Gqeberha (South Africa), August 31, 2026 (AFP) – The tide deposited thousands of dead sardines on the southern coast of South Africa last week. At dawn, the coast of Gqeberha was dotted with silvery reflections.
Along the beaches of Hobie and Pollock, stunned residents then saw the waves release more fish on the sand, raising fears that a virus that has already caused sardine hecatombs abroad is involved.
« It was a heartbreaking show, » according to the local environmental association Algoa Bay Conservation.
In the wake, « we received many calls, » recalls Nadine Strydom, a professor in the Department of Zoology at Nelson Mandela University in Port Elizabeth (South Africa).
Most of the dead fish were sardines and pilchards, she explains, adding that the real magnitude of mortality could be much greater than only stranded fish. « What we see on the beach is only a fraction of the total, because some fish could rest at the bottom of the water, » according to Strydom.
The massive stranding occurred only a few weeks after a similar hecatomb on the coast of the Western Cape, still in South Africa but hundreds of miles away.
These strandings reinforce fears that sardine herpesvirus (PHV), a disease that decimated sardine populations in Australia and New Zealand in the 1990s, is ravaging South African waters.
– Positives to PHV –
The Ministry of Forests, Fisheries and Environment (DFFE) said on Sunday that there was probably a link between the events in Gqeberha and those in the Western Cape, although it still needs confirmation.
« PHV remains the most likely explanation for the mortality episode in the Western Cape, » according to the DFFE, even if other causes and environmental factors will also be investigated.
The presence of the virus in South African waters was first confirmed in July, when sardines taken off Saldanha Bay, Cape Canyon, Elands Bay and Gansbaai were tested positive, the DFFE explained.
Genetic sequencing revealed a similarity of more than 99% with the strain associated with the epidemic that occurred in Australia.
« This is a first in the history of South Africa, » says Strydom.
Genetic material from PHV was detected in both dead sardines and apparently healthy sardines taken off Saldanha Bay, with the highest viral loads being recorded on dead fish.
However, this discovery does not prove that the PHV killed these fish, nuanced Zolile Nqayi, spokesman for the DFFE.
Scientists are therefore trying to determine whether the virus is the main cause of this excess mortality or whether it affects fish already weakened by environmental stress.
South Africa’s sardine stocks are already low, and oxygen-depleted waters, as well as the proliferation of harmful algae can make fish more vulnerable to diseases.
The tests carried out by the authorities revealed no traces of paralyzing toxins from shellfish and only low concentrations of other marine toxins, suggesting that poisoning of algae origin was probably not the main cause.
The investigation is now expanding, after the reports of new strandings of dead sardines in Namibia.
PHV does not present any known risk to human health, but the wider repercussions of its proliferation are already being felt.
At the Koeberg nuclear power plant near Cape Town, dead sardines have blocked a cooling water supply basin, forcing the national electricity company to reduce production.
– “Deeply worried” –
Scientists and environmental organizations fear that the consequences will extend far beyond the fishing sector.
« We are deeply concerned, » says Craig Smith, a technical specialist at the Global Wildlife Fund (WWF) in South Africa. « In Australia, the virus has decimated 70% of the population (of sardines). We fear that this is only the first wave, with the possibility of a more deadly second wave. »
Sardines occupy a crucial place in the marine food chain, serving as prey for dolphins, seals, seabirds and penguins of the Cape, a critically endangered species.
The consequences of the current excess mortality « are considerable » because a large amount of fish have perished, this can affect the entire environment, explains Nadine Strydom.
In Algoa Bay, which is home to one of the world’s largest colonies of penguins in the Cape, « penots are already struggling to feed because of uncontrolled fishing, and the situation will worsen even more with this virus that kills sardines, » laments Ronelle Friend, environmental chemist at Algoa Bay Conservation.
Fishermen are also concerned.
Bonny Adams, a seasoned Durban fisherman, had already found that sardine catches were worse than usual this year. « Now, with this virus, we don’t know what to expect. We are really worried, » he said.
An intergovernmental working group coordinates the monitoring, analysis, elimination of dead fish and impact assessment on sardine stocks. It is due to meet this week to consider whether further action is justified.
The extent of mortality, still uncertain, should be clarified later this year when the DFFE will carry out its annual hydroacoustic survey of sardine stocks.
source : marine oceans
