Taxonomy:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Family: Delphinidae
Genus: Orcinus
Species: Orcinus orca
English: Killer whale
German: Schwertwal
Spanish: Orca
French: Orque
Prelude:
The killer whale or orca (Orcinus orca), less commonly, 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 marine apex predators. Some populations feed mostly on bony fish while others hunt sharks and marine mammals, including sea lions, seals, walruses and even large whales. 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. 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 U.S. 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.
Distribution:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Family: Delphinidae
Genus: Orcinus
Species: Orcinus orca
English: Killer whale
German: Schwertwal
Spanish: Orca
French: Orque
Prelude:
The killer whale or orca (Orcinus orca), less commonly, 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 marine apex predators. Some populations feed mostly on bony fish while others hunt sharks and marine mammals, including sea lions, seals, walruses and even large whales. 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. 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 U.S. 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.
Distribution:
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.
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.
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, and Finnish the orca is called "sword whale" due to the shape of its dorsal fin. In Swedish, Danish and Norwegian , the orca is called "blubber snatcher", or "späckhuggare" 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.
Habitat:
Sightings range from the surf zone to the open sea, though usually within 800 km of the shoreline. Large concentrations are sometimes found over the continental shelf. Normally prefering depths of 20 to 60 m, killer whales also visit shallow waters along coastlines or dive to 300 m in search of food. Killer whales generally occupy the same home range year round. Generally, orcas prefer deep water but they can also be found in shallow bays, inland seas, and estuaries (but rarely in rivers). They readily enter areas of floe ice in search of prey. Resident killer whales in Pacific Northwest waters use regions of high relief topography along salmon migration routes, whereas transient whales forage for pinnipeds in shallow protected waters.
Home Range:
Home range size is unknown, but some studies have shown that killer whales live with their pods together in their home range for many years. While home range size is unknown, they have been documented to swim up to 160 km a day
Physical Description:
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 male killer whale on record was 9.8 m (32 ft) and weighing over 10 tonnes (22,000 lb), while the largest female was 8.5 m (28 ft) and weighing 7.5 tonnes (16,500 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).[citation needed] 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.
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.
Reproduction:
While killer whales are difficult to study in the wild some of their reproductive habits have been recorded and studied in captive whales. Killer whales can reproduce whenever females enter estrus, which can occur mutiple times a year. However, most breeding happens in the summer, In the North Atlantic, mating seems to peak in October and November; in the western North Pacific, mating seems to be at its highest between May and June, and killer whales are typically born in the fall. Females reach sexual maturity between 6 and 10 years of age. Males reach sexual maturity between 10 and 13 years old. Female killer whales begin to mate between 14 and 15 years of age. The youngest female whale on record to give birth was 11 years old. Females have a calf every 6 to 10 years and they stop breeding around the age of 40. The result is 4 to 6 offspring over a 25 year span.
Gestation takes about 14 months, although a gestation length in captivity was recorded at 539 days. Killer whales have a single calf at a time, twins have only been recorded once. Newborn calves nurse for about a year before weaning. Some studies show that almost half of all newborn calves die before their first birthday. Calves are born in the water. The majority of deliveries seen by humans have been tail-first births, although a head-first birth has been observed. Size estimates of captive-born orcas suggest that calves average 2.6 m in length and weigh between 136-181 kg.
Killer whale females invest a lot of energy in raising their offspring. They carry the calf for almost a year and a half, then give birth and nurse for another 12 months. During that time, mothers teach their calves to hunt and include their offspring in the social network of their pods. Because these animals are not monogamous, it is assumed that the fathers exhibit no parental involvement after mating. When a killer whale calf is born into a pod, it relies on its mother for nutrition and support. Calves remain in their natal pod after independence.
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.
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.
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, and Finnish the orca is called "sword whale" due to the shape of its dorsal fin. In Swedish, Danish and Norwegian , the orca is called "blubber snatcher", or "späckhuggare" 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.
Habitat:
Sightings range from the surf zone to the open sea, though usually within 800 km of the shoreline. Large concentrations are sometimes found over the continental shelf. Normally prefering depths of 20 to 60 m, killer whales also visit shallow waters along coastlines or dive to 300 m in search of food. Killer whales generally occupy the same home range year round. Generally, orcas prefer deep water but they can also be found in shallow bays, inland seas, and estuaries (but rarely in rivers). They readily enter areas of floe ice in search of prey. Resident killer whales in Pacific Northwest waters use regions of high relief topography along salmon migration routes, whereas transient whales forage for pinnipeds in shallow protected waters.
Home Range:
Home range size is unknown, but some studies have shown that killer whales live with their pods together in their home range for many years. While home range size is unknown, they have been documented to swim up to 160 km a day
Physical Description:
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 male killer whale on record was 9.8 m (32 ft) and weighing over 10 tonnes (22,000 lb), while the largest female was 8.5 m (28 ft) and weighing 7.5 tonnes (16,500 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).[citation needed] 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.
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.
Reproduction:
While killer whales are difficult to study in the wild some of their reproductive habits have been recorded and studied in captive whales. Killer whales can reproduce whenever females enter estrus, which can occur mutiple times a year. However, most breeding happens in the summer, In the North Atlantic, mating seems to peak in October and November; in the western North Pacific, mating seems to be at its highest between May and June, and killer whales are typically born in the fall. Females reach sexual maturity between 6 and 10 years of age. Males reach sexual maturity between 10 and 13 years old. Female killer whales begin to mate between 14 and 15 years of age. The youngest female whale on record to give birth was 11 years old. Females have a calf every 6 to 10 years and they stop breeding around the age of 40. The result is 4 to 6 offspring over a 25 year span.
