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Orcinus orca [1]
Transient Killer Whales near Unimak Island, eastern Aleutian Islands, Alaska
Conservation status
Data Deficient (IUCN 3.1)[2]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Cetacea
Suborder:	Odontoceti
Family:	Delphinidae
Genus:	Orcinus
Species:	O. orca
Binomial name
Orcinus orca Linnaeus, 1758
Orcinus Orca range (in blue)
Synonyms
Orca gladiator

Size comparison to an average human

The Killer Whale (Orcinus orca), commonly referred to as the Orca and, less commonly, Blackfish, is the largest species of the dolphin family. They are found in all of the world's oceans, from the frigid Arctic and Antarctic regions to tropical seas. Killer Whales as a species have a diverse diet, although populations often specialize in particular types of prey. Some feed exclusively on fish, particularly salmon, and other populations hunt marine mammals such as sea lions, seals, walruses and even large whales. As they are known to be predators of large sharks, Killer Whales are regarded as the ocean's apex predator.

There are up to five distinct Killer Whale types distinguished by geographical range, preferred prey items and physical appearance. Some of these may be separate races, subspecies or even species.^[3] Killer Whales are highly social; some populations are composed of matrilineal family groups which are the most stable of any animal species.^[4] The sophisticated social behavior, hunting techniques, and vocal behavior of Killer Whales have been described as manifestations of culture.^[5]

Although the Killer Whale is not considered to be an internationally endangered species, some local populations are considered threatened or endangered due to depletion of prey species, habitat loss, pollution by PCBs, historic capture for marine mammal parks, and conflicts with fisheries. In late 2007, the Killer Whales known as the "southern resident killer whales" were placed on the U.S. Endangered Species list.^[6][7][8][9] Because it is unlikely that all Killer Whales belong to a single species, the IUCN currently assesses the conservation status of the Killer Whale as data deficient.^[2]

Wild Killer Whales are not considered a threat to humans,^[10] although there have been cases of captive Killer Whales attacking, and in at least one instance, killing their handlers at marine theme parks.^[11][12] The Killer Whale features strongly in the mythologies of indigenous cultures. In Western cultures, it has had a reputation for being a fearsome predator, but in recent decades better understanding has led to widespread appreciation of the species.

Taxonomy and evolution

Orcinus orca is the only recognized species in the genus Orcinus, one of the many species originally described by Linnaeus in 1758 in Systema Naturae.^[13] It is one of thirty-five species in the dolphin family, which first appeared about 11 million years ago. The Killer Whale lineage probably branched off shortly thereafter.^[14] Although it has morphological similarities with Pilot Whales and Pygmy Killer Whales, its closest relative is the Irrawaddy Dolphin.^[15]

Common names

The name "Killer Whale" derives from the Spanish asesina ballenas or "asesino de la ballena" ("whale killer" in English), evidently coming from sailors who observed them hunting whales.^[16][17] English-speaking scientists most often use the term "killer whale."^[18]

"Killer Whale" advocates point out that its naming heritage is not limited to Spanish sailors. Indeed, the genus name Orcinus means "of or belonging to the kingdom of the dead",^[18] and although the name Orca (in use since antiquity) is probably not etymologically related, the assonance might have given some people the idea that it meant "whale that brings death" or "demon from hell." The name is also similar to Orcus, a Roman god of the underworld.

Ancient Romans originally applied Orca (plural Orcas) to these animals, possibly borrowing it from the Greek ὄρυξ, which referred (among other things) to a whale species. Since the 1960s, Orca has steadily grown in popularity; both names are now used. Orca advocates believe it avoids the negative connotations of "killer".^[19] Another point for orca is the fact that the species is more closely related to dolphins than to whales.

They are sometimes referred to as blackfish, a name also used for other whale species. Grampusis a former name for the species, but is now seldom used. This meaning of grampus should not be confused with the Grampus genus, whose only member is Risso's Dolphin. The term orc (or its variant ork) has been used to describe a large fish, whale or sea-monster. It is now considered an obsolete synonym for Orca.

