the seals in the wadden sea

Lasse Fast Jensen, Fiskeri- og Søfartsmuseet & Anne Würtz Pedersen, Vadehavscentret

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translation: nanna Mercer, Sirius translation of 4

Seals resting on bare sandbars are an eye-catching sight in the Wadden Sea

the SeALS in the WADDen SeA LiFe At the tOP OF the FOOD ChAin

Seals resting on bare sandbars are an eye-catch-ing sight in the Wadden Sea, and the area provi-des many opportunities for experiencing these fabulous animals close up in their natural envi-ronment.

the seals in the Wadden SeaThe harbor seal is by far the most common seal in the Wadden Sea, but it is also possible to meet its larger cousin, the grey seal. The harbor seal likes to rest on the Wadden Sea sandbars, where it also gi-ves birth to a pup during the summer. The pup suck-les its mother’s rich milk for the first 3 or 4 weeks of its life, at which point it must learn how to catch fish and crustaceans on its own. Although the grey seal is now more common, it still does not breed in the Danish part of the Wadden Sea. In the German and Dutch parts of the Wadden Sea, there are several breeding colonies for grey seals. As opposed to the harbor seal, the grey seal gives birth to its pup during the winter.

the seal - Denmark’s largest carnivore The seal is a carnivore and therefore related to wol-ves and bears, among others. It is thought that the seals closest contemporary relative is to be found in

the group of mustelids, which are otter-like carnivo-res. The harbor seal is between 1.3-1.6 m long and can weigh 130kg. The grey seal is much larger and with its 300kg, not only Denmark’s largest carnivore, but also our largest mammal.

Life in the waterThrough millions of years, the seal has evolved from a land habitat to almost exclusively living in or below the water. The seal is well adapted to life in the water. Its torpedo-formed body and the wide flippers make the seal a great swimmer, and the heavy layer of blubber helps the seal stay warm. The seal’s large eyes are very photosensitive and designed for see-ing under water. With its whiskers it can register the tiniest movement from fish swimming by. Because the seal’s body is designed to store and save oxy-gen, it can stay under water for several minutes at a time.

ExpEriEncE sEals in ...

AUTUMN WINTERSUMMERSPRING


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Although the seal is carefully designed for life in the water, there are periods when the seal must pull up. Although the seal can easily sleep while in the water, it rests better on land. Thus, seals can often be seen lolling about on the sandbars in the Wadden Sea. When the seals are ready to give birth to their pups, they are totally dependent on being able to pull up on land. The harbor seal gives birth during the sum-mer and at the low tide. The pup is born without the long haired lanugo coat so characteristic for other seal species. Instead, it has a coat reminiscent of the adult seal, so when the high tide is ready to roll in, the pup can follow its mother into the water.

the seal plagueTwice, in 1988 and 2002, the seal population was hit by seal plague, which killed 50-60 percent of the population. Seal plague is due to a virus that im-pairs the seal’s immune system by giving bacterial infections free reign. During the two epidemics most of the seals died from bacterial pneumonia. Both outbreaks started on the Danish island, Anholt, and from there spread to the whole of Northern Europe. Where the virus originated, is not totally clear, but the Greenland seal may have had a hand in it somehow. The Greenland seal normally lives in the arctic, but in 1987, a shortage of food displaced thousands of seals towards the south and some of them made it all the way to Denmark. It is known that Greenland

seals can be carriers of the virus without being ill and they can therefore have carried the virus with them and then infected the harbor seals.

the evolution of the seal populationThrough time, the harbor seal population in the Wad-den Sea has gone up and down. It is estimated that in the year 1900, there were 37 - 38,000 seals in the trilateral Wadden Sea, but hunting and pollution has caused a deep decline in the seal population that became a protected species in 1976-77. Since then, the seal population has grown, only interrupted by

The harbor seal likes to rest on the sandbars, where it also gives birth to a pup during the summer.

In Denmark, we have elected to follow the recommen-dations of the Trilateral Seal Expert Group (TSEG), and in 1995 we therefore stopped raising lost seal pups, the so-called squealers, for later to reintroduce them back into nature. One reason is that the seal population is now at a high level and no longer need human help to endure. Sque-alers that are reintroduced, risk being carriers of illnes-ses that can infect the wild population. At the same time, raising weak individuals counteracts natural se-lection that removes disadvantageous genes from the population. By raising and reintroducing weak seals there is a risk of damaging the population.

Why WE do not raisE squEalErs


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the two outbreaks of the seal plague, after which it has rallied fairly quickly and today, the Danish part of the Wadden Sea contains 4,500 harbor seals, while for the whole of the Wadden Sea, the number is 35,500 animals.

Seal huntingThe seals have been hunted for their blubber, their meat and their pelt, but also because their appetite for fish made then very unpopular among fisher-men, who saw them as competitors for the fish they wanted to catch. As well, the seals ruined the tools the fishermen used when they tried to eat the fish caught in the yarns. The seal have been hunted with clubs and firearms, but also with something called a seal harrow. The seal harrow contains a long board with pointed barbs that were dug into the sand. The seals could crawl up on the beach and over the har-row, but when they fled back across the sand to-wards the water; they were impaled on the barbs. At one time, the state even awarded the killing of seals and made rifles and ammunition available. This campaign caused a severe decline in the seal population.

Squealers and sick seals on the beachIn the harbor seal’s suckling period it sometimes happens that the pup gets away from its mother. Wit-hout milk, the pup is lost and crawls up on the beach where it calls to its mother. These young pups are called squealers. Squealers have very little chance of surviving on their own, and they are put down to avoid useless suffering. In Germany and Holland there are centers where squealers are taken in and cared for so they can later be put out into nature. In Denmark, this practice was stopped in 1995 sin-ce the seal population is thriving. Reintroduction of squealers is not without problems and in Denmark; we try to minimize human interference.

Especially in the late summer and autumn, you may see sick seals that have crawled up on the beach for better to stay warm. If you run into a squealing pup or a seal that appears ill, it is best to leave them in peace and quiet and to notify the Danish Nature Agency or the Fisheries and Maritime Museum.

The grey seal is now more common, but still does not breed in the Danish part of the Wadden Sea.


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The Wadden Sea is an obvious place to experience the seals. If you really want to get up close, the Fishe-ries and Maritime Museum is a great choice. Through large windows you can see harbor seals and grey se-als that majestically glide through the water, and if you come by at one of the two daily feedings, you will also hear about the life and the biology of the seals. The seals can also be experienced in nature. Seals are shy animals, so bring along a pair of binoculars so you can observe the seals close up. Some of the area’s nature guides also conduct tours out to the seal banks. Information about the tours can be found here: www.vadehav.dk. It is also possible to take a trip to the seal banks aboard a cutter.

things to do

NaturKulturVarde Gl. Skovfogedbolig Roustvej 111 DK-6800 VardeT: +45 75 22 22 50E: [email protected] W: www.naturkulturvarde.dk

The Fisheries and Maritme Musuem Tarphagevej 2-6 DK-6710 Esbjerg V.T: +45 76 12 20 00E: [email protected] W: www.fimus.dk

VadehavscentretOkholmvej 5 Vester Vedsted DK-6760 RibeT: +45 75 44 61 61E: [email protected] W: www.vadehavscentret.dk

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Vadehavets Formidlerforum is a partnership of visitor centers that mediate the Wadden Sea’s natural and cultural heritage. VFF’s main activity is to coordinate projects that highlight the nature and culture heritage of the Wadden Sea..Learn more at www.vadehav.dk

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the seals in the wadden sea

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