Gestation takes about 14 months, although a gestation length in captivity was recorded at 539 days. Killer whales have a single calf at a time, twins have only been recorded once. Newborn calves nurse for about a year before weaning. Some studies show that almost half of all newborn calves die before their first birthday. Calves are born in the water. The majority of deliveries seen by humans have been tail-first births, although a head-first birth has been observed. Size estimates of captive-born orcas suggest that calves average 2.6 m in length and weigh between 136-181 kg.
Killer whale females invest a lot of energy in raising their offspring. They carry the calf for almost a year and a half, then give birth and nurse for another 12 months. During that time, mothers teach their calves to hunt and include their offspring in the social network of their pods. Because these animals are not monogamous, it is assumed that the fathers exhibit no parental involvement after mating. When a killer whale calf is born into a pod, it relies on its mother for nutrition and support. Calves remain in their natal pod after independence.
Calves nurse below water, close to the surface. The mother glides in a horizontal position with her tail arched, and the calf swims on its side with its mouth on the right or left mammary gland. The mother's milk is very rich so that the calf rapidly develops a thick, insulating layer of blubber. The milk fat content fluctuates as the calf develops, ranging from about 48% milk fat at the beginning of the nursing period and gradually decreasing to approximately 28% in the months that follow. A calf may nurse for 12 months or more. A calf may essentially be weaned at one year of age but may continue to nurse occasionally for several more months.
Longevity:
Killer whale mortality rate varies with the age of the animal. Neonatal mortality is very high, in captivity neonatal mortality is between 37% and 50%. The reason for these high mortality rates is unknown, but predation is not considered a primary threat during this time. After six months, mortality rates steadily decline as killer whales learn how to protect and nourish themselves. Mortality rates are said to be the lowest around 12 to 13 years in males and 20 years in females. The average lifespan for a female in the wild is around 63 years, with a maximum of 80 to 90 years. Male life expectancy is a bit shorter, with the average lifespan being around 36 years, with a maximum of 50 to 60 years.
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.
Behavior:
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. Either the whale is looking for food, less common, the whale is seeing where it is, or where it is relative 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:
Killer whales are highly social and social structure is complex. They travel in pods which can contain several to as many as 50 individuals. There has even been reports of hundreds of individuals in one pod, but this was a temporary association between a group of smaller pods. Individuals in pods are generally multiple generations of related individuals and made up of about 20% mature males, 20% calves, and 60% females and immature males. Killer whales have limited dispersal from the maternal pod and young whales are always part of their mother's pod. Individuals in pods swim within 100 meters of each other and coordinate their activities. They may share prey and rarely leave the pod for more than a few hours. Killer whales teach pod members through apprenticeship. Skill in hunting and parenting are among the skills taught to younger whales.
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.
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.
Migration:
Based on photo-identification studies, numerous individual whales and/or pods have been documented to move between Puget Sound (Washington) / British Columbia and south-eastern Alaska; between south-eastern Alaska and Prince William Sound; and between Prince William Sound and Kodiak Island. On an international level, whale movements from Alaska (USA) and British Columbia (Canada) to California (USA) and from California to Mexico have been documented. In most geographical regions, killer whale movements may be related to movements of their prey. Orcas may travel 125 - 200 km per day while foraging.
In the Beaufort, Chukchi and northern Bering Seas, orcas move south with the advancing pack ice, performing long-range movements. Similar movements are reported for the western North Atlantic. Killer whales approach the Chukotka coasts in June and leave the area in November or even as late as December. On the other hand, year-round and seasonal occurrences are recorded for the waterways of British Columbia and Washington State, where pods are known to range approximately 370 nautical miles. Norwegian data indicate that killer whales occur in coastal waters all year-round, with concentrations in the Lofoten, More and Finnmark areas. However, orcas present in offshore Norwegian waters appear to arrive there from Icelandic waters, following the migration of herring.
Similae and Christensen (1992) photoidentified killer whales around the Lofoten and Vesteralen islands northern Norway during fall-winter (October-February) and summer (June-August) in 1990 and 1991. Based on a capture- recapture estimate, they determined that about 500 killer whales are present in these overwintering areas of the herring. Most of the whales leave the study area in January when herring migrate to the spawning grounds 700 km farther south. Based on the seasonal distribution, killer whale groups can be divided into three different types; whales present in fall-winter (25 groups), whales present both in fall and summer (12 groups) and whales present in summer (six groups).
Similae et al. (2002) satellite tagged Orca off Norway. Most of the positions were received from the wintering grounds of herring. However, five of the tagged whales made long distance movements away from this area; the swimming and diving behaviour of the whales as well as information on prey items suggests that the function of these trips was to survey areas where herring is abundant during other seasons than winter. Based on photoidentification data collected since 1987 the range of killer whales during October-January had been estimated to be 13 583 km² (estimated as a minimum convex polygon). The satellite tracking study expanded the known range of killer whales during this season considerably. The ranges varied between the individuals; the smallest estimated Kernel home range was 3566 km² (95 % isopleth) and the largest 288 284 km² (95 % isopleth; Similae et al. 2002).