Types

There are three to five types of Killer Whales that are distinct enough to be considered different races, subspecies, or possibly even species. 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."^[2] In the 1970s and 1980s, research off the west coast of Canada and the United States identified the following three types:

• Resident: These are the most commonly sighted of the three populations in the coastal waters of the northeast Pacific. Residents' diet consists primarily of fish and sometimes squid, and they live in complex and cohesive family groups. Pods possess lifelong family bonds, often living in matrilineal groups and vocalizing in variable and complex dialects.^[20] Female residents characteristically have a rounded dorsal fin tip that terminates in a sharp corner. They are known to visit the same areas consistently. British Columbia and Washington resident populations are amongst the most-intensively studied marine mammals. Researchers have identified and named over 300 Killer Whales over the past 30 years.
• Transient: Their diet consists almost exclusively of marine mammals; they do not eat fish. Transients in southern Alaska generally travel in small groups, usually of two to six animals. Unlike residents, transients may not always stay together as a family unit. Pods consist of smaller groups with less persistent family bonds. 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 gray or white area around the dorsal fin, known as the "saddle patch," often contains some black coloring in residents. However, the saddle patches of transients are solid and uniformly gray. Transients roam widely along the coast—some individuals have been sighted in both southern Alaska and California.
• Offshore: These Killer Whales were discovered in 1988 when humpback whale researcher Jim Darling signaled to Killer Whale researchers Michael Bigg and Graeme Ellis that he saw some in open water. They cruise the open oceans and are believed to feed primarily on schooling fish. However, because of the large presence of scarred and nicked dorsal fins resembling that of the mammal-hunting transients, the possibility that they eat mammals and sharks cannot be dismissed. They have mostly been encountered off the west coast of Vancouver Island and near the Queen Charlotte Islands. They have been seen traveling in groups of up to 60. Currently, little is known about their habits, but they can be distinguished genetically from residents and transients. Offshores appear to be shorter and females are characterized by dorsal fin tips that are continuously rounded.

Type C Killer Whales in the Ross Sea. The eye patch slants forward.

These types demonstrate a correlation between diet and social behavior. Transient and resident Killer Whales live in the same areas, but avoid each other. The name transient originated from the belief that these Killer Whales were outcasts from larger resident pods. Researchers later discovered that transients are not born into resident pods or vice-versa. The evolutionary split between the two groups is believed to have begun two million years ago.^[21] Genetic research indicates that the types have not interbred for up to 10,000 years.^[22]

Killer Whale populations in other parts of the world have not been as well studied. Fish-eating Killer Whales in Alaska and Norway have also been observed to have resident-like social structures. Mammal-eating Killer Whales in Argentina and the Crozet Islands have been observed to behave more like transients.^[4]

Three Killer Whale types have recently been documented in the Antarctic. (Two dwarf species, named Orcinus nanus and Orcinus glacialis, were described during the 1980s by Soviet researchers, but most cetacean researchers were skeptical about their status, and it is difficult to link these directly to the types described below.)^[3]

• Type A looks like a "typical" Killer Whale, a large, black and white form with a medium-sized white eye patch, living in open water and feeding mostly on minke whales.
• Type B is smaller than Type A. It has a large white eye patch. Most of the dark parts of its body are medium gray instead of black, although it has a dark gray patch called a "dorsal cape"^[23] stretching back from its forehead to just behind its dorsal fin. The white areas are stained slightly yellow. It feeds mostly on seals.
• Type C is the smallest type and lives in larger groups than any other type. Its eye patch is distinctively slanted forwards, rather than parallel to the body axis. Like Type B, it is primarily white and medium gray, with a dark gray dorsal cape and yellow-tinged patches. Its only observed prey is the Antarctic Cod.

Types B and C live close to the Antarctic ice pack, and diatoms in these waters may be responsible for the yellowish colouring of both types.^[3][24] Mitochondrial DNA sequences support the theory that these are separate species that have recently diverged.^[25]

Description

The dorsal fin and saddle patch of a resident Killer Whale in the northeastern Pacific Ocean. It may be either an adult female, or a juvenile of either sex.

Killer Whales are distinctively marked with a black back, white chest and sides, and a white patch above and behind the eye. Calves are born with a yellowish or orange tint, which fades to white. Killer Whales have a heavy and robust body (more so than other dolphins^[26]) and a large 2 meters (7 ft) dorsal fin with a dark grey "saddle patch" at the fin's rear. Antarctic Killer Whales may have pale grey to nearly white backs. Males typically range from 6–8 metres (20–26 ft) long and weigh in excess of 6 tonnes (5.9 LT; 6.6 ST).^[17] Females are smaller, generally ranging from 5–7 metres (16–23 ft) and weighing about 3 to 4 tonnes (3.0 to 3.9 LT; 3.3 to 4.4 ST).^[17] The largest male Killer Whale on record was 9.8 meters (32 ft), weighing over 10 tonnes (9.8 LT; 11 ST) while the largest female was 8.5 meters (28 ft), weighing 7.5 tonnes (7.4 LT; 8.3 ST).^[27] Calves at birth weigh about 180 kilograms (397 lb) and are about 2.4 meters (8 ft) long.^[28][29] The Killer Whale's large size and strength make it among the fastest marine mammals, often reaching speeds in excess of 35 knots (65 km/h).^[30] Unlike most dolphins, its pectoral fin is large and rounded—more of a paddle than with other dolphins. Males have significantly larger pectorals than females. At about 1.8 meters (6 ft) the male's dorsal fin is more than twice the size of the female's and is more of a triangular shape—a tall, elongated isosceles triangle— hers is shorter and more curved.^[31]

