|Scientific Name:||Kogia sima|
|Species Authority:||(Owen, 1866)|
Kogia simus (Owen, 1866)
|Taxonomic Notes:||This taxonomic unit is treated as one species even though there is genetic evidence to suggest that there may be two separate species of Dwarf Sperm Whales, one in the Atlantic and one in the Indo-Pacific (Chivers et al. 2005). If confirmed, the Red List Category of this taxon may change.
Because this species was not generally recognized until the mid-1960s, there is still some confusion in the older literature about which species of Kogia is represented. The specific name, simus, was recently changed to sima to reflect proper gender.
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor/s:||Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J.K.B., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L.|
|Reviewer/s:||Hammond, P.S. & Perrin, W.F.|
There is considerable uncertainty about the status of this species, which may span a range from Least Concern to a more threatened category. It is fairly abundant but there is no information on trends in global abundance. This species is potentially vulnerable to low-level threats and a 30% global reduction over three generations (36 years; Taylor et al. 2007) cannot be ruled out.
|Range Description:||This species appears to be distributed widely in offshore waters of tropical and warm temperate zones, apparently preferring warmer waters, and perhaps more offshore waters (Caldwell and Caldwell 1989). A single record exists for the Mediterranean; this is considered extralimital. The species occurs in the Sea of Japan and in the Persian Gulf.
Its distribution shows somewhat more of a preference for warmer waters than does that of the Pygmy Sperm Whale; this species probably does not range as far into high-latitude waters.
There are two problems in trying to establish ranges for Kogia spp. First, members of this genus are only rarely identified at sea (and then usually not to species), and second, it is only recently that the two species have been clearly recognized as separate. As a consequence, most reliable records of either species are based on stranded individuals or occasionally on those taken in small fisheries for small cetaceans (Nagorsen 1985; Caldwell and Caldwell 1989; McAlpine 2002).
The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states. States within the hypothetical range but for which no confirmed records exist are included in the Presence Uncertain list.
Native:American Samoa (American Samoa); Angola (Angola); Anguilla; Antigua and Barbuda; Argentina; Aruba; Australia; Bahamas; Bahrain; Bangladesh; Barbados; Belize; Benin; Bermuda; Brazil (Rio Grande do Sul); British Indian Ocean Territory; Brunei Darussalam; Cambodia; Cameroon; Canada (British Columbia); Cape Verde; Cayman Islands; Chile (Valparaíso); China; Christmas Island; Cocos (Keeling) Islands; Colombia; Comoros; Congo; Congo, The Democratic Republic of the; Cook Islands; Costa Rica; Côte d'Ivoire; Cuba; Djibouti; Dominica; Dominican Republic; Ecuador (Galápagos); El Salvador; Equatorial Guinea; Fiji; French Guiana; French Polynesia; Gabon; Gambia; Ghana; Gibraltar; Grenada; Guadeloupe; Guam; Guatemala; Guinea; Guinea-Bissau; Guyana; Haiti; Honduras; Hong Kong; India; Indonesia; Iran, Islamic Republic of; Jamaica; Japan (Honshu); Kenya; Kiribati; Korea, Democratic People's Republic of; Korea, Republic of; Kuwait; Liberia; Madagascar; Malaysia; Maldives; Marshall Islands; Martinique; Mauritania; Mauritius; Mayotte; Mexico; Micronesia, Federated States of ; Montserrat; Morocco; Mozambique; Myanmar; Namibia; Nauru; Netherlands Antilles; New Caledonia; New Zealand (Kermadec Is., North Is.); Nicaragua; Nigeria; Niue; Norfolk Island; Northern Mariana Islands; Oman; Pakistan; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Portugal (Azores, Madeira); Puerto Rico; Qatar; Réunion; Saint Helena, Ascension and Tristan da Cunha; Saint Kitts and Nevis; Saint Lucia; Saint Vincent and the Grenadines; Samoa; Sao Tomé and Principe; Senegal; Seychelles; Sierra Leone; Singapore; Solomon Islands; Somalia; South Africa; Spain (Canary Is.); Sri Lanka; Suriname; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Togo; Tokelau; Tonga; Trinidad and Tobago; Turks and Caicos Islands; Tuvalu; United Arab Emirates; United States (Hawaiian Is.); Uruguay; Vanuatu; Venezuela, Bolivarian Republic of; Viet Nam; Virgin Islands, British; Virgin Islands, U.S.; Wallis and Futuna; Western Sahara; Yemen
|FAO Marine Fishing Areas:||
Atlantic – western central; Atlantic – eastern central; Atlantic – northeast; Atlantic – northwest; Atlantic – southeast; Atlantic – southwest; Indian Ocean – western; Indian Ocean – eastern; Pacific – western central; Pacific – eastern central; Pacific – northeast; Pacific – southeast; Pacific – northwest; Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
No estimates of global abundance exist. Abundance is often underestimated using visual survey methods because they dive for long periods and are inconspicuous when they surface (Barlow 1999). Delineations between stocks are often difficult to determine, therefore assessments should be considered ongoing processes. In the case of the Dwarf Sperm Whale, concern that sightings may be confused with or for the congener K. breviceps (the Pygmy Sperm Whale) further complicates interpretation of past estimates of abundance.