In Northern Patagonia the seasonal distribution of killer whales is correlated to the distribution of South American sea lions and southern elephant seal. Most encounters with the whales at Punta Norte occurred in December and March-May, during the sea lions breeding cycle. Whales depart the area in May when pinnipeds migrate to winter rookeries. One pod, Patagonia Norte B (PNB) was photographed in Golfo San Jose on 9 January 1986 and in Punta Norte 1 day later, some 60 km apart.
Evidence of seasonality is also observed in the southern part of the north-eastern Atlantic. In the southern hemisphere, killer whales are found in warm waters in winter and migrate into high latitudes in the summer. This migration appears to be related to the migration of prey species, in particular the minke whale. However, Gill and Thiele (1997) report sighting killer whales in Antarctic sea ice in August, i.e. in late winter, indicating that some individuals may be resident year-round.
Transient whales appear to cover a more extensive range than residents. A distance of over 2600 km (California to Alaska) has been reported for a transient group: Forney and Barlow (1998) photographed three individuals in Monterey Bay, California, that had previously been identified off Alaska.
Ecosystem Roles:
Killer whales are top predators in most marine ecosystems and impact the populations of common prey, such as seals and sea lions in breeding areas. Killer whales are host to some endoparasites and ectoparasites. They are host to killer whale lice (Cyamus orcini), trematodes (Fasciola skiranini), cestodes (Trigonocotyle spasskyi), and nematodes (Anasakis simplex).
A disease that affects killer whales and is often studied is toxoplasmosis (Toxoplasma gondii). While this parasite is often benign, it can have serious and fatal effects.
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host:
killer whale lice (Cyamus orcini)
trematodes (Fasciola skirabini)
cestodes (Trigonocotyle fasciola)
nematodes (Anasakis simplex)
Communication and Perception and Vocalizations:
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.
There are 3 categories of vocalizations used by killer whales: whistles, discrete calls, and clicks. Vocalizations are used both for communication and navigation. They use discrete calls and whistles when communicating within and among pods. Each pod has their a discrete dialect that sounds slightly different from that of other pods. This dialect has been shown to stay the same in a pod for up to six generations. Clicks seem to be used only for echolocation. Killer whales do have good vision, but in dark water their vision is not helpful in catching prey or navigating. As in other toothed whales, killer whales use sonar to perceive their aquatic environment.
The whale's ears are very small openings behind the eyes, which have no outer flap. The killer whale hears the whistles and clicks through an auditory bulla (earbone complex) in its lower jaw. The sound waves enter through the jaw where they then enter into the earbone complex. In this auditory bulla, there are bones that are like the bones found in the human ear. They waves travel trough these bones, then enter into the brain via an auditory nerve.
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.
Predation:
Killer whales have no natural predators, although young killer whales may be attacked by other killer whales or large sharks. They are at the top of the marine food chain. Humans sometimes prey on killer whales, but not in great numbers.
Food Habits:
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.
Killer whales are exceptionally successful predators. Orcinus orca diet is difficult to study and is most frequently assessed through looking at stomach contents. They eat a wide variety of large prey including: seals, sea lions, smaller whales and dolphins, fish, sharks, squid, octopi, sea turtles, sea birds, sea otters, river otters, penguins, cetaceans (both mysticete and odontocete), polar bears, reptiles, and even a moose have all been found in the stomach contents of orcas. And, as their common name implies, the remains of other orcas have also been found in the stomachs of these "killer whales." It is uncertain why these animals are cannibalistic. They swallow small prey whole, but tend to tear up larger prey before consumption.
Much like packs of wolves or prides of lions, orcas often hunt cooperatively in pods for food. They work together to herd prey into a small area before attacking. When hunting a large whale, a
pod of orcas may attack from several angles.
The diets of orcas vary from one region to another. In the Antarctic, orcas eat about 67% fishes, 27% marine mammals and 6% squid. In the Bering Sea near Alaska, they eat about 65% fishes, 20% squids and 15% marine mammals.
The diets of resident and transient orcas differ as well. Resident pods eat a wide variety of fishes and rarely seek out marine mammals. Transient groups primarily eat marine mammals and occasionally eat fishes. Adult orcas eat approximately 3% to 4% of their body weight in food per day; fully weaned calves can eat up to approximately 10% of their body weight during growth periods.
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.
observed killer whales feeding on herring in a fjord in northern Norway using underwater video. The whales co-operatively herded herring into tight schools close to the surface. During herding and feeding, killer whales swam around and under a school of herring, periodically lunging at it and stunning the herring by slapping them with the underside of their flukes while completely submerged.
While herring constitute the whales' main diet in Norwegian waters, cod, flatfish, and cephalopods are the primary components off Japan. In Puget Sound, the main food of resident killer whales during the summer and fall is salmon. Most food items are swallowed whole. However, when whales attack larger prey, they rip away smaller pieces of flesh and then consume them. The tongues, lips, and genital regions of baleen whales seem to be the favoured parts.
Killer whales consume fish of commercial importance. Troll catches of salmon show a decline when killer whales are in the area and damage to fishing gear has also been reported. Off Iceland, killer whales are attracted to herring operations. Longline fisheries interactions involving killer whales have also been observed .Killer whales are known to follow fish-processing vessels for many miles feeding off discarded fish. In the Bering Sea, the same pod of whales was reported to follow a vessel for 31 days for approximately 1600 km .
Mammal prey:
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.
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.
