Researchers probe herpes virus link to recent sardine die-offs along South Africa's coast

Mass mortalities of sardines have been reported along South Africa's western and southern coastline, prompting an investigation by the Department of Forestry, Fisheries and the Environment. Scientists from the South African Institute for Aquatic Biodiversity and a local university have detected pilchard herpesvirus (PHV) in both dead and living fish, marking the first confirmed presence of this virus in South African sardines.

PHV, which caused two large die-offs in Australia during the 1990s, can inflame and thicken gills, reducing oxygen uptake. While officials note that the virus poses no known risk to human health or commercial sardine products, they are also evaluating other factors such as harmful algae, unusually cold sea temperatures, and low oxygen levels. Preliminary findings show consistently high PHV loads in dead fish and varied levels in live ones, strengthening the case for the virus as the primary cause.

The die-off has already impacted infrastructure, with the Koeberg Nuclear Power Station reducing power output by 50% at one unit after sardines blocked a seawater intake. Researchers caution that multiple stressors could be contributing to the event.