Thousands of fish have washed up dead along Gqeberha’s beaches, with sardines making up most of the deaths. Scientists are investigating whether pilchard herpesvirus, an algal bloom or sudden ocean temperature changes are to blame, while experts warn the die-off could affect marine life and the fishing industry.
Thousands of fish, mostly sardines, have washed up dead along Gqeberha’s beaches, prompting warnings not to touch or eat them as scientists investigate whether a virus, algal bloom or sudden ocean temperature shift is to blame.
Nelson Mandela Bay University Professor of Ichthyology Nadine Strydom said they strongly suspect the mortality is related to the pilchard herpesvirus (PHV) discovered in the Western Cape earlier this month.
“The [virus] has spread in the pilchard population, even though other species have been affected, but in small numbers. What we are seeing on the beaches is actually a small number compared to what lies on the ocean floor.”
Strydom said the sardine deaths would have major and far-reaching implications for the small-scale fishing industry.
“Penguins and other marine life will start starving. The government needs to start preparing and adjusting how [many] pilchards can be harvested to save the industry.”
Strydom said South Africa was experiencing what happened in Australia in the 1990s, when two large-scale mortality events were recorded in sardines due to PHV.
She said the virus was later detected in apparently healthy Australian sardine populations without causing continuous mortality.
“It took years for their marine ecosystem to recover; obviously the virus is still in their pilchard population because immunity has improved and they live with it. There’s no curing the virus, they have to live it out.”
Strydom said South Africa had been importing sardines from South America for several years and that increased shipping traffic in the Cape could provide a route for the virus to spread.
Strydom said ships would collect seawater from an area, and discharge it when they were close to a port elsewhere, “but international shipping laws dictate that the water is not to be released [inside] a certain distance, but this is not policed so they end up breaking the law”.
While tests have yet to determine the cause of the Gqeberha die-off, Wildlife and Environment Society of SA (Wessa) Eastern Cape chair Gary Koekemoer said there were three possible explanations.
“The majority of the fish are sardines, but there are also other fish; it seems it’s a huge die-off all the way from Pollock Beach, behind Something Good to Kings Beach. We think it’s a mixture of the virus that was detected in Cape Town on the West Coast, a sudden change in temperature or an algal bloom,” said Koekemoer.
“We had a massive amount of cold water recently for the last two weeks, and it could be that there’s warm water that has come into the system. Nothing has changed on the beach, but out in the current. But it’s likely the virus in combination with temperature change. Our other concern is that penguins and others live off the sardines, so it will impact them in time.”
The wash-up poses a particular risk to people living rough near the beaches, who could see the fish as an easy source of food. The Nelson Mandela Bay Municipality’s beaches and resorts unit has warned people not to consume dead or dying fish.
Municipal spokesperson Sithembiso Soyaya said Pollock, Hobie and Humewood beaches were also affected.
“As a precautionary measure, members of the public are strongly advised not to collect, handle, consume, sell, distribute or feed to animals the washed-up sardines. The fish may have been exposed to environmental conditions or contaminants for an unknown period of time. Therefore, until further assessment has been completed, the washed-up sardines should not be considered safe for human or animal consumption,” he said.
The municipality urged people to keep children and pets away from areas where large numbers of fish have washed ashore, and to report large accumulations or further sightings.
Soyaya said the municipality was monitoring the affected beaches and would continue assessing the situation in consultation with the relevant authorities.
“Members of the public are urged to comply with this precautionary advisory in the interest of public health, safety and environmental protection. Further information will be communicated should additional developments arise.”
After tests following the Western Cape incident, regional Department of Forestry, Fisheries and the Environment spokesperson Zolile Nqayi said on 14 August that the role in the recent sardine mortality in that province remained under investigation.
“The pilchard herpesvirus was detected in both dead sardines and, at lower levels, in some apparently healthy sardines collected from the West Coast. This suggests that the presence of the virus alone may not be sufficient to cause mass mortality.”
Nqayi said scientists are therefore also investigating whether an environmental stressor, such as harmful algae, low oxygen or unusual oceanographic conditions, may have triggered or intensified the event.
“This remains a hypothesis requiring further evidence. PHV is a virus associated with sardines, also known as pilchards, and there is no evidence that it infects people or other animals. The PHV finding alone does not indicate that healthy sardines caught commercially or canned products are unsafe, and does not currently justify a general suspension of fishing or canning,” he added.
In Gqeberha, the Kings Beach Lifesaving Club rallied its members and the wider community to help the municipality clear the thousands of fish that had washed ashore.
“As many of you will have seen, we are currently experiencing a massive sardine wash-up across the beaches of PE, with thousands of sardines washing ashore. The municipality is doing its best to manage the situation, but with the scale of the wash-up … there is only so much they can do.
“As a club that spends so much time on and around our beaches, we feel this is a great opportunity for KB to take some initiative and give our community a helping hand.”
The club organised its members to participate in the clearing of the affected beaches from Friday afternoon to assist the municipality
“This is not only about helping with the current situation, but also about showing what KB stands for — building better people and better lifesavers.” DM