Longevity:
Killer whale mortality rate varies with the age of the animal. Neonatal mortality is very high, in captivity neonatal mortality is between 37% and 50%. The reason for these high mortality rates is unknown, but predation is not considered a primary threat during this time. After six months, mortality rates steadily decline as killer whales learn how to protect and nourish themselves. Mortality rates are said to be the lowest around 12 to 13 years in males and 20 years in females. The average lifespan for a female in the wild is around 63 years, with a maximum of 80 to 90 years. Male life expectancy is a bit shorter, with the average lifespan being around 36 years, with a maximum of 50 to 60 years.
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.
Behavior:
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. Either the whale is looking for food, less common, the whale is seeing where it is, or where it is relative 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:
Killer whales are highly social and social structure is complex. They travel in pods which can contain several to as many as 50 individuals. There has even been reports of hundreds of individuals in one pod, but this was a temporary association between a group of smaller pods. Individuals in pods are generally multiple generations of related individuals and made up of about 20% mature males, 20% calves, and 60% females and immature males. Killer whales have limited dispersal from the maternal pod and young whales are always part of their mother's pod. Individuals in pods swim within 100 meters of each other and coordinate their activities. They may share prey and rarely leave the pod for more than a few hours. Killer whales teach pod members through apprenticeship. Skill in hunting and parenting are among the skills taught to younger whales.
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.
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.
Migration:
Based on photo-identification studies, numerous individual whales and/or pods have been documented to move between Puget Sound (Washington) / British Columbia and south-eastern Alaska; between south-eastern Alaska and Prince William Sound; and between Prince William Sound and Kodiak Island. On an international level, whale movements from Alaska (USA) and British Columbia (Canada) to California (USA) and from California to Mexico have been documented. In most geographical regions, killer whale movements may be related to movements of their prey. Orcas may travel 125 - 200 km per day while foraging.
In the Beaufort, Chukchi and northern Bering Seas, orcas move south with the advancing pack ice, performing long-range movements. Similar movements are reported for the western North Atlantic. Killer whales approach the Chukotka coasts in June and leave the area in November or even as late as December. On the other hand, year-round and seasonal occurrences are recorded for the waterways of British Columbia and Washington State, where pods are known to range approximately 370 nautical miles. Norwegian data indicate that killer whales occur in coastal waters all year-round, with concentrations in the Lofoten, More and Finnmark areas. However, orcas present in offshore Norwegian waters appear to arrive there from Icelandic waters, following the migration of herring.
Similae and Christensen (1992) photoidentified killer whales around the Lofoten and Vesteralen islands northern Norway during fall-winter (October-February) and summer (June-August) in 1990 and 1991. Based on a capture- recapture estimate, they determined that about 500 killer whales are present in these overwintering areas of the herring. Most of the whales leave the study area in January when herring migrate to the spawning grounds 700 km farther south. Based on the seasonal distribution, killer whale groups can be divided into three different types; whales present in fall-winter (25 groups), whales present both in fall and summer (12 groups) and whales present in summer (six groups).
Similae et al. (2002) satellite tagged Orca off Norway. Most of the positions were received from the wintering grounds of herring. However, five of the tagged whales made long distance movements away from this area; the swimming and diving behaviour of the whales as well as information on prey items suggests that the function of these trips was to survey areas where herring is abundant during other seasons than winter. Based on photoidentification data collected since 1987 the range of killer whales during October-January had been estimated to be 13 583 km² (estimated as a minimum convex polygon). The satellite tracking study expanded the known range of killer whales during this season considerably. The ranges varied between the individuals; the smallest estimated Kernel home range was 3566 km² (95 % isopleth) and the largest 288 284 km² (95 % isopleth; Similae et al. 2002).
In Northern Patagonia the seasonal distribution of killer whales is correlated to the distribution of South American sea lions and southern elephant seal. Most encounters with the whales at Punta Norte occurred in December and March-May, during the sea lions breeding cycle. Whales depart the area in May when pinnipeds migrate to winter rookeries. One pod, Patagonia Norte B (PNB) was photographed in Golfo San Jose on 9 January 1986 and in Punta Norte 1 day later, some 60 km apart.
Evidence of seasonality is also observed in the southern part of the north-eastern Atlantic. In the southern hemisphere, killer whales are found in warm waters in winter and migrate into high latitudes in the summer. This migration appears to be related to the migration of prey species, in particular the minke whale. However, Gill and Thiele (1997) report sighting killer whales in Antarctic sea ice in August, i.e. in late winter, indicating that some individuals may be resident year-round.
Transient whales appear to cover a more extensive range than residents. A distance of over 2600 km (California to Alaska) has been reported for a transient group: Forney and Barlow (1998) photographed three individuals in Monterey Bay, California, that had previously been identified off Alaska.
Ecosystem Roles:
Killer whales are top predators in most marine ecosystems and impact the populations of common prey, such as seals and sea lions in breeding areas. Killer whales are host to some endoparasites and ectoparasites. They are host to killer whale lice (Cyamus orcini), trematodes (Fasciola skiranini), cestodes (Trigonocotyle spasskyi), and nematodes (Anasakis simplex).
A disease that affects killer whales and is often studied is toxoplasmosis (Toxoplasma gondii). While this parasite is often benign, it can have serious and fatal effects.
