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Pilot whales are belonging to the genus Globicephala. The two Extant taxon species are the long-finned pilot whale ( G. melas) and the short-finned pilot whale ( G. macrorhynchus). The two are not readily distinguishable at sea, and analysis of the skulls is the best way to distinguish between the species. Between the two species, they range nearly worldwide, with long-finned pilot whales living in colder waters and short-finned pilot whales living in tropical and subtropical waters. Pilot whales are among the largest of the , exceeded in size only by the orca. They and other large members of the dolphin family are also known as blackfish.
Pilot whales feed primarily on squid, but will also hunt large demersal fish such as cod and turbot. They are highly social and may remain with their birth throughout their lifetime. Short-finned pilot whales are one of the few non-primate mammal species in which females go through menopause, and postreproductive females continue to contribute to their pod. Pilot whales are notorious for stranding themselves on beaches, but the reason behind this is not fully understood. Marine biologists have shed some light on the matter, suggesting that it is due to the mammals inner ear (their principal navigational sonar) being damaged from noise pollution in the ocean, such as from cargo ships or military exercises. The conservation status of short-finned and long-finned pilot whales has been determined to be least concern.
Fossils of an extinct relative, Globicephala baereckeii, have been found in Pleistocene deposits in Florida. Another Globicephala dolphin was discovered in Pliocene strata in Tuscany, Italy, and was named G. etruriae. Evolution of Tappanaga, the endemic, larger form of short-finned pilots found in northern Japan, with similar characteristics to the whales found along Vancouver Island and northern USA coasts,Hidaka T. Kasuya T. Izawa K. Kawamichi T. 1996. The encyclopaedia of animals in Japan (2) - Mammals 2.
(9784582545517) (4582545521). [[:ja:平凡社|Heibonsha]]
has indicated that the geniture of this form could be caused by the extinction of long-finned pilots in north Pacific in the 12th century, where ''Magondou'', the smaller, southern type possibly filled the former [[niche|Ecological niche]]s of long-finned pilots, adapting and colonizing into colder waters.
Long-finned and short-finned pilot whales are so similar, it is difficult to tell the two species apart. They were traditionally differentiated by the length of the pectoral flippers relative to total body length and the number of teeth. The long-finned pilot whale was thought to have 9–12 teeth in each row and flippers one-fifth of total body length, compared to the short-finned pilot whale with its 7–9 teeth in each row and flippers one-sixth of total body length. Studies of whales in the Atlantic showed much overlap in these characteristics between the species, making them clines instead of distinctive features. Thus, biologists have since used skull differences to distinguish the two species.
The size and weight depend on the species, as long-finned pilot whales are generally larger than short-finned pilot whales. Their lifespans are about 45 years in males and 60 years in females for both species. Both species exhibit sexual dimorphism. Adult long-finned pilot whales reach a body length of approximately 6.5 m, with males being 1 m longer than females. Their body mass reaches up to 1,300 kg in females and up to 2,300 kg in males.Jefferson, T. A, Webber, M. A., Pitman, R. L., (2008) Marine mammals of the world. Elsevier, Amsterdam. For short-finned pilot whales, adult females reach a body length of about 5.5 m, while males reach 7.2 m and may weigh up to 3,200 kg.
The short-finned pilot whale is less populous. It is found in temperate and tropical waters of the Indian Ocean, Atlantic and Pacific Ocean Oceans. Its population overlaps slightly with the long-finned pilot whale in the temperate waters of the North Atlantic and Southern Oceans.Olson, P.A. (2008) "Pilot whale Globicephala melas and G. muerorhynchus" pp. 847–52 in Encyclopedia of Marine Mammals, Perrin, W. F., Wursig, B., and Thewissen, J. G. M. (eds.), Academic Press; 2nd edition, About 150,000 individuals are found in the eastern tropical Pacific Ocean. More than 30,000 animals are estimated in the western Pacific, off the coast of Japan. Pilot whales are generally nomadic, but some populations stay year-round in places such as Hawaii and parts of California. They prefer the waters of the shelf break and slope. Once commonly seen off of Southern California, short-finned pilot whales disappeared from the area after a strong El Niño year in the early 1980s, according to the National Oceanic and Atmospheric Administration. In October 2014, crew and passengers on several boats spotted a pod of 50–200 off Dana Point, California.
