The orca or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

species in the genus '' Orcinus'' and is recognizable by its black-and-white patterned body. A cosmopolitan species, orcas can be found in all of the world's oceans in a variety of marine environments, from Arctic and Antarctic regions to tropical seas. Orcas have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals such as

seals Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impress an emblem, used as a means of a ...

and other species of dolphin. They have been known to attack

baleen whale Baleen whales (systematic name Mysticeti), also known as whalebone whales, are a parvorder of carnivorous marine mammals of the infraorder Cetacea (whales, dolphins and porpoises) which use keratinaceous baleen plates (or "whalebone") in their ...

calves, and even adult whales. Orcas are apex predators, as they have no natural predators. They are highly social; some populations are composed of very stable matrilineal family groups (pods) which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviours, which are often specific to a particular group and passed across generations, have been described as manifestations of animal culture. The International Union for Conservation of Nature assesses the orca's conservation status as

data deficient A data deficient (DD) species is one which has been categorized by the International Union for Conservation of Nature (IUCN) as offering insufficient information for a proper assessment of conservation status to be made. This does not necessaril ...

because of the likelihood that two or more orca types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with human fisheries. In late 2005, the

southern resident orca The southern resident orcas, also known as the southern resident killer whales (SRKW), are the smallest of four separate, non-interbreeding communities of the exclusively fish-eating ecotype of orca in the northeast portion of the North Pacific O ...

s, which swim in British Columbia and Washington waters, were placed on the U.S. Endangered Species list. Wild orcas are not considered a threat to humans, and no fatal attack on humans has ever been documented. There have been cases of captive orcas killing or injuring their handlers at marine theme parks. Orcas feature strongly in the mythologies of indigenous cultures, and their reputation in different cultures ranges from being the souls of humans to merciless killers.

Naming

Orcas are commonly referred to as "killer whales", despite being a type of dolphin. Since the 1960s, the use of "orca" instead of "killer whale" has steadily grown in common use. The genus name ''Orcinus'' means "of the kingdom of the dead", or "belonging to Orcus". Ancient Romans originally used ''orca'' (pl. ''orcae'') for these animals, possibly borrowing Ancient Greek (''óryx''). This Greek word which referred (among other things) to a whale species, perhaps a

narwhal The narwhal, also known as a narwhale (''Monodon monoceros''), is a medium-sized toothed whale that possesses a large "tusk" from a protruding canine tooth. It lives year-round in the Arctic waters around Greenland, Canada and Russia. It is o ...

. As part of the family Delphinidae, the species is more closely related to other oceanic dolphins than to other whales. They are sometimes referred to as "blackfish", a name also used for other whale species. "Grampus" is a former name for the species, but is now seldom used. This meaning of "grampus" should not be confused with the genus '' Grampus'', whose only member is Risso's dolphin.

Taxonomy

''Orcinus orca'' is the only recognized

species in the genus '' Orcinus'', and one of many animal species originally described by Carl Linnaeus in his landmark 1758 10th edition of ''Systema Naturae''.

Konrad Gessner Conrad Gessner (; la, Conradus Gesnerus 26 March 1516 – 13 December 1565) was a Old Swiss Confederacy, Swiss physician, natural history, naturalist, bibliographer, and philologist. Born into a poor family in Zürich, Switzerland, his father ...

wrote the first scientific description of an orca in his ''Piscium & aquatilium animantium natura'' of 1558, part of the larger '' Historia animalium'', based on examination of a dead stranded animal in the

Bay of Greifswald The Bay of Greifswald Zum Wal in der Marienkirche
(in German). St. Mary's Church, Greifswald. Retrieved February 16, 2010 The orca is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago. The orca lineage probably branched off shortly thereafter. Although it has morphological similarities with the false killer whale, the pygmy killer whale and the pilot whales, a study of cytochrome b gene sequences indicates that its closest extant relatives are the snubfin dolphins of the genus ''

Orcaella The snubfin dolphins (''Orcaella'') are a genus of cetaceans containing two members: the Irrawaddy dolphin (''Orcaella brevirostris'') and the Australian snubfin dolphin (''Orcaella heinsohni''). The genus was long believed to be monotypic with t ...

''. However, a more recent (2018) study places the orca as a sister taxon to the Lissodelphininae, a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

that includes '' Lagenorhynchus'' and '' Cephalorhynchus''. In contrast, a 2019 phylogenetic study found the orca to be the second most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

member of the Delphinidae, with only the Atlantic white-sided dolphin (''Leucopleurus acutus'') being more basal.

Types

The three to five types of orcas may be distinct enough to be considered different races,
Status of Killer Whales in Canada
. Contract report to the Committee on the Status of Endangered Wildlife in Canada, Ottawa, ON, Canada. Also published a
Status of Killer Whales, ''Orcinus orca'', in Canada
''The Canadian Field-Naturalist'' 115 (4) (2001), 676–701. Retrieved January 26, 2010.

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

, or possibly even species (see

Species problem The species problem is the set of questions that arises when biologists attempt to define what a species is. Such a definition is called a species concept; there are at least 26 recognized species concepts. A species concept that works well for se ...

). The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

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, research off the west coast of North America has identified fish-eating "residents", mammal-eating "transients" and "offshores". Other populations have not been as well studied, although specialized fish and mammal eating orcas have been distinguished elsewhere. Mammal-eating orcas in different regions were long thought likely to be closely related, but genetic testing has refuted this hypothesis. Four types have been documented in the

Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...

, Types A–D. 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 Complete mitochondrial sequencing indicates the two Antarctic groups (types B and C) should be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data. A 2019 study of Type D orcas also found them to be distinct from other populations and possibly even a unique species.