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host:
killer whale lice (Cyamus orcini)
trematodes (Fasciola skirabini)
cestodes (Trigonocotyle fasciola)
nematodes (Anasakis simplex)
Communication and Perception and Vocalizations:
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.
There are 3 categories of vocalizations used by killer whales: whistles, discrete calls, and clicks. Vocalizations are used both for communication and navigation. They use discrete calls and whistles when communicating within and among pods. Each pod has their a discrete dialect that sounds slightly different from that of other pods. This dialect has been shown to stay the same in a pod for up to six generations. Clicks seem to be used only for echolocation. Killer whales do have good vision, but in dark water their vision is not helpful in catching prey or navigating. As in other toothed whales, killer whales use sonar to perceive their aquatic environment.
The whale's ears are very small openings behind the eyes, which have no outer flap. The killer whale hears the whistles and clicks through an auditory bulla (earbone complex) in its lower jaw. The sound waves enter through the jaw where they then enter into the earbone complex. In this auditory bulla, there are bones that are like the bones found in the human ear. They waves travel trough these bones, then enter into the brain via an auditory nerve.
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.
Predation:
Killer whales have no natural predators, although young killer whales may be attacked by other killer whales or large sharks. They are at the top of the marine food chain. Humans sometimes prey on killer whales, but not in great numbers.
Food Habits:
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.
Killer whales are exceptionally successful predators. Orcinus orca diet is difficult to study and is most frequently assessed through looking at stomach contents. They eat a wide variety of large prey including: seals, sea lions, smaller whales and dolphins, fish, sharks, squid, octopi, sea turtles, sea birds, sea otters, river otters, penguins, cetaceans (both mysticete and odontocete), polar bears, reptiles, and even a moose have all been found in the stomach contents of orcas. And, as their common name implies, the remains of other orcas have also been found in the stomachs of these "killer whales." It is uncertain why these animals are cannibalistic. They swallow small prey whole, but tend to tear up larger prey before consumption.
Much like packs of wolves or prides of lions, orcas often hunt cooperatively in pods for food. They work together to herd prey into a small area before attacking. When hunting a large whale, a
pod of orcas may attack from several angles.
The diets of orcas vary from one region to another. In the Antarctic, orcas eat about 67% fishes, 27% marine mammals and 6% squid. In the Bering Sea near Alaska, they eat about 65% fishes, 20% squids and 15% marine mammals.
The diets of resident and transient orcas differ as well. Resident pods eat a wide variety of fishes and rarely seek out marine mammals. Transient groups primarily eat marine mammals and occasionally eat fishes. Adult orcas eat approximately 3% to 4% of their body weight in food per day; fully weaned calves can eat up to approximately 10% of their body weight during growth periods.
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.
observed killer whales feeding on herring in a fjord in northern Norway using underwater video. The whales co-operatively herded herring into tight schools close to the surface. During herding and feeding, killer whales swam around and under a school of herring, periodically lunging at it and stunning the herring by slapping them with the underside of their flukes while completely submerged.
While herring constitute the whales' main diet in Norwegian waters, cod, flatfish, and cephalopods are the primary components off Japan. In Puget Sound, the main food of resident killer whales during the summer and fall is salmon. Most food items are swallowed whole. However, when whales attack larger prey, they rip away smaller pieces of flesh and then consume them. The tongues, lips, and genital regions of baleen whales seem to be the favoured parts.
Killer whales consume fish of commercial importance. Troll catches of salmon show a decline when killer whales are in the area and damage to fishing gear has also been reported. Off Iceland, killer whales are attracted to herring operations. Longline fisheries interactions involving killer whales have also been observed .Killer whales are known to follow fish-processing vessels for many miles feeding off discarded fish. In the Bering Sea, the same pod of whales was reported to follow a vessel for 31 days for approximately 1600 km .
Mammal prey:
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.
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.
Killer whales and humans:
In Western cultures, attitudes towards killer whales have changed dramatically in recent decades. Before the mid-1960s, killer whales were widely feared as dangerous, savage predators, a reputation based on rumour and speculation.
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."
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. The U.S. Navy claimed to have deliberately killed hundreds of killer whales in Icelandic waters in 1956.
The mid 1960s and early 1970s saw the development of public and scientific awareness of the species, 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. 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.
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.
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. The Southern Resident community alone had lost 48 of its members to captivity; by 1976, only 80 of its members were left.
Paradoxically, the public's growing appreciation for the species also led to growing opposition to the practice of capturing wild whales and keeping them in aquaria. Only one whale has been taken from 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. 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, however his case was marked by controversy about whether and how to intervene, and in 2006 Luna was struck by a boat propeller and died
Whaling:
Killer whales were targeted in commercial whaling for the middle part of the twentieth century, once stocks of larger species had been depleted. Between 1954 and 1997, Japan took 1,178 killer whales and Norway took 987. 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. Today, no country carries out a substantial hunt. A small level of subsistence whaling is carried out by Indonesia and Greenland.
Killer whales have been known to co-operate with humans in the hunting of whales. One well-known example was the killer whales of Eden, Australia.
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 in the five years to 1985). Since then, killer whales have been successfully bred in captivity, and captive wild-born whales are considerably rarer.
The practice of keeping killer whales in captivity is controversial, and organizations 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 reaching 80 is a rare occurrence, and 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.
A video made popular on the Internet shows a killer whale appearing to jump on a group of kayakers. Regularly presented on TV news as a real attack and discussed by zoologists ,the event shown is a computer-composed fake used in an advertisement by Wieden Kennedy for a sports drink. 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.
