Pilchard herpesvirus identified as likely cause of South African sardine deaths

The South African Department of Forestry, Fisheries and the Environment (DFFE) has identified pilchard herpesvirus (PHV) as the likely cause of recent mass sardine deaths along the country's coast. While no new large-scale mortality incidents have been reported since August 16, 2026, investigations and monitoring remain ongoing.

Testing conducted by the South African Institute for Aquatic Biodiversity and Rhodes University detected PHV genetic material in all 15 initially examined fish. Ten of these were collected from the mortality event and showed consistently high viral levels. The viral sequence identified shows a 99.7% match to an Australian PHV gene. Of approximately 60 additional samples processed, preliminary results for half indicate high PHV levels.

Researchers are also conducting pathological examinations on 40 samples to check for gill inflammation and damage characteristic of active PHV disease. Investigations into other potential causes, such as harmful algae or paralytic shellfish toxins, have not found evidence that they were the primary drivers of the event. Environmental factors, including unusually cold water and low-oxygen conditions, were also noted along parts of the West Coast.