Traill,1809. The derivation of the name is from the Latin globus, for "globe or ball", the Greek kephale for "head" and from the Greek melanus for "black". The common name "pilot whale" refers to the belief that there is a leader, or "pilot" of the pod that leads the group and that the group will follow this leader, even when it means certain death. Fishermen and whalers referred to pilot whales as "potheads" because of their bulbous heads, and as "blackfish." The latter term, however, is also used for Killer, False Killer, Pygmy Killer and Melon-headed whales.
The oldest fossil of a pilot whale was found in Pliocene or Pleistocene deposits in England, and several younger fossils have been found in North America,in Florida and California.
Long and short-finned pilot whales are well-defined species (Rice 1998). The long-finned pilot whale is recognized as one species, although three subspecies may exist: one in the North Atlantic, one in the Southern Hemisphere, and one (extinct) in the North Pacific.
Order: Cetartiodactyla
Cetacea (unranked)
Odontoceti (unranked)
Family: Delphinidae
Genus: Globicephala
Size, shape and distinctive characteristics
Long-finned pilot whales are one of the largest members of the dolphin family, second only to the killer whale in size. Newborns are 1.6-2.0 m long and weigh approximately 100 kg. Adult males and adult females reach 6.7 m, 5.7 m in length, respectively. Males can weigh as much as 2,300 kg, while females are smaller, seldom exceeding 1,300 kg. Pilot whales have a bulbous and squarish forehead or melon, which overhangs the mouth. They have extremely short beaks and the mouth-line slants up to the eye. The flippers are extremely long (up to 1/5 of body length) and sickle-shaped, with pointed tips and an angled leading edge. The dorsal fin is forward of mid-body, has a long base and is falcate. Pilot whales are also sexually dimorphic in shape, with adult males having larger, more bulbous heads and larger dorsal fins than females. Pilot whales are dark gray to black, with a white to light gray anchor-shaped patch on the chest, a light gray saddle-patch behind the dorsal fin, and a light gray or white streak from behind each eye that extends to the front of the dorsal fin. There are 9-12 pairs of sharp, conical teeth in each jaw.
Can be Confused With: In some temperate waters (for example, off the mid-Atlantic coast of the U.S.), the distribution of long-finned and short-finned pilot whales overlap. In these areas, the two species are extremely difficult to distinguish at sea. The only reliable means of separating the two are from tooth counts and relative flipper lengths, neither of which is useful in distinguishing the two species at sea. In lower latitudes, the long-finned pilot whale can be confused with false killer whales or, pygmy killer and melon-headed whales; however, the head shape and dorsal fin shape and position are different.
The long-finned pilot whale is widely distributed in temperate and sub-polar waters, with the exception of the North Pacific. The long-finned pilot whale is found in cooler waters than the short-finned species and is divided into two discrete populations, separated from each other by tropical waters; these populations are recognized as subspecies (G.m.edwardii in the south and G.m.melas in the north). The southern sub-species occurs in a circumpolar band from approximately 20° S to 65° S and occurs frequently off the coasts of Chile, Argentina, South Africa, Australia and New Zealand.
The second sub-species inhabits the North Atlantic Ocean from North Carolina across to the Azores and Morocco at it's southern limit and from Newfoundland to Greenland, Iceland and northern Norway at its northern limit. This sub-species is also present in the western half of the Mediterranean Sea.
In general, long-finned pilot whales prefer areas of high relief, submerged banks, and especially edges of the continental shelf.
Ecology and Behaviour
Pilot whales are highly social; they are most often found in pods of 20-100 individuals, but some groups may number over 1000. Group size may be difficult to determine because large schools are dispersed, with smaller, tight groups of 10-20 scattered across a wide area. From photo-identification and genetic studies, researchers believe pilot whales live in stable family groups, similar to those of killer whales, and not in the more fluid groups characteristic of many smaller dolphin species. These stable family groups consist of related females and their offspring. Mature males also occur in these groups, but genetic evidence has shown that these males are not the fathers of the calves in the group. Several calves in one group may be fathered by the same male, suggesting that a male can enter a group for a brief period and mate with more than one female. Pilot whales appear to remain in their natal group for life; this type of social structure is very unusual among mammals. Consistent with their sexual dimorphism and adult sex ratio, pilot whales are polygynous.
Long-finned pilot whales are frequently involved in mass strandings; strandings are fairly common, for example, on beaches of Cape Cod (Massachusetts, USA) from October to January. Mass strandings of several hundred pilot whales have been recorded, although the cause of these strandings is not understood.
Their strong social bonds make pilot whales vulnerable to herding. Whalers have taken advantage of this trait in drive fisheries off Newfoundland, the Faroe Islands, and elsewhere.
