Southern African sardine (sardine run)

How it lives

A coastal schooling fish found from the surface to about 200 m. Adults live at roughly 16 to 23 degrees C in summer and 10 to 18 degrees C in winter, and they lay floating eggs. Sardines bunch together when threatened. During the run, shoals can be more than 7 km long, 1.5 km wide and 30 m deep. Common dolphins round them into bait balls about 10 to 20 m across that seldom last more than 10 minutes, and sharks (mainly bronze whalers), Cape gannets and Bryde's whales join in.

Where it goes

Each southern winter, hundreds of millions of sardines move north-east along the Eastern Cape and KwaZulu-Natal coast, usually from about May to July. A 2021 genomic study found that most run sardines come from the cool west coast stock and are drawn east by short spells of cold water. The run involves only a small part of the South African population, and in some years no run is detected. The sardines are thought to be a migration into a trap: they get squeezed between the coast and the warm Agulhas Current, which is too warm for them.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

Globally Least Concern (IUCN, assessed 2018). South Africa has two sardine stocks, one on the cool west coast and one on the warmer south and east coast. Catches peaked at just over 400,000 tonnes in the early 1960s and then collapsed, which is blamed on overfishing, fishing grounds moving south and variable recruitment. The population has since shifted east, and catches now come almost entirely off the south coast. The run itself is not reliable: in 2003 the sardines failed to run for the third time in 23 years. Researchers suggest that warming could end the run, with little effect on the population as a whole.