Conservation Status:
According to the IUCN red list there is insufficient data about killer whale populations to assess their status. The data on the endangered species act list states that killer whales are endangered,but conservation efforts must be employed to help keep them from moving closer to extinction. Killer whales have not been as directly impacted by human exploitation as other whale species. They are occasionally hunted but management of harvests seems to have been effective.
No attack on a human by an orca has ever been recorded in the wild. Orcas are not yet regarded as an endangered species overall. In 1946, 14 countries formed the International Whaling Commission (IWC) by signing the International Whaling Convention. The IWC set regulations of whaling to protect the future of whale stocks as a resource to humans.
Environmental degradation, depletion of prey species, conflicts with fishing activities, and habitat degradation are currently the most significant threats to killer whales worldwide.[4][9]
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. 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 incident as a "disaster". 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.
Direct catch:
Killer whales have been exploited at low levels in several regions world-wide. Norwegian whalers in the eastern North Atlantic took an average of 56 whales per year from 1938 to 1981. The Japanese took an average of 43 whales per year along their coastal waters from 1946 to 1981. The Soviets, whaling primarily in the Antarctic, took an average of 26 animals annually from 1935 to 1979, but took 916 animals in the 1979/80 Antarctic season.
After 1976, Iceland has been involved in live-captures of killer whales for export. During the period 1976-1988, 59 whales were collected, of which 8 were released, 3 died and 48 (an average 3.7 per year) were exported. In 1991, the lcelandic government announced that once current permits for live capture expire, no new ones will be issued. Live-captures of killer whales have also taken place in Japanese waters.
Incidental catch:
Incidental takes during fishing operations occur, but are considered rare.
Culling:
Fishermen in many areas see killer whales as competitors, and shooting of whales is known to occur. This problem is especially serious in Alaska, where conflicts with longline fisheries occur. Although much reduced, some such persecution continues today.
Pollution:
High levels of PCBs and DDT (250 ppm and 640 ppm, respectively) were reported in the blubber of an adult male transient killer whale in Washington State and 38 ppm PCB and 59 ppm DDE wet weight levels in a resident male. Ross et al. (2000) report that total PCB concentrations were surprisingly high in three killer whales communities (2 resident and 1 transient population) frequenting the coastal waters of British Columbia, Canada. Transient killer whales were particularly contaminated. Toxic Equivalents in most killer whales sampled, easily surpassed adverse effects levels established for harbour seals, suggesting that the majority of free-ranging killer whales in this region are at risk for toxic effects. The southern resident and transient killer whales of British Columbia can be considered among the most contaminated cetaceans in the world.
Habitat degradation:
Habitat disturbance may be a matter for concern in areas inhabited by killer whales and supporting whale-watching industries.e.g. reports on propeller scars observed on orcas and their possible causes of mortality.
Moving boats can also interfere with natural activities and resting, and underwater boat noise can affect social and echolocation signals of the whales or otherwise interfere with foraging. These effects are likely to be cumulative and may result in displacement or reduced fitness and death. From a sound propagation and impact model Erbe (2002) deduced that fast boats are audible to killer whales over 16 km, mask killer whale calls over 14 km, elicit a behavioral response over 200 m, and cause a temporary threshold shift (TTS) in hearing of 5 dB after 30-50 min within 450 m. For boats cruising at slow speeds, the predicted ranges were 1 km for audibility and masking, 50 m for behavioral responses, and 20 m for TTS. Superposed noise levels of a number of boats circulating around or following the whales were close to the critical level assumed to cause a permanent hearing loss over prolonged exposure. From a study on the effects of acoustic harassment devices, Morton and Symonds (2002) deduce that whale displacement resulted from the deliberate introduction of noise into their environment.
Williams et al. (2002) investigated whether the current guidelines for whalewatchers are sufficient to minimise disturbance to northern resident killer whales in Johnstone Strait, British Columbia, Canada. Local guidelines request that boaters approach whales no closer than 100m. Additionally, boaters are requested not to speed up when close to whales in order to place their boat in a whale’s predicted path: a practice known as ‘leapfrogging’. Williams et al. (2002) find that leapfrogging is a disruptive
style of whalewatching, and should be discouraged: as the experimental boat increased speed to overtake the whale’s path, the source level of engine noise increased by 14dB. Assuming a standard spherical transmission loss model, the fast-moving boat would need to be 500m from the whale for the received sound level to be the same as that received from a slow-moving boat at 100m. Whalewatching
guidelines should therefore encourage boaters to slow down around whales, and not to resume full speed while whales are within 500m.
The Exxon Valdez oil spill in Alaska was strongly correlated with the subsequent loss of 14 whales from a pod that had been seen swimming through light oil slicks early in the spill. Oil spills may also have an indirect effect by reducing prey abundance.
Overfishing:
Although in general opportunistic feeders, some populations of killer whales could be affected by reduction of their food supply. For example, coastal Norwegian populations reportedly feed mainly upon herring, a fish heavily exploited in the area. In Alaska, anthropogenic effects on the ecosystem have been made responsible for orca predation on sea-otters and associated ecological implications. In British Columbia, Canada, and Washington State, US, salmon stocks have significantly declined as an effect of overfishing, habitat degradation and reduced ocean survival. This is likely to affect fish-eating resident orca populations in that area.
