The outbreak, which began in the Western Cape in late July before spreading to Gqeberha, East London, and the northern Wild Coast, has been primarily linked to the pilchard herpesvirus.
Pilchard Herpesvirus Identified as Primary Driver
Laboratory analyses of samples collected before and during the die-off have confirmed the presence of the pilchard herpesvirus, making it the most probable primary cause of the mass strandings. Testing ruled out harmful algal blooms and marine biotoxins as contributing factors. Authorities continue to analyze samples from commercial catches and past collections to trace the origin and propagation of the pathogen, while also examining what role oceanographic conditions played in the event.
Ongoing Fishing Restrictions and Monitoring Protocols
To protect remaining fish stocks, the government instituted a temporary restriction on sardine fishing on September 11. This restriction remains in force until October 2. The Small Pelagics Scientific Working Group is scheduled to meet on September 29 to review available data and issue new recommendations for the fishery. Meanwhile, coastal authorities, commercial fishers, and the general public remain under instructions to report any new stranding cases immediately. Officials stress that the public must avoid collecting, consuming, or using the stranded sardines as bait or animal feed.
Regional Context and Future Biomass Assessments
Similar fish strandings have been reported in Namibia, though officials have not established a direct epidemiological link to the South African mortality event. Because the current data does not reveal when or how the virus entered South African waters, the government maintains active surveillance networks along the coast. A hydro-acoustic survey scheduled for October and November will provide the first formal estimate of the sardine biomass remaining in the wake of the mortality event.
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