Orca

"Orca" redirects here. For other uses, see Orca (disambiguation).

Orca
Transient Orcas near Unimak Island, eastern Aleutian Islands, Alaska
Conservation status
Data Deficient  (IUCN 3.1)
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)

Size comparison against an average human

The killer whale or orca (Orcinus orca), less commonly,also known as evan buss blackfish or seawolf, is the largest species of the dolphin family. It is found in all the world's oceans, from the frigid Arctic and Antarctic regions to warm, tropical seas. Killer whales are versatile and opportunistic predators. Some populations feed mostly on fish while other populations hunt marine mammals, including sea lions, seals, walruses and even large whales. They are considered the apex predator of the marine world, having no known predators. There are up to five distinct killer whale types, some of which may be separate races, subspecies or even species. Killer whales are highly social; some populations are composed of matrilineal family groups, which are the most stable of any animal species. The sophisticated social behavior, hunting techniques, and vocal behavior of killer whales have been described as manifestations of culture.

Although the killer whale population as a whole is not considered to be an endangered species, some local populations are considered threatened or endangered due to depletion of prey species and habitat loss, pollution by PCBs, captures for marine mammal parks, and conflicts with vessels. In late 2007, the killer whales known as the "southern resident killer whales," were placed on the Endangered Species list.

Wild killer whales are usually not considered a threat to humans. There have, however, been isolated reports of captive killer whales attacking and, in at least one instance, killing their handlers at marine theme parks. There is also a level of confusion surrounding the term "whale". While killer whales are members of the dolphin family, they, and all other members of the dolphin family, are members of the sub-order Odontoceti and the order Cetacea, meaning "toothed whale" and "whale", respectively.

Taxonomy and evolution

Orcinus orca is the sole species in the genus Orcinus, one of the many species originally described by Linnaeus in 1758 in Systema Naturae. It is one of thirty-five species in the dolphin family. Like the Sperm Whale genus Physeter, Orcinus is a genus with a single, abundant species. Thus, paleontologists believe that the killer whale is a prime candidate to have an anagenetic evolutionary history, forming descendant species from ancestral species without splitting of the lineage. If true, this would make the killer whale one of the oldest dolphin species. However, it is unlikely to be as old as the family itself, which is believed to date back at least five million years. However, there are at least three to five types of killer whales that are distinct enough to be considered different races, subspecies, or possibly even species. 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, including Puget Sound. The resident killer whales' 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 large matrilineal groups and vocalizing in highly variable and complex dialects. "The basic unit of resident Orca society is a mother, all of her dependent offspring (approximately ten years or younger), and her adult offspring as well, including her sons. Females will eventually spend less time with their mothers, as they begin producing calves of their own, but resident males appear to remain with their mothers for their entire lives. They leave for short periods to mate outside of their maternal group, but return to their mother afterwards." Female residents characteristically have a rounded dorsal fin tip that terminates in a sharp corner. They are known to visit the same areas consistently. The resident populations of British Columbia and Washington are amongst the most intensely studied marine mammals ever. Researchers have identified and named over 300 killer whales over the past 30 years.
• Transient: The diet of these killer whales 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 and vocalizing in less variable and less complex dialects. Female transients are characterized by dorsal fins that are more triangular and pointed 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 Southern Alaska and later in 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 killer whales in open water. These killer whales 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 ruled out. 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 animals. Currently, there is little known about the habits of this population, but they can be distinguished genetically from the residents and transients. Offshores appear to be shorter than the residents and the transients and females are characterized by dorsal fin tips that are continuously rounded.

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

killer whale populations in other parts of the world have not been as well studied. However, there appears to be a correlation between a population's diet and its social behaviour. 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. 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. Recent genetic research has found that the types have not interbred for up to 10,000 years. Three killer whale types have recently been documented in the Antarctic.

• Type A looks like a "typical" killer whale, living in open water and feeding mostly on minke whales.
• Type B is smaller than Type A. It has a large white eyepatch and a patch of grey colouring on its back, called a "dorsal cape". It feeds mostly on seals.
• Type C is the smallest type and lives in larger groups than any other type of killer whale. Its eyepatch is distinctively slanted forwards, rather than parallel to the body axis. Like Type B, it has a dorsal cape. Its only prey observed so far is the Antarctic Cod.

Type B and C killer whales live close to the Antarctic ice pack, and diatoms in these waters may be responsible for the yellowish colouring of both types. Research is ongoing whether Type B and C killer whales are different species.

