Long-finned Pilot Whale
Updated: February 2019
The long-finned pilot whale is a medium-sized toothed whale that is found in the North Atlantic and in mid-latitudes throughout the northern and southern hemisphere. Males are larger than females, reaching a length of 6.3 m and and a weight of 2.5 tonnes. They are dark brown to black in colour, with a light anchor-shaped pattern on the belly. The pilot whale is a social species, found in groups of 10’s to 100’s of animals.
From the largest survey in 1989: over 750,000 in the central and north-eastern North Atlantic (Buckland et al. 1993).
From surveys in 1989, 1995 and 2007: over 100.000 in the eastern index area containing the Faroe Islands.
In the subpolar and temperate waters of NAMMCO area, ranging from Disco Bay in western Greenland, to Iceland and up to the southern portion of Svalbard waters in summer months to northwestern Africa in the winter.
Most common in the Irminger Sea and in the area between Iceland and Scotland and Ireland during summer.
Average annual catches since 2000:
– Faroe Islands: 636 (incl. 2017, from 0 to 1203)
– Greenland: 232 (incl. 2016, from 5 to 433)
The removals by drive hunting at the Faroe Islands have been and are considered sustainable, although the last comprehensive assessment of the stock dates back from 1997 (NAMMCO 1998c).
A partial assessment of the sustainability of the Faroese hunt was conducted in 2012. It concluded that sustaining an annual catch of 678 animals (corresponding to the average annual Faroese catch 1997-2011) required that the population contributing to the catch counts 50,000 – 80,000 pilot whales (NAMMCO 2013). The population sustaining the catch is estimated to be over 100,000 whales.
A full assessment of the sustainability of both the Faroese and Greenlandic catches will be done after the 2015 surveys, when the new abundance data is available and the trend analysis completed, now scheduled for 2020.
Latin: Globicephala melas (Trail 1809)
Icelandic: Marsvin, grindahvalur
English: Long-finned pilot whale, blackfish, pothead, caaing whale
French: Globicephale noir, globicéphale commun, dauphin pilot, chaudron
Spanish: Caldéron negro, caldéron común, ballena piloto
552 cm in length and 1.7 tons for adult males and 432 cm and 0.9 tons for adult females
59 years in females and 46 years in males
One calf every 5 years from 9 years of age on average (range 6-15 years)
Primarily schooling squid in mid water, with some preferred species when available, but also including small pelagic fish
No definite migration patterns, but movements associated with prey sources, as in the Faroes, where the abundance of pilot whale seems to follow that of the European flying squid
The long-finned pilot whale is a medium sized toothed whale, belonging to the family of oceanic dolphins, also called the delphinid family.
Long-finned pilot whales are dark brown to black in colour, with younger animals being paler and new-borns being light grey. There is a light anchor-shaped pattern on the belly, and on some a whitish stripe extends towards the tail along the back and sometimes also behind dorsal fin. The flippers are long (to one-fifth of the body length or more) and sickle-shaped and acutely pointed on the tip. The tail is dorsally thickened just in front of the flukes, which have a concave trailing edge and a deep median notch. Long-finned and short-finned pilot (G. macrorhynchus) whales differ by their flipper length, skull shape and number of teeth (e.g., Bloch et al. 1993c, Culik 2011) and are therefore difficult to distinguish at sea.
The long-finned pilot whale is a very social species and are almost always seen in groups of tens or hundreds of animals of both sexes, but single animals are also observed. They are dark in colour with a thick and bulbous head, but the dorsal fin of the adults is their most distinctive feature. It is falcate (hooked) to flaglike, low in profile, markedly longer at the base than at the peak and set far forward on the animal’s back. It makes pilot whales easy to differentiate from any other species in the NAMMCO area. The two species they could be confused with, the short-finned pilot whale and the false killer whale, which overlap at the southern end of the range, do not occur commonly in the NAMMCO area.
The blow of the pilot whale is usually inconspicuous. Pilot whales only rarely show surface behaviours when swimming. Occasionally they can be seen resting or ‘logging’ at the surface, and sometimes spy hopping or lobtailing. They are relatively slow-swimming; radio-tagged individuals averaged a speed of 3.3 km/hr, with burst of up to 16 km/hr (Mate 1989), while the average speed of three satellite-tagged whales off the Faroes was 4.7 km/hr (Bloch et al. 2003).
Pilot whales are commonly observed in association with other species such as bottlenose (Tursiops truncatus), common (Delphinus delphis) and Atlantic white sided (Lagenorhynchus acutus) dolphins, but also with fin (Balaenoptera physalus) and minke (Balaenoptera acutorostrata) whales, sperm whales (Physeter macrocephalus) and Risso’s dolphins (Grampus griseus).
Off the Faroe Islands, males reach a length of 6.25 m and a weight of 2.3 tonnes, compared to 5.12 m and 1.3 tonnes for females. Calves average 178 cm (range: 163 – 191 cm) at birth (Bloch et al. 1993b). Pilot whales exhibit striking sexual dimorphism. In addition to their larger size, adult males develop a more pronounced and bulbous melon and have a much larger and rounder dorsal fin with a thicker leading edge. They also have longer flippers and larger flukes (Bloch et al 1993c).
Pilot whales at Tysfjord, northern Norway
Like many species of toothed whales, pilot whales are highly social animals and usually occur in pods of 10 to 200 whales, with larger pods occurring more rarely. The largest pod caught in the Faroese drive fishery numbered 1200 animals (Zachariasssen 1993, Bloch 1998). Pods ususally comprise animals of all ages and sexes, with adult females outnumbering adult males (Bloch et al. 1993a). Male-only pods and pods consisting mainly of males have been observed however (Desportes et al. 1994a).
All individuals in the pod, including adult males, are related but males tend not to be the fathers of the calves in the pod, and the pods constitute close matrilineal associations (Amos et al. 1991, 1993ab, Anderson 1990, 1993). Investigation in other areas, based on photo-identification and genetic work, confirm the existence of relatively stable pods, like those of killer whales and unlike the fluid groups characteristic of many smaller dolphins (Jefferson et al. 1993, Canadas and Sagarminaga 2000, Ottensmeyer and Whitehead 2003).
Pilot whales are loosely polygynous. During aggregation, males will temporarily leave their pods to mate with females from other pods (Amos et al. 1993b, Andersen and Siegismund 1994). Mating occur reciprocally between pods and there is no evidence of strong male reproductive dominance (Amos et al. 1993a). Individual males may sire several offspring in the same pod (Amos et al. 1991).
Long-finned pilot whales can exhibit highly synchronous breathing and diving behaviour, both during shallow and deep dives, coupled with body contact (Senigaglia and Whitehead 2012, Aoki et al. 2013). As synchronous swimming does not induce saving in locomotion effort, but on the contrary actually entails some locomotion costs, it must have other functions, such as reinforcing social bonds (Aoki et al. 2013). It allows for close proximity and rapid coordinated response of individuals, with the multiple functions such as showing afﬁliation and reacting to disturbance (Senigaglia et al. 2012).
