<p><strong>A volunteer feeds a gray seal pup a herring at a seal-rehabilitation center in </strong><a style="font-weight: bold;" href="http://travel.nationalgeographic.com/travel/countries/netherlands-guide/">the Netherlands</a> on January 12.</p> <p>More than a hundred of the young marine mammals have washed up along the country's northern coastline following recent storms, according to the Agence France-Presse news service.</p> <p>The incident is an extreme example among a recent increase in pup strandings, experts say. <a href="http://ocean.nationalgeographic.com/ocean/critical-issues-overfishing/">Overfishing</a> has reduced the seals' available prey, and the polluted fish the animals do catch often make them sick.</p> <p>"In the last two or three years we have seen more and more seals wash up too weak to look after themselves," Lenie 't Hart, director of the <a href="http://www.zeehondencreche.nl/wb/pages/actueel.php?lang=NL">Zeehondencrèche</a> seal nursery, told AFP.</p> <p>(See <a href="http://news.nationalgeographic.com/news/2012/01/120106-harp-seals-global-warming-sea-ice-science-environment/">"Baby Harp Seals Being Drowned, Crushed Amid Melting Ice."</a>)</p>