There are estimated to be about 19,172 (CV=66%) off Hawaii (Barlow 2006); 742 of both species of Kogia (CV=29%) in the northern Gulf of Mexico (Mullin and Fulling 2003); 395 of both species (CV=40/75%) in the western North Atlantic (Waring et al. 2006); and about 11,200 (CV=29%) in the eastern tropical Pacific (Wade and Gerrodette 1993). Using corrections for missed animals, Ferguson and Barlow (2001) re-estimated the abundance as approximately 150,000 of both species in the eastern tropical Pacific. There is evidence of site fidelity for individuals off the island of Hawaii (Baird et al. 2006), suggesting that within-basin population structure may exist.
|Habitat and Ecology:||Dwarf Sperm Whales appear to feed primarily on deep-water cephalopods, but also take other prey types (dos Santos and Haimovici 2001). About 38 different prey species are known from South African waters (Ross 1979).|
Although never hunted commercially, these animals were sometimes harpooned by 19th-century whalers. Dwarf Sperm Whales were taken in a small harpoon fishery for Pilot Whales at St. Vincent in the Lesser Antilles, in Japan, and occasionally in an aboriginal fishery on Lamalera Island in Indonesia, and have also been reported from fish markets in Sri Lanka (Caldwell and Caldwell, 1989). This species is also taken occasionally by harpoon off Taiwan (J. Wang pers. comm.).
A few Dwarf Sperm Whales are known to have died incidentally in fisheries throughout their range. When taken in commercial fisheries the numbers are so few that it is considered a rare bycatch. Zerbini and Kotas (1998) reported some bycatch in the Brazilian driftnet fishery.
Both Kogia species have been reported with plastic bags in their stomachs that may have prevented digestion of food and ultimately brought death. Perhaps the textural or visual quality of the plastic was similar to that of squid and thus enticed the whales to devour it (Caldwell and Caldwell 1989).
In general, there are not known to be any serious human impacts, and subpopulations are probably relatively less affected by human activities than are those of most other cetaceans (Caldwell and Caldwell 1989).
While impacts of high levels of anthropogenic sound have been well documented only for Beaked Whales (Simmonds and Lopez-Jurado 1991, Frantzis 1998, Balcomb and Claridge 2001, US Dept of Commerce and US Navy 2001, Jepson et al. 2003, Fernandez et al. 2005), there are examples for a number of other species of odontocetes of potential impacts. While conclusive evidence of cause and effect are often lacking, strong avoidance reactions, embayments or mass stranding events have been spatially and temporally associated with high levels of anthropogenic sound for Short-finned Pilot Whales (Hohn et al. 2006), Melon-headed Whales (Southall et al. 2006), Atlantic Spotted Dolphin (Balcomb and Claridge 2001), Dwarf Sperm Whales (Hohn et al. 2006), and Dall’s Porpoise (Balcomb pers. comm.). It should be recognized that high levels of anthropogenic sound have the potential to impact all deep diving odontocete species.
In 2005, a large series of unusual stranding events over about three weeks in and around Taiwan included at least 13 Dwarf Sperm Whales, many of which were live strandings (Wang and Yang 2006, Yang et al. 2008). It is unknown if high-intensity anthropogenic sounds resulted in these strandings. However, “bubble-like lesions” were reported in some individuals by Yang et al. (2008). There are high levels of unexplained strandings in the Gulf of Mexico and the Atlantic coast of Florida that warrant concern (Waring et al. 2006).
Predicted impacts of global climate change on the marine environment may affect Dwarf Sperm Whales, although the nature of impacts is unclear (Learmonth et al. 2006).
|Conservation Actions:||The species is listed in Appendix II of CITES. Research is needed to determine the impact of threats on this species.|
|Citation:||Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J.K.B., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. 2012. Kogia sima. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 17 April 2014.|