The Sardine Run is one of the planets greatest natural events. It pulls in many predators, both marine and bird. The little silver fish is also a human favourite. Although these fish are small, collectively they comprise nearly a quarter of the world’s fish catch by weight, making them one of our most valuable groups of fish.
Few places can match the marine diversity found along the shores of South Africa. Two very different ocean currents flank the coast at the southern base of Africa. The west coast has the cold Benguela Current moving south to north and on the east coast the warm Agulhas Current moves south from the warm tropics.
“Dominant and strong south easterly winds push coastal surface waters offshore forcing deep, cold and rich-nutrient waters to swell from the depths. When this cold soup full of nutrients reaches the sunlight at the surface it triggers one of the richest marine environments on earth, dominated by large production of plankton and massive kelp forests that fringe the rocky shallow coast. Giant kelp plants dominate the shallow reefs along the Benguela and it is under the shelter of this golden forest that there is a myriad of life. The west coast of South Africa is … the world largest biomass of marine flesh of grazers per unit of rock.”
On the east of Southern Africa the warm, fast flowing current moves south from the Mozambique Channel. This warm Agulhas Current of about 100km wide, has surface water reaching speeds of 2 meters per second.
During the months from May to July, the cooler Benguela current strengthens and moves up towards the east coast of South Africa and the warm Augulhas current weakens and flows off the continental shelf away from the coast. The sardines (Southern African pilchard Sardinops sagax), spawn in the cool waters of the Agulhas. This cold counter current ‘finger’ of the Benguela current now extends northwards along the Eastern Cape of South Africa, and up into the KwaZulu-Natal. It is this cool northwards current that opens a migratory pathway for some sardines to move northwards towards the Wild Coast and then KwaZulu-Natal. Most stay in the more nutrient rich and colder Cape waters.
Little is known of the phenomenon. It is believed that the surface water temperature has to drop below 21 °C in order for the migration to take place and in just some 3 years, it did not.
Game fish like Garrick, sailfish, dolphin, sharks of many types and Humpback and Bryde’s whales are attracted by the fish and a feasting frenzy happens. From above the water the birds, cormorants, terns and gulls drop in for a meal. The Cape Gannet are the most numerous and fold back their wings to dive at huge speed, between 40 and 120 kms per hour, depending on the height they start at. The water churns with activity and panicking sardines. The shoals are often more than 7 km long, 1.5 km wide and 30 metres deep and are clearly visible from spotter planes or from the surface. Dolphins (estimated as being up to 18,000 in number), mostly the common dolphin, are largely responsible for rounding up the sardines into bait balls. These are to protect themselves, and sharks swim repeatedly into the ball to feast.
Sardine are mainly plankton eaters and live for just 2 to 3 years but they produce a lot of eggs. “The presence of eggs off the KwaZulu-Natal coast suggests that sardine stay there for several months and their return migration, back south, during late winter to spring is nearly always unnoticeable because it probably occurs at depths where the water is cooler than at the surface.”
In 2017 the South African government reduced quotas for sardines and the subsequent re-building of stocks has made the Sardine Run quite spectacular. “The greatest shoal on earth” was the phrase dubbed by the BBC and it now attracts the world’s top marine and wildlife photographers.
The KZN Sharks Board lifts nets when they spot the sardine coming, so predators are not caught. It is advisable not to surf or swim in the breakers at this time. Caution is needed when wading in to collect dish not trapped by the nets. Teams with licenses and quota restrictions get the nets out to just beyond the breakers with little boats and both boats and waders work together to pull their filled nets onto the beach. The frenzy and excitement on shore matches what happens at sea as skirts, buckets and hands are used to scoop and grab.
Diving is very special and there are companies who specialize in this opportunity of a life time. You can also go out in a boat and watch this incredible spectacle from the boat.
African Watersports, home of the Shark Whisperer, is one of these and is based in Umkomaas but for the sardine migration they are in Mbotjie, Wild Coast..
Offshore Africa is another very highly regarded sardine run company, based in Port St Johns, Wild Coast…so in the heart of the action.. Call 084 951 1325
Pisces Diving is another top dive operation, normally based in Simon’s Town, but they are based in Cintsa, Wild Coast for the Sardine Run.
( photos from various sources including Greg Lecoeur, National Geographic winner with diving bird photo, and Offshore Africa with sharks on bait balls)