Adults are very distinctive and are unlikely to be confused with any other sea creature.^[32] When seen from a distance, juveniles can be confused with various other species, for example, the False Killer Whale or Risso's dolphin.

Individuals can be identified by their 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. Photo identification has enabled the local population of Killer Whales to be counted each year rather than estimated and has enabled great insight into lifecycles and social structures.^[33]

Life cycle

Females become mature at around age 15. Then they have periods of polyestrous cycling with non-cycling periods of between 3 and 16 months. The gestation period varies from 15 to 18 months. Mothers calve, with a single offspring, about once every 5 years. In resident pods, birth occurs at any time of year, although winter is the most popular. Mortality is extremely high during the first 6 months of life, when 37-50% of all calves die.^[34] Calves nurse for up to 2 years but start to take solid food at about 12 months. All resident Killer Whale pod members, including males of all ages, participate in the care of the young.^[21]

Cows breed until age 40, meaning that on average they raise 5 offspring. The lifespan of wild females averages 50 years, with a maximum of 80–90 years.^[35] Males become 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 50–60 years.^[35] One male, known as Old Tom, was reportedly spotted every winter between the 1840s and 1930 off New South Wales, Australia. This would have made him up to 90 years old, but examination of his teeth indicated he died around age 35.^[36] One male well known to researchers in the Pacific Northwest called Ruffles (J1) is estimated to have been born in 1951, making him 58 years old in 2009.^[37] Captive Killer Whale lifespans are typically significantly shorter, usually less than 25 years, however there are numerous individuals in their thirties, and a couple in their 40s. In many instances, the lifespans of Killer Whales depend on the will of the animal.^[38][39]

Range and habitat

To travel quickly, Killer Whales leap out of the water when swimming—a behavior known as porpoising

Killer Whales are found in all oceans and most seas, including (unusually for cetaceans) the Mediterranean and Arabian Seas. However, they prefer cooler temperate and polar regions. Although sometimes spotted in deep water, they generally prefer coastal areas to pelagic environments.^[40] The Killer Whale is particularly highly concentrated in the northeast Pacific Basin, where Canada curves into Alaska as well as the Johnstone Strait area and Washington state. There are also large populations off the coast of Iceland and off the coast of northern Norway. They are regularly sighted in Argentina and the Antarctic waters right up to the ice pack and are believed to venture under the pack and survive breathing in air pockets as do beluga whales. Killer Whales visit arctic waters in summer, but are rarely seen in winter and do not approach the ice pack.

Information for offshore regions and tropical waters is more scarce, but widespread, if not frequent, sightings indicate that the Killer Whale can survive in most water temperatures. Sightings are rare in Indonesian and Philippine waters. Worldwide population estimates are uncertain, but one recent study estimated more than 50,000. 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.^[41] Japan's Fisheries Agency estimated there were 2,321 Killer Whales in the seas around Japan.^[42][43]

With the rapid Arctic sea ice decline in the Hudson Strait, the range of now extends into Canada's far northern waters. In the 1990s, Killer Whales were sighted in western Hudson Bay only 6 times; there were over 30 sightings from 2001–2006.^[44]

White Killer Whales have been spotted in the northern Bering Sea and around St. Lawrence Island. Also, there have been sightings along the Russian coast. In February 2008, a white Killer Whale was photographed 3 miles (5 km) off Kanaga Volcano. The whale was a healthy, adult male about 25 to 30 feet (9.1 m) long and weighing upward of 10,000 pounds (4,536 kg).^[45]

Killer Whales migration patterns are poorly understood. Each summer, the same resident Killer Whales appear off the coasts of British Columbia and Washington State. After decades of research, it is still unknown where these animals go for the rest of the year. Transient pods have been sighted from southern Alaska to central California.