Common names

The name Orca (plural Orcas) was originally given to these animals by the ancient Romans, possibly borrowed from the Greek word ὄρυξ, which (among other things) referred to a species of whale. 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 equivalent for Orca. The name killer whale is widely used in common English. However, since the 1960s, Orca has steadily grown in popularity as the common name to identify the species, and both names are now used. This change was encouraged to avoid the negative connotations of "killer". The species is called Orca in most other European languages, and, as there has been a steady increase in the amount of international research on the species, there has been a convergence in naming. Supporters of the original name point out that the naming heritage is not limited to Spanish sailors. Indeed, the genus name Orcinus means "from hell" (see Orcus), 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, the Roman god of the underworld. The name of this species is similarly intimidating in many other languages, including Haida, Japanese and Chinese. In Afrikaans Dutch, German, Swedish and Finnish the orca is called "sword whale" due to the shape of its dorsal fin. They are sometimes referred to as blackfish, a name also used to refer to pilot whales, pygmy and false killer whales, and melon-headed whales. A former name for the species is grampus. This is now seldom used and should not be confused with the Grampus genus, whose only member is Risso's Dolphin.

Description

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

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 stocky body and a large 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 m long (19-26 ft) and weigh in excess of 6 tonnes. Females are smaller, generally ranging from 5-7 m (16-23 ft) and weighing about 3 to 4 tons. The largest killer whale ever recorded was a male off the coast of Japan, measuring 9.8 m (32 ft) and weighing over 8 tonnes (17,636 lb). Calves at birth weigh about 180 kg (350-500 lb) and are about 2.4 m long (6-8 ft).The killer whale's large size and strength make it among the fastest marine mammals, often reaching speeds in excess of 56 km/h (35 mph). Unlike most dolphins, the pectoral fin of a killer whale is large and rounded—more of a paddle than other dolphin species. Males have significantly larger pectoral fins than females. At about 1.8 m (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—whereas the dorsal fin of the female is shorter and generally more curved. Adult male killer whales are very distinctive and are unlikely to be confused with any other sea creature. When seen from a distance in temperate waters, adult females and juveniles can be confused with various other species, for example, the false killer whale or Risso's dolphin.

An Orca skull

Individual killer whales can be identified from a good photograph of the animal's dorsal fin and saddle patch, taken when it surfaces. Variations such as nicks, scratches, and tears on the dorsal fin and the pattern of white or grey in the saddle patch are sufficient to distinguish killer whales from each other. For the well-studied killer whales of the northeast Pacific, catalogues have been published with the photograph and name of each killer whale. Photo identification has enabled the local population of killer whales to be counted each year rather than estimated and has enabled great insight into killer whale lifecycles and social structures.

Lifecycle

Females become mature at around 15 years of age. Then they have periods of polyestrous cycling with non-cycling periods of between three and sixteen months. The gestation period varies from fifteen to 18 months. Mothers calve, with a single offspring, about once every five years. In analysed resident pods, birth occurs at any time of year, with the most popular months being those in winter. Newborn mortality is very high—one survey suggested that nearly half of all calves fail to reach one year old. Calves nurse for up to two years but will start to take solid food at about twelve months. All resident killer whale pod members, including males of all ages, participate in the care of the young. Cows breed until the age of 40, meaning that on average they raise five offspring. Typically, females' life spans average 50 but may survive well into their 70-80s in exceptional cases. Males become sexually mature at the age of 15 but do not typically reproduce until age 21. Male killer whales generally do not live as long as females. In the wild, males average 30 years, with a maximum of 50–60 years in exceptional cases. However, one male, known as Old Tom, was reportedly spotted every winter between 1843 and 1932 off New South Wales, Australia. This would have made him at least 89 years old. The lifespans of captive killer whales have been known to be 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 orcas often depend on the will of the animal.

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 two miles (3 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.

Distribution

To travel quickly, Orcas 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, coastal areas are generally preferred to pelagic environments. 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. They are making a bigger presence in California too. 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 like the beluga does. In the Arctic, however, the species is rarely seen in winter, as it does not approach the ice pack. It does visit these waters during summer.

