EVERY year around June, July and August billions of sardines ‘run’ or migrate up the east coast of South Africa between Port Elizabeth and Durban.
It is the biggest migration of any fish species, and the second biggest of any animal migration in the world, after East Africa’s great wildebeest migration.
The run occurs when a current of cold water heads north from the Agulhas Bank up to Mozambique, where it then leaves the coastline and goes further east into the Indian Ocean.
It is believed that the water temperature has to drop below 21 deg C in order for the migration to take place. In 2003, the sardines failed to ‘run’ for the third time in 23 years. While 2005 saw a good run, 2006 marked another non-run.
The shoals are often more than 7km long, 1.5km wide and 30m deep and are clearly visible from spotter planes or from the surface.
Dolphin pods 5,000 strong follow the shoals, as do Cape gannets. Humpback whales, too, are abundant as they are migrating north in these months for warmer water to mate and calve.
Copper sharks are also commonplace. Every so often, dolphins and sharks work together to separate a portion of a shoal and drive the fish to the surface, where the scared and confused sardines form a ball. It is then that a true mass feeding frenzy begins.
The gannets dive-bomb from the heavens in their thousands as dolphins, sharks, seals, whales and even penguins devour the ball from all sides.
Sardines group together when they are threatened. This instinctual behaviour is a defence mechanism, as lone individuals are more likely to be eaten than large groups.
The recent interest in the sardine run has had a significant impact on the local economy. The run has become important to tourism and is considered to be one of the main attractions in KwaZulu-Natal during the winter holiday period.
Both local and international tourists are attracted to the spectacle and are provided with opportunities to participate in activities such as dive charters and boat based predator viewing tours.