Morphology: How to Recognise a Grey Seal in the Field
The grey seal (Halichoerus grypus) is distinguished by several criteria visible at a good distance, even with 8x binoculars.
Muzzle Profile: The Key Criterion
The most reliable trait is the convex and elongated profile of the muzzle, often described as a “horse head”. In profile, the forehead and nose form a straight or slightly arched line, without a break in slope. This character is clear from 50 metres with standard binoculars.
Sexual Dimorphism: Size, Colour, Scars
Adult males reach 2.3 to 2.5 m and can weigh 300 kg. Their coat is dark, grey-brown to almost black, often marked with light scars from breeding fights. Females are smaller (1.6 to 1.9 m), with a lighter coat, silvery grey with irregular dark spots. This dimorphism is one of the most marked among European pinnipeds.
Adult Coat versus Pup
The newborn, called a pup, is born with an entirely white woolly coat. This milk coat is replaced in two to four weeks by the adult spotted livery. A pup on a beach is therefore a very young animal, still in the weaning period.
Characteristic Postures at the Haul-out
At rest, the grey seal often adopts the so-called “banana” posture: head and hind flippers raised simultaneously, body arched. This thermoregulation posture is frequent on rocks exposed to the sun. Grouped individuals tolerate each other at close range but males maintain a visible personal space.
Grey Seal or Harbour Seal: Key Differences
On French coasts, two seal species coexist. Confusion between the grey seal (Halichoerus grypus) and the harbour seal (Phoca vitulina) is most common among beginners. The table below summarises the discriminating criteria usable in the field.
| Criterion | Grey Seal (H. grypus) | Harbour Seal (P. vitulina) |
|---|---|---|
| Adult length | 1.6 to 2.5 m | 1.2 to 1.8 m |
| Muzzle profile | Long, convex (“horse head”) | Short, rounded (“dog head”) |
| Nostrils | Parallel, almost vertical | In V, meeting downwards |
| Male coat | Dark grey to brown, frequent scars | Grey-brown, more regular spots |
| Haul-out behaviour | Sometimes dense groups, banana posture | More dispersed, often in calm water |
| Presence in Iroise | Main species | Rare, occasional |
In practice, muzzle profile and size suffice in the vast majority of cases. An animal clearly larger than a Labrador, with a long straight nose, is almost certainly a grey seal. The harbour seal has a more compact silhouette and a head that more closely resembles a puppy.
Annual Cycle: Moult, Pupping and Feeding
Numbers visible at haul-outs vary greatly by season. Understanding the biological cycle of the grey seal allows anticipation of the best observation periods.
Winter Moult (January–March): Concentration on Haul-outs
From January to March, grey seals gather on islets and rocky foreshores to moult. Renewing the coat requires significant energy expenditure: animals reduce movements and remain on dry land for several hours. This is when groups are densest and easiest to observe from sea or shore.
Pupping and Weaning of the Pup
In France, births occur mainly from November to January, with a peak in December on Breton sites (data from Parc naturel marin d’Iroise). The female nurses her pup for about three weeks, then weans it abruptly before returning to sea. The pup remains alone on the beach while moulting and learning to hunt, explaining frequent reports of “abandoned young seals”.
Summer: Dispersion and Solitary Hunting
From April to September, seals disperse widely. Haul-outs are less frequented and groups smaller. Shore observations become less predictable. This is nevertheless when young of the year, newly weaned, explore new territories.
Diet and Diving
The grey seal is a generalist predator. It mainly hunts bottom fish (cod, pollock, plaice), cephalopods and crustaceans. It is capable of dives of 4 to 10 minutes and can reach several hundred metres depth. An adult consumes on average 5 to 7 kg of fish per day (OFB data).
Distribution and Observation Sites in France
The French population of grey seals is estimated at more than 700 individuals (OFB, recent data), slowly increasing since hunting ceased in the 20th century. It concentrates on two main nuclei, with gradual recolonisation southward.