Information for off-shore 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. No estimate for the total worldwide population exists. Local estimates include 70,000–80,000 in the Antarctic, 8,000 in the tropical Pacific (although tropical waters are not the killer whale's preferred environment, the sheer size of this area—19 million square kilometres—means there are thousands of killer whales), up to 2,000 off Japan, 1,500 off the cooler northeast Pacific and 1,500 off Norway. Adding very rough estimates for unsurveyed areas, the total population could be around 100,000.

With the rapid decline of Arctic sea ice in the Hudson Strait, the range of killer whales has now extended into the far northern waters of Canada. Through the 1990s, killer whales were sighted in western Hudson Bay at a rate of 6 per decade; sightings rose to more than 30 between 2001–2006.

The migration patterns of killer whales 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.

Scientists spotted a white killer whale off Alaska on February 23, 2008.

On some occasions, killer whales will swim into freshwater rivers. They have been documented 100 miles (160 km) up the Columbia River in the United States. They have also been found in the Fraser River in Canada and the Horikawa River in Japan.

Diet

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

The killer whale is an apex predator. They are sometimes called the wolves of the sea, because they hunt in pods like packs of wolves. On average, a killer whale eats 227 kg (500 lb) of food each day.

Killer whales prey on a diverse array of species. However, specific populations show a high degree of specialization on particular prey species. For example, some populations in the Norwegian and Greenland sea specialise in herring and follow that fish's migratory path to the Norwegian coast each autumn. Other populations in the area prey on seals. In field observations of the resident killer whales of the northeast Pacific, salmon accounted for 96% of animals' diet, with 65% of the salmon being the large, fatty Chinook. They have been observed to swim through schools of the smaller salmon species without attacking any of them. Depletion of specific prey species in an area is therefore cause for concern for the local killer whale population, despite the high overall diversity of potential killer whale prey.

Although, unlike transient killer whales, resident killer whales have never been observed to eat other marine mammals, they are known to occasionally harass and kill porpoises and seals for no apparent reason.

Fish and other cold-blooded prey

Fish-eating killer whales prey on 30 species of fish, particularly salmon (including Chinook and Coho), herring, and tuna, as well as basking sharks, whale sharks, oceanic whitetip sharks and smooth hammerheads. In one incident off the Farallon Islands, a great white shark was killed by a killer whale, which then ate the shark's nutrient-rich liver. In New Zealand, killer whales have been observed hunting mako sharks as well as stingrays, which seem to be their favorite treat as they will go to nearly any length to get them. Cephalopods, such as octopuses and a wide range of squids, and reptiles, such as sea turtles, are also targets.

While salmon are usually hunted by a single killer whale or a 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. The killer whales 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.

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 preyed on by killer whales, either through an examination of stomach contents, from examining scarring on the prey's body, or from observing the killer whales' feeding activity. Groups of killer whales attack even larger cetaceans such as Minke whales, Gray whales, and, very occasionally, Sperm Whales or Blue whales. Killer whales generally choose to attack whales which are young or weak. However, a group of five or more killer whales may attack healthy adult whales. Bull Sperm Whales are avoided, as they are large, powerful, and aggressive enough to kill killer whales. Bottlenose Dolphins are occasionally hunted by certain types of killer whales but they are generally avoided or in the case of some killer whales even befriended by them.

When hunting a young whale, a group chases it and its mother until they are worn out. Eventually the killer whales manage to separate the pair and surround the young whale, preventing it from returning to the surface to breathe. Whales are typically drowned in this manner. Pods of female Sperm Whales can sometimes protect themselves against a group of killer whales by forming a protective circle around their calves with their flukes facing outwards. This formation allows them to use their powerful flukes to repel the killer whales. Hunting large whales, however, takes a lot of time, usually several hours. Killer whale cannibalism has also been reported.

Other marine mammal prey species include most species of seal, sea lion and fur seal. Walruses and Sea otters are taken less frequently. Killer whales often use complex hunting strategies to find and subdue their prey. Sea lions are killed by head-butting or by being slapped and stunned by a tail fluke. They occasionally throw seals through the air in order to stun and kill them. 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. In the Aleutian Islands off Alaska, Sea otters became more frequent prey for killer whales during the 1990s. This is due to the decline in population of the killer whale's preferred prey in the area; Harbor seals and Steller sea lions.

Some highly specialized hunting techniques have been observed. Off Península Valdés, Argentina, and the Crozet Islands, killer whales feed on South American sea lions and Southern elephant seals in shallow water, even beaching themselves temporarily. Beaching, usually fatal to whales, is not an instinctive behaviour. Adult killer whales have been observed to teach the younger ones the skills of hunting in shallow water. Off Península Valdés, adults pull seals off the shoreline for younger killer whales to recapture. Off the Crozet Islands, mothers have been seen pushing their calves onto the beach, waiting to pull the youngster back if needed.

