Thousands of baby seals have been found dead at a key breeding colony in Namibia, and conservationists are trying to work out what's triggered it.
The unfolding tragedy at Pelican Point, near the coastal city of Walvis Bay, has created harrowing scenes as the mother Cape fur seals mourn their young.
“It’s horrible. You can’t walk three steps without seeing a dead pup,” said Naude Dreyer, co-founder of Ocean Conservation Namibia (OCN), a non-profit that mainly works to rescue seals that get entangled in fishing nets and other human rubbish floating in the sea.
“The mothers do sit beside the dead pups, or carry them around for a few days,” he told RFI.
Dreyer and his colleagues started noticing aborted seal foetuses at the colony, which stretches for around 5.5 kilometres along a beach of white sand, in mid-September. As the numbers rose they alerted other conservation groups. Dreyer estimates that between 4,000-6,000 have died so far.
'On the cusp of catastrophe'
OCN is assisting Namibia’s Ministry of Fisheries and Marine Resources to collect samples for testing in laboratories, but the cause of the deaths has not been confirmed.
"We are sitting at the cusp of a catastrophe," OCN said in a post on its Instagram feed.
Food shortages, disease or pollution have all been cited as possible causes.
Each year at this time there are some seal mothers that abort their foetuses if they don’t have enough fat reserves to sustain them, explained Dreyer. But the scale of this year’s deaths is alarming.
The last major die-off of seals in Namibia took place in 1994. It wiped out a third of the country’s population of Cape fur seals. Today, the population is estimated at 1.3 million, said Dreyer.
Its unclear how many other of Namibia's 15 seal colonies might be affected.
Dreyer said he had visited Namibia’s biggest seal breeding colony at Cape Cross, around 150 kilometres north of Walvis Bay that is home to an estimated 200,000 seals. He counted only around 100 dead seal pups, but the area has a high population of scavengers, including jackals and hyenas, which could mean carcasses disappear fast.
Starvation a likely factor
The Namibian Dolphin Project, another conservation group that is helping to investigate the seal deaths, said in a post on its Facebook page that the scale of this year’s losses would “significantly reduce the numbers of pups born this season and throw off female mating too, impacting two years (at least) of reproduction.”
“Starvation or nutritional stress are likely an underlying factor in this,” it added.
Namibia’s coastal waters, and the abundance of fish that seals feed on, are affected by cyclical changes in ocean currents and temperatures.
This could affect how far seals have to travel in order to find enough food.
At this time of the year pregnant females, which normally give birth between November-December, are still nursing pups from the previous mating season and are unable to move far, explained Dreyer. “They rely on fish coming in,” he said.