Molène Archipelago and Chaussée de Sein (Iroise)
The Molène archipelago and the Chaussée de Sein form the main French site, with more than 300 individuals counted, about 30 % of national numbers (Parc naturel marin d’Iroise). The archipelago rocks provide haul-outs inaccessible to terrestrial disturbance. Boat trips with park partner operators allow respectful approach from the sea.
Baie de Somme and Opale Sea
The second nucleus is in the Opale Sea, between the Baie de Somme and the Strait of Pas-de-Calais. Grey seals coexist here with harbour seals, making it an interesting site for comparing the two species. The sandbanks of the Baie de Somme are accessible at low tide, but regulatory distances fully apply.
Norman Coasts and Channel Islands
Norman coasts host individuals in transit or dispersion, notably around the Chausey Islands and near the Channel Islands. These sectors serve as relays between French populations and large British colonies (more than 120 000 individuals in the UK according to SCOS, 2022).
Breton Coasts outside Iroise
Regular observations are reported on the north coasts of Brittany (Côtes-d’Armor, north Finistère) and occasionally as far as Morbihan. These individuals are often dispersing juveniles. I myself receive several reports per season around the Crozon peninsula and the Brest roadstead, which I forward via Obs-MAM.
Observe Without Disturbing: Rules and Distances to Respect
Grey seal observation is governed by precise regulations. Ignoring them, even with good intentions, can cause real harm to the animals.
Legal Framework: Strict Protection in France
The grey seal benefits from strict protection under the ministerial order of 1 July 2011 on the protection of marine mammals. This order explicitly prohibits capturing, injuring, destroying or intentionally disturbing any individual. Disturbance includes any approach causing displacement or behavioural change.
Minimum Recommended Distances at Haul-outs
Recommendations from Parc naturel marin d’Iroise and Souffleurs d’Écume advise maintaining a minimum distance of 100 metres from any animal at a haul-out. At sea, this distance also applies to individuals swimming at the surface. If a seal lifts its head, moves or dives at your approach, you are too close.
Behaviours to Avoid (Dogs, Drones, Direct Approach)
Unleashed dogs are one of the main causes of disturbance on Breton beaches. Drones are prohibited within 150 metres of wild animals under the environmental code. Direct approach by swimming or kayak is particularly stressful for nursing females and pups.
What to Do with an Isolated or Stranded Animal
A young seal alone on a beach is not necessarily in distress. Females frequently leave their pup during hunting dives. The correct action: keep dogs and onlookers away, do not touch the animal, do not return it to the water, then contact the national stranding network (Observatoire Pelagis) or the nearest rehabilitation centre.
Conservation Status and Current Threats
The grey seal (Halichoerus grypus) is classified LC (Least Concern) on the IUCN Red List globally (IUCN, 2016). This classification must not mask the fragility of the modest, localised French population.
Global and French IUCN Status
While the global population exceeds 300 000 individuals, France hosts only a marginal fraction. The national Red List of marine mammals classifies the grey seal as NT (Near Threatened) in France (IUCN France, OFB, 2017), reflecting the vulnerability of a population still recovering.
Bycatch in Fishing Gear
Bycatch in fixed nets and crustacean pots is the main direct cause of mortality in France. Individuals are regularly found drowned in coastal fishing gear, especially in Iroise and the Opale Sea (Pelagis report, 2021).
Pollution and Bioaccumulation
As a top predator in the coastal trophic chain, the grey seal bioaccumulates persistent organic pollutants (PCBs, PBDEs) and heavy metals. Studies on stranded individuals in France reveal concerning levels that may affect reproduction and immunity (Observatoire Pelagis).
Population Dynamics: A Species Slowly Recovering
Since legal hunting ended in France in the 1970s, the population has increased slowly. This recovery generates tensions with some professional fishers, who report predation on catches and net damage. These conflicts are real and deserve mention without caricature: they are the subject of consultations within Parc naturel marin d’Iroise.