Pilot whales generally take several breaths before diving for a few minutes. Feeding dives may last over ten minutes. They are capable of diving to depths of 600 meters, but most dives are to a depth of 30–60 m. Shallow dives tend to take place during the day, while deeper ones take place at night. When making deep dives, pilot whales often make fast sprints to catch fast-moving prey such as squid. Compared to and beaked whales, foraging short-finned pilot whales are more energetic at the same depth. When they reach the end of their dives, pilot whales will sprint, possibly to catch prey, and then make a few buzzes. This is unusual, considering that deep-diving, breath-holding animals would be expected to swim slowly to conserve oxygen. The animal's high metabolism possibly allows it to sprint at deep depths, which would also give it shorter diving periods than some other marine mammals. This may also be the case for long-finned pilot whales. In 2024, a gps-fitted long-finned pilot whale recorded a diving depth over 1,100 meters.
Pilot whales are often infested with whale lice, cestodes, and nematodes. They also can be hosts to various pathogenic bacteria and viruses, such as Streptococcus, Pseudomonas, Escherichia, Staphylococcus, and influenza. One sample of Newfoundland pilot whales found that the most common illness was an upper respiratory tract infection.
Both species are loosely polygynous. Data suggest both males and females remain in their mother's pod for life; despite this, inbreeding within a pod does not seem to occur. During aggregations, males will temporarily leave their pods to mate with females from other pods. Male reproductive dominance or competition for mates does not seem to exist.Donovan, G. P., Lockyer, C. H., Martin, A. R., (1993) "Biology of Northern Hemisphere Pilot Whales", International Whaling Commission Special Issue 14. After mating, a male pilot whale usually spends only a few months with a female, and an individual may sire several offspring in the same pod. Males return to their own pods when the aggregations disband, and their presence may contribute to the survival of the other pod members. No evidence of "bachelor" groups has been found.
Pilot whale pods off southern California have been observed in three different groups: traveling/hunting groups, feeding groups and loafing groups. In traveling/hunting groups, individuals position themselves in chorus lines stretching two miles long, with only a few whales underneath.Leatherwood, S., Lingle, G. E., Evans, W. E., (1973) "The Pacific pilot whale, Globicephala spp". Naval Undersea Center Technical Note 933. Sexual and age-class segregation apparently occurs in these groups. In feeding groups, individuals are very loosely associated, but may move in the same direction. In loafing groups, whales number between 12 and 30 individuals resting. Mating and other behaviors may take place.
The calf nurses for 36–42 months, allowing for extensive mother-calf bonds. Young pilot whales will take milk until as old as 13–15 years of age. Short-finned pilot whale females will go through menopause,Marsh, H., Kasuya T. (1984). " Ovarian changes in the short-finned pilot whale, Globicephala macrorhynchus " Rep. Int. Whal. Comm. 6: 311–35. Special Issue. but this is not as common in females of long-finned pilot whales.Martin A.R, Rothery P. (1993). "Reproductive parameters of female long-finned pilot whales ( Globicephala melas) around the Faroe Islands" Rep. Int. Whal. Comm. 14 263–304. Special Issue. Postreproductive females possibly play important roles in the survival of the young. Postreproductive females will continue to lactate and nurse young. Since they can no longer bear young of their own, these females invest in the current young, allowing them to feed even though they are not their own. Short-finned pilot whales grow more slowly than long-finned pilot whales. For the short-finned pilot whale, females become sexually mature at 9 years old and males at about 13–16 years. For the long-finned pilot whale, females reach maturity at around eight years and males at around 12 years.