On some occasions, they swim into freshwater rivers. They have been documented 100 miles (161 km) up the Columbia River in the United States.^[17][46] They have also been found in the Fraser River in Canada and the Horikawa River in Japan.^[17]

Feeding

A Killer Whale skull

Killer Whales prey on diverse species. However, some populations specialize in particular prey species. For example, some populations in the Norwegian and Greenland sea specialize in herring and follow that fish's autumnal migration to the Norwegian coast. Other populations prey on seals. Field observations of northeast Pacific resident Killer Whales show that salmon accounted for 96% of their diet. 65% are the large, fatty Chinook.^[4] Chum salmon are also eaten, but smaler sockeye and pink salmon are not a significant food item.^[47] Depletion of specific prey species in an area is therefore cause for concern for local populations, despite the high diversity of prey. On average, a Killer Whale eats 227 kilograms (500 lb) each day.^[48]

Since some Killer Whales prey on large whales and sharks, they are considered to be apex predators. They are sometimes called the wolves of the sea, because they hunt in groups like wolf packs.^[49]

Fish and other cold-blooded prey

Resident (fish-eating) Killer Whales. The curved dorsal fins are typical of resident females.

Fish-eating Killer Whales prey on around 30 species of fish, particularly Chinook salmon, herring, and tuna. In New Zealand, rays are Killer Whales' most frequent prey,^[50] and they have also been observed hunting sharks (particularly makos, threshers and smooth hammerheads). Squid and sea turtles also taken.^[51]

Killer Whales can induce tonic immobility in sharks and rays by holding them upside down. Upside-down sharks and rays are helpless and incapable of injuring the whale, and suffocate within about 15 minutes. In one incident filmed near the Farallon Islands, a female killed a great white shark, apparently after inducing tonic immobility. She and another pod member ate the shark's nutricious liver and allowed the rest of the carcass to sink.^[52]

While salmon are usually hunted by a single or small group of individuals, herring are often caught using carousel feeding: the Killer Whales 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, either stunning or killing up to 10–15 herring with a successful slap. The herring are then eaten one at a time. Carousel feeding has only been documented in the Norwegian Killer Whale population and with some oceanic dolphin species.^[53]

Mammal prey

California sea lions are common prey for Killer Whales on the west coast of North America.

Twenty-two cetacean species have been recorded as Killer Whale prey, from examining either stomach contents, scarring on the prey's body, or feeding activity. Groups even attack larger cetaceans such as Minke whales, Gray whales, and, very occasionally, Sperm Whales or Blue whales. Cannibalism has also been reported. Bottlenose Dolphins are only rarely hunted by certain types of Killer Whales; conversely, some Killer Whales befriend dolphins. Although, unlike transient Killer Whales, resident Killer Whales have never been observed to eat other marine mammals, they occasionally harass and kill porpoises and seals for no apparent reason.^[4]

Hunting large whales usually takes several hours, and Killer Whales generally choose to attack young or weak whales. However, a group of five or more may attack healthy adults. Bull Sperm Whales are avoided, as they are large, powerful, and aggressively fight back. When hunting a young whale, a group chases it and its mother until they wear out. Eventually they separate the pair and surround the young whale, preventing it from surfacing to breathe. Whales are typically drowned in this manner. Pods of female Sperm Whales can sometimes protect themselves by forming a protective circle around their calves with their flukes facing outwards, using their powerful flukes to repel the attackers.

Other marine mammal prey species include most species of seal, sea lion and fur seal. Walruses and Sea otters are less popular. Killer Whales often use sophisticated hunting strategies to take their prey. Often, to avoid injury, they 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. Sea lions are killed by head-butting or after a stunning blow from a tail fluke. They occasionally throw seals into the air in order to stun and kill them. In the Aleutian Islands, sea otters became more frequent prey during the 1990s. This is due to the decline in Harbor seal and Steller sea lion populations, the Killer Whale's preferred prey,^[17][54] which in turn may be substitutes for their original prey, now decimated by industrial whaling.^[55][56][57]

Off Península Valdés, Argentina, and the Crozet Islands, they feed on South American sea lions and Southern elephant seals in shallow water, even beaching temporarily. Beaching, usually fatal, is not an instinctive behavior. Adults teach the younger ones hunting skills in shallow water. Off Península Valdés, adults pull seals off the shoreline for juveniles to recapture. Off the Crozet Islands, mothers have been seen pushing their calves onto the beach, waiting to pull the youngster back if needed.^[21]

Killer Whales swim by an iceberg with Adélie penguins in the Ross Sea, Antarctica. The Drygalski Ice Tongue is in the background.

