Mexico, Peru, and South Africa (Hammond et al. 2008).
However, Bernal et al. (2003) report on the long-term residency
of two long-beaked common dolphins in two small bays off the central
coast of Chile, extending the eastern South Pacific range southward
by 800 nm.
Distribution of Delphinus
capensis: disjunct populations in warm temperate and tropical
coastal waters (Hammond et al. 2008; © IUCN; Click
here for large map).
D. c. tropicalis - Ranges in the Indo-Pacific
from at least the Red Sea/Somalia to western Taiwan/southern China
and Indonesia, and including the Persian Gulf and Gulf of Thailand
(Hammond et al., 2008).
Beware that some authors have haphazardly applied the name D.
bairdii or D. delphis bairdii to all Pacific Ocean Delphinus
(Rice, 1998).
3. Population size
There is no estimate of global abundance for D. capensis
and few local abundance estimates. The distribution and abundance
of long-beaked common dolphins off California appears to be variable
on interannual and seasonal time scales (Heyning and Perrin 1994).
As oceanographic conditions change, long-beaked common dolphins
may spend time in Mexican waters, and therefore a multi-year average
abundance estimate is the most appropriate for management within
the U.S. waters. The most recent estimate of abundance in waters
of California, Oregon and Washington is 15, 334 (Barlow and Forney,
2007). Gerrodette and Palacios (1996) estimated 55,000 within Pacific
coast waters of the Mexican EEZ and 69,000 in the Gulf of California.
About 15,000-20,000 are estimated to occur off South Africa. The
tropicalis subspecies is widespread in the Indian and western Pacific
oceans, but there are no estimates of abundance for any portion
of its range Hammond et al. (2008).
Photograph by courtesy of Clinton Bauder, Metridium
Fields (see "links").
4. Biology and Behaviour
Habitat: D. capensis seems to prefer shallower and
warmer water and occurs generally closer to the coast than D.
delphis (Perrin, 2009). It is found mostly over continental
shelf water depths (< 180 m), and generally does not occur around
oceanic islands far from mainland coasts (Jefferson and Van Waerebeek
2002, Sanino et al. 2003).
Food: Off Brazil, D. capensis seems to prefer cephalopods
(De Oliveira Santos et al. 2002). D. capensis off southern California
feeds on sardines (Sardinops coerulea), anchovies (Engraulis
mordax), sauries (Cololabis saira), small bonitos (Sarda
chiliensis), and squids (Loligo opalescens). Long-beaked
common dolphins off southern Africa feed mainly on pilchards (Sardinops
ocellatus), anchovies (Engraulis capensis), and squids
(Loligo v. reynaudii) but had many other prey species of
fishes and squids, including myctophids in their stomachs (Ohizumi
et al. 1998). While these authors find that there seems to be no
obvious difference in the diet between C. delphis and C.
capensis, recent investigations on fatty acid composition of
blubber tissue of animals from the coast of California show differences
that seem to stem from dietary differences (Smith and Worthy, 2006).
5. Migration
Unknown.
6. Threats
Fisheries interactions: Miscellaneous lesions of the head,
skull, teeth, trunk, appendages, skin and genital tract were observed
in 120 of 930 long-beaked common dolphins taken in fisheries off
Peru between 1985 and 2000. The majority of traumas encountered
were diagnosed as caused by violent, fisheries-related interactions,
and the skin in 20.4% of specimens (n = 54) showed healed scars
from such interactions. There is concern that total fisheries-related
dolphin mortality is thought to be higher than can be accounted
for by the tallying of landed specimens. In Peru, long-beaked common
dolphins were frequently captured by industrial purse-seiners, including
in directed sets, at least until 1994. (Van Bressem et al. 2006).