Orcas swim by an iceberg with Adélie penguins in the Ross Sea, Antarctica. The Drygalski ice tongue is in the background.

Another technique for capturing seals is known as wave-hunting: killer whales spy-hop to locate Weddell seals, Ross seals, Crabeater seals and Leopard seals resting on ice floes and then create waves by swimming together in groups to wash over the floe. This causes the seal to be thrown into the water where another killer whale waits to kill it.

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.

Birds

Several species of birds are preyed upon, 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 them. Other killer whales then learned the behavior by example.

Behavior

File:Peeking Orca.jpg

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

There are at least two types of general killer whale behavior: resident and transient. Each type also has different food sources.

The day-to-day behavior of killer whales is generally divided into four activities: foraging, traveling, resting and socializing. Killer whales are generally enthusiastic in their socializing, engaging in behaviors such as breaching, spyhopping, and tail-slapping.

Killer whales often spy-hop. This behavior is when the killer whale propels itself half-way out of the water. A killer whale may do this for one of two reasons.The first, and most common, reason is that they are looking for food. The other reason is a lot less common. They might spy-hop to see where they are, or more to see how close they are to shore.

Type-C and Type-B killer whales may engage in a certain behavior to get seals on a lone, small iceberg. This behavior is where they nose the ice berg back and forth until they slide the seal off the iceberg into one of the killer whale's mouths. Another eating behavior is where they gain speed in the water and aim themselves at the shore. On this shore there are many seals. The killer whale will almost beach itself, scaring the seals off the shore, and into the waiting mouths of the other members of its group.

Resident killer whales can also be seen swimming 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 km (100 miles) in a day, but may be seen in a general area for a month or more. Range for resident killer whale pods may be as much as 1300 km (800 miles) or as little as 320 km (200 miles).

Social structure of resident killer whale communities

Fish-eating killer whales in the North Pacific have a complex but extremely stable system of social grouping. Unlike any other mammal species whose social structure is known, resident killer whales of both genders live with their mothers for their entire lives. Therefore, killer whale societies are based around matrilines consisting of a single female (the matriarch) and her descendants. The sons and daughters of the matriarch form part of the line, as do the sons and daughters of those daughters. The average size of a matriline is nine animals.

Because females can live for up to ninety years, it is not uncommon for four or even five generations to travel together. These matrilineal groups are highly stable. Individuals split off from their matrilineal group only for up to a few hours at a time, in order to mate or forage. No permanent casting-out of an individual from a matriline has ever been recorded.

Closely related matrilines form loose aggregations called pods, consisting on average of about 18 animals. All members of a pod use a similar set of calls, known as a dialect. Unlike matrilines, pods may split apart for days or weeks at a time in order to forage. Killer whales within a pod do not interbreed; mating occurs only between members of different pods.

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

Resident pods have up to 50 or more members, with an average of 15 in the Northern resident community in the Pacific Northwest. Occasionally, several pods join to form superpods, sometimes with more than 150 animals. Resident pods often include subpods, which comprises one daughter or cousin that sometimes travels only with her offspring and sometimes joins the rest of the pod.

The next level of grouping is the clan. A clan consists of pods which have a similar dialect. Again, the relationship between pods appears to be genealogical, consisting of fragments of families with a common heritage on the maternal side. Different clans can occupy the same geographical area; pods from different clans are often observed traveling together. When Resident pods come together to travel as a clan, they greet each other by forming two parallel lines akin to a face-off before mingling with each other.

The final layer of association, perhaps more arbitrary and devised by humans rather than the other very natural divisions, is called the community and is loosely defined as a set of clans that are regularly seen mixing with each other. Communities do not follow discernible familial or vocal patterns.

Transient groups are generally smaller because, although they too are based on matrilines, some male and female offspring eventually disperse from the maternal group. However, transient groups still have a loose connection defined by their dialect.

Vocalizations

Multimedia relating to the Orca

See also: Whale song

Like other dolphins, killer whales are highly vocal. They produce a variety of clicks and whistles used for communication and echolocation. The vocalization types vary with activity. While resting they are much quieter, emitting an occasional call that is distinct from those used when engaging in more active behavior.

