Two Species Under One Name: Long-finned or Short-finned?
The name « pilot whale » covers two distinct species. They look similar at first glance, but their geographic distribution, size, and dorsal fin shape allow them to be distinguished in the field.
Long-finned pilot whale (Globicephala melas): cold and temperate waters
The long-finned pilot whale (Globicephala melas) frequents the North Atlantic, from Norway to American coasts, as well as the Southern Hemisphere in subantarctic waters. It is the species present in the Bay of Biscay and western Mediterranean. Adult males reach 6 to 7 meters and can exceed 2 000 kg.
Short-finned pilot whale (Globicephala macrorhynchus): warm and tropical waters
The short-finned pilot whale (Globicephala macrorhynchus) occupies warm waters of the Indian, Pacific, and tropical Atlantic oceans. It is regularly observed in the Azores, Canaries, and Madeira. Its size is slightly smaller than that of the long-finned, and its dorsal fin is proportionally shorter and more curved backward.
Comparative Table: Size, Range, Dorsal Fin, IUCN Status
| Criterion | G. melas (long-finned) | G. macrorhynchus (short-finned) |
|---|---|---|
| Adult Length | 5 to 7 m | 4 to 6 m |
| Adult Weight | up to 2 300 kg | up to 1 800 kg |
| Preferred Waters | Cold and temperate | Warm and tropical |
| Dorsal Fin | Long, wide base | Shorter, very curved |
| IUCN Status | Least Concern | Data Deficient |
| Presence in France | Biscay, Mediterranean | Rare, mostly tropical Atlantic |
The two species can overlap in certain transition zones, notably around the Azores and Canaries, making identification tricky without quality photographs.
Recognizing a Pilot Whale at Sea: The Key Criteria
Several morphological features allow identifying a pilot whale even in rough seas or under overcast skies. The combination of these criteria is distinctive enough to avoid confusion with other large delphinids.
Melon: Shape, Size by Age and Sex
The melon is the fatty structure forming the bulbous forehead, characteristic of the Globicephala genus. It is particularly prominent in adult males, to the point of slightly overhanging the upper jaw. In females and juveniles, it is more rounded but still clearly visible. This is the first criterion to look for with binoculars.
Dorsal Fin: Long, Wide, Curved Backward
The dorsal fin is positioned forward of the mid-back, which is unusual among delphinids. It is long, with a very wide base, and curves markedly backward. In old males, it can take an almost horizontal shape. This profile is very different from that of a bottlenose dolphin or common dolphin.
Black Body and Light Throat Patch: Where to Look Exactly
The coloration is entirely black or very dark gray. Two light marks are present: an anchor-shaped patch on the throat and a pale gray ventral patch, visible when the animal rolls at the surface. A gray saddle patch behind the dorsal fin is sometimes perceptible depending on the angle and light.
Blow and Surface Behavior: What You See from a Boat
The blow is short, low (less than a meter), and often hard to distinguish in strong winds. What catches the eye first is the group formation: pilot whales often travel in a line or broad front, with several dorsal fins appearing simultaneously. Spy-hopping behavior (head out of the water) is occasional but spectacular. 🌊
Biology and Diving: An Odontocete Built for Great Depths
The pilot whale is an odontocete specialized in deep hunting. Its physiological and behavioral adaptations are directly linked to its diet.
Diet: Squid Primarily, Nocturnal Hunting Strategy
The pilot whale feeds mainly on squid, especially meso- and bathypelagic species that rise toward the surface at night. This nocturnal hunting strategy explains why groups are often seen at the surface during the day, apparently resting: they are recovering after intense nights of diving. Fish make up a secondary part of the diet.
Diving Capabilities: Duration, Maximum Recorded Depth
Telemetry data show that the long-finned pilot whale dives regularly to 400-600 meters, with maxima recorded around 800 meters for the short-finned. Dive duration can exceed 20 minutes. These performances rank the pilot whale among the most efficient divers among delphinids. The melon plays a role in focusing echolocation clicks used to detect prey in the dark.
Longevity and Sexual Dimorphism
Sexual dimorphism is pronounced: males are significantly larger and heavier than females, and their melon is more developed. Longevity is high: females can live up to 60 years, males rarely beyond 45 years. Females stop reproducing around 35-40 years but remain active within the group for decades, a key point for understanding social structure.
Matriarchal Social Structure: Why the Group Stays Together
The pilot whale's social structure is one of the most complex among cetaceans. It relies on stable family bonds and active cultural transmission, with direct consequences for mass stranding risks.