Characteristics

Orcas are the largest extant members of the dolphin family. Males typically range from long and weigh in excess of . Females are smaller, generally ranging from and weighing about . Calves at birth weigh about and are about long. The skeleton of the orca is typical for an oceanic dolphin, but more robust. With their distinctive pigmentation, adult orcas are seldom confused with any other species. When seen from a distance, juveniles can be confused with false orcas or Risso's dolphins. The orca typically has a sharply contrasted black-and-white body; being mostly black on the upper side and white on the underside. The entire lower jaw is white and from here, the colouration stretches across the underside to the genital area; narrowing between the flippers then widening some and extending into lateral flank patches close to the end. The tail fluke is also white on the underside, while the eyes have white oval-shaped patches behind and above them, and a grey or white "saddle patch" exists behind the dorsal fin and across the back. Males and females also have different patterns of black and white skin in their genital areas. In newborns, the white areas are yellow or orange coloured. Antarctic orcas may have pale grey to nearly white backs. Some Antarctic orcas are brown and yellow due to diatoms in the water. Both albino and

melanistic The term melanism refers to black pigment and is derived from the gr, μελανός. Melanism is the increased development of the dark-colored pigment melanin in the skin or hair. Pseudomelanism, also called abundism, is another variant of pi ...

orcas have been documented. Orca wal 3

Orca pectoral fins are large and rounded, resembling paddles, with those of males significantly larger than those of females. Dorsal fins also exhibit sexual dimorphism, with those of males about high, more than twice the size of the female's, with the male's fin more like a tall, elongated

isosceles triangle In geometry, an isosceles triangle () is a triangle that has two sides of equal length. Sometimes it is specified as having ''exactly'' two sides of equal length, and sometimes as having ''at least'' two sides of equal length, the latter versio ...

, whereas the female's is shorter and more curved. In the skull, adult males have longer lower jaws than females, as well as larger occipital crests. The snout is blunt and lacks the beak of other species. The orca's teeth are very strong, and its jaws exert a powerful grip; the upper teeth fall into the gaps between the lower teeth when the mouth is closed. The firm middle and back teeth hold prey in place, while the front teeth are inclined slightly forward and outward to protect them from powerful jerking movements. Orcas have good eyesight above and below the water, excellent hearing, and a good sense of touch. They have exceptionally sophisticated echolocation abilities, detecting the location and characteristics of prey and other objects in the water by emitting clicks and listening for echoes, as do other members of the dolphin family. The mean body temperature of the orca is . Like most marine mammals, orcas have a layer of insulating

blubber Blubber is a thick layer of vascularized adipose tissue under the skin of all cetaceans, pinnipeds, penguins, and sirenians. Description Lipid-rich, collagen fiber-laced blubber comprises the hypodermis and covers the whole body, except for pa ...

ranging from thick beneath the skin. The pulse is about 60 heartbeats per minute when the orca is at the surface, dropping to 30 beats/min when submerged.Spencer, M. P., Gornall 3rd, T. A., & Poulter, T. C. (1967). Respiratory and cardiac activity of killer whales. ''Journal of applied physiology'', 22(5), 974–981. https://doi.org/10.1152/jappl.1967.22.5.974 An individual orca can often be identified from its dorsal fin and saddle patch. Variations such as nicks, scratches, and tears on the dorsal fin and the pattern of white or grey in the saddle patch are unique. Published directories contain identifying photographs and names for hundreds of North Pacific animals. Photographic identification has enabled the local population of orcas to be counted each year rather than estimated, and has enabled great insight into life cycles and social structures.

Range and habitat

Orcas are found in all oceans and most seas. Due to their enormous range, numbers, and density, relative distribution is difficult to estimate, but they clearly prefer higher latitudes and coastal areas over pelagic environments. Areas which serve as major study sites for the species include the coasts of Iceland, Norway, the Valdes Peninsula of Argentina, the

Crozet Islands The Crozet Islands (french: Îles Crozet; or, officially, ''Archipel Crozet'') are a sub-Antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarcti ...

, New Zealand and parts of the west coast of North America, from California to Alaska. Systematic surveys indicate the highest densities of orcas (>0.40 individuals per 100 km²) in the northeast Atlantic around the Norwegian coast, in the north Pacific along the Aleutian Islands, the Gulf of Alaska and in the Southern Ocean off much of the coast of Antarctica. They are considered "common" (0.20–0.40 individuals per 100 km²) in the eastern Pacific along the coasts of British Columbia, Washington and Oregon, in the North Atlantic Ocean around Iceland and the Faroe Islands. In the Antarctic, orcas range up to the edge of the pack ice and are believed to venture into the denser pack ice, finding open

leads Lead is a chemical element with symbol Pb and atomic number 82. Lead or The Lead may also refer to: Animal handling * Leash, or lead * Lead (leg), the leg that advances most in a quadruped's cantering or galloping stride * Lead (tack), a lin ...

much like beluga whales in the Arctic. However, orcas are merely seasonal visitors to Arctic waters, and do not approach the pack ice in the summer. With the rapid

Arctic sea ice The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall a ...

decline in the Hudson Strait, their range now extends deep into the northwest Atlantic. Occasionally, orcas swim into freshwater rivers. They have been documented up the

Columbia River The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...

in the United States. They have also been found in the

Fraser River The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Blackrock Mountain in the Rocky Mountains and flowing for , into the Strait of Georgia just south of the City of Vancouver. The river's annual d ...

in Canada and the Horikawa River in Japan. Migration patterns are poorly understood. Each summer, the same individuals appear off the coasts of British Columbia and Washington. Despite decades of research, where these animals go for the rest of the year remains unknown. Transient pods have been sighted from southern Alaska to central California.

Population

Worldwide population estimates are uncertain, but recent consensus suggests a minimum of 50,000 (2006). Local estimates include roughly 25,000 in the Antarctic, 8,500 in the tropical Pacific, 2,250–2,700 off the cooler northeast Pacific and 500–1,500 off Norway. Japan's Fisheries Agency estimated in the 2000s that 2,321 orcas were in the seas around Japan.

Feeding

Orcas are apex predators, meaning that they themselves have no natural predators. They are sometimes called "wolves of the sea", because they hunt in groups like wolf packs. Orcas hunt varied prey including fish,

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s, mammals, seabirds, and

sea turtles Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, ...

. Different populations or ecotypes may specialize, and some can have a dramatic impact on prey species. However, whales in tropical areas appear to have more generalized diets due to lower food productivity. Orcas spend most of their time at shallow depths, but occasionally dive several hundred metres depending on their prey.

Fish

Fish-eating orcas prey on around 30 species of fish. Some populations in the Norwegian and Greenland sea specialize in

herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...

and follow that fish's autumnal migration to the Norwegian coast. Salmon account for 96% of northeast Pacific residents' diet, including 65% of large, fatty Chinook.