Contribute to Monitoring: Citizen Science and Photo-Identification
Every well-documented observation has real scientific value. Citizen-science tools allow contribution to species monitoring without specialised training.
Report an Observation on Obs-MAM and INPN
Obs-MAM is the national platform for recording marine mammal observations, managed by Observatoire Pelagis. I systematically enter my observations from Camaret, with GPS coordinates, time, number of individuals and observed behaviour. Data feed into the INPN (Inventaire National du Patrimoine Naturel) and OFB annual reports. Entry takes less than five minutes.
Photo-ID Applied to Grey Seals
Photo-identification relies on unique coat spots and scars. A clear photo of the flank or head, taken at regulatory distance with a telephoto lens, can allow recognition of an individual from one season to the next. Parc naturel marin d’Iroise maintains a photo-ID catalogue of individuals frequenting the Molène archipelago. Happywhale, originally designed for cetaceans, now accepts submissions for some pinnipeds and can facilitate data cross-referencing between sites.
Contact the Stranding Network in Case of Distress
In case of visibly injured, emaciated or breathing-difficulty animals, the national stranding network (Observatoire Pelagis, national number: 0800 10 20 30) coordinates intervention by competent teams. Never attempt to handle the animal alone: an adult seal can inflict severe bites and handling stress may worsen its condition.
Frequently asked
What is the difference between a grey seal and a harbour seal?
The grey seal (Halichoerus grypus) has a long convex muzzle, parallel nostrils and is noticeably larger, up to 2.3 m. The harbour seal (Phoca vitulina) has a rounded head, V-shaped nostrils and rarely exceeds 1.8 m. On a haul-out, the adult male grey seal is often covered with characteristic dark scars. Muzzle profile remains the most reliable criterion at distance.
How far should one stay from a grey seal on the beach?
Recommendations from Parc naturel marin d’Iroise and Souffleurs d’Écume advise staying at least 100 metres from any animal at a haul-out. Any approach causing the animal to move constitutes disturbance, prohibited by the order of 1 July 2011 on marine mammal protection. If the animal lifts its head toward you, you are already too close.
What should I do if I find a young seal alone on a beach?
Do not touch the animal and do not return it to the water. Females frequently leave their pup alone during hunting dives, sometimes for several hours. Priority is to keep dogs and onlookers away, then contact the national stranding network (Observatoire Pelagis) or the nearest rehabilitation centre for assessment.
Where to observe grey seals in Brittany?
The Molène archipelago and Chaussée de Sein concentrate more than 300 individuals, about 30 % of French numbers (Parc naturel marin d’Iroise data). Boat trips with park partner operators allow respectful observation from the sea at regulatory distance. Occasional sightings are also possible on the north coasts of Finistère and Côtes-d’Armor.
At what time of year are grey seals most visible?
From January to March, during the moult, seals concentrate on rocky haul-outs and form groups of several dozen individuals. This is the most favourable period for land or sea observation at regulatory distance. The pupping period, from November to January, is also interesting but requires extra vigilance not to disturb nursing females.
Is the grey seal a protected species in France?
Yes. The grey seal benefits from strict protection under the ministerial order of 1 July 2011. It is prohibited to capture, injure, destroy or intentionally disturb it. The French population is also classified NT (Near Threatened) on the national Red List (IUCN France, OFB, 2017).
How many grey seals are there in France?
Recent OFB estimates indicate more than 700 individuals on French coasts, mainly in Iroise and the Opale Sea. The population has increased slowly since hunting ended, but remains very modest compared with British numbers, estimated at more than 120 000 individuals (SCOS, 2022).
Does the grey seal dive deeply?
Yes. The species is capable of dives of 4 to 10 minutes and can reach several hundred metres depth. It mainly hunts bottom fish, crustaceans and cephalopods, consuming on average 5 to 7 kg of prey per day for an adult (OFB data).