Common names:

Arabic:

German: Kleiner schwertwal
Spanish: Orca falsa
French: Fausse-orque, pseudorque
Italian: Pseudorca

Description: The false killer whale belongs to the suborder of the Odontoceti, and is the third largest species in the family Delphinidae. The name originated from their large conical teeth similar to those of the killer whale. It is characterized by a small round conical head with no beak, that in adult males may show a pronounced melon. The body is black and slender and can reach up to 6 meters in adult males.  The dorsal fin is slender, falcate, and placed in the middle of the body. The flippers show a characteristic hump halfway on the external edge, resembling an elbow. Body mass is between 1,100 and 2,200 kg.

Range and habitat: False killer whales show world-wide distribution in tropical and temperate waters. They prefer deep oceanic waters although they are observed in several semi-enclosed seas and bays (the Sea of Japan, Bohai/Yellow Sea, Arabian Gulf, Red Sea) but only few sightings have been reported in Baltic Sea and Mediterranean Sea.  In this region the first sighting of this species has been reported in 1961 off the coasts of Oman followed by subsequent sightings in the Gulf and the Red Sea where it has also been observed closed to shore.

Behaviour: Very little is known on this species: the only information available derives mainly from stranding data and the only long-term research project studying the resident population inhabiting the Hawaiian waters.  False killer whales are gregarious animals, usually observed in pods of 10 to 50 individuals or more. They are extremely social mammals showing strong long-term affiliation among individuals and this is most likely to be the reason why they frequently strand together in big numbers. They are frequently observed engaged in surface activities and is not unusual to see them bow-riding and jumping.  Although they have been sighted with other species of cetaceans, in particular bottlenose dolphins, false killer whale have also been reported to attack other small cetacean species. They utilize echolocation and they communicate using a various range of sounds.

Reproduction:  False killer whales have a low reproductive rate, with a calving interval estimated around 7 years. Maturity in females is reached at about 8-11 years old, but after 45 years old are generally infertile. Males can reach maturity earlier but only around 16-21 years of age are actively breeding. Gestation period is between 14-16 months and the newborn is nursed for about 2 years. At birth it is about 2 meters long and can weights 80 kg.

Food and foraging:  False killer whales eat a variety of fish and cephalopods, but they specialize in specific type of preys according to the region. They preys generally include top predator fish, such as tuna, mahi mahi, swordfish often also main target of the fisheries. It has also been documented that they can attack small dolphins or even humpback or sperm whale, although this is not considered a usual behavior.

Threats and conservation:  False killer whales are listed as Data Deficient according to the IUCN Red List. However, the only population studied in Hawaii is considered endangered, having undergone a dramatic decline over the past 20 years. Main threats are by-catch, the widespread decline of their main preys as often overfished, the accumulation of high levels of persistent organic pollutants, which can potentially lower their resistance to disease.  They are also directly hunted in Japan, in Republic of South Korea, Indonesia Taiwan and West Indies.  As other deep ocean Delphinidae they are likely to be impacted by loud anthropogenic sounds.

 

References:

Whales and Dolphins of Arabia, Robert Baldwin, Park House England 2003, ISBN: 0952660504
http://www.iucnredlist.org/details/full/18596/0
http://www.cms.int/reports/small_cetaceans/data/P_crassidens/p_crassidens.htm
http://www.cascadiaresearch.org/hawaii/falsekillerwhale.htm