Fish-eating resident groups of killer whales in the northeast Pacific tend to be much more vocal than transient groups in the same waters. Resident killer whales 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 are approaching another marine mammal. Transient killer whales, on the other hand, feed mainly on marine mammals. Because all marine mammals have excellent underwater hearing, the usual silence of transients is probably necessary to avoid detection by their acoustically sensitive prey. They sometimes use a single click (called a cryptic click) rather than the long train of clicks observed in other populations.

Resident pods have group-specific dialects. Each pod has its own vocal repertoire, or set of particular stereotyped underwater calls (call types). Every member of the pod seems to know all the call types of the pod, so it is not possible to identify a single animal using voice alone. A particular call type might be used by only one group or shared among several.

The number of call types shared by two groups appears to be a function of their genealogical relatedness rather than their geographical distance. Two groups that share a common set of ancestors but have grown apart in distance are likely to have a similar set of call types, indicating that calls are a learned behavior.

Killer whale mothers have been observed training their young in the pod's dialect. The mother uses a simplified version of the pod's dialect, a sort of baby-talk, when training a calf. This suggests that killer whale vocalization has a learned basis in addition to an instinctual one.

Intelligence

Main article: Cetacean intelligence

The killer whale's use of dialects and the passing of other learned behaviors from generation to generation has been described as a form of culture. The paper Culture in Whales and Dolphins 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 male killer whales (Ahab and Ishmael) captured in Washington State and kept at NUC Hawaii in fenced sea pens. The killer whales 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.

Conservation

An adult female and her calf

Environmental degradation, depletion of prey species, conflicts with fishing activities, and habitat degradation are currently the most significant threats to killer whales worldwide.

Like other animals at the highest trophic levels of the food chain, the killer whale is particularly susceptible to poisoning via accumulation of Polychlorinated biphenyls (PCBs) in the body. A survey of animals 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.

Stocks of most species of salmon, a main food source for resident killer whales in the northeast Pacific, have declined dramatically in recent years. On the west coast of Alaska and the Aleutian Islands, populations of seals and sea lions have also undergone a major decline. If food is scarce, killer whales must draw from their blubber for energy, which further magnifies the effects of pollutants. In 2005, the United States government listed the southern resident community of killer whales 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 and Haro Straits and Puget Sound in British Columbia and Washington. These killer whales do not breed outside of their community, which was previously estimated at around 200 animals and had shrunk to around 90. In October 2008, the annual survey of resident killer whales revealed that seven killer whales were missing and presumed dead, reducing the known number to 83.

As recently as October 2008, in Seattle WA, seven Puget Sound killer whales went missing and are being presumed dead in what 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 incident as a "disaster". Balcomb has said that the population drop in killer whales is worse than the stock market. This is devastating to the Pacific Northwest Region as the current southern resident count now stands at 83. These deaths can be attributed to declines in chinook salmon.

Noise from shipping, drilling, and other human activities can interfere with the acoustic communication and echolocation of killer whales. In the mid-1990s, loud underwater noises from salmon farms were used to deter seals. Killer whales subsequently avoided the surrounding waters. In addition, high intensity navy sonar has become a new source of distress for killer whales. Killer whales are popular with whale watchers, which may change killer whale behaviour and stress killer whales, particularly if boats approach killer whales too closely or block their line of travel.

The Exxon Valdez oil spill had an adverse effect on killer whales in Prince William Sound and the Kenai Fjords region of Alaska. One Resident pod was caught in the spill; though the pod successfully swam to clear water, eleven members (about half) of the pod disappeared in the following year. The spill had a long-term effect by reducing the amount of available prey, such as salmon, and has thus been responsible for a local population decline. In December 2004, scientists at the North Gulf Oceanic Society said that the AT1 transient population of killer whales (currently considered part of a larger population of 346 transients), now only numbering 7 individuals, has failed to reproduce at all since the spill. This population is expected to become extinct.

Killer whales and humans

Although only scientifically identified as a species in 1758, the killer whale has been known to humans since prehistoric times.

The first written description of a killer whale is given in Pliny the Elder's Natural History (written circa AD 70). The aura of invincibility around the all-consuming killer whale was well established by this time. Having observed the public slaughter of a killer whale stranded at a harbour near Rome, Pliny writes, "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."

