逆戟鲸或虎鲸具有世界性分布，并且已经记录或建议了几个不同的种群或类型。三到五种类型的逆戟鲸可能截然不同，足以被视为不同的种族、亚种，甚至可能是物种（参见物种问题）。IUCN在 2008年报告说，“该属的分类学显然需要重新审视，很可能O. orca将在未来几年内分裂成许多不同的物种或至少是亚种。”尽管不同虎鲸群的生态独特性存在很大差异，这使得简单的类型区分变得复杂。长期以来，人们认为不同地区的食哺乳动物虎鲸可能是密切相关，但基因检测驳斥了这一假设。 北部海域 北太平洋 1970年代和 80年代加拿大和美国西海岸的研究确定了以下三种类型： 驻留（食鱼）逆戟鲸：弯曲的背鳍是驻留雌性的典型特征。 居民：这些是东北太平洋沿岸水域中最常见的三种种群。居民的饮食主要包括鱼类，有时还包括鱿鱼，他们生活在称为豆荚的复杂而有凝聚力的家庭群体中。女性居民的特征是具有圆形的背鳍尖端，终止于尖角。他们始终访问相同的区域。不列颠哥伦比亚省和华盛顿常驻种群是世界上研究最深入的海洋哺乳动物之一。常驻虎鲸可分为至少三个不同的社区；阿拉斯加北部、南部和南部.阿拉斯加南部常驻虎鲸分布于阿拉斯加东南部至科迪亚克群岛，数量超过 700只。这些鲸鱼由两个杂交氏族组成，它们以声音叫声区分，并且它们的活动范围重叠。北部居民社区居住在从阿拉斯加东南部到温哥华岛的沿海和内陆水域。它由三个部族和16个群组成，共有 300多头逆戟鲸。南部居民社区通常栖息在不列颠哥伦比亚省南部和华盛顿的内陆水域，但也可以在温哥华岛、华盛顿、俄勒冈和加利福尼亚的外海发现。它们由一个氏族和三个豆荚组成，数量不到 80只，被列为濒危物种。 Transient or Bigg's：这些逆戟鲸的饮食几乎完全由海洋哺乳动物组成.他们和居民住在同一地区，但两人互相避开。暂住者通常以小团体形式旅行，通常由两到六只动物组成，并且与居民相比，它们的家庭纽带不那么牢固。瞬变以较少变化和不太复杂的方言发声。与居民相比，雌性瞬变的特征是更多的三角形和尖背鳍。背鳍周围的灰色或白色区域，被称为“马鞍斑”，在居民身上通常含有一些黑色。然而，瞬变的马鞍斑块是实心的且均匀的灰色。瞬变沿海岸广泛漫游；在阿拉斯加南部和加利福尼亚州都发现了一些个体。瞬态也被称为Bigg's orca以纪念鲸鱼学家 Michael Bigg.该术语已变得越来越普遍，并可能最终取代瞬态标签。据估计，瞬态生态型在 70万年前就已经分化。北美至少有三种不同的瞬变“种群”，即从威廉王子湾到基奈峡湾的 AT1种群、阿拉斯加湾/阿留申群岛/白令海(GOA/AI/BS)种群和西海岸种群范围从阿拉斯加东南部到加利福尼亚。AT1被认为是耗尽的库存；它受到埃克森瓦尔迪兹号漏油事件的影响并在 1989年至 2004年间从 22只减少到 8只。GOA/AI/BS的鲸鱼数量可能约为 500头，而西海岸的瞬态逆戟鲸数量超过 320头，阿拉斯加东南部、不列颠哥伦比亚省和华盛顿有 200多头，加利福尼亚州外有 100多头逆戟鲸.加利福尼亚的瞬变似乎与那些更远的北部和西海岸的瞬变混合得不多，可能会被划分为子社区。 近海：1988年，一名座头鲸研究人员在开阔水域观察到它们时，在东北太平洋发现了第三个虎鲸种群。顾名思义，它们远离海岸，主要以成群的鱼为食。然而，由于它们的背鳍很大，有伤痕和缺口，类似于捕猎哺乳动物的瞬态背鳍，因此它们可能也吃哺乳动物和鲨鱼。它们大多在温哥华岛西海岸和海达瓜伊附近遇到.近海通常以 20-75只为一组聚集，偶尔会看到多达 200只的更大群体。人们对它们的习性知之甚少，但它们在基因上与居民和暂住者截然不同。Offshores似乎比其他的小，雌性的特征是背鳍尖端连续圆形。 在俄罗斯远东地区和日本北海道的沿海地区也存在独立的食鱼和食哺乳动物虎鲸群落。俄罗斯虎鲸常见于堪察加半岛和指挥官群岛周围。在俄罗斯海域发现了超过 2，000只类似居民的虎鲸和 130只类似暂住的虎鲸。在热带太平洋东部，至少有 195只虎鲸被编目，范围从北部的下加利福尼亚州和加利福尼亚湾到南部的南美洲西北海岸和西部的夏威夷。逆戟鲸似乎经常出现在加拉帕戈斯群岛附近.在夏威夷海域发现的逆戟鲸可能属于太平洋中部的一个更大的种群。 北大西洋及邻近地区 虎鲸在挪威Vestfjorden拍尾巴 据估计，北大西洋至少栖息着 15，000头鲸鱼。在东北大西洋，已经提出了两种逆戟鲸生态型。1型逆戟鲸由七种单倍型组成，包括挪威和冰岛的以鲱鱼为食的逆戟鲸和北海以鲭鱼为食的逆戟鲸，以及挪威以外的以海豹为食的逆戟鲸。2型逆戟鲸由两种单倍型组成，主要以须鲸为食。 在地中海，逆戟鲸被认为是“访客”，很可能来自北大西洋，而且越往东，虎鲸的踪迹就越少。然而，直布罗陀海峡全年都有少量种群，2011年约有 39只。热带非洲西海岸也可能存在不同的种群，它们的饮食普遍。 大西洋西北部的种群全年都在拉布拉多和纽芬兰周围发现，而当冰融化时，一些个体会季节性地前往加拿大东部北极地区的水域。南至科德角和长岛都有目击到这些鲸鱼的记录。这个种群可能与在格陵兰岛附近看到的逆戟鲸是连续的。全年都可以在加勒比海看到虎鲸，据估计，墨西哥湾北部有 267头虎鲸（截至 2020年）。 北印度洋 印度洋北部已对 50多头鲸鱼个体进行了编目，其中包括2008年在波斯湾和2015年在斯里兰卡附近发现的两只鲸鱼。 南部海域 逆戟鲸搁浅在瓦尔德斯半岛捕捉海狮 一小群逆戟鲸季节性地造访阿根廷东海岸瓦尔德斯半岛的北端，在岸边捕食海狮和象海豹，暂时搁浅自己。在南非外海，存在一种独特的“扁平牙齿”形态类型，它捕食鲨鱼。一对雄性逆戟鲸Port和 Starboard因在南非海岸捕猎大白鲨和其他鲨鱼而闻名。 虎鲸遍布澳大利亚、新西兰和巴布亚新几内亚的水域。它们全年都在新西兰水域被发现，而在澳大利亚附近，它们季节性地集中在西北部的宁格鲁礁近岸水域和西南部的布雷默地区。遗传证据表明，新西兰、澳大利亚西北部和西南部的虎鲸形成了三个不同的种群。新西兰逆戟鲸主要捕食鲨鱼和鳐鱼。 南极 据估计，南极周围大约有 25，000只逆戟鲸，有四种类型被记录在案。苏联研究人员在 1980年代描述了两个矮小物种，名为Orcinus nanus和Orcinus glacialis，但大多数鲸类研究人员对它们的地位持怀疑态度，并且很难将它们与下述类型直接联系起来。 逆戟鲸变异的一些例子 A型或南极逆戟鲸看起来像“典型”逆戟鲸，体型庞大，黑白相间，眼罩中等大小，生活在开阔水域，主要以小须鲸为食。 B1型或浮冰虎鲸比 A型小。它有一个大的白色眼罩。它身体的大部分深色部分是中灰色而不是黑色，尽管它有一块深灰色斑块，称为“背角”，从前额一直延伸到背鳍的后面。白色区域染成淡黄色。它主要以海豹为食。B1型逆戟鲸在阿德莱德岛和南极半岛大陆之间大量存在。 B2型或Gerlache逆戟鲸在形态上与 B1型相似，但更小。这种生态型已被记录为以企鹅和海豹为食，并且经常在Gerlache海峡发现。 C型或罗斯海虎鲸是最小的生态型，并且比其他虎鲸生活在更大的群体中。