Chum salmon The chum salmon (''Oncorhynchus keta''), also known as dog salmon or keta salmon, is a species of anadromous salmonid fish from the genus '' Oncorhynchus'' (Pacific salmon) native to the coastal rivers of the North Pacific and the Beringian A ...

are also eaten, but smaller sockeye and pink salmon are not a significant food item. Depletion of specific prey species in an area is, therefore, cause for concern for local populations, despite the high diversity of prey. On average, an orca eats each day. While salmon are usually hunted by an individual whale or a small group, herring are often caught using carousel feeding: the orcas force the herring into a tight ball by releasing bursts of bubbles or flashing their white undersides. They then slap the ball with their tail flukes, stunning or killing up to 15 fish at a time, then eating them one by one. Carousel feeding has only been documented in the Norwegian orca population, as well as some oceanic dolphin species. In New Zealand, sharks and rays appear to be important prey, including eagle rays,

long-tail In statistics and business, a long tail of some probability distribution, distributions of numbers is the portion of the distribution having many occurrences far from the "head" or central part of the distribution. The distribution could involv ...

and

short-tail stingray The short-tail stingray or smooth stingray (''Bathytoshia brevicaudata'') is a common species of stingray in the family Dasyatidae. It occurs off southern Africa, typically offshore at a depth of , and off southern Australia and New Zealand, fro ...

s, common threshers,

smooth hammerhead The smooth hammerhead (''Sphyrna zygaena'') is a species of hammerhead shark, and part of the family Sphyrnidae. This species is named "smooth hammerhead" because of the distinctive shape of the head, which is flattened and laterally extended int ...

blue shark The blue shark (''Prionace glauca''), also known as the great blue shark, is a species of requiem shark, in the family Carcharhinidae, which inhabits deep waters in the world's temperate and tropical oceans. Averaging around and preferring co ...

basking sharks The basking shark (''Cetorhinus maximus'') is the second-largest living shark and fish, after the whale shark, and one of three plankton-eating shark species, along with the whale shark and megamouth shark. Adults typically reach in length. ...

, and shortfin makos. With sharks, orcas may herd them to the surface and strike them with their tail flukes, while bottom-dwelling rays are cornered, pinned to the ground and taken to the surface. In other parts of the world, orcas have preyed on broadnose sevengill sharks, small whale sharks and even great white sharks. Competition between orcas and white sharks is probable in regions where their diets overlap. The arrival of orcas in an area can cause white sharks to flee and forage elsewhere. Orcas appear to target the liver of sharks.

Mammals and birds

Orcas are sophisticated and effective predators of marine mammals. They are recorded to prey on other cetacean species, usually smaller dolphins and

porpoise Porpoises are a group of fully aquatic marine mammals, all of which are classified under the family Phocoenidae, parvorder Odontoceti (toothed whales). Although similar in appearance to dolphins, they are more closely related to narwhals an ...

s such as common dolphins,

bottlenose dolphin Bottlenose dolphins are aquatic mammals in the genus ''Tursiops.'' They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus definitively contains two species: the common ...

s, Pacific white-sided dolphins, dusky dolphins, harbour porpoises and Dall's porpoises. While hunting these species, orcas usually have to chase them to exhaustion. For highly social species, orca pods try to separate an individual from its group. Larger groups have a better chance of preventing their prey from escaping, which is killed by being thrown around, rammed and jumped on. Arctic orcas may attack beluga whales and

s stuck in pools enclosed by sea ice, the former are also driven into shallower water where juveniles are grabbed. By contrast, orcas appear to be wary of pilot whales, which have been recorded to mob and chase them. KW attack STBW

Orcas also prey on larger species such as

sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus ''Physeter'' and one of three extant species in the sperm whale famil ...

grey whale The gray whale (''Eschrichtius robustus''), also known as the grey whale,Britannica Micro.: v. IV, p. 693. gray back whale, Pacific gray whale, Korean gray whale, or California gray whale, is a baleen whale that migrates between feeding and bree ...

s and humpback whales. In 2019, orcas were recorded to have killed a blue whale on three separate occasions off the south coast of Western Australia, including an estimated individual. Large whales require much effort and coordination to kill and orcas often target calves. A hunt begins with a chase followed by a violent attack on the exhausted prey. Large whales often show signs of orca attack via tooth rake marks. Pods of female sperm whales sometimes protect themselves by forming a protective circle around their calves with their flukes facing outwards, using them to repel the attackers. There is also evidence that humpback whales will defend against or mob orcas who are attacking either humpback calves or juveniles as well as members of other species. Prior to the advent of industrial whaling, great whales may have been the major food source for orcas. The introduction of modern whaling techniques may have aided orcas by the sound of exploding harpoons indicating the availability of prey to scavenge, and compressed air inflation of whale carcasses causing them to float, thus exposing them to scavenging. However, the devastation of great whale populations by unfettered whaling has possibly reduced their availability for orcas, and caused them to expand their consumption of smaller marine mammals, thus contributing to the decline of these as well. Orcas in Punta Norte Valdes Peninsula - panoramio

Orcas in Punta Norte Valdes Peninsula - panoramio

Other marine mammal prey includes seal species such as harbour seals, elephant seals, California sea lions,

Steller sea lion The Steller sea lion (''Eumetopias jubatus''), also known as the Steller's sea lion and northern sea lion, is a near-threatened species of sea lion in the northern Pacific. It is the sole member of the genus ''Eumetopias'' and the largest of t ...

South American sea lion The South American sea lion (''Otaria flavescens'', formerly ''Otaria byronia''), also called the southern sea lion and the Patagonian sea lion, is a sea lion found on the western and southeastern coasts of South America. It is the only member ...

s and walruses. Often, to avoid injury, orcas disable their prey before killing and eating it. This may involve throwing it in the air, slapping it with their tails, ramming it, or breaching and landing on it. In steeply banked beaches off Península Valdés, Argentina, and the

, orcas feed on sea lions and elephant seals in shallow water, even beaching temporarily to grab prey before wriggling back to the sea. Beaching, usually fatal to cetaceans, is not an instinctive behaviour, and can require years of practice for the young. Orcas can then release the animal near juvenile whales, allowing the younger whales to practice the difficult capture technique on the now-weakened prey. "Wave-hunting" orcas "spy-hop" to locate Weddell seals, crabeater seals and leopard seals resting on ice floes, and then swim in groups to create waves that wash over the floe. This washes the prey into the water, where other orcas lie in wait. In the Aleutian Islands, a decline in

sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the small ...

populations in the 1990s was controversially attributed by some scientists to orca predation, although with no direct evidence. The decline of sea otters followed a decline in seal populations, which in turn may be substitutes for their original prey, now decimated by industrial whaling. Orcas have been observed preying on terrestrial mammals, such as deer swimming between islands off the northwest coast of North America. Orca

cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, b ...

has also been reported based on analysis of stomach contents, but this is likely to be the result of scavenging remains dumped by whalers. One orca was also attacked by its companions after being shot. Although resident orcas have never been observed to eat other marine mammals, they occasionally harass and kill porpoises and seals for no apparent reason. Orcas do consume seabirds but are more likely to kill and leave them uneaten.