Whaling

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

Killer whales were targeted in commercial whaling for the middle part of the twentieth century, once stocks of larger species had been depleted. Commercial hunting of killer whales came to an abrupt halt in 1981 with the introduction of a moratorium on all whaling (although from a taxonomic point of view, a killer whale is a dolphin rather than a whale, it is sufficiently large to come under the purview of the International Whaling Commission).

The greatest hunter of killer whales was Norway, which took an average of 56 animals per year from 1938 to 1981. Japan took an average of 43 animals from 1946 to 1981 (war year figures are not available but are likely to be fewer). The Soviet Union took a few animals each year in the Antarctic, with the extraordinary exception of the 1980 season when it took 916.

Today, no country carries out a substantial hunt. A small level of subsistence whaling is carried out by Indonesia and Greenland. As well as being hunted for their meat, killer whales have also been killed because of competition with fishermen. In the 1950s, the United States Air Force, at the request of the Government of Iceland, used bombers and riflemen to slaughter killer whales in Icelandic waters because they competed with humans for fish. The operation was considered a great success at the time by fishermen and the Icelandic government. However, many were unconvinced that killer whales were responsible for the drop in fish stocks, blaming overfishing by humans instead. This debate has led to repeated studies of North Atlantic fish stocks, with neither side in the whaling debate giving ground since that time.

Killer whales have been known to co-operate with humans in the hunting of whales. One well-known example occurred near the port of Eden in southeastern Australia between 1840 and 1930. A pod of killer whales, which included amongst its members a distinctive male called Old Tom, would assist whalers in hunting baleen whales. The killer whales would find the target whales, shepherd them into Twofold Bay, and then alert the whalers to their presence and often help to kill the whales. Old Tom's role was commonly to alert the human whalers to the presence of a baleen whale in the bay by breaching or tailslapping at the mouth of the Kiah River, where the Davidson family had their tiny cottages. This role endeared him to the whalers and led to the idea that he was "leader of the pack", although such a role was more likely taken by a female as is more typical in killer whale cultures. After the harpooning, some of the killer whales would even grab the ropes in their teeth and aid the whalers in hauling. The skeleton of Old Tom is on display at the Eden Killer Whale Museum, and significant wear marks still exist on his teeth from repeatedly grabbing fast-moving ropes. In return for their help, the whalers allowed the killer whales to eat the tongue and lips of the whale before hauling it ashore. The killer whales would then also feed on the many fish and birds that would show up to pick at the smaller scraps and runoff from the fishing. The behaviour was recorded in detail in the 1840s by whaling overseer Sir Oswald Brierly and recorded in his extensive diaries. It was recorded in numerous publications over the period, and witnesses included Australian members of Parliament. The behaviour was recorded on movie film in 1910 by C.B. Jenkins and C.E. Wellings and publicly projected in Sydney, although the film is now missing. In 2005, the Australia Broadcasting Corporation produced a documentary, Killers in Eden, on the subject. The documentary featured numerous period photographs taken by C.E. Wellings and W.T. Hall of the phenomenon and also featured interviews with elderly eyewitnesses. Fear of killer whales has dissipated in recent years due to better education about the species, including the appearance of killer whales in aquariums.

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

Captivity

Main article: Captive orcas

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. The first killer whale capture and display occurred in Vancouver in 1964. Over the next 15 years, around 60 or 70 killer whales were taken from Pacific waters for this purpose. The Southern Resident community of the northeast Pacific lost 48 of its members to captivity; by 1976, only 80 killer whales were left in the community, which remains endangered. In the late 1970s and the first half of the 1980s, killer whales were generally taken from Icelandic waters (50 in the five years to 1985). Since then, killer whales have been successfully bred in captivity and wild specimens are considerably rarer.

The practice of keeping killer whales in captivity is controversial, and organisations such as the World Society for the Protection of Animals and the Whale and Dolphin Conservation Society campaign against the captivity of killer whales. Killer whales in captivity may develop physical 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 who are over 30 years old, and two killer whales (Corky II and Lolita/Tokitae of the Miami SeaQuarium) are around 40 years of age. In the wild, female killer whales can live to be 80 years old (though these individuals are indeed rare occurrences, 60 years of age is a more accurate estimate), while males can live to be 60 years old (while 30 years is the average). 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. Critics claim that captive life is stressful due to small tanks, false social groupings and chemically altered water. Captive killer whales have occasionally acted aggressively towards themselves, other killer whales, or humans, which critics say is a result of stress.

