The two species in the Netherlands
On the Dutch coast you'll meet two seal species: the common seal (also called harbour seal, Phoca vitulina) and the grey seal (Halichoerus grypus). Both belong to the true seal family (Phocidae) and share the same habitat — the Wadden Sea, the Oosterschelde and the Westerschelde — but they differ significantly in size, behaviour and the time of year their pups are born.
The common seal is the one you'll most often see resting on a dry sandbar at low tide: a round head, short snout, a spotted coat, and a weight between roughly 65 and 130 kg. Its pups are born in summer (mid-June to late July) and can take to the water within hours of birth. The grey seal is larger and heavier — adult males reach up to 300 kg — and is recognisable by a cone-shaped, "horse-like" head with a long snout. Its pups appear instead in winter, between November and January, wearing a white fluffy coat that is not waterproof. Those pups stay on the beach or sandbar for around three weeks before their first swim.
Comparison at a glance
| Feature | Common seal | Grey seal |
|---|---|---|
| Scientific name | Phoca vitulina | Halichoerus grypus |
| Dutch name | Gewone zeehond | Grijze zeehond / kegelrob |
| Head | Round, short snout | Cone-shaped, long snout |
| Nostrils | V-shaped, meeting at the bottom | Nearly parallel, separated |
| Adult weight | 65–130 kg | 150–300 kg (males largest) |
| Length | 1.3–1.9 m | 1.8–2.5 m |
| Pup season | June–July | November–January |
| Newborn pup | Short coat, swims immediately | White lanugo coat, ~3 weeks on land |
| Main Dutch habitat | Wadden Sea, Delta | Wadden Sea (nursery: de Richel), Delta |
| Return status | Always present | Returned ~1980; first pup 1985 |
A field rule of thumb: head rounder than an apple? Common seal. Cleaner profile, like a horse or cone? Grey seal. From a distance the nostrils are hard to see, but the head profile almost always gives the species away. See the difference for five practical identification points.
Read the full profile per species
Common seal
The seal most often seen on Dutch sandbars. Social in groups, hunts flatfish and cod relatives, rarely strays more than a few kilometres from the coast.
- HeadRound, short snout
- Weight65–130 kg
- PupsJune–July, swim immediately
- Trend NLStagnation / slight decline
Grey seal
The largest carnivorous mammal in the Netherlands. Nearly wiped out by centuries of hunting; returned around 1980. Pups born in winter with a white coat.
- HeadCone-shaped, long snout
- Weight150–300 kg
- PupsNovember–January, on land
- Trend NLStrong growth
Seal species worldwide
About 19 seal species exist worldwide, totalling more than 30 million animals. They belong to two large families: true seals (Phocidae, lacking external ear flaps, with hind flippers that cannot fold under the body) and eared seals (Otariidae — sea lions and fur seals — with visible ear flaps and rotating hind flippers that allow them to "walk" on land). Strictly speaking, biologists reserve "true seals" for Phocidae; the Dutch word "zeehond" is used more loosely. A third small group is the walrus, in its own family Odobenidae.
Both Dutch species are true seals. Other well-known relatives include the monk seal (Mediterranean — one of the rarest mammals in the world), the Weddell seal and crabeater seal in Antarctica, and the hooded seal and ringed seal of the Arctic. See species worldwide for the complete list and where our two species fit.
Why these two in the Netherlands?
The Dutch coast offers exactly what both species need: extensive intertidal sandbars to rest, nurse and moult on, plus shallow, food-rich waters with flatfish, herring, cod and sandeel close at hand. The Wadden Sea is therefore the most important seal area in north-west Europe. The Delta (Oosterschelde and Westerschelde) has been growing into a second core area since the Delta Works — mostly for the common seal, but the grey seal is gaining ground.
The grey seal disappeared from the Dutch coast for centuries due to hunting for fur and oil. Only after the 1962 hunting ban in the Wadden Sea — a year earlier in the Delta — could the population recover. Around 1980, the first grey seals swam back from British and Scottish colonies; the first pup on a Dutch sandbar was born in 1985. Today (2024 count) about 7,800 grey seals live in the Dutch Wadden Sea. For the common seal, the trajectory is the opposite: after growth up to around 2013 the population stagnated, and since 2022 numbers are slowly falling. Possible causes — food competition, disturbance, disease — are discussed on counts and threats.
How to use this guide
If you want to tell them apart in the field, go to the difference. Planning a visit? Spotting and the spotting map are your starting points. To dive into biology, see anatomy, diet, reproduction, life cycle and behaviour. And if you find a seal on the beach and wonder whether it needs help, read seal pup found first — most of the time, space and quiet are the best help you can give.