A Dutch marine rescue centre for baby seals said Friday more than 100 of the sea mammal pups had washed up along the country's northern coastline after recent storms.
The large numbers -- which the centre blamed in part on rising environmental pressures that leave the young seals weak -- had stretched the centre's capacity, forcing it to put up an extra tent and pool.
"In the last 10 days, as a result of storms, we have rescued more than 100 seals washed up, with the total number at the centre shooting up to 365," said Zeehondencreche (Seal Nursery) director Lenie t'Hart.
Usually the centre rescues about 150 seals a year, she said.
Although stormy weather in the Wadden Sea -- an intertidal zone spanning the coast and the Wadden Islands in the northern Netherlands -- played a role, t'Hart said growing numbers washing up, especially pups, showed the Dutch seal population is under increasing pressure.
"In the last two or three years, we have seen more and more seals wash up too weak to look after themselves," she told AFP.
"This is a result of commercial overfishing as well as seals getting sick from eating fish with toxins as a result of pollution."
Especially vulnerable were seal pups under one year old.
"These pups eat small fish, but even in protected areas, they cannot find food because there are no more small fish left," she said.
When a pup arrives at the creche, it is washed, given fluids "as many are severely dehydrated", and fed a "porridge" of ground herring and water.
They are then placed in a special pen to recuperate.
Because of the large numbers, an extra tent with pools and pens had to be set up, and the nursery asked other marine institutions for help, t'Hart said.
She said most seals recover sufficiently to be released back into the Wadden Sea or the North Sea within three months.
Partly declared a UNESCO World Heritage Site in 2009, the Wadden Sea consists of salt marshes, tidal and permanently flooded flats, sand banks and channels.
It is shared between the Netherlands and Germany and is a popular destination for water sports and nature lovers, with whom seal sight-seeing trips remain popular, according to the Wadden Sea World Heritage website.
Explore further: New study charts the global invasion of crop pests