Other factors:
For the Southern Indian Ocean, the strong decline reported by Poncelet et al. (2002) for the coastal waters of Possession Island between 1988 and 2000 may be attributed to several factors: i) a low and decreasing fecundity, possibly impacted by a density dependence (Allee effect); ii) the decline of the main preys: large baleen whales due to past whaling, and southern elephant seals (Mirounga leonina) from the 1970 to 1990 which remained in low numbers up to 1997 at least ; iii) the possible mortality induced by recent interactions with the Patagonian toothfish (Dissostichus eleginoides) longline fishery; and iv) the possible dispersion of individuals or groups from the coastal waters. A few individuals were observed with poorly known "offshore" killer whales interacting with longliners, but presently, there is no evidence of mixing with surrounding killer whale concentrations in Prince Edward Islands, south Africa or Antarctic. A preliminary toxicological study indicates that PCBs levels are considerably lower than in British Columbia transients, however the burdens are not negligible and the effects of PCBs on health at the observed concentrations are unknown. We fear that the killer whales of Possession Island might disappear with unique genetic diversity and social culture, like AT1 transients in Alaska.
Economic Importance for Humans:
Negative:
There are no known adverse effects of Orcinus orca on humans. Only one valid instance has been recorded when a killer whale attacked a human.
Positive:
Killer whales are hunted and used for a number of things. In various parts of the world, they are used for oil and meat. Meat is sold for human consumption or used for fertilizer or bait.
Fossil history:
The fossil history of killer whales dates to the Pliocene epoch, about 5 million years ago. The fossil history is not rich, but some finds link Orcinus orca to its early ancestors. Teeth, partial skulls, jaw bones, and periotic bones (found in a mammal's ear) have been found and identified in many countries of the world, including: Japan, Hungary, Italy, and South Africa.
Cultural significance:
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 disguise of a wolf: this wolf was thought to force the reindeer to allow itself to be killed by the hunters.
Resources:
In Western cultures, attitudes towards killer whales have changed dramatically in recent decades. Before the mid-1960s, killer whales were widely feared as dangerous, savage predators, a reputation based on rumour and speculation.
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."
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. The U.S. Navy claimed to have deliberately killed hundreds of killer whales in Icelandic waters in 1956.
The mid 1960s and early 1970s saw the development of public and scientific awareness of the species, 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. 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.
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.
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. The Southern Resident community alone had lost 48 of its members to captivity; by 1976, only 80 of its members were left.
Paradoxically, the public's growing appreciation for the species also led to growing opposition to the practice of capturing wild whales and keeping them in aquaria. Only one whale has been taken from 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. 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, however his case was marked by controversy about whether and how to intervene, and in 2006 Luna was struck by a boat propeller and died
Whaling:
Killer whales were targeted in commercial whaling for the middle part of the twentieth century, once stocks of larger species had been depleted. Between 1954 and 1997, Japan took 1,178 killer whales and Norway took 987. 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. Today, no country carries out a substantial hunt. A small level of subsistence whaling is carried out by Indonesia and Greenland.
Killer whales have been known to co-operate with humans in the hunting of whales. One well-known example was the killer whales of Eden, Australia.
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 in the five years to 1985). Since then, killer whales have been successfully bred in captivity, and captive wild-born whales are considerably rarer.
The practice of keeping killer whales in captivity is controversial, and organizations 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 reaching 80 is a rare occurrence, and 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.
A video made popular on the Internet shows a killer whale appearing to jump on a group of kayakers. Regularly presented on TV news as a real attack and discussed by zoologists ,the event shown is a computer-composed fake used in an advertisement by Wieden Kennedy for a sports drink. 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.
Conservation Status:
According to the IUCN red list there is insufficient data about killer whale populations to assess their status. The data on the endangered species act list states that killer whales are endangered,but conservation efforts must be employed to help keep them from moving closer to extinction. Killer whales have not been as directly impacted by human exploitation as other whale species. They are occasionally hunted but management of harvests seems to have been effective.
No attack on a human by an orca has ever been recorded in the wild. Orcas are not yet regarded as an endangered species overall. In 1946, 14 countries formed the International Whaling Commission (IWC) by signing the International Whaling Convention. The IWC set regulations of whaling to protect the future of whale stocks as a resource to humans.
Environmental degradation, depletion of prey species, conflicts with fishing activities, and habitat degradation are currently the most significant threats to killer whales worldwide.[4][9]
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. 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 incident as a "disaster". 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.
Direct catch:
Killer whales have been exploited at low levels in several regions world-wide. Norwegian whalers in the eastern North Atlantic took an average of 56 whales per year from 1938 to 1981. The Japanese took an average of 43 whales per year along their coastal waters from 1946 to 1981. The Soviets, whaling primarily in the Antarctic, took an average of 26 animals annually from 1935 to 1979, but took 916 animals in the 1979/80 Antarctic season.
After 1976, Iceland has been involved in live-captures of killer whales for export. During the period 1976-1988, 59 whales were collected, of which 8 were released, 3 died and 48 (an average 3.7 per year) were exported. In 1991, the lcelandic government announced that once current permits for live capture expire, no new ones will be issued. Live-captures of killer whales have also taken place in Japanese waters.
Incidental catch:
Incidental takes during fishing operations occur, but are considered rare.
Culling:
Fishermen in many areas see killer whales as competitors, and shooting of whales is known to occur. This problem is especially serious in Alaska, where conflicts with longline fisheries occur. Although much reduced, some such persecution continues today.