Penguin Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...

species recorded as prey in Antarctic and sub-Antarctic waters include gentoo penguins, chinstrap penguins, king penguins and

rockhopper penguin The rockhopper penguins are three closely related taxa of crested penguins that have been traditionally treated as a single species and are sometimes split into three species. Not all experts agree on the classification of these penguins. Some c ...

s. Orcas in many areas may prey on

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the IOC adopted a consensus taxonomy of seven ge ...

s and gulls. A captive orca at Marineland of Canada discovered it could regurgitate fish onto the surface, attracting sea gulls, and then eat the birds. Four others then learned to copy the behaviour.

Behaviour

Day-to-day orca behaviour generally consists of foraging, travelling, resting and socializing. Orcas frequently engage in surface behaviour such as breaching (jumping completely out of the water) and tail-slapping. These activities may have a variety of purposes, such as courtship, communication, dislodging parasites, or play. Spyhopping is a behaviour in which a whale holds its head above water to view its surroundings. Resident orcas swim alongside

s and other dolphins.

Social structure

Orcas are notable for their complex societies. Only elephants and higher primates live in comparably complex social structures. Due to orcas' complex social bonds, many marine experts have concerns about how humane it is to keep them in captivity. Resident orcas in the eastern North Pacific live in particularly complex and stable social groups. Unlike any other known mammal social structure, resident whales live with their mothers for their entire lives. These family groups are based on matrilines consisting of the eldest female (matriarch) and her sons and daughters, and the descendants of her daughters, etc. The average size of a matriline is 5.5 animals. Because females can reach age 90, as many as four generations travel together. These matrilineal groups are highly stable. Individuals separate for only a few hours at a time, to mate or forage. With one exception, an orca named Luna, no permanent separation of an individual from a resident matriline has been recorded. Transient Orcas (3727711709)

Closely related matrilines form loose aggregations called pods, usually consisting of one to four matrilines. Unlike matrilines, pods may separate for weeks or months at a time. DNA testing indicates resident males nearly always mate with females from other pods. Clans, the next level of resident social structure, are composed of pods with similar dialects, and common but older maternal heritage. Clan ranges overlap, mingling pods from different clans. The highest association layer is the community, which consists of pods that regularly associate with each other but share no maternal relations or dialects. Transient pods are smaller than resident pods, typically consisting of an adult female and one or two of her offspring. Males typically maintain stronger relationships with their mothers than other females. These bonds can extend well into adulthood. Unlike residents, extended or permanent separation of transient offspring from natal matrilines is common, with juveniles and adults of both sexes participating. Some males become "rovers" and do not form long-term associations, occasionally joining groups that contain reproductive females. As in resident clans, transient community members share an acoustic repertoire, although regional differences in vocalizations have been noted. As with residents and transients, the lifestyle of these whales appears to reflect their diet; fish-eating orcas off Norway have resident-like social structures, while mammal-eating orcas in Argentina and the

behave more like transients. Orcas of the same sex and age group may engage in physical contact and synchronous surfacing. These behaviours do not occur randomly among individuals in a pod, providing evidence of "friendships".

Vocalizations

Like all

cetaceans Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...

, orcas depend heavily on underwater sound for orientation, feeding, and communication. They produce three categories of sounds: clicks, whistles, and pulsed calls. Clicks are believed to be used primarily for navigation and discriminating prey and other objects in the surrounding environment, but are also commonly heard during social interactions. Northeast Pacific resident groups tend to be much more vocal than transient groups in the same waters. Residents feed primarily on Chinook and

chum Chum may refer to: Broadcasting * CHUM Limited, a defunct Canadian media company * CHUM Radio, now Bell Media Radio, a Canadian radio broadcasting company * CHUM (AM), a Toronto radio station * CHUM-FM, a Toronto radio station * CHUM Chart, a C ...

salmon, which are insensitive to orca calls (inferred from the audiogram of Atlantic salmon). In contrast, the marine mammal prey of transients hear whale calls well and thus transients are typically silent. Vocal behaviour in these whales is mainly limited to surfacing activities and milling (slow swimming with no apparent direction) after a kill. All members of a resident pod use similar calls, known collectively as a dialect. Dialects are composed of specific numbers and types of discrete, repetitive calls. They are complex and stable over time. Call patterns and structure are distinctive within matrilines. Newborns produce calls similar to their mothers, but have a more limited repertoire. Individuals likely learn their dialect through contact with pod members. Family-specific calls have been observed more frequently in the days following a calf's birth, which may help the calf learn them. Dialects are probably an important means of maintaining group identity and cohesiveness. Similarity in dialects likely reflects the degree of relatedness between pods, with variation growing over time. When pods meet, dominant call types decrease and subset call types increase. The use of both call types is called biphonation. The increased subset call types may be the distinguishing factor between pods and inter-pod relations. Dialects also distinguish types. Resident dialects contain seven to 17 (mean = 11) distinctive call types. All members of the North American west coast transient community express the same basic dialect, although minor regional variation in call types is evident. Preliminary research indicates offshore orcas have group-specific dialects unlike those of residents and transients. Norwegian and Icelandic

-eating orcas appear to have different vocalizations for activities like hunting. A population that live in McMurdo Sound, Antarctica have 28 complex burst-pulse and whistle calls.