A study of short-finned pilot whales off the southwest coast of Tenerife in the Canary Islands has found the members of a pod maintained contact with each other through call repertoires unique to their pod.Scheer, M., Hofmann, B., Behr, I.P. (1998) "Discrete pod-specific call repertoires among short-finned pilot whales (Globicephala macrorhynchus) off the SW coast of Tenerife, Canary Islands". Abstract World Marine Mammal Science Conference, 20–24. January, Monaco by European Cetacean Society and Society for Marine Mammalogy. A later study found, when foraging at around 800 m deep, short-finned pilot whales make tonal calls. The number and length of the calls seem to decrease with depth despite being farther away from Conspecificity at the surface. As such, the surrounding water pressure affects the energy of the calls, but it does not appear to affect the frequency levels.
When in stressful situations, pilot whales produce "shrills" or "plaintive cries", which are variations of their whistles. To elude predators, long-finned pilot whales off the southern coast of Australia have been observed to mimic the calls of orcas while scavenging for food. This behaviour is thought to deter orca pods from approaching the pilot whales.
Based on experimentation involving familiar sounds of Orcas that consume fish and unfamiliar vocalizations of mammal-hunting Killer Whales, one study suggests that long-finned pilot whales can distinguish between familiar and unaccustomed types of Orca, noting behavioral differences like the ceasing of feeding when mammal-hunting Orcas' sounds were played. The study suggests that antagonistic interactions against fish-eating Killer Whales could either be an anti-predatory behavior or an attempt to maintain territory, while actions done in response to mammal-hunting Killer Whales could be a response to a more dangerous threat.
In September 2022, nearly 200 pilot whales died after becoming stranded on Ocean Beach, part of Tasmania's west coast. Authorities said only about 35 survived of the 230 that were stranded.
According to the IUCN the harvesting of this species for food in the Faroe Islands and Greenland has not resulted in any detectable declines in abundance.
The short-finned pilot whale has also been hunted for many centuries, particularly by Japanese whalers. Between 1948 and 1980, hundreds of whales were exploited at Hokkaido and Sanriku in the north and Taiji, Izu, and Okinawa in the south. These fisheries were at their highest in the late 1940s and early 1950s; 2,326 short-finned pilot whales were harvested in the mid- to late 1980s. This had decreased to about 400 per year by the 1990s.
Pilot whales have also fallen victim to Cetacean bycatch. In one year, around 30 short-finned pilot whales were caught by the squid round-haul fishery in southern California.Miller, D. J., Herder, M. J., Scholl, J. P. (1983) "California marine mammal- fishery interaction study. 1979–81", NMFS Southwest Fish. Cent., Admin. Rep. No. LJ-83-13C Likewise, California's drift gill net fishery took around 20 whales a year in the mid-1990s. In 1988, 141 whales caught on the east coast of the U.S. were taken by the foreign Atlantic mackerel fishery, which forced it to be shut down.
In both Japan and the Faroe Islands, the meat is contaminated with mercury and cadmium, causing a health risk for those who frequently eat it, especially children and pregnant women.Haslam, Nick (14 September 2003) Faroes' controversial whale hunt, BBC. In November 2008, an article in New Scientist reported that research done on the Faroe Islands resulted in two chief medical officers recommending against the consumption of pilot whale meat, considering it to be too toxic.MacKenzie, Debora (28 November 2008) Faroe Islanders told to stop eating 'toxic' whales, New Scientist. In 2008, the local authorities recommended that pilot whale meat should no longer be eaten due to the contamination. This has resulted in reduced consumption, according to a senior Faroese health official. Pilot Whale Meat On The Way Out Of Faroese Food Culture , wdcs.org (9 July 2009).
Pilot whales have historically had low survival rates in captivity, with the average annual survival being 0.51 years during the mid-1960s to early 1970s. There have been a few exceptions to the rule. Bubbles, a female short-finned pilot whale, who was displayed in Marineland of the Pacific and eventually at Sea World California, lived to be somewhere in her 50s when she eventually died on 12 June 2016.
