Grey seal — Halichoerus grypus

The short profile

The grey seal (Halichoerus grypus) is known in Dutch as the kegelrob, or "cone seal", for a reason: its most striking feature is the cone-shaped, "horse-like" head with a long, straight snout. It's the larger of the two seal species in the Netherlands and the largest wild predator in the country. The scientific name Halichoerus grypus roughly translates as "hook-nosed sea pig" — a nod to the profile of an adult male. The species occurs along the north-western Atlantic coasts of Europe and North America; by far the largest population is found in the British Isles.

• NicknameKegelrob (cone seal)
• HeadCone-shaped, "horse-like"
• SnoutLong, straight
• NostrilsNearly parallel, separated
• Length1.8–2.5 m (males longest)
• Weight150–300 kg (males heaviest)
• Lifespan25–35 years (females up to 45)
• Pup seasonNovember–January
• Feeding typeCarnivore — fish, occasionally seabirds

How to recognise a grey seal

The most reliable clue is again the head. On the grey seal the forehead runs almost without a break into a long, straight snout — a profile that suggests a horse or a greyhound rather than a dog or a cat. Adult males develop a pronounced "Roman nose" and a fleshy neck with deep folds, a trait that becomes more obvious with age.

The nostrils are nearly parallel and don't meet at the bottom; a clear gap stays visible between the two openings. That's an important contrast with the V-shaped nostrils of the common seal.

A third clue is size. Adult females weigh 150 to 200 kg and measure 1.8 to 2.1 m; males reach 230 to 300 kg and can hit 2.5 m. On a shared haul-out, grey seals almost always stand out visibly above the common seals. Coat colour is variable — females are often paler with dark spots, males darker with light patches — but coat colour alone is unreliable; go by head shape, snout and size.

The story of the return

The grey seal was a familiar sight along the Dutch coast for centuries. Subfossil bones from terps and mounds show that the species lived in large numbers along the Wadden coast in the Middle Ages and was hunted for its pelt, oil and meat. Through the seventeenth and eighteenth centuries hunting pressure rose so sharply that the species became increasingly rare; by the nineteenth century it had vanished almost entirely from Dutch waters.

The tide only turned with the 1962 hunting ban in the Waddenzee — the Delta area had been placed under a similar regime a year earlier. From the British and Scottish colonies, where grey seals had held on better, the first animals swam back to our coast around 1980. In 1985 the first pup was born on a Dutch sandbar, an event that definitively marked the recovery. From that moment the population grew by double digits every year. The 2024 count recorded roughly 7,800 grey seals in the Dutch Waddenzee. The recovery is one of the most striking nature stories in the Netherlands since 1950.

De Richel as nursery

The heart of the Dutch grey seal population lies on de Richel, an uninhabited sandbar between Vlieland and Terschelling. Each year, between November and January, females give birth to hundreds of pups there — more than at any other site in the Netherlands. The bar dries out at low tide and is surrounded by deep channels, a combination that adult animals can cross effortlessly with their heavy bodies, but which keeps the white-coated pups safely on dry ground.

De Richel is closed to the public during the pupping and nursing season and has protected status under Natura 2000. Boat trips keep a wide berth in these months. Outside the pupping season the bar is also used as a moulting haul-out (March–April).

Reproduction

The grey seal is a quintessential winter pupper. Between early November and late January, females give birth to a single pup on a dry sandbar or a rocky shore. At birth the pup wears a dense, soft, almost white lanugo coat that keeps it warm on land but is not waterproof. The young therefore stays on dry ground for the first three weeks.

During those three weeks the mother nurses it on milk of around 60% fat content. The pup quadruples its weight in that period — from roughly 14 kg at birth to 45 kg at weaning. Then the mother leaves abruptly; the pup sheds its white coat and heads out into the water to learn to hunt. Meanwhile, adult males fight for access to the females in oestrus. Those fights are rough — bite wounds on the neck are standard — and decide who eventually breeds. After mating, delayed implantation gives a visible gestation of about eleven months.

Diet & hunting

The grey seal is a versatile fish predator. The menu includes cod relatives, flatfish, sandeel, herring and mackerel, with squid in smaller amounts. An adult animal eats 4 to 7 kg per day. Unlike the common seal, the grey seal dives on average deeper and longer: routine dives of fifty to a hundred metres are not unusual, and the species has been documented occasionally taking seabirds — and even harbour porpoise on rare occasions. That makes the grey seal not only the larger but also the more opportunistic of the two Dutch species.

Population and trend

The grey seal in the Netherlands is still in a phase of strong growth. The Waddenzee population grew by roughly 15% per year between 1990 and 2010, slightly slower since. In the Delta (Voordelta, Oosterschelde, Westerschelde), grey seals are now a regular presence, with a handful of pups born each year. The European population is estimated at over 80,000 animals, with the centre of gravity in Britain. For current Dutch figures, see counts.

In the field: where to see them

You'll spot grey seals on the same sandbars as common seals — particularly around Vlieland, Terschelling and in the Eems-Dollard — but you'll recognise them by their heavier build and long snout. In winter, a boat trip to de Richel or a walk along the Brouwersdam (Voordelta) gives you the best chance. Plan your trip with the spotting guide and check haul-out sites on the spotting map.