Thousands of dead seal pups have washed ashore on the coast of Namibia, raising grave concerns from conservationist groups.

Locals were in shock after an estimated 5,000 premature cape fur seal pups washed up along the coast of Pelican Point peninsula, turning the popular tourist destination known for its thriving schools of dolphins and seal colonies into a pup graveyard.

Cape fur seals are often referred to as the “dogs of the ocean,” owing to their playful nature and abundant energy. However, the seals are known to desert their young or suffer miscarriages when food supplies are scarce.

The unprecedented die-off of the 5,000 Cape fur seals is now being probed by the country’s fisheries ministry, reports Bloomberg.

Nearly all were born prematurely before quickly dying, according to marine biologist Naude Dreyer of  Ocean Conservation Namibia.

“When the pregnant female feels she does not have enough reserves, she can abort,” he explained. “A few premature deaths is a natural event, but thousands of premature dead pups is extremely rare.”

Dreyer noticed the masses of dead seal pups while flying his drone over the Pelican Point seal colony on Oct. 5.

“This is the situation at Pelican Point, Namibia,” his non-profit group wrote in a Facebook post. “All the little red circles mark dead seal pups. A rough estimate brings the numbers to more than 5,000 at our seal colony alone. This is tragic, as it makes up a large portion of the new pup arrivals expected in late November.”

The seals are commonly found across the southern Atlantic coastlines of the African continent, spanning Namibia and South Africa to the southern tip of Angola.

“Normally cape fur seals would give birth from mid-November until early December,” Dr. Tess Gridley told Africa News.  “That’s the height of pupping that we would normally expect but what has been happening this year is there has been an increase in abortions that was first seen starting in August and really sort of peaked just last week in October.”

However, female cape fur seals are increasingly appearing emaciated and starving, raising alarm among conservationists about the long-term health of the typically thriving seal population.

 “There are about 1.7 million cape fur seals in total and about a million of those are actually in Namibia so in terms of the overall number of animals, they are quite resilient to these effects,” Gridley explained.

“But one issue that we do think might happen in the future is you will see a dip in reproduction potentially going forward particularly now for those animals that have unfortunately died,” she continued. “They are not going to be recruited into the population, so you might see a localized effect at the Pelican Point colony and also we are trying to monitor to see whether there is a wider scale impact that might affect other colonies as well.”

An absence of fish in the region and the spread of disease and toxins in the water are among the possible reasons behind the die-off. 

“The seals look a bit thin and it could likely be caused by a lack of food,” Dreyer said. “Other seal colonies at other beaches look much better and they do not record the same amount of premature pups.”