它的眼罩明显向前倾斜，而不是平行于身体轴线。和 B型一样，它主要是白色和中灰色，有深灰色的背披和黄色斑块。它唯一观察到的猎物是南极鳕鱼。 根据 1955年在新西兰大规模搁浅的照片以及自 2004年以来的六次海上目击事件， D型或亚南极逆戟鲸首次被识别出来。这种类型的第一个视频记录是在 2014年在凯尔盖朗群岛和克罗泽群岛之间拍摄的，并且再次2017年在智利合恩角海岸外。它可以通过白色的小眼罩、比通常的背鳍更窄更短、球状头部（类似于领航鲸）和更小的牙齿来识别。它的地理范围似乎在南纬40°S和60°S之间的亚南极海域环绕全球.虽然它的饮食尚未确定，但根据延绳钓船只周围的照片确定，它可能包括鱼类，其中 D型逆戟鲸似乎正在捕食巴塔哥尼亚齿鱼( Dissostichus eleginoides )。 B型和 C型生活在靠近冰的地方，这些水域中的硅藻可能是这两种类型的淡黄色的原因。线粒体 DNA序列支持这些是最近分化的独立物种的理论。最近，完整的线粒体测序表明 B型和 C型被认为是不同的物种，北太平洋的瞬变物种也应如此，而将其他物种作为亚种等待更多数据。对整个线粒体基因组进行测序的先进方法揭示了不同人群之间 DNA的系统差异。2019年对 D型虎鲸的一项研究还发现，它们与其他种群不同，甚至可能是一个独特的物种。 英文原文： Orcas or killer whales have a cosmopolitan distribution and several distinct populations or types have been documented or suggested. Three to five types of orcas may be distinct enough to be considered different races， subspecies， or possibly even species (see Species problem). The IUCN reported in 2008，“The taxonomy of this genus is clearly in need of review， and it is likely that O. orca will be split into a number of different species or at least subspecies over the next few years.“ Although large variation in the ecological distinctiveness of different orca groups complicate simple differentiation into types. Mammal-eating orcas in different regions were long thought likely to be closely related， but genetic testing has refuted this hypothesis. Northern waters North Pacific Research off the west coast of Canada and the United States in the 1970s and 1980s identified the following three types: Resident (fish-eating) orcas: The curved dorsal fins are typical of resident females. Resident: These are the most commonly sighted of the three populations in the coastal waters of the northeast Pacific. Residents' diets consist primarily of fish and sometimes squid， and they live in complex and cohesive family groups called pods. Female residents characteristically have rounded dorsal fin tips that terminate in a sharp corner. They visit the same areas consistently. British Columbia and Washington resident populations are amongst the most intensively studied marine mammals anywhere in the world. Resident orcas can be divided into at least three distinct communities; northern， southern and southern Alaskan. Southern Alaskan resident orcas are distributed from southeastern Alaska to the Kodiak Archipelago and number over 700 individuals. These whales consist of two interbreeding clans distinguished by acoustic calls and whose ranges overlap. The northern resident community lives in coastal and inland waters from southeastern Alaska to Vancouver Island. It consists of three clans and 16 pods and number over 300 orcas total. The southern resident community generally inhabits the inland waters of southern British Columbia and Washington， but can be found in the outer waters off Vancouver Island， Washington， Oregon and California. They consist of one clan and three pods， and number less than 80 individuals and are listed as