(Owen, 1846) - False killer whale
Distinctive Characteristics
The false killer whale is one of several species of delphinids that some fishermen call blackfish. It has a long slender body, a rounded overhanging forehead, and no beak. The dorsal fin is falcate and slender, and generally somewhat rounded at the tip. The flippers have a characteristic hump on the leading edge, perhaps the species' most diagnostic character.
This is a large, dark grey to black dolphin, with a faint light grey patch on the chest, and sometimes light grey areas on the head.
Skulls of false killer whales from Australia, South Africa, and Scotland have been shown to differ, and this suggests the existence of different populations in these areas.
Each jaw contains 7 to 12 pairs of large conical teeth, which are round in cross-section.
Can be confused with
False killer whales are most commonly confused with pygmy killer and melon-headed whales, and less commonly, pilot whales. Shape of the head, dorsal fin, and flippers will be the best characters to use in distinguishing them (the flipper hump of false killer whales is diagnostic).
Size
Adults are up to 6 m (males) or 5 m (females) long. Large males may weigh up to 2000 kg. Newborns are 1.5 to 2.1 m.
Geographical Distribution
False killer whales are found in tropical to warm temperate zones, in deep offshore waters. They generally do not range further north or south 50° in either hemisphere.
Biology and Behaviour
As is the case for most of the tropical oceanic delphinids, this species is poorly known. In some areas, false killer whales take bait from longlines and thus irritate fishermen. Groups of 10 to 60 are typical, though much larger groups are known. This is one of the most common species involved in cetacean mass strandings. The false killer whale is a lively, fast-swimming cetacean, which often behaves more like the spritely smaller dolphins than other mid-sized cetaceans.
No seasonality in breeding is known for the false killer whale.
Although false killer whales eat primarily fish and cephalopods, they also have been known to attack small cetaceans and, on one occasion, even a humpback whale.
Exploitation
Small numbers of false killer whales are taken in fishing nets and lines throughout their range, but only in Japan has there been a major catch. This is one of several species killed in the now infamous Iki Island drives, in which cetaceans are driven ashore and killed because they are held responsible for depleting an overfished stock of yellowtail amberjack (Seriola lalandi). A few may be shot by fishermen who regard them as competitors, and small numbers have been captured live off California and Hawaii. Incidental catches of small numbers occur in several areas.
IUCN Status
Insufficiently known.