Pairs of long-finned pilot whales can perform highly synchronous surfacing behaviour, at less than one body length apart (Senigaglia and Whitehead, 2012). This behavioural synchrony can be maintained during deep foraging dives, when pilot whales jointly swim to several hundred meters of depth in search for prey (Aoki et al. 2013). This suggests that long-finned pilot whales employ a social foraging strategy, whereby individuals synchronize their foraging behaviour, although they do not always synchronize their individual dives (Visser 2014, Visser et al. 2014). During foraging, groups sometimes break up into smaller and more widely spaced units with a higher degree of milling behaviour (Visser 2014).
An original diving and foraging behaviour?
Diving behaviour was studied off the Faroes by equipping pilot whales with satellite-linked time-depth recorders (Heide-Jørgensen et al. 2002, Bloch et al. 2003, Mikkelsen 2008 and pers. com.).
Dives may last op to 18 min to a maximum depth of 852 m. However 60% of the dives lasted less than three minutes and most diving activity occurred at depth of less than 36 m, although the whales were also travelling off the shelf over water depths exceeding 1,500 m. The whales spent 60% of their time above 7 m. This behaviour is similar to that observed in the Mediterranean Sea (Baird et al. 2002). This intermediate diving behaviour, with the animals spending most of their time close to the surface but typically conducting bouts of foraging dives to intermediate depth of 300-600 m was also observed in the Norwegian sea using Dtags (digital tags) (Sivle et al. 2012).
Compared to other similarly-sized odontocetes, the long-finned pilot whale spent a higher proportion of their time at the surface and exhibited less extreme diving in terms of duration and maximum depth of dives. This may be linked with lower dive capability, the use of a foraging niche in the water column requiring less extreme diving and/or a similar foraging behavious as the short-finned pilot whales using deep sprints for catching prey capable of moving fast, such as Todarodes (flying squid). The sprints, which appear to challenge the common view on optimal foraging in breath-holding, deep-diving predators, reflect a high-cost foraging strategy that is necessary to capture high-value, evasive prey (Aguilar de Soto et al. 2008).
Vocalisations produced by pilot whales incude clicks, whistles and pulse sounds and calls vary with behavioural context (Taruski 1979). Vocalisations are more complex with active behaviour and greater dispersal of the group or more subgroups present, they are simpler with less active behavior, such as resting at the surface. The vocalisations possibly serve to maintain contact and coordinate the movements of the herd (Weilgart and Whitehead 1990, Kok 2012).
With a mean frequency of 4480 Hz, the calls of long-finned pilot whales are lower in frequency, longer and of a narrower frequency range than those of the short-finned pilot whales and there are geographical differences (Rendell et al. 1999). Pilot whale clicks are also different in duration (shorter), frequency (higher), and energy distribution than those of killer whales in the same area (Eskesen et al. 2011). Whistles last less than a second and are repeated typically 14-41 times per minutes. Some may act as ‘signature-whistles’ unique to individual whales (Martin et al. 1990).
As one of the most abundant cetaceans in the North Atlantic, pilot whales are important consumers in the marine ecosystem. They may be one of the most important marine mammal predators in the offshore waters of northwestern North America (Gannon et al. 1997ab). In the central North Atlantic around Iceland, pilot whales are likely the 4th most important marine mammal predator in the marine ecosystem, consuming 200 to 300 thousand tonnes of fish, and 900 to 1100 thousand tonnes of squid per year (Sigurjónsson and Víkingsson 1997). Much of this consumption is concentrated on species presently of little importance to commercial fisheries, so direct competition with fisheries is probably minimal.
Predation and parasites
Pilot whales have few predators besides humans, but may be preyed upon by killer whales (Orcinus orca) and large sharks. Striking changes in behaviour have been observed during playback of killer whale sounds (Miller et al. 2011, Curé et al.2012).
Pilot whales are often infested with whale lice (Isocyamus delfini), cestodes and nematodes (Balbuena and Raga 1991, 1993, Raga and Balbuena 1993). The stomach parasites Annisakis simplex is particularly prevalent in pilot whales from the Faroes, the infestation beginning with the onset of feeding and increasing with age (Raga and Balbuena 1993).
Male pilot whales reach sexual maturity at 11 to 22 years of age (Desportes et al. 1993, 1994d), while females do so at age 5 to 15 and both sexes reach physical maturity at age 25 to 30 (Bloch et al. 1993b, Martin and Rothery 1993). Gestation lasts about 12 months (Martin and Rothery 1993), with a significant overall foetal mortality (Desportes et al. 1994b). The fertility of females declines with age, and whales older than 40 years rarely become pregnant (Martin and Rothery 1993, ICES 1996), although the phenomenon is less accentuated than in short-finned pilot whales (Foote 2008).
The mean size at birth is 178 cm and 75 kg. Although remains of prey, together with milk, are observed in calves only a few months old, young nurse on average for 3–4 years. Lactation can however last much longer; up to 7 years in males and 12 years in females. This protracted lactation period is believed to be of social rather than nutritional importance (Desportes and Mouritsen 1993), allowing for long-lasting mother-calf bonds. It is consistent with the stable matrilineal school structure described for the species (Andersen 1990, 1993, Amos et al. 1991, 1993a,b). Post-reproductive females possibly play important roles in the survival of their last young. As they can no longer bear young of their own, they invest in their current one and continue to lactate and nurse.
Pilot whales are primarily consumers of squid and are essentially oceanic and deep water feeders, but they seem to be opportunistic feeders that may exploit any locally abundant prey and both the oceanic and neritic (coastal) habitats.
Off the Faroe Islands, pilot whales are clearly squid specialists and feed mainly on the European flying squid (Todarodes sagittatus) and the harmhook squid (Gonatus spp.), although other species, some benthic, are present in the same areas. Fish such as greater argentine (Argentina silus), blue whiting (Micromisistius poutassou), Greenland halibut (Reinhardtius hippoglossoides) and pandalid shrimps are also consumed. Although cod, herring and mackerel are common species in the neritic zone around the Faroes and have been reported as pilot whale prey elsewhere, they do not appear in the diet (Desportes 1985, Desportes and Mouritsen 1993).
Off Scotland, the French Atlantic coast and the NW Iberian Peninsula, the main component of the diet is also cephalopods, although fish are also present in varying importance (Martin et al. 1987, Gonzáles et al. 1994, Pierrepont et al. 2005, Spitz et al. 2011, Santos et al. 2013). Scottish whales consumed oceanic squid species, while the benthic octopods constitute the most numerous prey off the Iberian Peninsula and France.
In the Northwest Atlantic, the short and long-finned squids Illex illecebrosus and Loligo pealei dominate the diet of pilot whales, the Atlantic mackerel (Scomber scombrus) and Atlantic herring (Clupea harengus) are also present (Overholtz and Waring 1991, Abend and Smith 1997, Gannon et al. 1997a, 1997b). Cod (Gadus morhua) was reported as a secondary prey in earlier studies (Sergeant 1962, Mercer 1975).
Pilot whales can thus feed on a wide variety of prey and consume both oceanic and neritic species and pelagic and benthic species. They adjust their diet in response to changes in prey abundance. Off the Faroes, in years where Todarodes is abundant on the Faroe shelf, the diet becomes nearly mono-specific, centered upon that species. In years where Todarodes is not abundant, the diet is more diverse and other species of squid and fish are consumed, species which were also abundant in Todarodes years but not preyed upon. They may feed predominantly on fish when squid are not readily available (Desportes and Mouritsen 1993).