endangered. Transient or Bigg's: The diets of these orcas consist almost exclusively of marine mammals. They live in the same areas as residents， but the two avoid each other. Transients generally travel in small groups， usually of two to six animals， and have less persistent family bonds than residents. Transients vocalize in less variable and less complex dialects. Female transients are characterized by more triangular and pointed dorsal fins than those of residents. The grey or white area around the dorsal fin， known as the “saddle patch“， often contains some black colouring in residents. However， the saddle patches of transients are solid and uniformly grey. Transients roam widely along the coast; some individuals have been sighted in both southern Alaska and California. Transients are also referred to as Bigg's orca in honour of cetologist Michael Bigg. The term has become increasingly common and may eventually replace the transient label. The transient ecotype is estimated to have diverged 700，000 years ago. There are at least three different “stocks“ of transients off North America， the AT1 stock which occurs from Prince William Sound to Kenai Fjords， the Gulf of Alaska/Aleutian Islands/Bering Sea (GOA/AI/BS) stock and the west coast stock which ranges from southeast Alaska to California. AT1 is considered a depleted stock; it was affected by the Exxon Valdez oil spill and declined from 22 individuals to eight between 1989 and 2004. The GOA/AI/BS stock may number around 500 whales while the west coast transients number over 320 orcas with over 200 along southeast Alaska， British Columbia and Washington and over 100 orcas off California. California transients do not appear to intermingle much with those further north and west coast transients may be divided into sub-communities. Offshore: A third population of orcas in the northeast Pacific was discovered in 1988， when a humpback whale researcher observed them in open water. As their name suggests， they travel far from shore and feed primarily on schooling fish. However， because they have large， scarred and nicked dorsal fins resembling those of mammal-hunting transients， it may be that they also eat mammals and sharks. They have mostly been encountered off the west coast of Vancouver Island and near Haida Gwaii. Offshores typically congregate in groups of 20–75， with occasional sightings of larger groups of up to 200. Little is known about their habits， but they are genetically distinct from residents and transients. Offshores appear to be smaller than the others， and females are characterized by dorsal fin tips that are continuously rounded. Separate fish-eating and mammal-eating orca communities also exist off the coast of the Russian Far East and Hokkaido， Japan. Russian orcas are commonly seen around the Kamchatka Peninsula and Commander Islands. Over 2，000 individual resident-like orcas and 130 transient-like