"Wave-hunting" Killer Whales spy-hop to locate Weddell seals, Ross 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 seal into the water where another Killer Whale waits to kill it.^[58]

Killer Whales have also been observed preying on terrestrial mammals, such as deer and moose swimming between islands off the northwest coast of North America.^[17]

Birds

They prey on several bird species, including penguins, cormorants and sea gulls. A captive Killer Whale in Friendship Cove discovered that it could regurgitate fish onto the surface, attracting sea gulls, and then eat the birds. Other Killer Whales then learn the behavior by example.^[59]

Behavior

Killer Whales often raise their bodies out of the water in a behaviour called spyhopping.

Day-to-day behavior generally divides into four activities: foraging, traveling, resting and socializing. Killer Whales are frequently active at the surface, engaging in acrobatic behaviors such as breaching, spyhopping, and tail-slapping. These activities may have a variety of purposes, such as courtship, communication, dislodging parasites, or play. Spyhopping, a behavior in which a whale holds its head above water, helps the animal view its surroundings.^[60][61]

Resident Killer Whales swim with porpoises, other dolphins, seals, and sea lions, which are common prey for transient Killer Whales. Resident Killer Whales are continually on the move, sometimes traveling as much as 160 kilometers (99 mi) in a day, but may be seen in a general area for a month or more. Resident Killer Whale pod ranges vary from 320 to 1,300 kilometres (200 to 810 mi).

Social structure

North Pacific fish-eaters have a complex but stable social grouping system. Unlike any other mammal species whose social structure is known, resident Killer Whales live with their mothers for their entire lives. Therefore, Killer Whale societies are based around matrilines consisting of (the matriarch) and her descendants who form part of the line, as do their descendants. The average size of a matriline is 5.5 animals.^[62]

Because females can reach age ninety, 4 generations may travel together. These matrilineal groups are highly stable. Individuals separate for only a few hours at a time, to mate or forage. No permanent dispersal of an individual from a resident matriline has been recorded.^[62]

Closely related matrilines form loose aggregations called pods, usually consisting of one to four matrilines. Unlike matrilines, pods may split up for weeks or months at a time.^[62] DNA testing indicates that resident males nearly always mate with females from other pods.^[63]

Killer Whales, like this one spotted near Alaska, commonly breach, often lifting their entire body out of the water.

Clans are the next level of social structure and are composed of pods with similar dialects and common but older maternal heritage. Geographic ranges of clans overlap. Pods from different clans frequently intermingle.^[62]

The final association layer, perhaps more arbitrary than the other, familial groupings, is called the community and is defined as a set of clans that regularly commingle. Clans within a community do not share vocal patterns.^[64]

Transient pods are smaller than resident pods, consisting of one to four individuals. They typically consist of an adult female and one or two of her offspring. Males typically maintain stronger relationships with their mother than females. These bonds can extend well into adulthood. Unlike residents, extended or permanent dispersal of transient offspring from natal matrilines is common, with juveniles and adults of both sexes participating. Some males become “roving” males that do not form long-term associations, living alone while occasionally joining groups that contain reproductive females.^[65] As in resident clans, transient community members share an acoustic repertoire, although regional differences in vocalizations have been noted.^[66]

Vocalizations

Like other dolphins, Killer Whales are highly vocal, producing a variety of clicks and whistles for communication and echolocation. Vocalization types vary with activity. While resting they are much quieter, emitting an occasional call that is distinct from those used during active behavior.

Northeast Pacific resident groups tend to be much more vocal than transient groups in the same waters.^[67] Residents feed primarily on salmon, whose hearing is too poor to detect Killer Whale calls at any significant distance. Residents make sounds to identify themselves when they approach another marine mammal.

Transient Killer Whales feed mainly on marine mammals. Because all marine mammals have excellent underwater hearing, the typical silence of transients is probably necessary to avoid detection by their prey.^[67] They sometimes use a single click (called a cryptic click) rather than the long train of clicks observed in other populations.

All members of a resident pod use similar calls, known collectively as a dialect. Dialects are comprised of specific numbers and types of discrete, repetitive calls. They are complex and stable over time. Call patterns and structure are distinctive within matrilines. Individuals likely learn their dialect through contact with their mother and other pod members. For instance, family-specific calls have been observed more frequently in the days following a calf's birth, which may help the calf learn them.^[68] 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 building over time.^[69]

Researchers have not determined whether calls have particular meanings or are associated with specific types of activity. Dialects of resident Killer Whale pods contain 7-17 (mean = 11) distinctive call types. Transient dialects are much different, having only 4-6 discrete calls, none of which are shared with residents. 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 that offshore Killer Whales have group-specific dialects unlike those of residents and transients.^[69]

Newborns produce calls similar to adults, but have a more limited repertoire.^[66] Mothers train their young in the pod's dialect. The mother uses a simplified version, a sort of baby-talk, when training a calf. This suggests that Killer Whale vocalization have both a learned and an instinctual basis.

