Estimated 5,000 Cape fur seal foetuses found on Namibian coast
An estimated 5,000 Cape fur seal foetuses have been found along the shores of Namibia, a large portion of the expected new pup arrivals.
The bodies were spotted by Naude Dreyer of Ocean Conservation Namibia (OCN), who flew his drone over Walvis Bay’s Pelican Point seal colony on 5 October and counted hundreds of bodies. “This is tragic, as it makes up a large portion of the new pup arrivals expected in late November,” he tweeted.
Cape fur seals are mostly found along the coasts of Namibia and South Africa, with females giving birth in November and December. When there is a shortage of food, they will often abandon their young or abort their foetuses.
Dr Tess Gridley, of the Namibian dolphin project and Stellenbosch University in South Africa, who is part of the research team monitoring the situation, said dead pups are commonly found at this time of year – but not on this scale.
Dreyer started noticing bodies in August, but became concerned when he found hundreds on one day in October. An estimated 150 pre-term pups have also been found in the Cape Cross colony, further north.
Total deaths are estimated at 5,000, although Gridley says it is difficult to be certain as many carcasses are eaten by scavengers, such as black-backed jackals. She says: “We are concerned about emaciated juveniles and adult females as well, which have also been observed at Pelican Point and to the north – indicating a wider scale to this event.
“This event could disrupt the normal breeding cycle at the affected colonies. Normally females will give birth to a pup each year, and they come into oestrus shortly afterwards and mate with the bulls. With females aborting pregnancies, they may come into oestrus earlier, but the males may not have organised themselves for mating. Also, the females are very thin and may not be healthy enough to reproduce.”
Lack of food, disease and toxins are all possible causes, but there is not enough data yet to confirm the reason, Gridley says.
There was a similar large-scale dieoff in 1994, where a combination of malnutrition and a secondary bacterial infection, Streptococcus phocae, were identified as causes.
Dr Brett Gardner, a vet, says: “In addition to females being thin and possible having a decreased likelihood of falling pregnant in the coming breeding season, there will be a significant lack of recruitment of new young individuals into the population in the next few years once the foetuses that were now lost are supposed to be maturing into reproductive adults.
“Without knowing the extent of this or what is causing it means we do not know what risk it carries for repeat events of catastrophic die-offs in the future.”
The scientists are gathering data for analysis, using drones to count the bodies and collecting biological samples to establish causes. They have told authorities monitoring other Cape fur seal colonies to remain vigilant.