orcas have been identified off Russia. At least 195 individual orcas have been cataloged in the eastern tropical Pacific， ranging from Baja California and the Gulf of California in the north to the northwest coast of South America in the south and west towards Hawaii. Orcas appear to regularly occur off the Galápagos Islands. Orcas sighted in Hawaiian waters may belong to a greater population in the central Pacific. North Atlantic and adjacent Orca tail-slapping in Vestfjorden， Norway At least 15，000 whales are estimated to inhabit the North Atlantic. In the Northeast Atlantic， two orca ecotypes have been proposed. Type 1 orcas consist of seven haplotypes and include herring-eating orcas of Norway and Iceland and mackerel-eating orcas of the North Sea， as well as seal-eating orcas off Norway. Type 2 orcas consist of two haplotypes， and mainly feed on baleen whales. In the Mediterranean Sea， orcas are considered “visitors“， likely from the North Atlantic， and sightings become less frequent further east. However， a small year-round population exists in the Strait of Gibraltar， which numbered around 39 in 2011. Distinct populations may also exist off the west coast of tropical Africa， which have generalized diets. The northwest Atlantic population is found year-round around Labrador and Newfoundland， while some individuals seasonally travel to the waters of the eastern Canadian Arctic when the ice has melted. Sightings of these whales have been documented as far south as Cape Cod and Long Island. This population is possibly continuous with orcas sighted off Greenland. Orcas are sighted year-round in the Caribbean Sea， and an estimated 267 (as of 2020) is documented in the northern Gulf of Mexico. North Indian Ocean Over 50 individual whales have been cataloged in the northern Indian Ocean， including two individuals that were sighted in the Persian Gulf in 2008 and off Sri Lanka in 2015. Southern waters Orca beaching to capture sea lion at Valdes Peninsula A small population of orcas seasonally visits the northern point of the Valdes Peninsula on the east coast of Argentina and hunt for sea lions and elephant seals on the shore， temporary stranding themselves. Off South Africa， a distinctive “flat-tooth“ morphotype exists and preys on sharks. A pair of male orcas， Port and Starboard， have become well known for hunting great whites and other sharks off the South African coast. Orcas occur throughout the waters of Australia， New Zealand and Papua New Guinea. They are sighted year round in New Zealand waters， while off Australia， they are seasonally concentrated off the northwest， in the inshore waters of Ningaloo Reef， and the southwest， at the Bremer region. Genetic evidence shows that the orcas of New Zealand， and northwest and southwest Australia form three distinct populations. New Zealand orcas mainly prey on sharks and rays. Antarctic Around 25，000 orcas are estimated around