Intelligence

The Killer Whale's use of dialects and the passing of other learned behaviors across generations has been described as a form of culture. The paper Culture in Whales and Dolphins^[70] goes as far as to say:

"The complex and stable vocal and behavioral cultures of sympatric groups of Killer Whales (Orcinus orca) appear to have no parallel outside humans and represent an independent evolution of cultural faculties."

From 1968 to 1971, the US Navy attempted to train two males (Ahab and Ishmael) captured in Washington State and kept at NUC Hawaii in fenced sea pens. They were trained for "open ocean reliability", but on February 17, 1971, Ishmael did not return when called and was never seen again. Ahab died in 1974.^[71]

Conservation

The Type C Killer Whale has two-toned gray colouring, including a dark "dorsal cape," in body areas where most Killer Whales have solid black colouring. Research is ongoing into whether one or more Killer Whale types is a distinct species in need of protection.

In 2008, the IUCN changed its assessment of the Killer Whale's conservation status from conservation dependent to data deficient, recognizing that one or more Killer Whale types may actually be separate, endangered species.^[2] Depletion of prey, pollution, conflicts with fishing, and habitat degradation are currently the most significant, worldwide threats.^[4][10]

Like other animals at the highest trophic levels of the food chain, the Killer Whale is particularly at risk of poisoning from accumulation of Polychlorinated biphenyls (PCBs). A survey off the Washington coast found that PCB levels in Killer Whales were higher than those in harbour seals in Europe that have been sickened by the chemical. Samples from the blubber of Killer Whales in the Norwegian Arctic show higher levels of PCBs, pesticides and brominated flame-retardants than in polar bears. When food is scarce, Killer Whales must metabolize their blubber for energy, which increases pollutant concentrations.

In the Pacific Northwest, wild salmon stocks, a main food source for resident Killer Whales, have declined dramatically in recent years.^[2] On the west coast of Alaska and the Aleutian Islands, seal and sea lion populations have also undergone a major decline.^[4]

An adult female and her calf

In 2005, the United States government listed the southern resident community as an endangered population under the Endangered Species Act. The southern resident community comprises three pods which spend most of the year in the Georgia, Haro Straits and Puget Sound in British Columbia and Washington. They do not breed outside of their community, which was previously estimated at around 200 animals and had shrunk to around 90.^[72] In October 2008, the annual survey revealed that seven were missing and presumed dead, reducing the count to 83.^[73] This is potentially the largest decline in the population in the past ten years. Ken Balcomb, a senior scientist at the Center for Whale Research on the San Juan Islands, has proclaimed this loss as a "disaster". These deaths can be attributed to declines in chinook salmon.^[73]

The last known AT1 pod offspring, AT3, swimming in Resurrection Bay.

Noise from shipping, drilling, and other human activities can interfere with communication and echolocation. In the mid-1990s, loud underwater noises from salmon farms were used to deter seals. Killer Whales also avoided the surrounding waters.^[74] High-intensity sonar used by the Navy disturbs Killer Whales along with other marine mammals.^[75] Killer Whales are popular with whale watchers, which may stress the whales and alter their behavior, particularly if boats approach too closely or block their line of travel.^[76]

The Exxon Valdez oil spill had an adverse effect on Killer Whales in Prince William Sound and the Kenai Fjords region of Alaska. 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 Killer Whales. By 2009, scientists at the North Gulf Oceanic Society estimated the AT1 transient population (considered part of a larger population of 346 transients), numbered only 7 individuals and had not reproduced since the spill. This population is expected to become extinct.^[77][78]

Relation to humans

An adult male Killer Whale with its characteristic tall dorsal fin swims in the waters near Tysfjord, Norway

Historically, Killer Whales were widely feared as dangerous, savage predators, a reputation based on rumour and speculation.^[79] There have been very few confirmed attacks on humans by Killer Whales, none of which has been fatal.^[80] In one instance, Killer Whales tried to tip ice floes on which a dog team and photographer of the Terra Nova Expedition was standing.^[81] There is speculation that the barking of the sled dogs may have sounded enough like seal calls to trigger the Killer Whale'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 harbor seals was bumped by a Killer Whale that apparently misidentified him as prey.^[80]

The first written description of a Killer Whale was given by Pliny the Elder in 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 [other whales]... they charge and pierce them like warships ramming."^[82]

