Following the previous media statements issued by the Department of Forestry, Fisheries and the Environment (the Department) we can confirm that laboratory sequencing has confirmed that pilchard herpesvirus (PHV) genetic material is present in sampled sardines.
Its role in the recent sardine mortality remains under investigation. PHV was detected in both dead sardines and, at lower levels, in some apparently healthy sardine collected from the West Coast. This suggests that the presence of the virus alone may not be sufficient to cause mass mortality.
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.
Tests for toxins in sardines collected off Saldanha Bay, the Cape Canyon and Gansbaai, together with an apparently healthy comparison sample from St Helena Bay, found none of the paralytic toxins associated with a harmful algal bloom in Saldanha Bay. Two other algal toxins, domoic acid and yessotoxin, were detected at low levels, with the highest levels found in the apparently healthy comparison sample. No other toxins included in the screening were detected.
These findings suggest that the toxins tested for were unlikely to have been the primary cause of the sardine deaths. However, they do not entirely rule out harmful algae or environmental conditions as factors that may have placed additional stress on the fish.
The Department has convened an urgent briefing with small pelagic fishing industry stakeholders. A task team comprising the Department, the fishing industry and other relevant stakeholders will be established to urgently formulate a high-level coordinated response plan for PHV-associated sardine mortality in South African waters.
Through a coordinated inter-agency effort, the Department is expanding disease surveillance along the West, South and East coasts, while further disease, pathology and environmental investigations continue. The Department’s routine October/November hydroacoustic biomass survey will be the first opportunity to assess the possible effect on the sardine population.
PHV has not previously been reported in South African sardines. It was associated with two large-scale sardine mortality events in Australasia during the 1990s. However, the virus was subsequently detected in apparently healthy Australian populations without causing continuous mortality.
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. The biotoxin results are also reassuring, although they do not constitute a general clearance of all commercial catches. Monitoring and normal food-safety controls should therefore continue.
Members of the public should not collect or consume dead or dying fish. They should also not feed dead or dying fish to pets.
The Department will provide further information as results become available.
For media enquiries, please contact: Zolile Nqayi on 082 898 6483 / znqayi@dffe.gov.za
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