In 1968, a pilot whale was captured, given the name Morgan, and trained by the U.S. Navy's Deep Ops to retrieve deeper-attached objects from the ocean floor. He dove a record depth of 1654 feet and was used for training until 1971.
Behavior and life history
Foraging and parasites
Although pilot whales are not known to have many predators, possible threats come from humans and killer whales.
Both species eat primarily squid. The whales make seasonal inshore and offshore movements in response to the dispersal of their prey. Fish that are consumed include Atlantic cod, Greenland turbot, Atlantic mackerel, Atlantic herring, hake, and spiny dogfish in the northwest Atlantic. In the Faroe Islands, whales mostly eat squid, but will also eat fish species such as greater argentine and blue whiting. However, Faroe whales do not seem to feed on cod, herring, or mackerel, even when they are abundant.Desportes, G., Mouritsen, R. (1993) "Preliminary results on the diet of long-finned pilot whales off the Faroe Islands". Rep. Int. Whal. Comm. (special issue 14): 305–24.
Social structure
Both species live in groups of 10–30, but some groups may number 100 or more. Data suggest the social structures of pilot whale pods are similar to those of "resident" killer whales. The pods are highly stable and the members have close matrilineal relationships. Pod members are of various age and sex classes, although adult females tend to outnumber adult males. They have been observed making various kin-directed behaviors, such as providing food.Pryor, K., Norris K. S, Marsh, H., Kasuya, T. (1991) "Changes in the role of a female pilot whale with age", pp. 281–86 in Dolphin societies, Pryor, K., Norris K. S. (eds), Berkeley, CA: University of California Press. Numerous pods will temporarily gather, perhaps to allow individuals from different pods to interact and mate, as well as provide protection.
Reproduction and lifecycle
Pilot whales have one of the longest birth intervals of the cetaceans, calving once every three to five years. Most matings and calvings occur during the summer for long-finned pilot whales.Jefferson T. A., Leatherwood, S., Webber, M. A. (1993) "FAO Species identification guide. Marine mammals of the world". UNEP/FAO, Rome. ftp://ftp.fao.org/docrep/fao/009/t0725e/t0725e00.pdf For short-finned pilot whales of the Southern Hemisphere, births are at their highest in spring and autumn, while in Northern Hemisphere, the time in which calving peaks can vary by population. For long-finned pilot whales, gestation lasts 12–16 months, and short-finned pilot whales have a 15-month gestation period.
Vocalizations
Pilot whales emit echolocation clicks for foraging and whistles and burst pulses as social signals (e.g. to keep contact with members of their pod). With active behavior, vocalizations are more complex, while less-active behavior is accompanied by simple vocalizations. Differences have been found in the calls of the two species. Compared with short-finned pilot whales, long-finned pilot whales have relatively low-frequency calls with narrow frequency ranges. In one study of North Atlantic long-finned pilot whales, certain vocalizations were heard to accompany certain behaviors. When resting or "milling", simple whistles are emitted. Surfacing behavior is accompanied by more complex whistles and pulsed sounds. The number of whistles made increases with the number of subgroups and the distance in which the whales are spread apart.
Antagonistic interactions with other species
Pilot whales have been occasionally observed mobbing or chasing other species of cetaceans. In several parts of the world, including off Iceland, long-finned pilot whales have been frequently documented chasing killer whales. The reasons for these chases are unknown, but it has been proposed that they might be due to either competition for prey or an anti-predation strategy. In 2021 an adult female killer whale with a newborn pilot whale travelling alongside her was observed off Western Iceland, leading scientists to question whether the relationship between these species might be far more complex than previously suggested. It is not known whether the newborn was adopted or abducted, but this same female killer whale was seen a year later interacting with a larger group of pilot whales.