Pollution:
High levels of PCBs and DDT (250 ppm and 640 ppm, respectively) were reported in the blubber of an adult male transient killer whale in Washington State and 38 ppm PCB and 59 ppm DDE wet weight levels in a resident male. Ross et al. (2000) report that total PCB concentrations were surprisingly high in three killer whales communities (2 resident and 1 transient population) frequenting the coastal waters of British Columbia, Canada. Transient killer whales were particularly contaminated. Toxic Equivalents in most killer whales sampled, easily surpassed adverse effects levels established for harbour seals, suggesting that the majority of free-ranging killer whales in this region are at risk for toxic effects. The southern resident and transient killer whales of British Columbia can be considered among the most contaminated cetaceans in the world.
Habitat degradation:
Habitat disturbance may be a matter for concern in areas inhabited by killer whales and supporting whale-watching industries.e.g. reports on propeller scars observed on orcas and their possible causes of mortality.
Moving boats can also interfere with natural activities and resting, and underwater boat noise can affect social and echolocation signals of the whales or otherwise interfere with foraging. These effects are likely to be cumulative and may result in displacement or reduced fitness and death. From a sound propagation and impact model Erbe (2002) deduced that fast boats are audible to killer whales over 16 km, mask killer whale calls over 14 km, elicit a behavioral response over 200 m, and cause a temporary threshold shift (TTS) in hearing of 5 dB after 30-50 min within 450 m. For boats cruising at slow speeds, the predicted ranges were 1 km for audibility and masking, 50 m for behavioral responses, and 20 m for TTS. Superposed noise levels of a number of boats circulating around or following the whales were close to the critical level assumed to cause a permanent hearing loss over prolonged exposure. From a study on the effects of acoustic harassment devices, Morton and Symonds (2002) deduce that whale displacement resulted from the deliberate introduction of noise into their environment.
Williams et al. (2002) investigated whether the current guidelines for whalewatchers are sufficient to minimise disturbance to northern resident killer whales in Johnstone Strait, British Columbia, Canada. Local guidelines request that boaters approach whales no closer than 100m. Additionally, boaters are requested not to speed up when close to whales in order to place their boat in a whale’s predicted path: a practice known as ‘leapfrogging’. Williams et al. (2002) find that leapfrogging is a disruptive
style of whalewatching, and should be discouraged: as the experimental boat increased speed to overtake the whale’s path, the source level of engine noise increased by 14dB. Assuming a standard spherical transmission loss model, the fast-moving boat would need to be 500m from the whale for the received sound level to be the same as that received from a slow-moving boat at 100m. Whalewatching
guidelines should therefore encourage boaters to slow down around whales, and not to resume full speed while whales are within 500m.
The Exxon Valdez oil spill in Alaska was strongly correlated with the subsequent loss of 14 whales from a pod that had been seen swimming through light oil slicks early in the spill. Oil spills may also have an indirect effect by reducing prey abundance.
Overfishing:
Although in general opportunistic feeders, some populations of killer whales could be affected by reduction of their food supply. For example, coastal Norwegian populations reportedly feed mainly upon herring, a fish heavily exploited in the area. In Alaska, anthropogenic effects on the ecosystem have been made responsible for orca predation on sea-otters and associated ecological implications. In British Columbia, Canada, and Washington State, US, salmon stocks have significantly declined as an effect of overfishing, habitat degradation and reduced ocean survival. This is likely to affect fish-eating resident orca populations in that area.
Other factors:
For the Southern Indian Ocean, the strong decline reported by Poncelet et al. (2002) for the coastal waters of Possession Island between 1988 and 2000 may be attributed to several factors: i) a low and decreasing fecundity, possibly impacted by a density dependence (Allee effect); ii) the decline of the main preys: large baleen whales due to past whaling, and southern elephant seals (Mirounga leonina) from the 1970 to 1990 which remained in low numbers up to 1997 at least ; iii) the possible mortality induced by recent interactions with the Patagonian toothfish (Dissostichus eleginoides) longline fishery; and iv) the possible dispersion of individuals or groups from the coastal waters. A few individuals were observed with poorly known "offshore" killer whales interacting with longliners, but presently, there is no evidence of mixing with surrounding killer whale concentrations in Prince Edward Islands, south Africa or Antarctic. A preliminary toxicological study indicates that PCBs levels are considerably lower than in British Columbia transients, however the burdens are not negligible and the effects of PCBs on health at the observed concentrations are unknown. We fear that the killer whales of Possession Island might disappear with unique genetic diversity and social culture, like AT1 transients in Alaska.
Economic Importance for Humans:
Negative:
There are no known adverse effects of Orcinus orca on humans. Only one valid instance has been recorded when a killer whale attacked a human.
Positive:
Killer whales are hunted and used for a number of things. In various parts of the world, they are used for oil and meat. Meat is sold for human consumption or used for fertilizer or bait.
Fossil history:
The fossil history of killer whales dates to the Pliocene epoch, about 5 million years ago. The fossil history is not rich, but some finds link Orcinus orca to its early ancestors. Teeth, partial skulls, jaw bones, and periotic bones (found in a mammal's ear) have been found and identified in many countries of the world, including: Japan, Hungary, Italy, and South Africa.
Cultural significance:
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 disguise of a wolf: this wolf was thought to force the reindeer to allow itself to be killed by the hunters.
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