Feresa attenuata Gray,
English: Pygmy killer whale
Spanish: Orca pigmea
French: Orque pygmée
Drawing of Feresa attenuata © Würtz-Artescienza
Pygmy killer whales have a robust body that narrows towards the
dorsal fin, hence the name "attenuata" (Latin)
meaning "thinning". The head is round and blunt and lacks
a beak typical of many dolphin species. The moderately long flippers
are rounded at the tips with convex leading and concave trailing
edges. Pygmy killer whales are mostly grey to black, with a subtle
dark cape on the side, below the high, falcate dorsal fin. There
is a paler grey area on each flank and an irregularly white patch
on the ventral side between the flippers, around the genitals and
occasionally the tail stock. The lips are also edged with white.
Body size ranges from 2.1 to 2.6m (Donahue and Perryman, 2009).
Maximum known weight is 225 kg (Jefferson et al. 2008).
This is a tropical and subtropical species that inhabits oceanic
waters around the globe, generally not ranging north of 40°N
or south of 35°S (Jefferson et al. 1993; Taylor et al. 2008).
It ranges north to the Gulf of Mexico, east coast of Florida, Senegal,
Arabian Sea, Sri Lanka, Honshu, Hawaii, and Gulf of Tehuantepec,
and south to Buenos Aires, Cape Province, Queensland, and Peru (Rice,
The distribution of F. attenuata is poorly known from sparse
but widely distributed records worldwide. It is seen relatively
frequently in the eastern tropical Pacific, Hawaii, and Japan, though
it is not particularly abundant anywhere. Because it tends to avoid
boats it may be more common than the records suggest (Carwardine,
Distribution of Feresa attenuata (Taylor et al. 2008; ©
IUCN). The species prefers tropical
and subtropical offshore waters around the world between 40°N
and 35°S .
here for large map)
It is notable that most of the records outside the tropics are
associated with strong, warm western boundary currents which effectively
extend tropical conditions into higher latitudes (Ross and Leatherwood,
1994 and ref. therein). Williams et al. (2002) e.g. observed two
groups in the north-eastern Atlantic in the Bay of Biscay at 45°16'N,
30°56'W and at 45°26'N, 40°26'W, respectively. In both
cases the cetaceans were in close proximity to newly born or first-year
Records of whales on the cool west coasts of southern Africa and
Peru are exceptions, though these could well have originated in
far warmer waters comparatively close by (Ross and Leatherwood,
1994 and ref. therein).
3. Population size
There is very little information on population size, and the species
appears to be uncommon. The population size of the western north
Atlantic stock is unknown. The population size for the Northern
Gulf of Mexico stock is 408 (Reviewed in Waring et al. 2007). Wade
and Gerrodette (1993) estimated that there were about 38,900 (CV=31%)
in the eastern tropical Pacific. There are estimated to be 956 pygmy
killer whales (CV=83%) in the Hawaiian portion of the US EEZ (Barlow
4. Biology and Behaviour
Habitat: Occurs in deep, warm waters, rarely close to shore
(except near oceanic islands). Mainly tropical, but occasionally
strays into warm temperate regions (Carwardine, 1995).
Behaviour: F. attenuata may be difficult to approach
and is known to avoid boats, though there are reports of bow- and
wake-riding (Carwardine, 1995). Castro (2004) e.g. observed pygmy
killer whales off Machalilla National Park,Ecuador, "The school
of dolphins was travelling at a speed of around 30 km/h. During
the whole length of the observation, while the animals were travelling,
they conducted running leaps and hard splash with their whole bodies
outside of the water. On some occasions, their heads were outside
of the water and they were bowriding in the waves produced by the
Schooling: Groups generally contain 50 or fewer individuals,
although herds of up to several hundred have been seen (Jefferson
et al. 1993; Ross and Leatherwood, 1994). Pods often swim abreast
in perfectly co-ordinated "chorus lines" and, when alarmed,
bunch together to rush away. Growling sounds may be heard above
the surface. Herds often strand (Carwardine, 1995), e.g. at Hawaii
(Mazzuca et al. 1999) or in Brazil (Zerbini and de Oliveira 1997).
A record mass stranding of pygmy killer whales in the British Virgin
Islands was documented by Mignucci-Giannoni et al. (2000), who associating
the stranding process with the meteorological and oceanographic
disturbance of hurricane Marilyn, which devastated the Virgin Islands
a day prior to the stranding.