This dietary plasticity is also illustrated in the fact that pilot whales can forage in, and occupy successfully or shift to and from both oceanic and neritic habitats (Desportes 1985, Desportes and Mouritsen 1993, Spitz et al. 2011, Santos et al.2013). The use of ecological tracers reflecting longer-term diet, such as cadmium, carbon and nitrogen isotope ratios, and fatty acid signatures have also confirmed this foraging plasticity (Méndez-Fernandez et al. 2012, 2013, Monteiro 2013).
Distribution and Habitat
The long-finned pilot whale has a boreal distribution in the cold temperate and subpolar waters of all oceans except the North Pacific (Taylor et al. 2008), with a typical temperature range of 0-25° C (Martin et al. 1990). Globicephala melas melas occurs in the northern hemisphere and Globicephala melas edwardii inhabits the southern hemisphere (Olson 2009). This oceanic species occurs far offshore, but can also be found in coastal areas.
Distribution in the North Atlantic
Long-finned pilot whales are very widely distributed in the North Atlantic, from about 35°–65° N in the west and from about 40°–75° N in the east (ICES 1996; NAMMCO 1998ab, Abend and Smith 1999, Reid et al. 2003; Garrison et al. 2011; Roberts et al. 2016).
The 28-year long series of NASS and T-NASS summer sightings surveys, centered upon the three first weeks of July, provides a good understanding of the potential summer distribution of the species in the North Atlantic. There is an apparent gap in distribution in the area south of Greenland, however, this area has not been surveyed extensively so the gap may be an artefact.
Pilot whales can shift to and from oceanic and coastal habitats, as revealed by their feeding ecology (Desportes 1985, Desportes and Mouritsen 1993, Spitz et al. 2011, Méndez-Fernandez et al. 2012, 2013, Monteiro 2013). A recent spatial analysis of pilot whale distribution in the Northeast Atlantic (Rogan et al. 2017) indicated that summer numbers were highest in water depths >1,000 m and that they tended to be most abundant over areas of moderate slope. Abundance was also strongly associated with latitude, peaking at about 55° N and declining further north and south.
Pilot whale distribution does change from year to year, as is apparent from the distributions observed during the six NASS surveys (see sightings map). Although there is no indication that pilot whales undertake extensive seasonal migrations, their distribution also changes on a seasonal basis, with whales moving onto the slope, shelf and shelf edges over the summer months and moving back southwards into deeper offshore waters in winter (Sergeant and Fisher 1957, Sergeant 1962, Evans 1980, Payne & Heinemann 1993, Roberts et al. 2016). This also reflects in the July–August peak in the frequency of pilot whale drives in the Faroes (Zachariassen 1993).
The abundance and movements of preferred prey seem to drive pilot whale abundance and movements, as with the flying squid (Todarodes sagittatus) off the Faroes (Desportes and Mouritsen 1993, Zachariassen 1993, Jákopsstovu 2002), the northern shortfin squid (Illex illecebrosus) off Newfoundland (Mercer 1975) and the longfin inshore squid (Loligo pealei) and Atlantic mackerel (Scomber scombrus) off the United States (Smith et al. 1990, Payne and Heinemann 1993, Gannon et al. 1997b). The same pattern seems also present off the Iberian Peninsula, with the movements of the northern shortfin and lesser flying (Todaropsis eblanae) squids correlated with the distribution of pilot whales in the area (Santos et al. 2013).
North Atlantic Stocks
The stock structure of the North Atlantic population remains uncertain, despite genetic, morphometric, physiological and observational studies (ICES 1993, 1996; Fullard et al. 2000).
Studies analyzing differences in mitochondrial DNA (mtDNA) and allozymes in pilot whales across the North Atlantic have shown no significant differences between pilot whales from the western Atlantic, Iceland and the eastern Atlantic (Andersen 1993, Siemann 1994). This could be considered as evidence that there is only one stock of pilot whales in the North Atlantic. However, this uniformity may be related the social structure of pilot whales. If they occur in strong matrilineal (derived from mother) schools, as suspected, then the actual population unit is the school rather than the individual, making the genetically effective population size relatively small, in the order of several thousands rather than hundreds of thousands (ICES 1996, NAMMCO 1998b). This small effective population might be expected to have a low mtDNA variability. Andersen (1993) found that schools captured in the Faroes differed in their allozyme composition, suggesting that genetic differences between schools do exist.
More recently, however, a study using neutral microsatellite markers (Fullard 2000, Fullard et al. 2000) revealed significant genetic differentiation within the North Atlantic, and particularly between West Greenland and other both western and eastern regions (Cape Cod, Faroes and UK). This could not be explained by a simple isolation-by-distance model. Instead, the pattern of genetic differentiation suggested that population isolation occurs between areas of the ocean which differ in sea surface temperature, with 1) a cold-water population west of the Labrador/North Atlantic current, and 2) a warm-water population that extends across the Atlantic in the Gulf Stream.
Recently, Monteiro (2013) used both mitochondrial DNA (mitochondrial control region, neutral marker) and two loci of the Major Histocompatibility Complex (MHC, adaptive marker) on samples from USA, Faroes, Norway, UK and Northwest Iberia to revealed a level of genetic substructure in the North Atlantic, with consistent divergence patterns describing Northwest Iberia as a separate group.
Other lines of evidence suggest that there are at least two stocks in the North Atlantic. There are morphometric (body shape) differences between pilot whales caught in the Northwest and Northeast Atlantic (Bloch and Lastein 1993, ICES 1996). This indicates that pilot whales from the two areas are unlikely to be from the same stock. In addition, the depletion of pilot whales off Newfoundland from 1947 to 1972 apparently had no effect on pilot whale abundance elsewhere, indicating that there is probably little or no exchange between this area and others (Mercer 1975, Nelson and Lien 1996).
There may also be differences over smaller spatial and temporal scales. There were significant differences in pollutant concentrations (Aguilar et al. 1993, Caurant et al. 1993) and parasite burdens (Balbuena et al. 1993, 1994, 1995) between schools of whales landed in the Faroe Islands at different times and locations. This suggests that these schools spend different proportions of their time in different areas, which again may be indicative of stock differences and negate the hypothesis of just one resident Faroese population (ICES 1993).
In 1997, the Scientific Committee of NAMMCO concluded that, based on the evidence noted above, it was likely that there was more than one stock of pilot whales in the North Atlantic, and more than one stock subject to harvesting in the Faroe Islands (NAMMCO 1998b). It was apparent that further research was still required to resolve the stock delineation of pilot whales in the North Atlantic and this is still the case. However, the new genetic information strongly point to the existence of substructuring in the North Atlantic and the 2011 and 2012 satellite tagging clearly support that pilot whales caught in the Faroes do not belong to a resident population.
Current Abundance and Trends
Estimates of the abundance of pilot and other species of whales in the North Atlantic have been based largely on sightings surveys conducted from ships and airplanes. The North Atlantic Sightings Surveys (NASS) provide a time-series of abundance estimates from 1987 to 2015, covering a large part of the North Atlantic. Norwegian “mosaic” surveys cover most of the Northeast Atlantic, surveying a portion of the area annually on a six year rotation. In addition, the European CODA, American SNESSA (Southern New England to Scotian Shelf Abundance) and Canadian NAISS surveys have contributed to our knowledge of pilot whale abundance and distribution.
