Pilot whales are cetaceans belonging to the genus Globicephala. The two extant 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 oceanic dolphins, 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 pod 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.

Naming

The animals were named "pilot whales" because pods were believed to be "piloted" by a leader. Its scientific name was eventually changed to Globicephala melaena. Since 1986, the specific name of the long-finned pilot whale was changed to its original form melas. Other species classifications have been proposed but only two have been accepted. There exist geographic forms of short-finned pilot whales off the east coast of Japan, which comprise genetically isolated stocks.

Fossils of an extinct relative, Globicephala baereckeii, have been found in Pleistocene deposits in Florida. 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 niches of long-finned pilots, adapting and colonizing into colder waters.

Description

thumb|left|250px|Long-finned pilot whale skeleton

Pilot whales are mostly dark grey, brown, or black, but have some light areas such as a grey saddle patch behind the dorsal fin.

thumb|250px|right|A pilot whale [[spyhopping]]

Long-finned and short-finned pilot whales are so similar, it is difficult to tell the two species apart. Their body mass reaches up to 1,300 kg in females and up to 2,300 kg in males. 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. 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. In October 2014, crew and passengers on several boats spotted a pod of 50–200 off Dana Point, California. The whales make seasonal inshore and offshore movements in response to the dispersal of their prey.

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 sperm whales 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. 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.

Social structure

thumb|left|250px|Pilot whale pod near Ireland

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. Numerous pods will temporarily gather, perhaps to allow individuals from different pods to interact and mate, 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. Male reproductive dominance or competition for mates does not seem to exist. 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. In traveling/hunting groups, individuals position themselves in chorus lines stretching two miles long, with only a few whales underneath. Sexual and age-class segregation apparently occurs in these groups. 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. but this is not as common in females of long-finned pilot whales. 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. Compared with short-finned pilot whales, long-finned pilot whales have relatively low-frequency calls with narrow frequency ranges. When resting or "milling", simple whistles are emitted. 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 conspecifics 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. 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.

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.

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.

Stranding

thumb|left|Volunteers attempt to keep body temperatures of beached pilot whales from rising at [[Farewell Spit, New Zealand.]]

thumb|Pilot whale stranded on Sennen Beach in Cornwall, England

Of the cetaceans, pilot whales are among the most common stranders. Because of their strong social bonds, whole groups of pilot whales will strand. Single stranders have been recorded and these are usually diseased. 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 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

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. This had decreased to about 400 per year by the 1990s.

Pilot whales have also fallen victim to bycatches. In one year, around 30 short-finned pilot whales were caught by the squid round-haul fishery in southern California. Likewise, California's drift gill net fishery took around 20 whales a year in the mid-1990s. 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. 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 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. 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. 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.

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 aquariums and oceanariums. 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.

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.

Films

There are two documentaries entirely dedicated to the pilot whales.

  • Full-length Cheetahs of the deep (49', 2014, directed by Rafa Herrero Massieu) — tells about the way of life, features of social interaction, the subtleties of hunting, games and breeding on the example of a group of non-migrating short-finned pilot whales living between the Islands of Tenerife and La Gomera of the Canary archipelago. A curious feature of the film is that: "all marine mammals filmed in freediving".
  • Short film My Pilot, Whale (28', 2014, directed by Alexander and Nicole Gratovsky) demonstrates the possibility of interaction between humans and free-living pilot whales, offering the viewer a number of philosophical questions related to cetaceans: about their attitude to the world, what we have in common, what we — humans — can learn from them, and so on. The film has received a number awards of international film festivals.

See also

  • Unihemispheric slow-wave sleep

References

  • Pilot Whales.org
  • Voices in the Sea