|Scientific Name:||Pseudorca crassidens|
|Species Authority:||(Owen, 1846)|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor/s:||Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L.|
|Reviewer/s:||Hammond, P.S. & Perrin, W.F. (Cetacean Red List Authority)|
Global trend or abundance data for this species are unavailable. Threats that could cause widespread declines include high levels of anthropogenic sound, especially military sonar and seismic surveys, and bycatch. Bycatch is particularly worrisome because of known unsustainable levels where fisheries are monitored in Hawaii and the presence of similar fisheries throughout the range of the species. The relative rarity of this species implied from the existing records makes it potentially vulnerable to low-level threats. The combination of possible declines driven by vulnerability to high-level anthropogenic sound sources and bycatch is believed sufficient that a 30% global reduction over three generations cannot be ruled out (criterion A).
|Range Description:||False killer whales are found in tropical to warm temperate zones, generally in relatively deep, offshore waters of all three major oceans. They do not generally range into latitudes higher than 50° in either hemisphere. However, some animals occasionally move into higher latitude waters. They are found in many semi-enclosed seas and bays (including the Sea of Japan, Bohai/Yellow Sea, Red Sea, and Persian Gulf), but they only occasionally occur in the Mediterranean Sea (Leatherwood et al. 1989). There are a few records for the Baltic Sea, which are considered extralimital. There are also records of false killer whales being found far into large rivers in China.|
Native:American Samoa (American Samoa); Anguilla; Antigua and Barbuda; Argentina; Aruba; Australia; Bahamas; Bangladesh; Barbados; Belize; Benin; Bermuda; Brazil; British Indian Ocean Territory; Brunei Darussalam; Cambodia; Cameroon; Canada; Cape Verde; Cayman Islands; Chile; China; Cocos (Keeling) Islands; Colombia; Congo; Congo, The Democratic Republic of the; Cook Islands; Costa Rica; Côte d'Ivoire; Croatia; Cuba; Denmark; Djibouti; Dominica; Dominican Republic; Ecuador; Egypt; El Salvador; Equatorial Guinea; Fiji; France; French Guiana; French Polynesia; Gabon; Gambia; Germany; Ghana; Gibraltar; Greece; Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Hong Kong; India; Indonesia; Iran, Islamic Republic of; Ireland; Israel; Italy; Jamaica; Japan; Jordan; Kenya; Kiribati; Kuwait; Liberia; Madagascar; Malaysia; Maldives; Malta; Marshall Islands; Martinique; Mauritania; Mexico; Micronesia, Federated States of; Morocco; Mozambique; Myanmar; Namibia; Netherlands; Netherlands Antilles; New Caledonia; New Zealand; Nicaragua; Nigeria; Niue; Northern Mariana Islands; Norway; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Portugal; Puerto Rico; Qatar; Saint Helena, Ascension and Tristan da Cunha; Saint Kitts and Nevis; Saint Lucia; Saint Pierre and Miquelon; Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Senegal; Sierra Leone; Singapore; Solomon Islands; Somalia; South Africa; Spain; Sri Lanka; Suriname; Syrian Arab Republic; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Tokelau; Tonga; Trinidad and Tobago; Turkmenistan; Turks and Caicos Islands; United Arab Emirates; United Kingdom; United States; Uruguay; Vanuatu; Venezuela; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Western Sahara; Yemen
|FAO Marine Fishing Areas:||
Atlantic – western central; Atlantic – northeast; Atlantic – eastern central; Atlantic – southwest; Atlantic – southeast; Atlantic – northwest; Indian Ocean – western; Indian Ocean – eastern; Mediterranean and Black Sea; Pacific – southeast; Pacific – northeast; Pacific – northwest; Pacific – eastern central; Pacific – western central; Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Studies on population structure in this species indicate both broad-scale (between-ocean) limits on gene flow (e.g., Kitchener et al. 1990), and limited gene flow on smaller (within-ocean) scales (Chivers et al. 2007). Abundance has been estimated for the coastal waters of China and Japan (16,000, CV=26%; Miyashita 1993), the northern Gulf of Mexico (1,038, CV = 71%; Mullin and Fulling 2004), and the U.S. EEZ of Hawaii (268, CV=108%; Barlow 2006). Abundance in the eastern tropical Pacific has been estimated as 39,800, CV=64%; Wade and Gerrodette 1993). There is no information on global trends in abundance.|
|Habitat and Ecology:||
False killer whales occur in tropical and temperate waters worldwide (Stacey et al. 1994; Odell and McClune 1999), generally in relatively deep, offshore waters. However, some animals may move into shallow and higher latitude waters, on occasion (including some semi-enclosed seas such as the Red Sea and the Mediterranean). The species seems to prefer warmer water temperatures. Off Hawaii, this species is found in both shallow (less than 200 m) and deep water (greater than 2000 m) habitats (Baird et al. 2008).