Abundance and trends in the North East Atlantic
The six NASS covered substantially different areas and, not surprisingly, yielded different population estimates for pilot whales. Year-to-year shifts in distribution are also apparent. The 1989 survey, conducted about two weeks later in the summer than the other surveys, extended farther south to cover the largest area of potential pilot whale habitat (1,279,741 nm²) and yielded the most reliable total estimate of 778,000 (CV=0.295) for the northeastern North Atlantic Ocean, although small numbers occur outside the area considered (Buckland et al. 1993). No sightings were made in the area North and northeast of the area, thus indicating that the joint survey covered the northernmost areas of pilot whale distribution.
The table below gives the abundance of pilot whales for the first five NASS for the Faroese and Icelandic areas with all data re-analysed similarly (Pike et al. 2013). It also presents an estimate from the NASS, SCANS and CODA areas combined from 2005-7, covering a very large area of the Northeast Atlantic. The 1989 estimate is significantly higher than the 1987, 2001 and 2007 estimates, but the 1989 survey had a substantially different timing and coverage (larger area, extending more to the south and west) than the others, with the possibility of more pilot whales having moved inside the area. The numbers suggest that the occupation or timing of occupation of the Northeast and Central Atlantic by pilot whales varies greatly from year to year. The table also provides estimates of pilot whales for West and East Greenland and Eastern Canada from 2007 and 2015. Taken together, these estimates suggest that up to 560,000 pilot whales occupy the Northeast and Central Atlantic area in some years, with somewhat smaller numbers in the Western Atlantic.
Trends in abundance
The estimates listed above are not directly comparable to one another because the area covered is not the same for all surveys. However, Pike et al. (2018) restricted the estimates to the area covered by all six surveys, and to the area covered by the three larger surveys (1989, 1995 and 2007). Because they cover exactly the same area, these “Survey Index Regions” are directly comparable between surveys. The Index Region covered by all six surveys shows a general decline in numbers from 1987 to 2007, followed by a recovery to the highest numbers yet observed in 2015. The Index Region covered by the three largest surveys shows a general decline from 1989 to 2007. However, the estimate from the smaller six-survey Index Region in 2015 is higher than most of those from the larger three-survey Index Region, indicating that a recovery would have been observed had the larger area been surveyed in 2015. This analysis therefore provides no evidence of any trend in pilot whale numbers in the Northeast Atlantic over the 28 year period from 1987 to 2015. The great variations in numbers between surveys within the Index Regions again confirms that the distribution of pilot whales differs greatly from year to year.
An indication of long term historical trends in the abundance of pilot whales around the Faroe Islands can be gained from analysis of catch data. Catch records from the Faroes go as far back as 1584, and are unbroken since 1709 (Bloch 1994). Catch, corrected for hunting effort, shows a cyclic pattern with a period of 100–120 years, with peaks in catch occurring in 1720–1730, 1840–1850, and 1935–1985 (Hoydal and Lastein 1993). There is no long-term indication of declining or increasing abundance over the period (Bloch and Lastein 1995). The local availability of pilot whales to the Faroese may be related to changes in sea temperature and the abundance of their favoured prey. See under ‘Life history and Ecology‘ for further detail.
Abundance and trends off the eastern U.S. and Canadian Atlantic coast
Pilot whales are common in the offshore waters of the northeastern USA and Canada (Mercer 1975, Lynch 1987, Nelson and Lien 1996, Gannon et al. 1997a, 1997b, Waring et al. 1999, Garrison et al. 2011, Roberts et al. 2016). However, the abundance and trends in abundance are uncertain, although several abundance estimates are available from selected regions for select time periods.
Long-finned and short-finned pilot whales overlap spatially along the mid-Atlantic shelf break between Cape Hatteras, North Carolina, and New Jersey. As the two species are difficult to distinguish at sea, sighting data during abundance surveys are reported as Globicephala sp. and thus combined abundance estimates for the two species have previously been derived from line-transect surveys. Sightings from shipboard and aerial surveys have been strongly concentrated along the continental shelf break; however, pilot whales are also observed over the continental slope in waters associated with the Gulf Stream (Roberts et al. 2016).
The best available abundance estimates are from surveys conducted during the summer of 2004 (Waring et al. 2012). These survey data have been combined with an analysis of the spatial distribution of the two species based on genetic analyses of biopsy samples to derive separate abundance estimates. The best resulting abundance estimate for long-finned pilot whales in U.S. waters is 12,619 (CV=0.37). More recently Roberts et al. (2016) estimated pilot whale abundance off the eastern USA as 18,977 (cv 0.11), however this included both short- and long-finned pilot whales.
Although there is no information on abundance trends, abundance is likely increasing because human-induced mortality has declined in recent years (Waring et al. 1999).
Pilot whales were subject to an intensive drive fishery in Newfoundland from 1947 to 1972, and this fishery apparently reduced the stock to very low levels (Mercer 1975, Hay 1982, Nelson and Lien 1996). Abundance at the onset of the fishery was likely about 60,000 animals (Mercer 1975). Hay (1982) conducted in 1980 an aerial survey in eastern Newfoundland and Labrador waters, and estimated 13,167 whales (95% C.I. 6,731 to 19,602, not corrected for diving whales or whales missed by observers). In July–August 2007, the Canadian part of the Trans-North Atlantic Sighting Survey (T-NASS) covered the area from northern Labrador to the Scotian Shelf, thus providing full coverage of the Atlantic Canadian coast (Lawson and Gosselin 2009, 2011, 2018). This aerial survey generated an abundance estimate of 32,999 pilot whales (95% CI approximately 14,468-75,265) (Lawson and Gosselin 2018). Almost all pilot whales were sighted off Nova Scotia in the southern part of the survey area (Lawson and Gosselin 2009). The survey was repeated in 2016, resulting in an estimate of similar magnitude (see table above). However, in this survey, which was conducted about 2 weeks later than in 2007, pilot whales had a more northerly distribution, suggesting seasonal movement in to the area (Lawson and Gosselin 2018). Taken together, these surveys suggest that pilot whale numbers are stable or recovering in the area.
A trend analysis incorporating all six NASS surveys covering the 28 year period from 1987 to 2017 found no trend in pilot whale numbers over the period (Pike et al. 2018). Given the minimum size of the population, as indicated by the 1989 survey, of over 500,000 animals in the Northeast and Central Atlantic, it seems very unlikely that an annual harvest of around 1,000 whales in the period 1987–2015 would cause a reduction in the population. The fact that the population has been subject to approximately the same level of harvest for at least 300 years, with apparently little change in availability (Hátún and Gaard 2010), also suggests that the Faroese harvest is likely not causing the stock to decline in numbers. In 1997, NAMMCO concluded that the drive hunt was sustainable (NAMMCO 1998c).
The effect of catches of pilot whales in the Faroe Islands depend critically about the geographic range of the population, which is affected by these catches (ICES 1996, see figure below). If the whales come from the Mid-Atlantic Ridge-Iceland Area (A+B+C) or the area covered by the NASS 1989 (A+B+C+D) sighting survey, then catches over the last 150 years have hardly any impact on the population trajectory. However the qualitative effect of the catches is very different if they have come from a population with a geographic range the size of the Rockall-Iceland Area (A+B) or the Faroese Islands Area (A).