Intelligence

Orcas have the second-heaviest brains among marine mammals (after

s, which have the largest brain of any animal). They can be

trained Training is teaching, or developing in oneself or others, any skills and knowledge or fitness that relate to specific useful competencies. Training has specific goals of improving one's capability, capacity, productivity and performance. I ...

in captivity and are often described as intelligent, although defining and measuring "intelligence" is difficult in a species whose environment and behavioural strategies are very different from those of humans. Orcas imitate others, and seem to deliberately teach skills to their kin. Off the

, mothers push their calves onto the beach, waiting to pull the youngster back if needed. Orca with iceball cropped

People who have interacted closely with orcas offer numerous

anecdotes An anecdote is "a story with a point", such as to communicate an abstract idea about a person, place, or thing through the concrete details of a short narrative or to characterize by delineating a specific quirk or trait. Occasionally humorous, ...

demonstrating the whales' curiosity, playfulness, and ability to solve problems. Alaskan orcas have not only learned how to steal fish from longlines, but have also overcome a variety of techniques designed to stop them, such as the use of unbaited lines as decoys. Once, fishermen placed their boats several miles apart, taking turns retrieving small amounts of their catch, in the hope that the whales would not have enough time to move between boats to steal the catch as it was being retrieved. The tactic worked initially, but the orcas figured it out quickly and split into groups. In other anecdotes, researchers describe incidents in which wild orcas playfully tease humans by repeatedly moving objects the humans are trying to reach, or suddenly start to toss around a chunk of ice after a human throws a snowball. The orca's use of dialects and the passing of other learned behaviours from generation to generation have been described as a form of animal culture.

Life cycle

091201 south georgia orca 5227 (4173390858)

Female orcas begin to mature at around the age of 10 and reach peak fertility around 20, experiencing periods of

polyestrous The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous p ...

cycling separated by non-cycling periods of three to 16 months. Females can often breed until age 40, followed by a rapid decrease in fertility. Orcas are among the few animals that undergo menopause and live for decades after they have finished breeding. The lifespans of wild females average 50 to 80 years. Some are claimed to have lived substantially longer: Granny (J2) was estimated by some researchers to have been as old as 105 years at the time of her death, though a biopsy sample indicated her age as 65 to 80 years. It is thought that orcas held in captivity tend to have shorter lives than those in the wild, although this is subject to scientific debate. Males mate with females from other pods, which prevents inbreeding.

Gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...

varies from 15 to 18 months. Mothers usually calve a single offspring about once every five years. In resident pods, births occur at any time of year, although winter is the most common. Mortality is extremely high during the first seven months of life, when 37–50% of all calves die. Weaning begins at about 12 months of age, and is complete by two years. According to observations in several regions, all male and female pod members participate in the care of the young. Males sexually mature at the age of 15, but do not typically reproduce until age 21. Wild males live around 29 years on average, with a maximum of about 60 years. One male, known as Old Tom, was reportedly spotted every winter between the 1840s and 1930 off New South Wales, Australia, which would have made him up to 90 years old. Examination of his teeth indicated he died around age 35, but this method of age determination is now believed to be inaccurate for older animals. One male known to researchers in the Pacific Northwest (identified as J1) was estimated to have been 59 years old when he died in 2010. Orcas are unique among cetaceans, as their caudal sections elongate with age, making their heads relatively shorter.

Infanticide Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose is the prevention of reso ...

, once thought to occur only in captive orcas, was observed in wild populations by researchers off British Columbia on December 2, 2016. In this incident, an adult male killed the calf of a female within the same pod, with the adult male's mother also joining in the assault. It is theorized that the male killed the young calf in order to mate with its mother (something that occurs in other carnivore species), while the male's mother supported the breeding opportunity for her son. The attack ended when the calf's mother struck and injured the attacking male. Such behaviour matches that of many smaller dolphin species, such as the

Conservation

In 2008, the

(International Union for Conservation of Nature) changed its assessment of the orca's conservation status from

conservation dependent A conservation-dependent species is a species which has been categorised as "Conservation Dependent" ("LR/cd") by the International Union for Conservation of Nature (IUCN), i.e. as dependent on conservation efforts to prevent it from becoming e ...

, recognizing that one or more orca types may actually be separate,

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

. Depletion of prey species, pollution, large-scale

oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...

s, and habitat disturbance caused by noise and conflicts with boats are the most significant worldwide threats. In January 2020, the first orca in England and Wales since 2001 was found dead with a large fragment of plastic in its stomach. Like other animals at the highest trophic levels, the orca is particularly at risk of poisoning from

bioaccumulation Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...

of toxins, including Polychlorinated biphenyls (PCBs). European harbour seals have problems in reproductive and immune functions associated with high levels of PCBs and related contaminants, and a survey off the Washington coast found PCB levels in orcas were higher than levels that had caused health problems in harbour seals. Blubber samples in the Norwegian Arctic show higher levels of PCBs, pesticides and

brominated flame-retardant Brominated flame retardants (BFRs) are organobromine compounds that have an inhibitory effect on combustion chemistry and tend to reduce the flammability of products containing them. The brominated variety of commercialized chemical flame retardants ...

s than in

polar bear The polar bear (''Ursus maritimus'') is a hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the largest extant bear specie ...

s. A 2018 study published in '' Science'' found that global orca populations are poised to dramatically decline due such toxic pollution. In the Pacific Northwest, wild salmon stocks, a main resident food source, have declined dramatically in recent years. In the Puget Sound region, only 75 whales remain with few births over the last few years. On the west coast of Alaska and the Aleutian Islands, seal and sea lion populations have also substantially declined. In 2005, the United States government listed the southern resident community as an endangered population under the

Endangered Species Act The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of ec ...

