Battle against extinction of seabirds - 'In order to save penguins, should we cull seals?'

At the current rate of population loss, African penguins may go extinct in the wild in about 10 years. But Yves Chesselet will feature as someone who prolonged their survival as long as possible.

He did so during an eight-year posting on the tiny island of Mercury off Namibia in the 1990s, by killing the seals that were killing the penguins and other endangered seabirds nesting on the three-hectare outcrop of barren rock.

It was a strategy that would have been highly controversial if anyone had known about it; the need to cull seals to protect seabirds is an issue that many conservationists still avoid.

During his time on Mercury as a government conservationist — living alone but for the occasional company of a helper — Chesselet single-handedly drove off the seals that were encroaching on the breeding zones of penguins, Cape gannets, Cape cormorants and bank cormorants.

His seal management crusade laid the foundation for what became a thriving penguin colony on Mercury, 90km north of Luderitz and 800m from the mainland.

“When Yves arrived there it was a carpet of seals,” says Dr Jessica Kemper, a member of the executive council of the Namibian Foundation for the Conservation of Seabirds (Namcob).

“He physically had to sjambok seals off the islands every day by the hundreds.”

Between 2015 and 2019, Mercury had between 2,300 to 2,600 penguin nests at peak breeding season, says Kemper.

But today, she says, there are zero. “Not. A. Single. One.”

The shocking population crash for penguins over the past five years is true also in varying degrees for the other three seabird species and for the other Namibian islands near Mercury – Ichaboe, Possession and Halifax.

Kemper and others say a factor in the collapse was the Namibian Ministry of Fisheries and Marine Resources (MFMR) withdrawal of full-time staff on the islands just before the Covid pandemic, due to budget constraints. Since then, seals have been left to their own devices.

The toll the seals are taking has been amplified by the fact that populations of the four seabird species – all endemic to the coasts of Namibia and South Africa – have declined dramatically over the past few decades because sardines and anchovies, which are their main food source, have been overfished.

Namibia’s sardine fishery collapsed in the 1960s and 1970s, and, despite a moratorium implemented in 2018, the fish have not returned in significant numbers.

“[Seabird numbers] have been hovering along on a relatively low number, it seemed to be the number that the system could sustain with the food there was,” says research manager at the Southern African Foundation for the Conservation of Coastal Birds (Sanccob), Dr Katta Ludynia.

But Ludynia said that when numbers were low, it didn’t take much to push the population over the edge. She said this could be due to an avian flu outbreak – such as one causing the death of 600 penguins on Halifax Island in 2019 – or “a few seals killing a few hundred birds”.

“Basically the sardine is the key to the entire northern Benguela ecosystem. You take out the sardines, you cause a whole lot of shit. Bringing back the sardine is the key,” said Kemper.

Additionally, Ludynia says Sanccob suspects rogue seals are raiding the Namibian islands now that the government conservationists are gone. “A permanent human presence was actually good for the birds.”

She stresses that not all seals are seabird killers.

“It’s very specific seals that learn this behaviour. So the headmen [government conservationists] would basically shoot this one individual seal and the problem would be solved. But if you don’t do that, then the one seal teaches the next seal and it just continues.”

Today, not a single penguin nests on Mercury Island. Seal tracks are visible on the sand in the middle of the photograph. (Photo: Katta Ludynia)