Although the stock delineation of pilot whales remains uncertain, non-genetic evidence (pollutant concentrations and parasite burdens, see above) indicate that there is likely more than one stock subject to harvesting in the Faroe Islands (ICES 1996, NAMMCO 1998b) and that Faroese harvesting is not concentrated on a small resident population. The satellite tagging data also show that pilot whales caught off the Faroes moved well beyond the Faroe Islands Area. Indeed the satellite tagging data from 2012 indicate that the whales moved well beyond the Mid-Atlantic Ridge Area (A+B+C below), as well as beyond the extent of the 3-NASS Survey Eastern Index Region.
The abundance of pilot whales in the population contributing to the catch required to sustain an annual catch of 678 animals (the average annual Faroese catch 1997–2011) is between 50,000 and 80,000 whales (with a precision equivalent to that of the sightings survey in 2007) (NAMMCO 2013). The population in the Eastern Index Area, which is smaller than the range of the population affected by the catch, is alone over 100,000 pilot whales. That said, the last formal assessment (ICES 1996) is dated and the NAMMCO Scientific Committee is planning a new assessment tentatively scheduled for 2020, which will take into account all new information, including new estimates of abundance and trend analyses.
The average annual catch of long-finned pilot whales in West Greenland during 1993–2007 was 126 whales. The aerial NASS 2015 survey off west Greenland yielded an abundance of 8,133 pilot whales (95% CI = 3,635–23,234), but only partly covered the potential pilot whale habitat, as aggregations of pilot whales were encountered at the western edge of the survey area (Hansen et al. 2018). The estimate from a similar survey carried out in 2007 was of similar magnitude (Guldborg Hansen and Heide-Jørgensen 2013). The NAMMCO Scientific Committee (2013) suggested that a sustainable harvest level of pilot whales taken from this abundance would be between 50–70 whales per year. However, it seems likely that the size of the stock subject to the Greenlandic hunting is larger than that revealed by the survey, and that the summer aggregation off West Greenland cannot be considered an isolated stock. Instead, it is likely connected to pilot whales along Labrador and at Newfoundland, and the occurrence and abundance in West Greenland is probably influenced by the sea temperature regimes in the area (Fullard et al. 2000). For these reasons the stock status of West Greenland pilot whales remains uncertain.
The 2011 US assessment (Waring et al. 2012) concluded that the status of long-finned pilot whales in the U.S. Atlantic EEZ was unknown. There were insufficient data to determine population trends for this species. The total U.S. fishery-related mortality and serious injury for long-finned pilot whales was unknown, since it was not possible to partition mortality estimates between the long-finned and short-finned pilot whales. However, this mortality was most likely not less than 10% of the calculated PBR (Potential Biological Removal) and therefore could not be considered to be insignificant and approaching zero mortality and serious injury rate. Therefore, it was recommended that the stock should be considered a strategic stock. However, the inability to partition mortality estimates between the two pilot whale species limited the ability to adequately assess the status of the long-finned pilot whale stock.
Pilot whales were subject to an intensive drive fishery in Newfoundland from 1947 to 1972, and this fishery apparently reduced the stock to very low levels (Mercer 1975, Hay 1982, Nelson and Lien 1996). Abundance at the onset of the fishery was likely about 60,000 animals (Mercer 1975). Hay (1982) conducted in 1980 an aerial survey in eastern Newfoundland and southeastern Labrador waters, and estimated 13,167 whales (95% CI = 6,731-19,602, not corrected for diving whales or whales missed by observers).
Nelson and Lien (1996) concluded that the population had likely not yet recovered to its pre-exploitation size. This seems confirmed by the results of the 2015 Canadian NAISS survey part of the T-NASS survey (Lawson and Gosselin 2018), which provided a full coverage of the Atlantic Canadian coast and yielded a fully corrected abundance estimate of 28,218 (approximate 95% CI = 14,236–55,934). The estimate from the Canadian component of the 2007 T-NASS survey was of similar magnitude (Lawson and Gosselin 2011). Taken together, these surveys suggest that pilot whale numbers are stable or recovering in the area.
Pilot whales are likely one of the most abundant odontocetes in the North Atlantic. The harvesting of pilot whales that continues today in the Faroe Islands has proven sustainable over a period of more than 400 years. In 1997, NAMMCO concluded that the drive hunt was sustainable (NAMMCO 1998c). The population off Newfoundland is likely slowly recovering after a period of excessive harvesting.
In some other areas, by-catch of pilot whales in fisheries continues, but apparently at relatively low levels. While there is no indication at present that pilot whales are being affected by contaminants, their occupation of a relatively high trophic level and the high level of contaminants observed does make them susceptible to this threat.
Better information on the abundance and trends in abundance of pilot whales is required to ensure the long-term sustainability of these harvests. In addition, further information on stock delineation, and geographical range of any stock components found, would improve the ability to design and carry out effective surveys for this species. In the light of the new genetic information, the recent tagging data, as well as the new abundance estimates obtained from the 2015 NASS survey (analysis in progress) and the 2016 SCANS III survey, a new assessment is warranted. NAMMCO will conduct a full assessment of the species in 2019.
Conservation Status according to other international organisations
CITES – Convention on International Trade in Endangered Species of Wild Fauna and Flora
Long-finned pilot whales are currently listed on Appendix II of the CITES. CITES is a legally-binding multilateral environmental agreement that aims to ensure that international trade does not threaten the survival of species in the wild. Both Greenland and the Faroes are signatories to the convention through Denmark. A listing on Appendix II means that an export permit shall only be granted when the Scientific Authority of the State of export has advised that such export will not be detrimental to the survival of the species in the wild. There is however no export of pilot whale products from Greenland or the Faroes, except for a very small non-commercial export of meat and blubber for family consumption.
IUCN – International Union for Conservation of Nature
IUCN classify long-finned pilot whales, treated as one species, as Data Deficient, with the following justification: There is evidence that long-finned pilot whales may comprise a complex of two or more species. Because additional data should resolve this taxonomic uncertainty, the current species is listed as Data Deficient. Threats that could cause widespread declines include high levels of anthropogenic sound, especially from military sonar and seismic surveys, and by-catch. Primary threats that could cause widespread declines include entanglement in fisheries and competition with squid fisheries. The combination of possible declines driven by these factors is believed sufficient that a 30% global reduction over three generations (72 years; Taylor et al. 2007) cannot be ruled out (criterion A) (Taylor et al. 2008).
Long-finned pilot whales inhabit the waters of the four NAMMCO member countries: Faroe Islands, Greenland, Iceland and Norway.
The long finned pilot whale is not protected in Iceland, but pilot whales are not hunted there. However, mass strandings happen from time to time (see under Mass strandings).
Pilot whales are protected in Norway, both in Svalbard and on mainland Norway.
Pilot whales are taken in southwest Greenland on an opportunistic basis (a few hundreds a year, see under Recent harvests). There are no quotas for pilot whales in Greenland, however there are regulations pertaining to hunting methods and equipment.
