A mass die-off of sardines along the Western Cape coast has triggered an investigation by the Department of Forestry, Fisheries and the Environment (DFFE).

Dead and dying fish have been reported from Saldanha Bay to Gansbaai. Carcasses have also been seen offshore near Hout Bay.

The department said some sardines were drifting on the surface up to eight nautical miles from the coast. Reports, photographs and videos from fishers and members of the public have helped officials map the scale of the incident.

Fish samples sent for testing

Officials collected fish samples off Saldanha Bay on Saturday, 1 August 2026, with help from the fishing vessel Shivon.

The samples reached the department the following morning. Diagnostic testing began on Monday, 3 August.

Scientific observers have also been placed aboard purse-seine fishing vessels. They are gathering more information about where the deaths are occurring and how widely they have spread.

Possible causes under investigation

The department has not confirmed what is killing the sardines.

A harmful algal bloom involving Alexandrium catenella is known to be present in Saldanha Bay. However, officials said this alone may not explain deaths across such a large section of coastline.

Investigators will consider several possible causes. These include harmful algal blooms and related toxins, environmental conditions and fish disease.

The DFFE warned against drawing conclusions before laboratory samples and environmental information have been fully assessed.

Public warned to avoid affected fish

Residents have been urged not to collect, touch or eat dead or dying fish found on beaches or floating at sea.

The warning remains in place while testing continues. This precaution aims to reduce possible health risks before officials know whether toxins, disease or another environmental factor caused the die-off.

Further updates expected

The department said it would release more information once the first test results become available.

For now, the cause remains unknown. Officials are continuing to collect data from vessels, coastal reports and laboratory testing as they work to understand the extent of the sardine deaths.