Vocalizations produced by pilot whales include echolocation clicks, whistles, and pulsed sounds. The calls of the long-finned pilot whale are usually more narrow and lower in frequency than short-finned pilot whale vocalizations (Rendell et al. 1999). Whistles of the long-finned pilot whale range from 1 to 8 kHz with a mean duration of about 1 second.
Life History
Breeding may occur at any time of the year, but most occurs in spring and early summer in both hemispheres. Pilot whale gestation lasts for 16 months and most calves are born in the summer, though calving may occur throughout the year. Calves nurse for periods of up to 22 months, with some evidence for longer lactation periods and long-lasting mother-calf bonds. Females give birth to calves as old as 35 years old, and lactate as late as 51 years old. The calving interval is about three to five years. Age at sexual maturity in females is approximately six to eight years, and in males, twelve years. The life span of pilot whales is about 35-45 years in males and females may live past 60 years old.
Diet
Pilot whales are suction feeders that primarily eat squid, supplemented by small fish. In the western North Atlantic the main prey are Illex illecebrosus and Loligo pealei (Gannon et al. 2007a, Olson 2009), although Atlantic mackerel (Scomber scombrus) is also consumed, often in association with fishing operations (Abend and Smith, 1997, Gannon et al. 2007b,). In the eastern North Atlantic the squid Todarodes sagittatus and species of the genus Gonatus are consumed (Olson 2009). In New Zealand the major prey are arrow squid Nototodarus spp. and common octopus Pinnoctopus cordiformis (Beatson and O'Shea, 2009).
Global Abundance
Pilot whales are not considered to be endangered and there are likely to be almost a million long-finned pilot whales worldwide. The International Whaling Commission estimated abundance in the central and northeastern North Atlantic at between 440,000 and 1,370,000 (Buckland et al. 1993). Abundance estimates for the Southern Ocean are in the order of 200,000 whales (Bernard and Reilly, 1999). In the Exclusive Economic Zone of the eastern U.S. there are an estimated 31,000 (CV=0.27) pilot whales, but this estimate includes both long- and short-finned pilot whales (Waring et al. 2009).
There is little information on population structure within the species, and there is no information on global trends in abundance (Taylor et al. 2008).
IUCN status
The long-finned pilot whale is listed as, "Data Deficient" by the IUCN. The species is listed on CITES Appendix II.
Harvest: Humans have long taken advantage of the highly social nature of pilot whales by hunting them in "drive fisheries," in which pods of whales are herded into shallow water and driven to the beach where they are slaughtered.
These drive fisheries have taken place on Cape Cod, Newfoundland, the Faroes Islands, Scotland, Iceland, and Norway. Whales have been killed for meat, bone, fertilizer, and oil. The drive fishery in Newfoundland killed over 50,000 whales between 1951-1961, significantly reducing the number of pilot whales in these waters.
The drive fishery in the Faroe Islands continues today. This fishery dates back to the 9th century, and in the last decade, an average of 1,200 pilot whales was killed each year. These harvests have been sustained at steady levels, perhaps because these whales are taken from a large population (Bloch et al. 2003).
Incidental catch: Pilot whales are taken as incidental catches in trawls, driftnets, and longlines.
A foreign Atlantic mackerel fishery working off the U.S. east coast took 141 whales as by-catch pilot in 1988; the fishery was suspended due to this high take. More recently, most by-catch in the U.S. Atlantic occurs in the pelagic longline fishery. The annual estimated mortality or serious injury (of both species of pilot whales) in this fishery from 2003-2007 was 110 whales (Waring et al. 2009). As a result, the by-catch of pilot whales was addressed by the Atlantic Pelagic Longline Take Reduction Team. Leeney et al. (2008) found that 61% of stranded individuals in Cornwall (UK) died as a result of by-catch in fishing gear.
There are very few reported incidental takes of pilot whales in fisheries in the southern hemisphere (Reyes 1991). However, Zerbini and Kotas (1998) reported that a pelagic driftnet fishery targeting sharks took 15 long-finned pilot whales in 1995 and 1997.
Pollution: Pollutants are a concern for these long-lived marine mammals. Pilot whales in the North Atlantic carry high levels of DDT and PCB in their tissues. In areas where whales are consumed by humans, residents have high burdens of organohalogens, e.g. in the Faroes (Faengstroem et al. 2005). These contaminants accumulate in tissues over time, so older animals (especially adult males) tend to exhibit very high concentrations (Borell and Aguilar, 1993; Caurant et al. 1993; Caurant and Amiard-Triquet, 1995).
Weisbrod et al. (2000) described organochlorine bioaccumulation from observations of stranded and by-caught pilot whales in Massachusetts. The high variation in tissue concentrations among pods and the similarity within stranded groups suggest that pods are exposed to a wide range of pollutant sources, but that groups vary in their prey types and feeding locations (Desportes et al. 1994).
Noise pollution: Long-finned pilot whales, like some beaked whales, are likely to be vulnerable to some anthropogenic sounds,
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Globicephala melas