Regulation of the Faroese pilot whale hunt is based on old Norse laws, and is regulated by government order which deals in detail with all aspects of the hunt, including driving procedures, beaching, killing methods and approved equipment, valuation, distribution and beach cleanup. These regulations are subject to regular review and have been updated and revised a number of times in recent years, both to keep them consistent with technological developments and to refine some of the organisational aspects of the drive and the distribution. A recently developed spinal lance has been introduced as mandatory for the killing of pilot whales. The spinal lance has been shown to reduce killing time to 1-2 seconds, while also improving accuracy and safety (Anonym 2013). A blowhole hook has also been developed and from May 2015, only persons having attended a certified course of instructions in the whaling regulations and killing methods will be permitted to kill whales. NAMMCO (2014) has recently published an Instruction Manual on Pilot Whaling (The manual exists in Faroese and English).
Only some specific bays, today numbering 23, which meet the requirements for suitable whale beaching conditions, are allowed for the slaughtering of the whales. The hunt is supervised by elected grindforemen, who are themselves under the supervision of the sýslumaður, or district sheriff. The sýslumaður also oversees the valuation and division of the catch, and is responsible for keeping records of the harvest (e.g. Bloch et al. 1990, Bloch 2007, Anonym 2013).
There are no quotas, but certain beaches or entire whaling districts can be closed when harvests are considered sufficient.
The catch is shared freely among those taking part in the drive and the local residents of the whaling bay and district in accordance with a complex, traditional community sharing system. The division of the catch is administered by the relevant sýslumaður. The catch is divided into shares known in Faroese as a skinn, which is a age-old measurement value that derives from agriculture practices. One skinn is roughly equivalent to 34 kilograms of blubber and 38 kilograms of meat. Whales in the cacth are numbered, their condition is assessed and they are valued using a traditional wooden pole calibrated in logarithmic division representing the value in skinn. Their value in skinn is marked in roman numerals on the flipper (e.g. Joensen 1976, Bloch et al. 1990, Bloch 2007).
Levels of PCB’s and mercury are relatively high in the blubber and meat of pilot whales taken in the Faroes (Borrell and Aguilar 1993, Caurant et al. 1993). In some cases, the level of consumption of pilot whale by Faroese may lead to intake of these substances that exceeds recommended levels. This is of particular concern given the documented neurotoxicity of methylmercury, in particularly to the developing foetus (Weihe et al. 1996; for more details see under Contaminants). Consequently, since 1998 the Faroese health authorities have been provided regular recommendations for the consumption of pilot whale meat and blubber, in response to most current research and based on the latest internationally applied standards for precautionary limits, the latest one in June 2011.
You can find more information on the Faroese pilot whaling here, as well as accessing the last executive order on the pilot whale drive (July 2013) in English translation.
Pilot whales have a long history of utilisation by humans in the North Atlantic. In the 20th century, they have been harvested in Greenland, Iceland, the Faroe Islands, western Ireland, Shetland and Orkney Islands and Norway, the eastern USA and Newfoundland in Canada (Mitchell 1975, Nelson and Lien 1996). They continue to be harvested in the Faroe Islands and Greenland. In most places, pilot whaling was conducted as drive fisheries. Meat and blubber were used for human consumption.
Pilot whales are taken in southwest Greenland on an opportunistic basis. They are usually hunted from small boats using rifles and hand harpoons. Recent catches have ranged between 0 and 365 animals (Table below).
Drive fisheries for pilot whales in the Faroe Islands—known in Faroese as grindadráp—date back to the Norse settlement in the 9th century with written descriptions from as early as 1632 (Sanderson 1992). It represents “a distinctive cultural characteristic for the Faroe Islands” (Joensen 1976) and “an established symbol of Faroese national identity” (Sanderson 1992). In addition to the objects of material culture it has produced, the grindadráp has inspired authors, poets and songwriters in the Faroe Islands for centuries (e.g. Sanderson 1992).
Catch statistics exist since 1584 and are unbroken from 1709 to today. They show and annual average catch of 850 pilot whales (range 0-4,480) with a cyclic variation correlated with North Atlantic climatic variations and oceanic events (Hoydal and Lastein 1993, Bloch and Lastein 1995. Block 1998, Jákupsstovu 2002, Hátún et al. 2009, Hátún and Gaard 2010).
From 1709 to 1999, a total of 246,434 pilot whales have been caught in 1,766 pods. There have been an average of 6.1 grinds (whale drives) per year in that period, and grind size has ranged from 1 to 1200 whales, with a mean of 139.5 whales per grind (Zachariassen 1993, Bloch 1994). Since 2000, the pilot whale catch at the Faroes has ranged between 0 and 1107, with a yearly average for the period 2000–2013 of 671 animals (Table below).
In the Faroes, harvesting of pilot whales has been an important source of food for the inhabitants since the islands were colonized (e.g. Williamson 1970). Pilot whales are taken in an organised drive hunt, or grind. When whales are sighted, local small fishing vessels cooperate to drive the whales into designated beaches. Once ashore, they are killed by severing the neck arteries and veins using a specialized knife. The catch is then evaluated by designated officials who measure and mark the whales. The catch is divided into shares and distributed free of charge following specified rules to hunt participants and residents in the district. Larger catches are distributed more widely (e.g. Bloch et al. 1990, Bloch 2007, Ministry of Fisheries).
USA and Canada
An important pilot whale drive fishery was active at Cape Cod from the mid-1700s to the 1920s. During the late 1800s the mean annual catch was in the order of 2–3,000 animals. A drive fishery was also active off the shores of Virginia and North Caroline (Mitchell 1975 a,b).
Newfoundland’s drive fishery was active from 1947 to 1964 and at its highest in 1956, with catches reaching almost 10,000 animals (Sergeant 1962, Mitchell 1975a). It declined shortly after and is now defunct.
Pilot whale 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 has a dark red colour (e.g. Bloch 2007).
Both the meat and blubber of pilot whales have long been—and continue to be—a valued part of the national diet. Catches are shared largely without the exchange of money among the participants in a whale drive and residents of the local district where they are landed (e.g. Bloch 2007, Ministry of Fisheries).
On average, 54% of the total weight of a whale is consumed as meat and blubber, with up to 60% in larger whales, which have proportionally larger muscle mass than smaller whales. In comparison, in average 47% of a fish weight is consumed (Bloch 2007).
Whale meat and blubber are stored, prepared and eaten in a variety of ways (e.g., Bloch 2007, Ministry of Fisheries). When fresh, the meat is boiled or served as steaks, with blubber and potatoes. The meat and blubber can be frozen, or preserved using traditional Faroese methods such as dry-salting or storing in brine. Strips of whale meat are also hung to wind-dry for several weeks and then eaten raw in thin slices. Thin slivers of blubber are also a popular accompaniment to dried fish.
Catch statistics exist since 1584 and are unbroken from 1709 to today. They show an annual average catch of 850 pilot whales (range 0- 4,480) with a cyclic variation correlated with North Atlantic climatic variations and oceanic events (Hoydal and Lastein 1993, Bloch and Lastein 1995, Bloch 1998, Jákupsstovu 2002, Hátún et al. 2009, Hátún and Gaard 2010).
From 1709 to 1999, a total of 246,434 pilot whales have been caught in 1,766 pods. There have been an average of 6.1 grinds (whale drives) per year in that period, and grind size has ranged from 1 to 1200 whales, with a mean of 139.5 whales per grind (Zachariassen 1993, Bloch 1994).
Since 2000, the pilot whale catch at the Faroes has ranged between 0 and 1203, with a yearly average for the period 2000-2017 of 614 animals (see table of catches to the right).