Food: Pygmy killer whales eat mostly fish and squid, although
they occasionally attack other dolphins, at least when those dolphins
are involved in tuna fishery interactions in the eastern tropical
Pacific (Jefferson et al., 1993; Carwardine, 1995). Santos and Haimovici
(1998) found mainly squids of the families Onychoteuthidae and especially
Ommastrephidae in the stomach contents of F. attenuata. Pygmy
killer whales use similar echolocation clicks as similar sized,
whistling delphinids, suggesting comparable diets. Recorded clicks
are directional, short (25 µs) transients with estimated source
levels between 197 and 223 dB re. 1 µPa (pp). Spectra of clicks
recorded close to or on the acoustic axis were bimodal with peak
frequencies between 45 and 117 kHz, and with centroid frequencies
between 70 and 85 kHz (Madsen et al., 2004).
No migrations are known (Carwardine, 1995). Incidental catches
by Sri Lankan fishermen have been reported in all months except
September, November and December, indicating that pygmy killer whales
are present almost throughout the year in this region. Similarly,
whalers of St Vincent, Lesser Antilles, indicated that they might
encounter pygmy killer whales at any time of the year, implying
residency (Ross and Leatherwood, 1994). Jefferson et al. (2008)
confirmed this for Hawaiian waters, where pygmy killer whales show
high fidelity to specific islands, with strong and stable association
Direct catch: A few individuals are known to be taken in
drives and in driftnets in various regions, most notably Japan and
Sri Lanka (Jefferson et al. 1993). Reports on the small-cetacean
fisheries of St Vincent and Lamelera suggest that pygmy killer whales
form a very small proportion of the catch and that catches probably
have little impact on the populations in those areas. In Sri Lanka,
there has been additional mortality of this and other species due
to harpooning of dolphins for use as bait on long-lines for sharks,
billfish, and other oceanic fishes (Ross and Leatherwood, 1994 and
Incidental catch: Although they comprise less than 2% of
all cetaceans in monitored by-catches in gillnet fisheries in Trincomalee,
Sri Lanka and in villages on the south-west coast of Sri Lanka,
this may amount to 300-900 of the 15,000-45,000 dolphins estimated
to die each year in such fisheries (Ross and Leatherwood, 1994,
and refs. therein). The numbers of animals killed incidentally in
net fisheries, such as those in Sri Lanka, may be much higher than
is so far documented because monitoring of these widespread activities
is incomplete. In the long term, such takes may have a significant
impact on stocks resident in areas where pygmy killer whales (and
other small cetaceans) and extensive gillnetting operations overlap
(Ross and Leatherwood, 1994). Small incidental catches are known
in fisheries in other areas (Jefferson et al. 1993), e.g. the Philippines
(Dolar et al. 1999) or Indonesia (Rudolph and Smeenk, 2009).
Pollution: There have been reports on the presence of hydrocarbon
residues, including DDT, Dieldrin and PCBs in various tissues of
three pygmy killer whales from the Gulf and Atlantic coasts of Florida
(Ross and Leatherwood, 1994 and refs. therein).
Noise pollution: In early 2004 and in 2005, several unusual
stranding events occurred in Taiwan during a period of large-scale
naval exercises. Gross examination of the partial remains of a pygmy
killer whale revealed internal injuries to structures associated
with or related to acoustics or diving, suggestive that nearby naval
exercises may have contributed to or caused the death of at least
one cetacean in this region and that species other than beaked whales
may also be susceptible to such activities. With an increasing number
of military exercises in this region, more attention to the impacts
of such activities on cetaceans is needed (Wang and Yang, 2006).
Range states (Taylor et al. 2008):
Algeria; Anguilla; Antigua and Barbuda; Aruba; Australia; Bahamas;
Bangladesh; Barbados; Belize; Benin; Brazil; Brunei Darussalam;
Cambodia; Cameroon; Cayman Islands; China; Cocos (Keeling) Islands;
Colombia; Comoros; Congo; Congo, The Democratic Republic of the;
Cook Islands; Costa Rica; Cuba; Côte d'Ivoire; Djibouti; Dominica;
Dominican Republic; Ecuador; El Salvador; Equatorial Guinea; Fiji;
France; French Guiana; French Polynesia; Gabon; Gambia; Ghana; Grenada;
Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras;
India; Indonesia; Iran, Islamic Republic of; Italy; Jamaica; Japan;
Kenya; Kiribati; Korea, Republic of; Liberia; Madagascar; Malaysia
(Peninsular Malaysia, Sabah, Sarawak); Maldives; Marshall Islands;
Mauritania; Mayotte; Mexico; Micronesia, Federated States of; Morocco;
Mozambique; Myanmar; Nauru; Netherlands Antilles (Bonaire, Curaçao,
Netherlands Leeward Is.); New Caledonia; Nicaragua; Nigeria; Niue;
Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New
Guinea; Peru; Philippines; Pitcairn; Portugal; Puerto Rico; Saint
Kitts and Nevis; Saint Vincent and the Grenadines; Samoa; Senegal;
Sierra Leone; Singapore; Solomon Islands; Somalia; South Africa;
Spain; Sri Lanka; Suriname; Taiwan, Province of China; Tanzania,
United Republic of; Thailand; Timor-Leste; Togo; Tokelau; Tonga;
Trinidad and Tobago; United States; Venezuela; Viet Nam; Virgin
Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Western
Feresa attenuata is considered as "Data Deficient"
by the IUCN (Taylor et al. 2008). The species is not listed by CMS.