Delphinus capensis © Parissa Yazdi, Hamburg
A total of 44 specimens were reported as incidental marine mammal
bycatch in the California drift gillnet fishery for broadbill swordfish
Xiphia gladius and common thresher shark, Alopias vulpinus,
in the 7-year period, 1996 to 2002 (Carretta et al. 2004). Hammond
et al. (2008) report that they are presently only occasionally involved
as bycatch in the eastern tropical Pacific tuna fishery. There are
anecdotal reports of potentially large numbers of dolphins, including
long-beaked common dolphins, killed for bait in some coastal fisheries
off Baja California, Mexico.
.
Long-beaked common dolphins have been taken opportunistically by
harpoon in northeastern Taiwan and are caught incidentally by oceanic
driftnets off eastern Taiwan. In the Indian Ocean and Chinese waters,
they are taken in gillnets, trawls, and purse seines. They are present
off Japan, and some have been taken in drive fisheries there. Incidental
catches of Delphinus sp. in pelagic driftnets in southern and south-eastern
Brazil have been recorded, but no current estimates of bycatch are
available. There is a large direct kill around Margarita Island,
off eastern Venezuela, in which dolphins are harpooned in large
numbers (Hammond et al. 2008).
Pollution: Wide ranges of organochlorine residues were determined
in the blubber of long-beaked common dolphin incidentally caught
in Brazilian coastal waters (Kajiwara, 2004). Concentrations of
DDTs and PCBs were the highest, followed by CHLs, TCPMOH, dieldrin,
TCPMe, heptachlor epoxide, HCB, and HCHs. Unexpectedly, significant
contamination by PCBs, DDTs, TCPMe, and TCPMOH was observed, implying
the occurrence of local sources in the Southern Hemisphere comparable
to those in the Northern Hemisphere, probably due to high industrialization
in Brazil.
7. Remarks
Range states :
Argentina; Brazil; Chile; China; Côte d'Ivoire; Djibouti;
Egypt; Eritrea; Gabon; Guyana; Hong Kong; India; Indonesia; Iran,
Islamic Republic of; Japan; Korea, Democratic People's Republic
of; Korea, Republic of; Kuwait; Madagascar; Malaysia; Mauritania;
Mexico (Baja California, Sinaloa, Sonora); New Zealand; Oman; Pakistan;
Peru; Saudi Arabia; Senegal; South Africa; Sri Lanka; Sudan; Suriname;
Taiwan, Province of China; Thailand; United Arab Emirates; United
States (California); Uruguay; Venezuela; Viet Nam; Western Sahara;
Yemen (Hammond et al. 2008).
Because of past confusion with D. delphis, very little is
known about this species. Overall distribution, behaviour at sea,
movements, reproduction and other key parameters, such as abundance,
are poorly known. Threats are presumably similar to those affecting
D.delphis. The lower density, however, could reflect that
this species is not as abundant as D. delphis and thus could
be more strongly affected by by-catch in fisheries. See further
recommendations on South American stocks in Hucke-Gaete (2000) (see
Appendix 1) and on Southeast
Asian stocks in Perrin et al. (1996) (see Appendix
2).
D. capensis is categorized as "Data Deficient"
by the IUCN. The species is listed in Appendix II of CITES. Not
listed by CMS.
8. Sources
Barlow J, Forney KA (2007) Abundance and population density of
cetaceans in the California Current ecosystem. Fish. Bull., U.S.
105:509-526.
· Bernal R, Olavarria C, Moraga R (2003) Occurrence and long-term
residency of two long-beaked common dolphins, Delphinus capensis
(Gray 1828), in adjacent small bays on the Chilean central coast.
Aquat. Mamm. 29: 396-399
. Bree PJH van (1971) Delphinus tropicalis, a new name for
Delphinus longirostris Cuvier 1829. Mammalia 35: 345-346
· Bree PJH van, Gallagher MD (1978) On the taxonomic status
of Delphinus tropicalis van Bree, 1971 (Notes on Cetacea,
Delphinoidea IX). Beaufortia 28: 1-8.
· Carretta JV, Price T, Petersen D, Read R (2004) Estimates
of marine mammal, sea turtle, and seabird mortality in the California
drift gillnet fishery for swordfish and thresher shark, 1996-2002.