Pilot whales are taken on an opportunistic basis and principally in southwest Greenland. Recent catches have ranged between 0 and 433 animals, with a yearly average for the period 2000-2013 of 204 animals (see table of catches to the right).
DID YOU KNOW?
A pilot whale stomach can be used as a buoy
Pilot whale stomachs were used as buoys until the 70s. Pilot whale stomachs have three compartments. The first one, called mechanical stomach, is made of very strong tissues and acts as a grinder. This part was emptied, placed in brine, then tanned and inflated for use as buoys with the long-lines (left). In former days, thongs of the dried skin were used in the boats to tie the oars to the wooden tollars which take the places of rowlock (right).
Other Human Impacts
Anthropogenic activities which may affect marine mammals generally and pilot whales specifically can be divided into two main categories: habitat degradation and oceanographic changes. Knowledge about pilot whale habitat use is limited and it is therefore difficult to assess the relative impact that such changes may represent for the species.
A range of human activities has the potential to degrade habitat important to pilot whale survival. The species occurs in coastal waters, but is essentially oceanic. Main threats include:
• changing water quality and pollution (e.g. runoff from agriculture, oil spills) • entanglement (e.g. in marine debris, fishing gear, etc.) • prey depletion due to over-harvesting • acoustic pollution with disturbance from low-frequency noise (vessels, seismic surveys, military activities)
In addition to their direct toxicity, anthropogenic contaminants may affect the resilience and increase susceptibility to disease in marine mammals (Reijnders and de Ruiter-Dijkman 1995). The accumulation of contaminants in pilot whales has been studied on both sides of the Atlantic (e.g. Aguillar et al. 1993, Borrell 1993; Borrell and Aguilar 1993, Borrell et al. 1995, Caurant et al. 1993, 1994, 1996, Caurant and Amiard-Triquet 1995, Tilbury et al. 1999, Dam and Bloch 2000, Weisbrod et al. 2000, 2001, Sonne et al. 2010, Méndez-Fernandez et al. 2014ab). Studies dating back to 1977 have shown an overall increase in contamination of the meat, blubber, liver and kidneys of pilot whales. Together with the killer whale (Orcinus orca), the long-finned pilot whale is one of the most polluted species in the world (AMAP 2004, 2005; Dam and Bloch 2000).
Faroese pilot whales have concentrations of organic contaminants in their blubber which are roughly in the mid-range of such concentrations in other species of toothed whales in the North Atlantic (Borrell and Aguilar 1993, Mendez-Fernandez et al. 2014b). It is not known if these contaminants are affecting the health of pilot whales in the North Atlantic.
The concentration of trace metals (other than copper) in the liver of pilot whales from the Faroe Islands is on the higher end of the range of what is found in other marine mammal species of the North Atlantic (Caurant et al. 1993) and pilot whales from other area of the North Atlantic (Méndez-Fernandez et al. 2014a). Cadmium levels, in particular, are very high and even higher than in species from highly industrialized areas (Caurant et al. 1993). This is probably related to their heavy consumption of squids (Bustamante et al. 1998).
The heavy metals mercury (Hg) and cadmium (Cd) produce adverse effects in various mammals, with risks of health impacts on internal organs, such as the liver and kidneys. Possible direct and indirect effects (e.g. immunodeficiency) of trace metals on pilot whales have been little studied. However, a recent study showed a high prevalence of histopathological changes in liver and renal tissues of Faroe Island pilot whales and suggested that age, heavy metal, and organic contaminants may be important factors in pathology development (Sonne et al. 2010).
The Faroe Islanders rely on pilot whales as an aboriginal and important wildlife food resource. However, the consumption of pilot whale meat is thought to representing a hazard to the health of consumers (e.g., Weihe et al. 1996, Steuerwald et al. 2000, Weihe and Joensen 2008, 2012, Choi et al. 2009, Grandjean et al. 2011). Pilot whales today contain contaminants (both organochlorines or metals) in concentrations such that neither meat nor blubber would comply with current limits for acceptable concentrations of toxic contaminants, and it has been recommended that pilot whales should no longer be used for human consumption (latest: Weihe and Joensen, 2012). As more developing nations industrialize, marine pollution is likely to increase. As the meat and blubber become more contaminated, their risk may increasingly outweigh their benefits (Fielding 2010).
Pilot whales are taken as by-catch in some fisheries on both sides of the Atlantic. They were taken in significant numbers in the Mediterranean driftnet fishery for swordfish (Xiphias gladius) in the 1980’s, however limitations on net size imposed in 1990 have probably ameliorated this problem (Notarbartolo-di-Sciara 1990, Natale and Notarboartolo-di-Sciara 1994). Currently, by-catch of pilot whales in the eastern Atlantic appears to be insignificant. For the period 2008–2012, the ICES Working Group on Bycatch of Protected Species reports only a few observed pilot whale by-catch in European Fisheries, all in the Atlantic: four in 2008 by a French midwater pair trawl; five in 2011 by a German midwater otter trawl; and one in in 2012 by a Dutch midwater otter trawl (ICES 2010, 2011, 2012, 2013, 2014).
In the western Atlantic, pilot whales have been taken as by-catch in several types of fisheries, including squid traps (Lien 1994), pelagic drift gillnets, trawls, purse seines and longlines (Waring et al. 1999). By-catches were highest in the pelagic drift gillnet fishery for swordfish, ranging from 9 to 135 whales per year between 1989 and 1996. This fishery was closed in 1997. By-catch of pilot whales in the western Atlantic was not considered to be causing stock decline or significantly impeding stock recovery (Nelson and Lien 1996, Waring et al. 1999), although there were probably more pilot whales taken incidentally than were documented (Bernard and Reilly 1999). The average annual estimated fishery-related mortality during 2000–2004 in the Northeast mid-water trawl fishery was 8.9 (CV=0.35) pilot whales and in the Atlantic herring mid-water trawl fishery 11 animals (Waring et al. 2007ab). The average annual mortality in the pelagic long-line fishery was 114 (CV=0.20) pilot whales during 2005–2009 (Waring et al. 2012). The 2005–2009 average mortality attributed to the mid-Atlantic bottom trawl was 30 animals (CV=0.16), to the northeast bottom trawl 12 animals (CV=0.14) and to the to the Mid-Atlantic mid-water trawl fishery was 2.4 (CV=0.99) (Waring et al. 2012). The total U.S. fishery-related mortality and serious injury for long-finned pilot whales is unknown, since it is not possible to partition mortality estimates between the long-finned and short-finned pilot whales, but it cannot be considered insignificant (Waring et al. 2012).
Competition with fisheries
Pilot whales prey on some commercially important invertebrate and fish species such as squid, shrimp, mackerel, blue whiting and herring. The availability of these for whales might therefore be reduced by commercial fisheries. Fisheries for squid are widespread on both side of the North Atlantic, targeting species which are the main prey eaten by pilot whales in the area: short-finned squid (Illex illecebrosus) off Newfoundland, long-finned squid (Loligo pealeii) off the US coast, European flying squid (Todarodes sagittatus) off the Faroe Islands, Norway and Portugal, curled octopus (Eledone cirrhosa) off Spain and Portugal. This raises the possibility of prey depletion for pilot whales.
