Science
South African scientists investigate herpes virus link to mass sardine die-off
Researchers cite pilchard herpesvirus as the leading potential cause of sardine deaths along the coast, which also affected operations at a local nuclear plant.
The short version
- South African authorities and researchers are investigating mass die-offs of sardines along the country's south and west coasts.
- Initial tests show high levels of pilchard herpesvirus (PHV), which is known to cause gill damage that impairs oxygen absorption, though environmental factors are also under consideration.
- Officials report that PHV poses no known health risk to humans and does not affect the safety of commercial sardine products.
- The accumulation of dead fish clogged a seawater intake at the Koeberg Nuclear Power Station, forcing a 50% power reduction at one of its units.
Key facts
- Sardines have been washing up dead or dying along South Africa's west and south coasts during August 2026.[Associated Press · ABC News]
- This marks the first time pilchard herpesvirus (PHV) has been detected in sardines off the South African coast.[Associated Press · ABC News]
- The South African Department of Forestry, Fisheries and the Environment stated initial testing showed consistently high levels of PHV in collected dead fish, making it the leading potential explanation.[Associated Press · ABC News]
- PHV can cause inflammation and thickening of fish gills, which impairs oxygen intake.[Associated Press · ABC News]
- The environment department stated that PHV presents no known danger to human health and does not compromise commercially caught or canned sardines.[Associated Press · ABC News]
- The Koeberg Nuclear Power Station had to reduce output by 50% at one unit after dead sardines blocked its cooling water intake.[Associated Press · ABC News]
What remains uncertain
- It remains unconfirmed whether PHV is the sole cause of the mortality event or if it interacted with external environmental stressors like water temperature changes, oxygen drops, or toxic algae.[Associated Press · ABC News]