. This community comprises three pods which live mostly in the Georgia and

Haro Straits , image = Southern Gulf Islands, BC, Canada - panoramio.jpg , image_size = 250px , alt = , caption = View of Haro Strait from South Pender Island , image_bathymetry = Locmap-Haro-Boundary ad ...

and Puget Sound in British Columbia and Washington. They do not breed outside of their community, which was once estimated at around 200 animals and later shrank to around 90. In October 2008, the annual survey revealed seven were missing and presumed dead, reducing the count to 83. This is potentially the largest decline in the population in the past 10 years. These deaths can be attributed to declines in Chinook salmon.Le Phuong
Researchers: 7 Orcas Missing from Puget Sound
, Associated Press. USA Today, October 25, 2008 Scientist Ken Balcomb has extensively studied orcas since 1976; he is the research biologist responsible for discovering U.S. Navy sonar may harm orcas. He studied orcas from the Center for Whale Research, located in Friday Harbor, Washington. He was also able to study orcas from "his home porch perched above Puget Sound, where the animals hunt and play in summer months". In May 2003, Balcomb (along with other whale watchers near the Puget Sound coastline) noticed uncharacteristic behaviour displayed by the orcas. The whales seemed "agitated and were moving haphazardly, attempting to lift their heads free of the water" to escape the sound of the sonars. "Balcomb confirmed at the time that strange underwater pinging noises detected with underwater microphones were sonar. The sound originated from a U.S. Navy frigate 12 miles (19 kilometres) distant, Balcomb said." The impact of sonar waves on orcas is potentially life-threatening. Three years prior to Balcomb's discovery, research in the Bahamas showed 14 beaked whales washed up on the shore. These whales were beached on the day U.S. Navy destroyers were activated into sonar exercise. Of the 14 whales beached, six of them died. These six dead whales were studied, and

CAT scan A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

s of two of the whale heads showed hemorrhaging around the brain and the ears, which is consistent with decompression sickness. Another conservation concern was made public in September 2008 when the Canadian government decided it was not necessary to enforce further protections (including the Species at Risk Act in place to protect endangered animals along with their habitats) for orcas aside from the laws already in place. In response to this decision, six environmental groups sued the federal government, claiming orcas were facing many threats on the

British Columbia Coast , settlement_type = Region of British Columbia , image_skyline = , nickname = "The Coast" , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province , subdivision_name1 = British ...

and the federal government did nothing to protect them from these threats. A legal and scientific nonprofit organization,

Ecojustice Ecojustice Canada (formerly Sierra Legal Defence Fund prior to September 2007), is a Canadian non-profit environmental law organization that provides funding to lawyers to use litigation to defend and protect the environment. Ecojustice is Canad ...

, led the lawsuit and represented the

David Suzuki Foundation The David Suzuki Foundation is a science-based non-profit environmental organization headquartered in Vancouver, British Columbia, Canada, with offices in Montreal and Toronto. It was established as a federally registered Canadian charity on Jan ...

Environmental Defence Environmental Defence (formerly known as the Canadian Environmental Defence Fund) is a Canadian environmental organization, founded in 1984. Its areas of education and research include toxic chemicals, urban sprawl, oil sands, global warming, wa ...

, Greenpeace Canada, International Fund for Animal Welfare, the Raincoast Conservation Foundation, and the Wilderness Committee. Many scientists involved in this lawsuit, including Bill Wareham, a marine scientist with the David Suzuki Foundation, noted increased boat traffic, water toxic wastes, and low salmon population as major threats, putting approximately 87 orcas on the British Columbia Coast in danger. Underwater noise from shipping, drilling, and other human activities is a significant concern in some key orca habitats, including Johnstone Strait and Haro Strait. In the mid-1990s, loud underwater noises from

salmon farm The aquaculture of salmonids is the farming and harvesting of salmonids under controlled conditions for both commercial and recreational purposes. Salmonids (particularly salmon and rainbow trout), along with carp, and tilapia are the three most ...

s were used to deter seals. Orcas also avoided the surrounding waters. High-intensity sonar used by the Navy disturbs orcas along with other marine mammals. Orcas are popular with whale watchers, which may stress the whales and alter their behaviour, particularly if boats approach too closely or block their lines of travel. The ''Exxon Valdez'' oil spill adversely affected orcas in Prince William Sound and Alaska's Kenai Fjords region. Eleven members (about half) of one resident pod disappeared in the following year. The spill damaged salmon and other prey populations, which in turn damaged local orcas. By 2009, scientists estimated the AT1 transient population (considered part of a larger population of 346 transients), numbered only seven individuals and had not reproduced since the spill. This population is expected to die out. Orcas are included in Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning international trade (including in parts/derivatives) is regulated.

Relationship with humans

Indigenous cultures

The

indigenous peoples of the Pacific Northwest Coast The Indigenous peoples of the Americas, Indigenous peoples of the Pacific Northwest Coast are composed of many nations and tribal affiliations, each with distinctive cultural and political identities. They share certain beliefs, traditions and prac ...

feature orcas throughout their art, history, spirituality and religion. The

Haida Haida may refer to: Places * Haida, an old name for Nový Bor * Haida Gwaii, meaning "Islands of the People", formerly called the Queen Charlotte Islands * Haida Islands, a different archipelago near Bella Bella, British Columbia Ships * , a 1 ...

regarded orcas as the most powerful animals in the ocean, and their mythology tells of orcas living in houses and towns under the sea. According to these myths, they took on human form when submerged, and humans who drowned went to live with them. For the Kwakwaka'wakw, the orca was regarded as the ruler of the undersea world, with sea lions for slaves and dolphins for warriors. In Nuu-chah-nulth and Kwakwaka'wakw mythology, orcas may embody the souls of deceased chiefs. The Tlingit of southeastern Alaska regarded the orca as custodian of the sea and a benefactor of humans. The Maritime Archaic people of

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

also had great respect for orcas, as evidenced by stone carvings found in a 4,000-year-old burial at the Port au Choix Archaeological Site. In the tales and beliefs of the

Siberian Yupik Siberian Yupiks, or Yuits (russian: Юиты), are a Yupik peoples, Yupik people who reside along the coast of the Chukchi Peninsula in the far Russian Far East, northeast of the Russia, Russian Federation and on St. Lawrence Island in Alask ...

people, orcas are said to appear as wolves in winter, and wolves as orcas in summer.''The orphan boy with his sister'', p. 156 in Rubcova, E. S. (1954). ''Materials on the Language and Folklore of the Eskimoes, Vol. I, Chaplino Dialect''. Leningrad: Academy of Sciences of the USSR. Original data: Е.С. Рубцова: Материалы по языку и фольклору эскимосов (чаплинский диалект). Академия Наук СССР. Москва-Ленинград, 1954Menovshchikov, G. A. (1962). ''Grammar of the language of Asian Eskimos''. Vol. I., pp. 439, 441. Moscow and Leningrad: Academy of Sciences of the USSR. Original data: Г. А. Меновщиков: Грамматиκа языка азиатских эскимосов. Часть первая. Академия Наук СССР. Москва-Ленинград, 1962 Orcas are believed to assist their hunters in driving walrus. A radio interview with Russian scientists about man and animal, examples taken especially from Asian Eskimos Reverence is expressed in several forms: the boat represents the animal, and a wooden carving hung from the hunter's belt. Small

sacrifice Sacrifice is the offering of material possessions or the lives of animals or humans to a deity as an act of propitiation or worship. Evidence of ritual animal sacrifice has been seen at least since ancient Hebrews and Greeks, and possibly exi ...

