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False Killer Whale
Maximum Length:
Male 19'6"’ (6 m), Female 16'6" (5 m)
Maximum Weight: 3,000 lb (1,360 kg)
Life Span: More than 60 years
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Cetacea (whales and dolphins)
Sub-Order: Odontoceti (toothed whales)
Family: Delphinidae (ocean dolphins)
Genus: Pseudorca (false orca)
Species: crassidens (dens tooth)
False-killer whales belong to a group of dolphins known as “blackfish.” Included in this group are the killer whale, pygmy-killer whale, pilot whale, and melon-headed whale.
The
false killer whale has a long, slender body, and a small
rounded head with
little or no beak (Jefferson et al. 1993). The body is almost completely dark,
with some light areas around the throat, chest, and ventral midline. Sometimes
light gray areas exist on the sides of the head. The dorsal fin is falcate and
positioned about midback. The flippers are wider at the base than the tip and
have a characteristic hump on the leading edge. This bulge is perhaps the best
characteristic for distinguishing this species from the other “blackfish”
(killer, pygmy killer, melon-headed, and pilot whales) (Jefferson et al. 1993).
False
killer whales are found in all tropical and warm temperate waters, including the
Mediterranean and Red Seas, the Gulf of Mexico, and the Sea of Japan. They are
seen from Japan to British Columbia in the Pacific as far south as South
Australia and Chile. In the Atlantic they are seen from Scotland in the north
down to Argentina and South Africa in the south. They are usual encountered in
waters deeper than 3,300 ft (1,000 m), although they do approach close to shore
around oceanic islands (Baird 2002). Inshore movements are occasionally
associated with movements of prey and shoreward flooding of warm ocean currents
(Stacey et al. 1994).
Hawaii
See False Killer Whale Research in Hawaii
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False killer whales are very social and may be seen in groups of 10 to 20 animals (group sizes as large as 300 have been reported) (Brown et al. 1966). Their strong social affiliations are apparent from frequent mass strandings. Like their killer whale cousins, false killer whales are one of the few marine mammals to attack and kill other marine mammals including dolphins and large whales. They are often seen traveling together with bottlenose dolphins. The known maximum dive depth is about 500 m (Odell and McClune 1999).
Sound
False killer whales have very distinct vocalizations. The dominant frequencies of their whistles are 4 to 9.5 kHz; and those of their clicks are 25 to 30 kHz and 95 to 130 kHz (Thomas et al. 1990b; Thomson and Richardson 1995). Source levels have been measure at 220 to 228 dB re 1 μPa-m (Ketten 1998). The hearing sensitivity for a false killer whale was measured around 16 to 64 kHz (Thomas et al. 1988, 1990b).
False killer whales have a very low reproductive rate. The calving interval can be al long as 7 years between calves. The gestation period is 14 to 16 months and calves are nursed for 1.5 to 2 years. Females older than 45 years of age are barren. No seasonality in reproduction is known for the false killer whale (Jefferson et al. 1993).
This slow growing population makes them very vulnerable to overexploitation.
False killer whales are known to feed
on a fairly large variety of fish and cephalopods (Odell and McClune 1999).
They may specialize on certain types of prey depending on the region. For
example, in South Africa, squid is the primary food type, whereas in Hawaii,
mahimahi and yellowfin tuna are preferred. However, they have been known to
attack other cetaceans, including dolphins (Perryman and Foster 1980; Stacey and
Baird 1991), sperm whales (Palacios and Mate 1996), and even baleen whales. In
some regions they have been observed to take tuna as large as 70 lbs (30 kg)
from longlines (Mitchell 1975; Nitta and Henderson 1993). False killer whales
will sometimes travel in large bands up to several miles wide, presumably to
increase their chances of finding prey.
False
killer whales are sometimes a targeted fishery in Indonesia, and the West
Indies. Small numbers are killed in Japan with a few being sold to oceanariums.
More than 900 were killed at Iki Island between 1965 and 1980 when they were
believed to be interfering with the yellowtail fishery. They are also killed
incidentally in various fisheries.
There is an estimated 16,500 in the western north Pacific, 40,000 in the eastern tropical Pacific, a few hundred in the Gulf of Mexico. This species is designated as least concern on the IUCN Red List (Reeves et al. 2003). Nothing is known of the stock structure of false killer whales in the North Pacific Ocean.
Hawaii
Estimates for the Hawaiian islands include 236 individuals (CV=1.13) for the Hawaii Exclusive Economic Zone (EEZ) (Barlow, 2006), and 123 individuals (CV=0.72) around near shore main Hawaiian Islands (Baird et al., 2005).
See False Killer Whale Research Hawaii
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