Competition with fishermen also led to Killer Whales being regarded as pests. In the waters of the Pacific Northwest and Iceland, the shooting of Killer Whales was accepted and even encouraged by governments.^[79] The U.S. Navy claimed to have deliberately killed hundreds of Killer Whales in Icelandic waters in 1956.^[83][84]

Modern Western attitudes

Western attitudes towards Killer Whales have changed dramatically in recent decades. In the mid 1960s and early 1970s, Killer Whales came to much greater public and scientific awareness, starting with the first live-capture and display of a Killer Whale known as Moby Doll, a resident whale that had been harpooned off Saturna Island in 1964.^[79] So little was known about Killer Whales at the time that 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 that made no attempts to attack humans.^[85]

Between 1964 and 1976, 50 Killer Whales from the Pacific Northwest were captured for display in aquaria, and public interest in the animals grew. Millions of people gained an appreciation for Killer Whales by viewing them in captivity. In the 1970s, research pioneered by the late Dr. 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.

In 2002, the orphan Springer was successfully returned to her family.

Bigg's techniques also revealed that the number of Killer Whales in the Pacific Northwest was small - in the low hundreds rather than the thousands that had been previously assumed.^[79] The Southern Resident community alone had lost 48 of its members to captivity; by 1976, only 80 remained.^[21]

Paradoxically, the public's growing appreciation also led to growing opposition to the practice of keeping wild whales in aquaria. Only one whale has been taken in North American waters since 1976. In recent years, the extent of the public's interest in Killer Whales 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 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 Killer Whales.^[86] The saving of Springer raised hopes that another young Killer Whale named Luna who had become separated from his pod could be returned to it. His case was marked by controversy about whether and how to intervene, however, and in 2006 Luna was killed by a boat propeller.^[87]

Whaling

Killer Whales were targeted in commercial whaling in the middle part of the twentieth century, after depleting the stocks of larger species. Between 1954 and 1997, Japan took 1,178 Killer Whales and Norway took 987.^[88] Between 1979 and 1980, Soviet whalers in the Antarctic took 906 Killer Whales, prompting the International Whaling Commission to recommend a ban on commercial hunting of the species pending further research.^[88] Today, no country carries out a substantial hunt, although Indonesia and Greenland permit small subsistence hunts.

Killer Whales have co-operated with humans in the hunting of whales. One well-known example was the Killer Whales of Eden, Australia.

Shamu (played by Orkid) posing at Seaworld, San Diego

Captivity

The Killer Whale's intelligence, trainability, striking appearance, playfulness in captivity and sheer size have made it a popular exhibit at aquariums and aquatic theme parks. Killer Whales were taken from the coasts of British Columbia and Washington until 1976, and since then have generally been taken from Icelandic waters (50 between 1980 and 1985). Since then, Killer Whales have been successfully bred in captivity, and captive wild-born whales are considerably rarer.

Organizations such as the World Society for the Protection of Animals and the Whale and Dolphin Conservation Society campaign against the practice of keeping them in captivity.

Killer Whales in captivity often develop pathologies, such as the dorsal fin collapse seen in 60–90% of captive males. Captive Killer Whales have vastly reduced life expectancies, on average only living into their 20s; however, there are examples of Killer Whales living longer, including many over 30 years old, and two Killer Whales (Corky II and Lolita/Tokitae of the Miami SeaQuarium) are in their mid-40s. In the wild, female Killer Whales can live to be 70–80 years old (though this is a rare occurrence, and 50 years is the average lifespan expected for those who survive infancy), while males can live to be 50–60 years old (while 30 years is the average).^[89] The captive environment usually bears little resemblance to their wild habitat, and the social groups that the Killer Whales are put into are foreign to those found in the wild.^[90] Critics claim that captive life is stressful due to small tanks, false social groupings and chemically altered water. Captive Killer Whales occasionally act aggressively towards themselves, other Killer Whales, or humans, which critics say is a result of stress.

Haida sculpture

Unlike wild Killer Whales, captives have attacked people, such as their handlers or pool intruders, much more frequently, numbering nearly two dozen since the 1970s.^[91]

Cultural significance

The indigenous peoples of the Pacific Northwest Coast feature it throughout their history, art, spirituality and religion.