the Antarctic， and four types have been documented. Two dwarf species， named Orcinus nanus and Orcinus glacialis， were described during the 1980s by Soviet researchers， but most cetacean researchers are skeptical about their status， and linking these directly to the types described below is difficult. Some examples of variations in orcas Type A or Antarctic orcas look like a “typical“ orca， a large， black-and-white form with a medium-sized white eye patch， living in open water and feeding mostly on minke whales. Type B1 or pack ice orcas are smaller than type A. It has a large white eye patch. Most of the dark parts of its body are medium grey instead of black， although it has a dark grey patch called a “dorsal cape“ stretching back from its forehead to just behind its dorsal fin. The white areas are stained slightly yellow. It feeds mostly on seals. Type B1 orca are abundant between Adelaide Island and the mainland Antarctic peninsula. Type B2 or Gerlache orcas are morphologically similar to Type B1， but smaller. This ecotype has been recorded feeding on penguins and seals， and is often found in the Gerlache Strait. Type C or Ross Sea orcas are the smallest ecotype and live in larger groups than the others. Its eye patch is distinctively slanted forwards， rather than parallel to the body axis. Like type B， it is primarily white and medium grey， with a dark grey dorsal cape and yellow-tinged patches. Its only observed prey is the Antarctic cod. Type D or Sub-Antarctic orcas were first identified based on photographs of a 1955 mass stranding in New Zealand and six at-sea sightings since 2004. The first video record of this type was made in 2014 between the Kerguelen and Crozet Islands， and again in 2017 off the coast of Cape Horn， Chile. It is recognizable by its small white eye patch， narrower and shorter than usual dorsal fin， bulbous head (similar to a pilot whale)， and smaller teeth. Its geographic range appears to be circumglobal in sub-Antarctic waters between latitudes 40°S and 60°S. Although its diet is not determined， it likely includes fish， as determined by photographs around longline vessels， where Type D orcas appeared to be preying on Patagonian toothfish (Dissostichus eleginoides). Types B and C live close to the ice， and diatoms in these waters may be responsible for the yellowish colouring of both types. Mitochondrial DNA sequences support the theory that these are recently diverged separate species. More recently， complete mitochondrial sequencing indicates the types B and C be recognized as distinct species， as should the North Pacific transients， leaving the others as subspecies pending additional data. Advanced methods that sequenced the entire mitochondrial genome revealed systematic differences in DNA between different populations. A 2019 study of Type D orcas also found them to be distinct from other populations and possibly even a unique species.
