South African Sardine Die-Offs Linked to Pilchard Herpesvirus

In August 2026, thousands of sardines washed ashore and died along South Africa’s western and southern coastline, from Saldanha Bay to Gansbaai and later on beaches in the Nelson Mandela Bay municipality. Laboratory analysis detected pilchard herpesvirus (PHV) in the fish, prompting a multi-agency investigation. The virus, previously linked to two mass-mortality events in Australian sardines in the 1990s, inflames and thickens gills, impairing oxygen uptake. The Department of Forestry, Fisheries and the Environment (DFFE) reported that PHV poses no known risk to human health, but its presence forced the Koeberg Nuclear Power Station to reduce output by 50 % at one unit after dead sardines clogged a seawater intake.

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Sardines and pilchards are the same species; “sardine” refers to younger, smaller individuals. PHV was first identified in Australian sardine die-offs in 1995 and 1998-99, killing an estimated 60-75 % of adult stock. The 2026 detections mark the first confirmed appearance of PHV in South Africa’s wild sardine populations.

Canned sardines safe to eat despite pilchard herpesvirus, authorities say

Dalene Vosloo, a lecturer at the University of KwaZulu-Natal, cautioned that the virus may not explain the entire event, noting that “multiple factors could have contributed.” Ichthyology professor Nadine Strydom of Nelson Mandela University suggested ballast-water discharge from increased ship traffic and imports of baitfish could have introduced or amplified the pathogen, while low-oxygen conditions and unusually cold water may act as additional stressors. DFFE has found no evidence that harmful algae were the primary cause.

Dead sardines along Bay coastline raise grave environmental concerns

• DFFE and the National Regulator for Compulsory Specifications (NRCS) affirmed that PHV is a “disease of sardines” with no known infection risk for humans or animals, and that canned sardines remain safe because heat-treatment destroys viruses.

Canned sardines safe to eat despite pilchard herpesvirus, authorities say

• The NRCS emphasized that the validated retort/sterilisation process meets standards required to inactivate PHV.

Canned sardines safe to eat despite pilchard herpesvirus, authorities say

• The municipality’s beaches and resorts sub-directorate advised the public not to collect, handle, consume, sell, distribute or feed the washed-up sardines, citing unknown environmental contaminants and potential bacterial growth.

Avoid possibly contaminated sardines washing ashore in Gqeberha

• The national electricity company operating Koeberg confirmed the temporary intake blockage and the consequent reduction in power generation.

Avoid possibly contaminated sardines washing ashore in Gqeberha

Local authorities in Nelson Mandela Bay posted precautionary advisories, urging residents to keep children and pets away from affected shorelines and to report further sightings. The public was asked to avoid using the dead fish as bait or animal feed and to submit photographs and location data to a DFFE-designated email address to assist in mapping the mortality’s extent.

Avoid possibly contaminated sardines washing ashore in Gqeberha

While PHV is viewed as the leading explanation, investigators have not ruled out synergistic effects from environmental stressors such as low oxygen, cold water, or possible algal blooms. The exact pathway by which the virus entered South African waters remains unconfirmed, with hypotheses ranging from ballast-water discharge to imported baitfish. Further sampling of live sardines is needed to establish causality definitively.

Associated Press

DFFE, NRCS, and university researchers will continue collecting specimens, expanding testing to live fish, and monitoring the coastline for additional mortalities. The agencies plan to update the public as new findings emerge and to maintain safety assurances for commercially canned sardines. Koeberg is evaluating alternative intake filtration options to mitigate future blockage risks. Beach municipalities will keep issuing precautionary notices until the source of the die-off is fully understood.

Avoid possibly contaminated sardines washing ashore in Gqeberha