In the tales and beliefs of the Siberian Yupik people, Killer Whales are said to appear as wolves in winter, and wolves as Killer Whales in summer.^{[92][93][94][95]} Killer Whales are believed to assist their hunters in driving walrus.^[96] Reverence is expressed in several forms: the boat represents the animal, and a wooden carving hung from the hunter's belt.^[94] Small sacrifices such as tobacco are strewn into the sea for them.^[96] They believe that it helps the hunters even in wolf guise: they force the reindeer to allow itself to be killed by the hunters.^[95]

Killer Whale depicted in St Mary's in Greifswald, Germany, 1545. The long fluke indicates the whale as a male.^[97]

On 30 March 1545, a Killer Whale stranded in the Bay of Greifswald, a bodden of the Baltic Sea. This caused great excitement among the local population, because whales seldom enter these waters. In Greifswald, the locals portrayed the whale with a life-size painting on the walls of the St. Mary's church. Konrad Gessner evaluated the whale's body, and based on this evaluation was the first to scientifically describe a Killer Whale in his "Fish book" of 1558.^[97][98]

A popular Internet video shows a Killer Whale appearing to jump on a group of kayakers. The event shown is a fake used in an advertisement for a sports drink.^[99][100]

Cetaceans portal

References

General references

• Orcinus orca (TSN 180469). Integrated Taxonomic Information System. Retrieved on 18 March 2006.
• Baird, Robin W.: Killer Whales of the World Voyageur Press, Stillwater, MN, 2002.
• Ford, John K.B. 2002. "Killer Whale", pp. 669–675 in the Encyclopedia of Marine Mammals, Academic Press, ISBN 0-12-551340-2
• Ford, John K.B., Ellis, Graeme M. and Balcomb, Kenneth C. (2000). Killer Whales, Second Edition. Vancouver, BC: UBC Press. ISBN 0-7748-0800-4.  
• Francis, Daniel; Gil Hewlett (2007). Operation Orca: Springer, Luna and the Struggle to Save West Coast Killer Whales. Harbour Publishing. ISBN 1550174266.  
• Hoyt, Erich. 1998. Orca: The Whale Called Killer, Camden House Publishing, ISBN 9780920656259
• Kirkevold, B. C.; J. S. Lockard (1986). Behavioral Biology of Killer Whales. Alan R. Liss. ISBN 0845131001.  
• Klinowska, Margaret (1991). The IUCN Red Data Book: Dolphins, Porpoises, and Whales of the World. IUCN. ISBN 2880329361.  
• Menoščikov, G. A.: "Popular Conceptions, Religious Beliefs and Rites of the Asiatic Eskimoes". Published in Diószegi, Vilmos and Hoppál, Mihály: Folk Beliefs and Shamanistic Traditions in Siberia. Akadémiai Kiadó, Budapest, 1968, 1996.
• Menovshchikov, G. A.: Grammar of the language of Asian Eskimos. Vol. I. Academy of Sciences of the USSR, Moscow • Leningrad, 1962. Original data: Г.А. Меновщиков: Грамматиκа языка азиатских эскимосов. Часть первая. Академия Наук СССР. Москва • Ленинград, 1962.
• National Marine Fisheries Service (NMFS) Northwest Regional Office (2005) "Conservation Plan for Southern Resident Killer Whales (Orcinus orca) " Seattle, U.S.A. Retrieved on January 2, 2009
• Obee, Bruce; Graeme Ellis (1992). Elaine Jones. ed. Guardians of the Whales: The Quest to Study Whales in the Wild. North Vancouver, British Columbia: Whitecap Books. pp. 1–27. ISBN 1-55110-034-7.  
• Reeves, Stewart and Clapham and Powell, Alfred A. Knopf. 2002. National Audubon Society Guide to Marine Mammals of the World ISBN 0-375-41141-0
• Ridgway, Sam H.; Richard Harrison (1998). Handbook Of Marine Mammals Volume 6: The second book of dolphins and the porpoises. Academic Press. ISBN 0125885067.  
• Rubcova, E. S.: Materials on the Language and Folklore of the Eskimoes, Vol. I, Chaplino Dialect. Academy of Sciences of the USSR * Leningrad, 1954. Original data: Е.С. Рубцова: Материалы по языку и фольклору эскимосов (чаплинский диалект). Академия Наук СССР. Москва * Ленинград, 1954
• Shevchenko, I.V. "Kharakter vzaimootnoshenii kasatok i drugikh kitoobraznykh'" in Morskie mlekopitayushchie (in Russian, transliterations vary). "The nature of interrelationships between Killer Whales and Other Cetaceans", 1975, pp. 173–175. The author describes his discovery of Orca cannibalism.

External links

• US National Marine Fisheries Service Killer Whale page
• Orca-Live - Orcas in Johnstone Strait, British Columbia
• Video:Orca Attack Seal with Waves (YouTube)
• Video of Type C Killer Whales in the Antarctic
• Killer Whale watching guidelines