s such as tobacco or meat are strewn into the sea for them. The

Ainu people The Ainu are the indigenous people of the lands surrounding the Sea of Okhotsk, including Hokkaido Island, Northeast Honshu Island, Sakhalin Island, the Kuril Islands, the Kamchatka Peninsula and Khabarovsk Krai, before the arrival of the Y ...

of Hokkaido, the Kuril Islands, and southern Sakhalin often referred to orcas in their folklore and myth as '' Repun Kamuy'' (God of Sea/Offshore) to bring fortunes (whales) to the coasts, and there had been traditional funerals for stranded or deceased orcas akin to funerals for other animals such as brown bears.

"Killer" stereotype

In Western cultures, orcas were historically feared as dangerous, savage predators. The first written description of an orca was given by Pliny the Elder ''circa'' AD 70, who wrote, "Orcas (the appearance of which no image can express, other than an enormous mass of savage flesh with teeth) are the enemy of

ther kinds of whale Ther may refer to: *''Thér.'', taxonomic author abbreviation of Irénée Thériot (1859–1947), French bryologist *Agroha Mound, archaeological site in Agroha, Hisar district, India *Therapy *Therapeutic drugs See also *''Ther Thiruvizha'', 1968 ...

.. they charge and pierce them like warships ramming." Of the very few confirmed attacks on humans by wild orcas, none have been fatal. In one instance, orcas tried to tip ice floes on which a dog team and photographer of the Terra Nova Expedition were standing. The sled dogs' barking is speculated to have sounded enough like seal calls to trigger the orca's hunting curiosity. In the 1970s, a surfer in California was bitten, and in 2005, a boy in Alaska who was splashing in a region frequented by harbour seals was bumped by an orca that apparently misidentified him as prey. Unlike wild orcas, captive orcas have made nearly two dozen attacks on humans since the 1970s, some of which have been fatal. Competition with fishermen also led to orcas being regarded as pests. In the waters of the Pacific Northwest and Iceland, the shooting of orcas was accepted and even encouraged by governments. As an indication of the intensity of shooting that occurred until fairly recently, about 25% of the orcas captured in Puget Sound for aquariums through 1970 bore bullet scars. The U.S. Navy claimed to have deliberately killed hundreds of orcas in Icelandic waters in 1956 with machine guns, rockets, and

depth charge A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive Shock factor, hydraulic shock. Most depth ...

Modern Western attitudes

Western attitudes towards orcas have changed dramatically in recent decades. In the mid-1960s and early 1970s, orcas came to much greater public and scientific awareness, starting with the live-capture and display of an orca known as Moby Doll, a

harpooned off Saturna Island in 1964. He was the first ever orca to be studied at close quarters alive, not postmortem.

Moby Doll's impact in scientific research Moby Doll's impact in scientific research was enormous and in a sense unrepeatable. He was the first ever killer whale (orca) to be studied at close quarters alive, initiating pioneering research about his very misunderstood species. Few other ind ...

at the time, including the first scientific studies of an orca's sound production, led to two articles about him in the journal ''Zoologica''. So little was known at the time, it was nearly two months before the whale's keepers discovered what food (fish) it was willing to eat. To the surprise of those who saw him, Moby Doll was a docile, non-aggressive whale who made no attempts to attack humans. A73 whale transport

Between 1964 and 1976, 50 orcas from the Pacific Northwest were captured for display in aquaria, and public interest in the animals grew. In the 1970s, research pioneered by Michael Bigg led to the discovery of the species' complex social structure, its use of vocal communication, and its extraordinarily stable mother–offspring bonds. Through photo-identification techniques, individuals were named and tracked over decades. Bigg's techniques also revealed the Pacific Northwest population was in the low hundreds rather than the thousands that had been previously assumed. The southern resident community alone had lost 48 of its members to captivity; by 1976, only 80 remained. In the Pacific Northwest, the species that had unthinkingly been targeted became a cultural icon within a few decades. The public's growing appreciation also led to growing opposition to whale–keeping in aquarium. Only one whale has been taken in North American waters since 1976. In recent years, the extent of the public's interest in orcas has manifested itself in several high-profile efforts surrounding individuals. Following the success of the 1993 film '' Free Willy'', the movie's captive star Keiko was returned to the coast of his native Iceland in 2002. The director of the International Marine Mammal Project for the

Earth Island Institute The Earth Island Institute is a non-profit environmental group founded in 1982 by David Brower. Located in Berkeley, California, it supports activism around environmental issues through fiscal sponsorship that provides the administrative and org ...

, David Phillips, led the efforts to return Keiko to the Iceland waters. Keiko however did not adapt to the harsh climate of the Arctic Ocean, and died a year into his release after contracting pneumonia, at the age of 27. In 2002, the orphan Springer was discovered in Puget Sound, Washington. She became the first whale to be successfully reintegrated into a wild pod after human intervention, crystallizing decades of research into the vocal behaviour and social structure of the region's orcas. The saving of Springer raised hopes that another young orca named Luna, which had become separated from his pod, could be returned to it. However, his case was marked by controversy about whether and how to intervene, and in 2006, Luna was killed by a boat propeller.