Stable Family Units and Cultural Transmission
Pilot whale groups are organized around matrilineal lineages: individuals stay with their birth group for life, whether male or female. This stability favors the transmission of learned behaviors, especially hunting routes and feeding areas. Genetic studies have confirmed that groups observed together often share direct common ancestry.
Role of Post-Reproductive Females: A Parallel with Orcas
Post-reproductive older females play a central role in group cohesion and navigation. This phenomenon, documented in resident killer whales (Orcinus orca) and killer whales in general, is also observed in Globicephala melas (Souffleurs d'Écume report, Bay of Biscay data). These females accumulate irreplaceable spatial and social memory for the group.
Mass Strandings: The Direct Link to Social Cohesion
The same group fidelity that is an evolutionary advantage becomes a vulnerability factor during mass strandings. If one individual, often a dominant male or sick animal, approaches shallow coastlines, the others follow. Social pressure is such that refloating attempts often fail unless the entire group is moved simultaneously. Underwater noise pollution and local magnetic anomalies are studied as additional triggers (IUCN, 2022). This is why pilot whale stranding intervention protocols always involve collective management, never individual.
Global Distribution and Presence in French Waters
The pilot whale is present in all major ocean basins, but its precise distribution varies by species and season.
Bay of Biscay: Regular Species, PELAGIS and Souffleurs d'Écume Data
The Bay of Biscay is the best-documented French area for the long-finned pilot whale. The PELAGIS Observatory (UMS 3462, CNRS/La Rochelle Université) records regular sightings, especially over the continental slope where squid are abundant. Souffleurs d'Écume reports recurrent sightings from Finistère to Basque coasts, with groups exceeding 50 individuals. Presence is possible year-round, with increased frequency in autumn.
Mediterranean: Status and Presence Areas
In the Mediterranean, the long-finned pilot whale is present but less abundant than in the Atlantic. Sightings concentrate in the Pelagos sanctuary (Ligurian Sea and Corsica), where ACCOBAMS survey data confirm regular presence. The Mediterranean status of the species remains to be clarified due to insufficient systematic monitoring.
Azores, Canaries, and Madeira: Atlantic Hotspots According to Local Operators
Local operators in the Azores and Canaries report the short-finned pilot whale as one of the most regularly encountered species, sometimes year-round. The deep waters around these archipelagos offer ideal conditions for squid hunting. In Madeira, whale watching trips frequently include encounters with groups of several dozen individuals, according to certified operator reports.
Faroe Islands and Iceland: Context of Traditional Hunting (grindadráp)
In the Faroe Islands, the traditional hunt called grindadráp targets the long-finned pilot whale primarily. Hundreds to thousands of individuals are killed each year in these collective hunts, making it one of the largest direct hunts impacting the species in the North Atlantic. This practice is the subject of ongoing international debate between defenders of Faroese cultural heritage and cetacean protection organizations (WDC, Sea Shepherd).
Observing Pilot Whales Responsibly: Distances and Guidelines
Observing a group of pilot whales is a memorable experience. It requires concrete responsibilities, whether on a commercial boat or private vessel.
Minimum Regulatory Distances in France and the Mediterranean
In metropolitan France, regulations require a minimum distance of 100 meters for all cetaceans. In the Pelagos sanctuary, additional rules apply to professional operators, including prohibition of cutting across a group's path and limiting presence to 30 minutes per encounter. These distances are non-negotiable: fast-moving pilot whales or those with calves are particularly sensitive to disturbances.
High Quality Whale Watching Charter: Principles for Pilot Whales
The High Quality Whale Watching (HQWW) charter recommends approaching by gradually reducing speed, never intercepting the group's trajectory, and turning off the engine if animals approach spontaneously. For pilot whales, whose groups are often large and compact, it is essential not to fragment the group with repeated maneuvers.
Stress Signals to Recognize: Sudden Changes in Direction, Acceleration, Repeated Dives
A group that suddenly changes course, accelerates, or repeats short dives without resuming its normal rhythm is disturbed. These signals must trigger an immediate retreat of the boat. In pilot whales, flight reactions can be delayed: the group may seem to tolerate a too-close approach before reacting strongly.
Contribute to Citizen Science: Obs-MAM, Happywhale, Dorsal Fin Photo-ID
Any sighting can be reported on Obs-MAM (INPN platform) or Happywhale. A clear photograph of the dorsal fin, taken from the animal's side, enables individual photo-identification: notches, scars, and curvatures are unique to each individual. These data directly feed into PELAGIS databases and partner NGOs. I systematically use Happywhale for my Iroise sea observations, and matches with other Atlantic observers are frequent. 🐬
Threats and Conservation Status: What the Data Say
The conservation status of the two pilot whale species is not identical, and documented threats deserve to be distinguished from assumptions.
