The Sardine Run with Raggy Charters

Posted in Day Trips | Tourism | Tourist Attractions | Water Activities | Whales, Dolphins & Marine

The Sardine Run, a natural phenomenon, has been described as one of the greatest marine displays on earth, and rivals events such as the great Serengeti wildebeest migration.

The annual sardine run is an unpredictable event, sometimes beginning as early as February along some parts of the coast and lasting until late July.

The South African sardine (Sardinops sagax) spawns in the cool waters of the Agulhas Bank, off the Southern Cape coast. Between spring and early summer females will release their eggs into the water for the males to fertilize. Fertilized eggs are then left to drift off in the open ocean. Larvae are then carried by the oceans currents up the west coast until juveniles reach maturity and are strong enough to swim south. Forming large shoals, millions of sardines will then begin their journey, hugging the shore as they head up the east coast.

Scientists believe that the sardines start moving when a cold ocean current moving east from the Agulhas Bank is established. This ocean current needs to be below 21°C, as sardines prefer water temperatures between 14 and 20°C. The current is also rich in plankton, the sardine’s staple diet. Sardines follow this current, staying close to shore to avoid the warm temperatures of the Agulhas current, which is flowing in the opposite direction. These large shoals of sardines can be 15km long, 3.5km wide and 40 metres deep, making them clearly visible from high above the surface. Following these huge shoals of fish are some of the top marine predators in South Africa.

In Algoa Bay the sardine run can sometimes coincide with the appearance of a ‘red tide’. This is due to upwelling which is caused by strong easterly winds (causing water temperatures to plummet) and the shearing effect of the Agulhas current. Upwelling brings dormant phytoplankton spores to the surface which when exposed to sunlight blooms so densely they colour the water red. This phytoplankton attracts masses of zooplankton which in turn attracts bait fish, such as sardines. Large shoals of sardines feeding near the ocean’s surface are then targeted by hungry predators. Bait balls are usually started by groups of either African penguins or common dolphins. These animals work cooperatively to trap the sardines (or other bait fish) in a tight circle making it easier for fish to be eaten. The bait fish referred to above includes anchovies, sardines (pilchards), redeye round herring, saury and horse mackerel (maasbankers).

Once the feeding frenzy begins, frightened sardines emit a strong odour which then alerts other nearby predators to the activity. Cape gannets, Cape cormorants, and various species of terns and shearwaters will then dive from above picking off fish from near the surface. Copper sharks, hammerhead sharks and game fish will have already joined the action. Then comes the bryde’s whales and minke whales to finish it all off. Lunging from below with mouths agape taking in both water and food, these magnificent animals launch themselves out of the water as the birds and sharks race to get out of their way. Although feeding frenzies may not last long, patient observers will see the animals regroup around another ball of fish and repeat the process until all the animals are satiated.