Although false killer whales eat primarily fish and cephalopods, they also have been known to attack small cetaceans, humpback whales, and sperm whales. They eat some large species of fish, such as mahi-mahi (also called dorado or dolphinfish), tunas (Alonso et al. 1999) and sailfish. In Hawaiian waters observational studies suggest that large game fish (mahi-mahi, tunas, billfish) may form the majority of their diet (Baird et al. 2008).
Although there is considerable controversy regarding the absolute level of declines, there is good evidence of large-scale reductions in many predatory fish populations (e.g., Baum et al. 2003, 2005; Sibert et al. 2006; Polacheck 2006) and over-fishing and collapse of several important “prey” fish stocks world-wide (e.g., Jackson et al. 2001). The effects of such fish population reductions and subsequent ecosystem changes on world-wide populations of false killer whales are unknown but could result in population declines.
False killer whales are occasionally taken in Japan for food and in St. Vincent in the Caribbean for meat and cooking oil (Jefferson et al. 1993; Odell and McClune, 1999). Considerable numbers of false killer whales may have also been killed in a past drive fishery in the Penghu Islands of Taiwan. Their interactions with fisheries, particularly their tendency to remove desired target species from longlines and sport fishing gear, have made them the targets of culling efforts. Around Iki Island, Japan, over 900 false killer whales were killed in drive fisheries from 1965 to 1980 in an attempt to reduce interactions with the yellowtail fishery (Jefferson et al. 1993; Odell and McClune, 1999). They continue to be taken opportunistically in Japanese harpoon and drive fisheries (Kishiro and Kasuya 1993). They are also hunted at least opportunistically in Indonesia, Taiwan and the West Indies. Some of the animals caught in the Japanese and Taiwanese drive fisheries have been kept alive and sold to oceanaria (Reeves et al. 2003).
Incidental takes of small numbers of false killer whales in gill nets has occurred off northern Australia, the Andaman Islands, the southern coasts of Brazil and in tuna purse seines in the eastern tropical Pacific. Dolphin entrapment in tuna purse seine nets may be providing artificial feeding opportunities for Pseudorca on other marine mammals (Odell and McClune, 1999). Although there have not been any records of false killer whale being killed in the large-mesh pelagic driftnets off eastern Taiwan, some are likely to be caught. Yang et al. (1999) reported on by-catch rates in Chinese coastal fisheries (trawl, gill and stow net), which may number in the hundreds per year for P. crassidens alone. False killer whales are occasionally hooked in longline fisheries, presumably as they are removing fish from the hooks. Death has been observed as a result of some hookings (Forney 2006). Many of the other hookings are inside the mouth or gullet and are likely to result in the subsequent death of the animals (Forney and Kobayashi 2005). Other types of non-lethal injuries may also occur (Baird and Gorgone 2005). Such longline fisheries are found throughout the central and western tropical Pacific, and similar interactions with false killer whales occur in other regions (e.g. Mediterranean, Bearzi 2002). Observer programs to monitor bycatch are limited.
Evidence from stranded individuals of several similar species indicates that they have swallowed discarded plastic items, which may eventually lead to death (e.g. Scott et al. 2001); this species may also be at risk
This species, like beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006).
Predicted impacts of global climate change on the marine environment may affect false killer whales, although the nature of impacts is unclear (Learmonth et al. 2006).
The species is listed in Appendix II of CITES
This is a relatively poorly-known species which, although mostly observed over deep water, is known to strand from many coasts. Abundance estimates as well as by-catch data do not exist for most areas, nor are there detailed accounts on migratory behaviour. Clearly, more research is needed.
|Citation:||Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. 2008. Pseudorca crassidens. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 22 May 2013.|
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