Stranding
Of the cetaceans, pilot whales are among the most common beached whale. Because of their strong social bonds, whole groups of pilot whales will strand. Single stranders have been recorded and these are usually diseased. Group stranding tends to be of mostly healthy individuals. Several hypotheses have been proposed to explain group strandings. When using magnetic fields for navigation, the whales have been suggested to get perplexed by geomagnetic anomalies or they may be following a sick member of their group that got stranded. The pod also may be following a member of high importance that got stranded and a secondary social response makes them keep returning.Ridgway, S. H. (1998). Handbook of Marine Mammals: The second book of dolphins and the porpoises, Volume 6, Elsevier. pp. 245–69. Researchers from New Zealand have successfully used secondary social responses to keep a stranding pod of long-finned pilot whales from returning to the beach. In addition, the young members of the pod were taken offshore to buoys, and their distress calls lured the older whales back out to sea.
Human interaction
The IUCN lists long-finned pilot whales as "least concern" in the Red List of Threatened Species. Long-finned pilot whales in the North and Baltic Seas are listed in Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). Those from northwest and northeast Atlantic may also need to be included to Appendix II of CMS. The short-finned pilot whale is listed on Appendix II of CITES.
Hunting
The long-finned pilot whale has traditionally been hunted by "driving", which involves many hunters and boats gathering in a semicircle behind a pod of whales close to shore, and slowly driving them towards a bay, where they become stranded and are then slaughtered. This practice was common in both the 19th and 20th centuries. The whales were hunted for bone, meat, oil, and fertilizer. In the Faroe Islands, pilot whale hunting started at least in the 16th century, and continues into modern times, with thousands being killed during the 1970s and 1980s. The use of motorboats and jet skis has increased the efficiency of the Faroese hunts beyond its traditional origins, allowing 1203 whales to be killed in a single grindadráp in 2017. In other parts of the North Atlantic, such as Norway, West Greenland, Ireland and Cape Cod, pilot whales have also been hunted, but to a lesser extent. One fishery at Cape Cod harvested 2,000–3,000 whales per year during the late 19th and early 20th centuries. Newfoundland's long-finned pilot whale fishery was at its highest in 1956, but declined shortly after and is now defunct. In the Southern Hemisphere, exploitation of long-finned pilot whales has been sporadic and low. Currently, long-finned pilot whales are only hunted at the Faroe Islands and Greenland.
Pollution
As with other marine mammals, pilot whales are susceptible to certain pollutants. Off the Faroes, France, the UK, and the eastern US, pilot whales were found to have been contaminated with high amounts of DDT and PCB. Pollutants such as DDT and mercury can be passed from mothers to their babies during gestation and lactation. The Faroes whales have also been contaminated with cadmium and mercury. However, pilot whales from Newfoundland and Tasmania were found to have had very low levels of DDT. Short-finned pilot whales off the west coast of the US have had high amounts of DDT and PCB in contrast to the low amounts found in whales from Japan and the Antilles.
Cuisine
Pilot whale meat is available for consumption in very few areas of Japan, mainly along the central Pacific coast, and also in other areas of the world, such as the Faroe Islands. The meat is high in protein (higher than beef) and low in fat. Because a whale's fat is contained in the layer of blubber beneath the skin, and the muscle is high in myoglobin, the meat is a dark shade of red. In Japan, where pilot whale meat can be found in certain restaurants and , the meat is sometimes served raw, as sashimi, but just as often pilot whale steaks are marinated, cut into small chunks, and grilled. When grilled, the meat is slightly flaky and quite flavorful, somewhat gamey, though similar to a quality cut of beef, with distinct yet subtle undertones recalling its marine origin.
Captivity
Pilot whales, mostly short-finned pilot whales, have been kept in captivity in various marine parks, arguably starting in the late 1940s. Since 1973, some long-finned pilot whales from New England waters were taken and temporarily kept in captivity. Short-finned pilot whales off southern California, Hawaii and Japan have been kept in and . Several pilot whales from southern California and Hawaii were taken into captivity during the 1960s and early 1970s, two of which were placed at SeaWorld San Diego. During the 1970s and early 1980s, six pilot whales were captured alive by drive hunts and taken for public display.
Films
There are two documentaries entirely dedicated to the pilot whales.
See also
External links
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