Mar. Fish. Rev. 66: 21-30
· De Oliveira, Santos MC, Rosso S, Dos Santos RA, Lucato
SHB (2002) Insights on small cetacean feeding habits in southeastern
Brazil. Aquat. Mamm. 28: 38-45.
· Gerrodette T, Palacios DM (1996) Estimates of cetacean
abundance in EEZ waters of the eastern tropical Pacific. SWFSC Admin.
Rep. LJ-96-10, 28 pp.
· Hammond PS, Bearzi G, Bjørge A, Forney K, Karczmarski
L, Kasuya T, Perrin WF, Scott MD, Wang JY, Wells RS , Wilson B (2008)
Delphinus capensis. In: IUCN 2009. IUCN Red List of Threatened
Species. Version 2009.1. <www.iucnredlist.org>
· Heyning JE, Perrin W F (1994) Evidence for two species
of common dolphins (genus Delphinus) from the eastern North Pacific.
Los Angeles County Mus. Nat. Hist. Contr. Sci. 442: 1-35.
· 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, Van Waerebeek K (2002) The taxonomic status
of the nominal dolphin species Delphinus tropicalis van Bree
, 1971. Mar. Mamm. Sci. 18: 787-818
· Jefferson TA, Webber MA , Pitman RL (2008) Marine mammals
of the world. Elsevier, Amsterdam, 573 pp.
· Kajiwara N, Matsuoka S, Iwata H, Tanabe S, Rosas FCW, Fillmann
G, Readman JW(2004) Contamination by persistent organochlorines
in cetaceans incidentally caught along Brazilian coastal waters.
Arch. Environ. Contam. Toxicol. 46: 124-134
· Kingston SE, Rosel PE (2004) Genetic differentiation among
recently diverged delphinid taxa determined using AFLP markers.
J. Hered. 95: 1-10
· Li S (1997) Studies on sea mammals and its distribution
from Fujian coastal waters. J. Oceanogr. Taiwan Strait; Taiwan Haixia
16: 479-485.
· Ohizumi H, Yoshioka M, Mori K, Miyazaki N (1998) Stomach
contents of common dolphins (Delphinus delphis) in the pelagic
western North Pacific. Mar. Mamm. Sci. 14: 835-844.
· Perrin WF (2009) Common dolphins. In: Encyclopedia of marine
mammals 2nd Ed. (Perrin WF, Würsig B, Thewissen JGM, eds.)
Academic Press, Amsterdam, pp. 255-259.
· Perrin WF, Dolar MLL, Alava MNR (1996) Report of the Workshop
on the Biology and Conservation of Small Cetaceans and Dugongs of
Southeast Asia. East Asia Seas Action Plan. UNEP(W)/EAS WG. 1/2,
Bangkok, Thailand. 101 pp.
· Rice DW (1998) Marine mammals of the world: systematics
and distribution. Society for Marine Mammalogy, Spec. Pub. 4, Lawrence,
KS. USA.
· Sanino GP, Van Waerebeek K, Yanez J (2003) Revision de
la distribucion del género Delphinus y registros documentados
de Delphinus delphis en Chile. Bol. Mus. Nac. Hist Nat. (Chile)
52: 97-102.
· Smith HR, Worthy GAJ (2006) Stratification and intra- and
inter-specific differences in fatty acid composition of common dolphin
(Delphinus sp.) blubber: Implications for dietary analysis. Comp.
Biochem. Physiol. B143: 486-499
· Van Bressem M-F, Van Waerebeek K, Montes D, Kennedy S,
Reyes JC, Garcia-Godos IA, Onton-Silva K, Alfaro-Shigueto Joanna
(2006) Diseases, lesions and malformations in the long-beaked common
dolphin Delphinus capensis from the Southeast Pacific. Dis.
Aquat. Org. 68: 149-165
© Boris Culik (2010) Odontocetes.
The toothed whales: "Delphinus capensis". UNEP/CMS
Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.
|