There are few confirmed attacks on humans by wild killer whales. Two recorded instances include a boy charged while swimming in Alaska and killer whales trying to tip ice floes on which a dog team and photographer of the Terra Nova Expedition was standing. In the case of the boy in Ketchikan, Alaska, the boy was splashing in a region frequented by harbour seals, leading to speculation that the killer whales misidentified him as prey and aborted their attack. In the case of the Terra Nova expedition, there is speculation that the seal-like barking of the sled dogs may have triggered the Killer Whale's hunting curiosity.

An internet distributed video with millions of views shows an orca appearing to jump on a group of kayakers. Regularly presented on TV news as a real attack and discussed by zoologists, it is really an advertisement by Wieden Kennedy advertising agency for a sports drink using computer compositing. Much more common than wild killer whales attacking people are captive killer whales attacking people, either their handlers or intruders. ABC News has reported that killer whales have attacked nearly two dozen people since the 1970s.

Cultural significance

Haida Jade Orca

The indigenous peoples of the Pacific Northwest Coast have featured the killer whale prominently in their culture through history, art, spirituality and religion.

In the tales and beliefs of the Siberian Yupik people, the wolf and the killer whale were thought to be identical: killer whales were said to appear as wolves in winter, and wolves as killer whales in summer. Killer whales were believed to help people in hunting on the sea: they were thought to assist the sea hunter in driving walrus. Thus, reverence was expressed in several forms: the boat represented the image of this animal, and a wooden representation of a killer whale also hung from the hunter's belt. Small sacrifices could also be given to killer whales: tobacco was strewn into the sea for them. It was believed that the killer whale was a help to the hunters even if it was in the guise of a wolf: this wolf was thought to force the reindeer to allow itself to be killed by the hunters.

See also

• Captive orcas
• Killer Whales in popular culture
• Famous Orcas

References

General references

• "Orcinus orca". Integrated Taxonomic Information System. 18 March. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
• Orca: The Whale Called Killer, Erich Hoyt, Camden House Publishing, ISBN 0-920656-25-0
• "Killer Whale", John K.B. Ford, pp. 669–675 in the Encyclopedia of Marine Mammals, Academic Press, ISBN 0-12-551340-2
• National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell, Alfred A. Knopf, ISBN 0-375-41141-0
• "Kharakter vzaimootnoshenii kasatok i drugikh kitoobraznykh'" in Morskie mlekopitayushchie (in Russian, transliterations vary). "The nature of interrelationships between Killer Whales and Other Cetaceans", I.V.Shevchenko, 1975, pp. 173–175. (The author describes his discovery of Orca cannibalism.)
• Ridgway, Sam H. (1998). Handbook Of Marine Mammals Volume 6: The second book of dolphins and the porpoises. Academic Press. ISBN 0125885067. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Kirkevold, B. C. (1986). Behavioral Biology of Killer Whales. Alan R. Liss. ISBN 0845131001. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Klinowska, Margaret (1991). The IUCN Red Data Book: Dolphins, Porpoises, and Whales of the World. IUCN. ISBN 2880329361.
• Ellis, Graeme. Guardians of the Whales. Whitecap Books. ISBN 1-55110-034-7. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Ford, John K.B. Killer Whales. UBC Press. ISBN 0-7748-0469-6. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• 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.
• 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.
• 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.
• Baird, Robin W.: Killer Whales of the WorldVoyageur Press, Stillwater, MN, 2002.

External links

Pictures and videos

• Orca Guardians - short documentary on the Northern Residents of San Juan Islands
• Orca-Live - Orcas in Johnstone Strait, British Columbia
• Killer whale images, Tysfjord, Norway
• Orcafilm from Lofoten Islands
• Monterey Bay Whale Watch Photos: Killer Whales Attacking Gray Whales
• Video:Orca Attack Seal with Waves (YouTube)
• Video:Faked attack on Kayaker (YouTube)

Regions

Strait of Gibraltar:

• Killer Whale diet in the Strait of Gibraltar

Northeast Pacific:

• Southern Residents (research by undergraduates at Beam Reach)
• Residents of the Pacific Northwest (general info from The Whale Museum)
• Residents of Southern Alaska (research)
• Southern Residents (Human-Orca Interaction)

North Atlantic and Arctic:

• Research project studying Killer whales in the Norwegian Arctic

Southern Oceans:

• New Zealand, Papua New Guinea and Antarctic Orca research

General

• Killers of Eden
• Whale and Dolphin Conservation Society