The species is listed on Appendix II of CITES.
There is very little knowledge about this species, its abundance,
migratory behaviour or by-catch rates in offshore fisheries. For
South American populations, see recommendations in Hucke-Gaete (2000)
(see Appendix 1).
General recommendations on Southeast Asian stocks can be found in
Perrin et al. (1996) (see Appendix 2).
· Barlow J (2006) Cetacean abundance in Hawaiian
waters estimated from a summer/ fall survey in 2002. Mar Mamm Sci
· Carwardine M (1995) Whales, dolphins and porpoises. Dorling
Kindersley, London, UK, 257 pp.
· Castro C (2004) Encounter with a school of pygmy killer
whales (Feresa attenuata) in Ecuador, Southeast Tropical
Pacific. Aquat Mamm 30: 441-444
Dolar M L L, Suarez P, Ponganis P J, Kooyman G L (1999) Myoglobin
in pelagic small cetaceans. J Exp Biol 202: 227-236.
· Donahue MA, Perryman WL (2009) Pygmy Killer Whale - Feresa
attenuata. In: Encyclopedia of marine mammals 2nd Ed. (Perrin
WF, Würsig B, Thewissen JGM, eds.) Academic Press, Amsterdam,
· 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,
· Jefferson TA, Webber MA Pitman RL (2008) Marine mammals
of the world. Elsevier, Amsterdam, 573 pp.
· Madsen PT, Kerr I, Payne R (2004) Source parameter estimates
of echolocation clicks from wild pygmy killer whales (Feresa
attenuata) (L). J Acoust Soc Amer 116: 1909-1912
· Mazzuca L, Atkinson S, Keating B, Nitta E (1999) Cetacean
mass strandings in the Hawaiian Archipelago, 1957-1998. Aquat Mamm
· Mignucci-Giannoni AA, Toyos-Gonzalez GM, Perez-Padilla
J, Rodriguez-Lopez MA, Overing J. (2000) Mass stranding of pygmy
killer whales (Feresa attenuata) in the British Virgin Islands.
J Mar Biol Assoc U-K 80: 759-760.
· 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 Publ. 4, Lawrence,
· Ross GJB, Leatherwood S (1994) Pygmy killer whale - Feresa
attenuata. In: Handbook of marine mammals (Ridgway SH, Harrison
SR, eds.) Vol. 5: The first book of dolphins. Academic Press, London,
· Rudolph P, Smeenk C (2009) Indo-West Pacific marine mammals.
In: Encyclopedia of marine mammals (Perrin WF, Würsig B, Thewissen
JGM, eds.) Academic Press, Amsterdam, pp. 608-616.
· Santos RA, Haimovici M (1998) Cephalopods in the diet of
marine mammals stranded or incidentally caught along southeast and
southern Brazil (21° to 34°S). Copenhagen Denmark Ices,
· Taylor BL, Baird R, Barlow J, Dawson SM, Ford J, Mead JG,
Notarbartolo di Sciara G, Wade P, Pitman RL (2008). Feresa attenuata.
In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.1.
· Wade P, Gerrodette T (1993). Estimates of cetacean abundance
and distribution in the eastern tropical Pacific. Rep Int Whal.
· Wang JY, Yang S-C (2006) Unusual cetacean stranding events
of Taiwan in 2004 and 2005. J Cetacean Res Manage 8: 283-292
· Waring GT, Josephson E, Fairfield CP, Maze-Foley K, editors.
2007. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments
-- 2006. NOAA Tech Memo NMFS NE 201; 378 p
· Williams AD, Williams R, Brereton T (2002) The sighting
of pygmy killer whales (Feresa attenuata) in the southern
Bay of Biscay and their association with cetacean calves. J Mar
Biol Assoc UK 82: 509-511
· Zerbini AN, De Ooliveira Santos MC (1997) First record
of the pygmy killer whale Feresa attenuata (Gray, 1874) for
the Brazilian coast. Aquat Mamm 23:105-109.
© Boris Culik (2010) Odontocetes.
The toothed whales: "Feresa attenuata". UNEP/CMS
Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.