Whaling

The earlier of known records of commercial hunting of orcas date to the 18th century in Japan. During the 19th and early 20th centuries, the global whaling industry caught immense numbers of

baleen Baleen is a filter-feeding system inside the mouths of baleen whales. To use baleen, the whale first opens its mouth underwater to take in water. The whale then pushes the water out, and animals such as krill are filtered by the baleen and ...

and sperm whales, but largely ignored orcas because of their limited amounts of recoverable oil, their smaller populations, and the difficulty of taking them. Once the stocks of larger species were depleted, orcas were targeted by commercial whalers in the mid-20th century. Between 1954 and 1997, Japan took 1,178 orcas (although the Ministry of the Environment claims that there had been domestic catches of about 1,600 whales between late 1940s to 1960s) and Norway took 987. Extensive hunting of orcas, including an

catch of 916 in 1979–80 alone, prompted the International Whaling Commission to recommend a ban on commercial hunting of the species pending further research. Today, no country carries out a substantial hunt, although Indonesia and Greenland permit small subsistence hunts (see Aboriginal whaling). Other than commercial hunts, orcas were hunted along Japanese coasts out of public concern for potential conflicts with fisheries. Such cases include a semi-resident male-female pair in Akashi Strait and Harimanada being killed in the

Seto Inland Sea The , sometimes shortened to the Inland Sea, is the body of water separating Honshū, Shikoku, and Kyūshū, three of the four main islands of Japan. It serves as a waterway connecting the Pacific Ocean to the Sea of Japan. It connects to Osaka ...

in 1957, the killing of five whales from a pod of 11 members that swam into Tokyo Bay in 1970, and a catch record in southern Taiwan in the 1990s.

Cooperation with humans

Orcas have helped humans hunting other whales. One well-known example was the orcas of Eden, Australia, including the male known as Old Tom. Whalers more often considered them a nuisance, however, as orcas would gather to scavenge meat from the whalers' catch. Some populations, such as in Alaska's Prince William Sound, may have been reduced significantly by whalers shooting them in retaliation.

Whale watching

Whale watching continues to increase in popularity, but may have some problematic impacts on orcas. Exposure to exhaust gases from large amounts of vessel traffic is causing concern for the overall health of the 75 remaining southern resident orcas (SRKWs) left as of early 2019. This population is followed by approximately 20 vessels for 12 hours a day during the months May–September. Researchers discovered that these vessels are in the line of sight for these whales for 98–99.5% of daylight hours. With so many vessels, the air quality around these whales deteriorates and impacts their health. Air pollutants that bind with exhaust fumes are responsible for the activation of the cytochrome P450 1A gene family. Researchers have successfully identified this gene in skin biopsies of live whales and also the lungs of deceased whales. A direct correlation between activation of this gene and the air pollutants can not be made because there are other known factors that will induce the same gene. Vessels can have either wet or dry exhaust systems, with wet exhaust systems leaving more pollutants in the water due to various gas solubility. A modelling study determined that the lowest-observed-adverse-effect-level (LOAEL) of exhaust pollutants was about 12% of the human dose. As a response to this, in 2017 boats off the British Columbia coast now have a minimum approach distance of 200 metres compared to the previous 100 metres. This new rule complements Washington State's minimum approach zone of 180 metres that has been in effect since 2011. If a whale approaches a vessel it must be placed in neutral until the whale passes. The World Health Organization has set air quality standards in an effort to control the emissions produced by these vessels.

Captivity

The orca's intelligence, trainability, striking appearance, playfulness in captivity and sheer size have made it a popular exhibit at aquaria and aquatic theme parks. From 1976 to 1997, 55 whales were taken from the wild in Iceland, 19 from Japan, and three from Argentina. These figures exclude animals that died during capture. Live captures fell dramatically in the 1990s, and by 1999, about 40% of the 48 animals on display in the world were captive-born. Organizations such as World Animal Protection and the

Whale and Dolphin Conservation Whale and Dolphin Conservation (WDC), formerly Whale and Dolphin Conservation Society in the UK, is a wildlife charity that is dedicated solely to the worldwide conservation and welfare of all whales, dolphins and porpoises (cetaceans). It has ...

campaign against the practice of keeping them in captivity. In captivity, they often develop pathologies, such as the dorsal fin collapse seen in 60–90% of captive males. Captives have vastly reduced life expectancies, on average only living into their 20s. That said, a 2015 study coauthored by staff at SeaWorld and the Minnesota Zoo suggested no significant difference in survivorship between free-ranging and captive orcas. However, in the wild, females who survive infancy live 46 years on average, and up to 70–80 years in rare cases. Wild males who survive infancy live 31 years on average, and up to 50–60 years. Captivity usually bears little resemblance to wild habitat, and captive whales' social groups are foreign to those found in the wild. Critics claim captive life is stressful due to these factors and the requirement to perform

circus trick Circus skills are a group of disciplines that have been performed as entertainment in circus, sideshow, busking, or variety, vaudeville, or music hall shows. Most circus skills are still being performed today. Many are also practiced by non-perfo ...

s that are not part of wild orca behaviour, see above. Wild orcas may travel up to in a day, and critics say the animals are too big and intelligent to be suitable for captivity.Associated Press
Whale Attack Renews Captive Animal Debate
''CBS News'', March 1, 2010. Retrieved March 7, 2010 Captives occasionally act aggressively towards themselves, their tankmates, or humans, which critics say is a result of stress. Between 1991 and 2010, the bull orca known as

Tilikum Tillicum or Tilikum is a word in Chinook Jargon that means people, family, tribe, and relatives, and may refer to: Places * Tilikum Crossing, a bridge in Portland, Oregon * Tillicum, Lakewood, a neighborhood in Lakewood, Washington ** Tillicum st ...

was involved in the death of three people, and was featured in the critically acclaimed 2013 film ''Blackfish''. Tilikum lived at SeaWorld from 1992 until his death in 2017. In March 2016, SeaWorld announced that they would be ending their orca breeding program and their theatrical shows. As of 2020, theatrical shows featuring orcas are still ongoing, however.

Footnotes

References

Works cited

* * * * * * * * * *

External links

Orca-Live
nbsp;– Orcas in Johnstone Strait, British Columbia
Salish Sea Hydrophone Network
nbsp;– Listen live to orcas in Washington State, U.S.
Keep Whales Wild

HowStuffWorks.com, article by Jacob Silverman

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Pod of orcas vs group of great whites
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Orcas Preying On Dolphins (Caught On Drone)
off the coast of San Clemente
Orcas vs Sperm Whales

Watch: Killer Whales Charge Blue Whale (Rare Drone Footage)
,

National Geographic ''National Geographic'' (formerly the ''National Geographic Magazine'', sometimes branded as NAT GEO) is a popular American monthly magazine published by National Geographic Partners. Known for its photojournalism, it is one of the most widely ...

{{Featured article Apex predators Cosmopolitan mammals Oceanic dolphins Predators Animals that use echolocation Mammals described in 1758 Articles containing video clips Taxa named by Carl Linnaeus