False Killer Whale

False Killer Whale: Pseudorca crassidens

IUCN Status: data deficient

Status and distribution summary:

A poorly known species, with no accurate population estimates. Thought to occupy most tropical to warm temperate seas of the world, though is thought to be nowhere common.

Exploitation:

Small skill-killing for food in the Caribbean and Japan. Previous drive hunts have apparently died out.

Other threats:

Is regularly caught on long-lines and in gill nets set for fish like Yellow-fin Tuna. Hundreds are thought to be killed in this way in the western Pacific Ocean. Also known to be a victim of plastic ingestion, and may be vulnerable to loud sounds like modern sonar.

Where it is seen:

Over deeper waters south of 500 in the Bay of Biscay.

Frequency of sightings:

Rare, there have only been a handful of sightings in recent years. Its status prior to the 1990s is unknown, and it may have been under-recorded in the past due to potential confusion with female Long-finned Pilot Whales. Only recorded in spring and summer in the Bay of Biscay.

Recognition:

Medium sized, adults are 4-6 metres in length. Very slender and streamlined, being built for speed.

All blackish or charcoal grey, with a paler grey patch on the underside, between the pectoral fins.

The head is rounded, and 'bullet' shaped. Lacks any beak.

The dorsal fin is set at the mid point of the back, and is reasonably prominent and falcate with a strongly concave trailing edge, and in some cases the tip may be rounded.

Behaviour:

Usually occurs in pods of 10 - 50, though most Biscay sightings are of 3 - 7 animals, with one of over 30 in summer 2000.

Generally fast swimming in groups, giving an impression of large dolphins.

When surfacing, the head frequently (may even be invariable) breaks clear of the surface, even when slow swimming [as for record of 30 in August 2000].

When fast swimming frequently leaps clear of the water, also breaches, belly flops, lob tails, and makes sudden changes of course.

Hunts in groups, mainly for larger fish including bill fish and tuna, but is also known to attack dolphins and even immature larger cetaceans.

Confusion species:

  • Female Killer Whale; is similar in size but more robust, and the dorsal fin is much more prominant, and the white head patch is normally quite visible.
  • Female Pilot Whale; is similar in size, but bulkier with a lower, less falcate dorsal fin set well forward on the back. Less frequently shows the whole head on surfacing, if seen the domed melon (forehead) should be diagnostic.