Four centuries of history of the Dutch seal.

Centuries of hunting: oil, pelts and meat

Seals were hunted along the Dutch coast as early as the Middle Ages. For coastal residents from Texel to Schiermonnikoog they were a versatile commodity: the blubber was rendered into oil, a fatty fluid used for lamps, for impregnating leather and for soap. The pelts served for clothing and upholstery, and the meat was eaten or used as livestock feed. Nothing was wasted — bones were ground into fertiliser.

Hunting was initially small-scale: a village community heading out in spring along a sandbar with clubs, taking a few animals. Targeted and seasonal, but not yet threatening to the population. Only from the 17th century onwards, with growing population and trade, did hunting become commercial.

19th and early 20th century: industrial hunting and bounties

In the 19th century seal hunting changed radically. Rifles replaced clubs; boats became faster, and the market for seal oil grew with industrialisation. On top of that, hostility towards the seal developed: fishermen saw it as competition for fish and as net damage.

The Dutch government — like Germany, Denmark and the United Kingdom — introduced bounties on killed seals. Anyone who brought a dead seal to the municipality received money or compensation for pelt and oil. The bounties stayed in place far into the 20th century: in the Netherlands the last bounty was abolished in 1955. The result was predictable: hundreds to thousands of animals were killed each year. It is estimated that across the whole Wadden region (NL, DE, DK) in the 19th and first half of the 20th century more than a million seals were killed.

Near-extinction of the grey seal in the Netherlands

The grey seal was once native to the Netherlands — fossil remains and medieval sources confirm it. But through the combination of targeted hunting and disturbance of breeding sites the species disappeared from Dutch waters. The last reliably documented grey seal in the Netherlands dates from several centuries ago; some sources place the loss of an established population somewhere in the 16th century.

What remained in the Netherlands was the common seal — smaller, more numerous, and somewhat less vulnerable to hunting because it lives scattered on sandbars rather than concentrated in nursery colonies like the grey. Yet this species too came under heavy pressure by the mid-20th century.

The crisis of the common seal around 1960

By the late 1950s and early 1960s the Dutch common seal population had crashed. Estimates suggest a decline to a few hundred animals — a fraction of the original population. Three causes combined:

• Continuing hunting. Bounties existed in the Netherlands until 1955; in Germany and Denmark longer.
• Water pollution. Industrialisation of the Ruhr and the Dutch delta brought PCBs, mercury and dioxins into the Waddenzee. These substances affect reproduction: seals had fewer pups, and pups survived less often.
• Disturbance. Tourism, recreational boating and industrial fishing made undisturbed sandbars rare.

Biologists like Lies Vedder and Lenie 't Hart sounded the alarm. It became clear: without intervention, the common seal too would disappear from the Netherlands.

The hunting ban: 1961 and 1962

The turning point came in two steps. In 1961, seal hunting was banned in the Delta region. A year later, in 1962, the Waddenzee followed. With that, hunting in the whole of the Netherlands was a thing of the past — a radical decision for a country where seals had been treated as economic game for centuries.

Germany followed in 1973, Denmark in 1976. With that, the entire trilateral Wadden region became hunting-free. The Wadden Sea Seals Agreement (1991, under the Bonn Convention) anchored this protection internationally.

Timeline: from loss to return

The return of the grey seal

One of the finest chapters in Dutch natural history is the spontaneous return of the grey seal. From around 1980, wanderers from the large British and Scottish colonies appeared in the southern North Sea. In 1985, the first pup was born on a Wadden sandbar — for the first time in presumably hundreds of years.

Growth was rapid from then on. De Richel, a sandbar between Vlieland and Terschelling, developed into the nursery of the Dutch grey seal. Today, thousands of animals lie there in winter (the nursing season). A similar development is taking place in the Voordelta, where grey seals have only been actively breeding since 2014–2015. Read more about the species at species/grey-seal.

The PDV outbreaks: 1988 and 2002

Recovery did not come without setbacks. In 1988 Phocine Distemper Virus (PDV) broke out in the North Sea — presumably brought by migrating harp seals from the north. Within months, around 18,000 seals died across northwest Europe, a large share of them in the Waddenzee. The Dutch population halved in a single season.

Recovery was surprisingly fast, helped by protection and monitoring. But in 2002 PDV struck again, this time with ~22,000 deaths across the same region. Since 2002 there has been no major PDV outbreak, although research occasionally shows minor flare-ups in the current population.

Recovery to today

The 2024 numbers tell the story: about 6,000 common seals and 7,800 grey seals in the Dutch Waddenzee, with a growing population in the Delta. It is one of the finest recovery stories in European natural history. At the same time there are new challenges: the stagnation of the common seal since 2018, avian flu, plastic, bycatch and disturbance. The history continues — see counts for the most current numbers, and threats for what is happening now.