IUCN Status: Data Deficient for Short-finned, Least Concern for Long-finned
The IUCN classifies the long-finned pilot whale (G. melas) as Least Concern (LC), with a global population estimated at several hundred thousand individuals. The short-finned pilot whale (G. macrorhynchus) is classified as Data Deficient (DD): population sizes are poorly known, especially in Indo-Pacific basins (IUCN, 2022). This uncertainty does not mean the species is out of danger.
Bycatch and Underwater Noise Pollution
Bycatch in drift nets and longlines is a documented threat in the Mediterranean and Northeast Atlantic (ACCOBAMS report, 2022). Underwater noise pollution from military sonars and seismic surveys is associated with several mass stranding events, although direct causal links are still under study.
Direct Hunting: Faroe Islands, Japan, Lesser Antilles
Besides the Faroese grindadráp mentioned earlier, the short-finned pilot whale is hunted in Japan (notably Taiji) and some Lesser Antilles islands. The total number of individuals taken annually by direct hunting remains hard to assess globally, but WDC and Sea Shepherd document these takes regularly.
Plastic Ingestion and Persistent Organic Pollutant Contamination
Post-mortem analyses of stranded pilot whales in Europe reveal high concentrations of persistent organic pollutants (POPs), especially PCBs, in fatty tissues. These substances accumulate through the food chain (bioaccumulation in squid). Microplastic ingestion is also documented, although its impact on individual and population health remains to be precisely quantified (OFB, 2021-2023 data).
Frequently asked
What is the difference between the long-finned and short-finned pilot whale?
The long-finned pilot whale (Globicephala melas) lives in cold and temperate waters of the North Atlantic and Southern Hemisphere; it is the species present in France. The short-finned pilot whale (Globicephala macrorhynchus) occupies warm waters of the Indian, Pacific, and tropical Atlantic oceans. The short-finned is slightly smaller, and its dorsal fin is proportionally shorter and more curved. The two species can coexist in transition zones like the Azores or Canaries.
Why do pilot whales strand en masse?
Group social cohesion is very strong: individuals follow dominant or distressed members, even into shallow waters. One disoriented animal can lead dozens of conspecifics to strand. Underwater noise pollution and local magnetic anomalies are also studied as triggers (IUCN, 2022). This is why interventions must always manage the entire group, not just distressed individuals.
Where to observe pilot whales in France?
The Bay of Biscay is the best-documented area, with regular reports from the PELAGIS Observatory and Souffleurs d'Écume, especially over the continental slope. Sightings are also reported in the Mediterranean, notably off Corsica and in the Pelagos sanctuary. Presence is possible year-round, with increased frequency in autumn in the Bay of Biscay.
How to identify a pilot whale from a boat?
Look for an entirely black animal with no visible beak, a very bulbous melon, and a long, wide dorsal fin curved backward. Groups are often large (10 to 50 individuals or more) and travel in tight formation, with several dorsal fins appearing simultaneously. The blow is short and inconspicuous; it's the group formation that catches the eye first.
Is the pilot whale a dolphin or a whale?
It is an odontocete from the delphinid family, so taxonomically a large dolphin in the broad sense. It does not belong to the baleen whale group (mysticetes). Its English name pilot whale can be confusing, but classification is clear: it is closer to the bottlenose dolphin (Tursiops truncatus) than to a minke whale.
How far should you stay from a pilot whale?
In France, regulations require a minimum distance of 100 meters for cetaceans in general. In the Pelagos sanctuary, specific rules apply to operators, with a 30-minute limit per encounter. The High Quality Whale Watching charter recommends never intercepting the group's path and turning off the engine if animals approach spontaneously.
What does a pilot whale eat?
The pilot whale feeds mainly on squid, which it hunts at depth, often at night when prey rise toward the surface. It can dive to 600 meters (long-finned) or 800 meters (short-finned) and stay submerged for over 20 minutes. Fish make up a secondary part of the diet.
Can you contribute to pilot whale scientific monitoring?
Yes. Any sighting can be reported on Obs-MAM (INPN) or Happywhale. A clear photo of the dorsal fin enables individual photo-identification, as notches and scars are unique to each animal. These data directly feed into the PELAGIS Observatory and NGOs like Souffleurs d'Écume.