The abundance of squid available to fisheries is known to exhibit dramatic yearly fluctuations, with no obvious pattern. Periods of either high or low abundance may last for several years. These changes would be determined by the interaction of fluctuating year-class strength and varying hydrographic conditions influencing natural mortality and the distribution of the early life stages (Arnold 1979, Fisheries and Oceans Canada 2013).
Long-finned pilot whales feed on a wide variety of prey, and appear to be able to adjust their diet in response to changes in prey abundance (Desportes and Mouritsen 1993; Santos et al. 2013). They are therefore likely less vulnerable to prey depletion than more specialised species. However, pilot whale diet includes several high quality species, the quality of food being dictated by the cost of living for each species; shifting to food of lower-quality species (species with lower energy densities per mass unit) may negatively affect the population dynamics of a species (Spitz et al. 2011, 2012). The intensified pelagic fishery targeting blue whiting (Micromesistius poutassou) west of the British Isles is likely one of the factors reinforcing the apparent decrease in abundance of pilot whales since the 1990s (Hátun and Gaard 2010). The blue whiting is preyed upon both by the flying squid and the pilot whale.
This species, like many beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006), and almost all behavioural responses are expected to result in a change in dive pattern (Sivle et al 2012). Indeed intense military sonar signals should be audible to cetaceans over large distances given the efficient propagation of sound and the sensitive hearing capabilities of cetaceans.
Exposure to military sonar pulses is associated with changes in behaviour in pilot whales, suggesting acoustic disturbance. Changes in vocalizations, traveling, surfacing and diving/foraging behaviours have been observed, the latter potentially reducing the foraging efficiency of the affected animals (Rendell and Gordon 1999, Miller et al. 2011, 2012, Sivle et al. 2012).
Pilot whales may, however, be less sensitive to sonar exposure, compared to species such as killer whales and beaked whales. They exhibit higher response thresholds to sonar exposure than these species, and an avoidance response restricted to the duration of sonar exposure, while the responses reported for killer whales and beaked whales may last longer than the sound exposure. There are however individual differences and the behavioral responses to sound stimuli are strongly affected by the context of the exposure (Antunes et al. 2014).
Predicted impacts of global climate change on the marine environment may affect long-finned pilot whales, and may induce changes in the species’ range, abundance and/or migration patterns (Learmont et al. 2006). In particular, pilot whales may be affected indirectly, through their prey, as the migration and survival of squid is very temperature-dependent.
MacLeod et al. (2005) suggest that the late 1980s warming of local waters has, indeed, led to changes in the cetacean community of north-west Scotland, with a decline in occurrence of cold water species, including pilot whales, an increase in the occurrence of existing warm water species and the addition of new warm water species to the community. They predicted that if the temperature rise continues, colder water species like the pilot whale might be entirely lost from the north-west Scottish cetacean community.
A clear link has been identified between the abundance of long-finned pilot whales and the marine climate in the northeastern Atlantic throughout the last three centuries (Hoydal and Lastein 1993, Hátun et al. 2009). During warm periods the whales are observed in high abundances while they can be completely absent from the region during cold periods. The linkage between the marine climate and the abundance of pilot whales probably involves their main prey items, the flying squid and the large but highly variable blue whiting stock (Hátun and Gaard 2010). This link, however, was broken post-1980s, when warming and an increase in the blue whiting stock were not followed by an increase in the abundance of flying squids and pilot whales. Hátun and Gaard (2010) identified potential causes rooted in global warming and an intensified pelagic fishery, which collectively might explain this apparent disruption.
Pilot whales have a tendency to mass-strand throughout their range in the North Atlantic (e.g. Sergeant 1962, Bloch et al. 1993a, Sigurjónsson et al. 1993, Waring et al. 1999, 2007ab, 2012). It is not known whether human activity influences these occurrences, and at present, such strandings must be considered a component of the natural mortality of the species. However Culik (2011) report on three mass stranding events in Tasmania, just prior to and after the arrival of naval vessels using high frequency (5–200 Kz) sonar, where a behavioural reaction to the sonar facilitating the second and third events could not be ruled out.
Research in NAMMCO Member Countries
All NAMMCO member countries as well as Canada have participated in the NASS and T-NASS surveys, and the pilot whale has been one of the target species (see under Current Abundance and Trends). These surveys are coordinated through the Scientific Committee of NAMMCO. In addition, the Faroe Islands conduct research on ecology, population structure, levels and trends in the accumulation of contaminants and impacts of climate change on pilot whale distribution and abundance.
An intensive international research programme on the ecology and status of the long-finned pilot whale off the Faroe Islands and the impact of the fishery on the population was initiated and supported by the Faroese Governement in 1986, under the auspices of the IWC and UNEP (Desportes 1988, 1990, Desportes et al. 1994c). Some of the results were compiled in the first monograph on Northern Hemisphere pilot whales (Donovan et al. 1993).
Following pilot whales movements through satellite tracking
Satellite transmitters have been successfully attached to pilot whales from different schools since July 2000 (see Table). In each case, the schools of whales were driven into a bay, the tags attached to the selected whales, and the entire school driven back out to sea again. The maps below shows the overall movements of the whales from the four last tracking events.
These tagging experiments are very important because they shed light on the extent of the population affected by the Faroese catch. As described under Stock status the effects of the catch are very different if the catch comes from a population restricted to the Faroe Island area or from a population spread over a wider geographical area.
Ongoing sampling of pilot whale catches
The measurement of skinn values, which has been used traditionally in Faroese whaling (see under Hunting and Utilisation), continue being recorded. This measure, together with the sex and total body length which have been recorded from most pilot whales caught since 1984, allows researchers to follow trends in the size of the whales landed. The Faroese Museum of Natural History also conducts a small-scale opportunistic sampling of the catch to monitor trends in life history parameters and feeding habits.
On-going biological sampling of pilot whales landed in the Faroe Islands, together with satellite tracking projects and regular sighting surveys are important tools that provide updated information for management to ensure that the pilot whale catch remains being sustainable.
Level of contaminants in pilot whales
Samples of pilot whale tissue are taken regularly by the Environment Agency to examine and follow the levels of heavy metals in the meat and organochlorines in the blubber of the whales.
The focus of the monitoring of muscle and blubber is to elucidate possible changes in concentrations over time in the exposure of the Faroese human population utilizing pilot whale blubber and meat for food. The focus of the monitoring of heavy metals in kidney and liver tissues is to follow the possible risk to the pilot whales of elevated tissue metal concentrations, which are known to impair reproduction in may species.
Since 2008, the monitoring data collected by the Environment Agency are part of the Arctic Monitoring and Assessment Programme (AMAP) and are available online, under the heading ENVOFAR). ENVOFAR is a cooperation of Faroese institutions that works actively to describe and study the environment in the AMAP and CAFF (Conservation of Arctic Flora and Fauna) working groups under the Arctic Council.
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- Canadian – SARA registry – Long-finned Pilot WhaleCMS – Long-finned Pilot Whale status reportCAFF – Conservation of Arctic Flora and Fauna (Arctic Biodiversity portal – Arctic Council)Faroe islands
- ENVOFAR – Environmental data on terrestrial and mairne ecosystems in the Faroe Islands
- Faroe Islands – Ministry of Fisheries – Whales and whaling in the Faroe IslandsGreenland
- Greenland Institute of Natural ResourcesIceland
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