The "Greatest Shoal on Earth"
Each year in June or July along the KwaZulu-Natal coast the word gets out and, within hours, crowds of frenzied human predators converge on the area to join sharks, gamefish, marine mammals and birds in a feeding orgy. It is a time of plenty for all as large shoals of sardines move in a band up the coast. Fresh, frozen, canned, pickled or bait - whatever way you consider them, sardines (also known as pilchards) will have featured somewhere in the lives of many South Africans. Like their close relatives, the anchovies and herrings, sardines (Sardinops sagax) live out their lives in huge shoals in the surface layers of the ocean. 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.
Sardines are cold-water fish and are usually associated with areas of cold ocean upwelling, where deeper, cooler, nutrient-rich water currents surge to the surface when they strike shallow coastal areas. Sardines are commonly found in enormous shoals on the west coasts of California, South America, Japan, Australia and, of course, southern Africa.
In the large sardine (pilchard) fishery along the Western Cape coast, about 200 000 tonnes are caught annually. Each night, weather and season dependent, fleets of purse-seiners set out from harbours dotted along the coastline. Once a shoal has been located, huge nets are used to encircle and draw the fish up alongside the vessel before they are pumped on board. Depending on the quality of the fish, the catch may be canned or ground into fishmeal. This fishery employs thousands of people in the Western Cape, and is the economic backbone of many coastal communities in the area. Up the east coast, the annual catch drops progressively from about 10 000 tonnes in the Eastern Cape to several hundred tonnes in KwaZulu-Natal waters.
Sardines live fast and die young. They grow rapidly to reach a length of just under 20 cm and sexual maturity in two years, but rarely live longer than three years. In compensation, they are highly fecund, each female producing many thousands of eggs in her short lifespan. The main spawning grounds are on the Agulhas banks off the southern Cape coast, where the adults gather for a prolonged breeding season through spring and early summer. The eggs are simply released into the water, fertilized and left to drift off in the open ocean. A benign ocean current carries most of the developing larvae westwards and northwards into the productive waters along the west coast. After growing into juvenile fish that are strong enough to swim against the current, they aggregate into dense shoals and slowly make their way back to their spawning grounds in the south, thereby completing their life cycle.
Sardines feed primarily on plankton, minute plants and animals that they filter from the sea using sieve-like gill rakers. In turn, the exceptional productivity of sardines fuels the populations of most of the larger marine predators. Gamefish, birds, seals and dolphins compete with man for a share of the bounty. The sight of wheeling squadrons of gannets folding their wings to plummet into the water around a school of hundreds of dolphins surging after a boiling mass of panic-stricken fish is an extraordinary spectacle. So too is the equally frenzied behaviour of man when shoals of sardines are pushed ashore during the famous 'Sardine Run'.
The Sardine Run is an annual phenomenon sparked by the entry of large shoals of sardines into the waters of southern KwaZulu-Natal during the winter months. Although the great bulk of South Africa's sardine stock is to be found in the cooler Cape waters, each winter a small proportion of the stock moves eastwards up the Wild Coast. These shoals take advantage of cool water on the continental shelf of the east coast that occurs seasonally as a narrow band between the coast and the warm, southward flowing Agulhas Current.
It is not clear what advantage the sardines gain by entering KwaZulu-Natal waters. On the contrary, in fact, local waters are less food-rich than are Cape waters, the favourable cooler conditions are only temporary and, to make matters worse for the sardines, they are accompanied by many predators which prey on them heavily. Because the fish become concentrated near the surface in a narrow inshore band of water, the shoals are quickly located by schools of marauding predators that are whipped into a frenzy by this brief period of plenty in these otherwise less productive waters. Sharks, such as the copper, dusky, blacktip and spinner, join gamefish such as shad, garrick and geelbek, and marine mammals like Cape fur seals and dolphins in hot pursuit of the shimmering mass of sardines, or each other. As the shoals are driven to the surface, birds - Cape gannets, cormorants, terns and gulls - plummet out of the sky to pillage from above. The appearance of common dolphins along the KwaZulu-Natal south coast is closely associated with the arrival of the Sardine Run and it has even been suggested that the female dolphins use the plentiful food supply to wean their calves and replenish their depleted fat stores.
The progress of the Sardine Run is closely monitored by anglers, who flock to the beaches and rocks to participate in excellent game-fishing. Commercial fishing of the sardines themselves is also undertaken using beach seine nets, which are pulled from the shore. While one group of fishers holds a rope at one end of the net, the other end is cast around the shoal of fish using a small boat. The encircled fish are then dragged ashore, where they are quickly scooped into baskets both by the fishers and many eager helpers. These fish are usually sold for human consumption or bait. Particular wind and current conditions may force the sardines very close to the beach, where they are easily caught using baskets, hand nets or even skirts! In fact, when sardines are beaching anything goes, and it is not uncommon to see grandmothers competing with teenagers for 'their' share of the feast in a social occasion that draws crowds into the surf and even larger crowds of awed and amused spectators.
The Sardine Run and the KZN Sharks Board
The melee of predators accompanying the sardine shoals is problematic, not just to the sardines, but also to the KZNSB. The shark nets that provide bather protection along the beaches take a heavy toll of sharks and dolphins if they are not lifted before the arrival of the Sardine Run. In addition, damage to the nets themselves carries a heavy financial cost to the KZNSB. The organization's ability to monitor the movements of the run has improved over the years. Although it has long been Board practice to lift the nets prior to the arrival of the shoals, the organisation's capacity to monitor the movements of the shoals has improved over the years. This capacity was significantly enhanced by the acquisition of an aircraft, enabling the Board to conduct regular sardine monitoring flights.
The improvement in monitoring efficiency is demonstrated by the following figures. In the decade from 1978 to 1987, an average of 356 sharks was caught annually at the beaches south of Durban in the June-July period. In the subsequent decade, 1988-1997, this number was reduced to 228 sharks and in the decade 1998-2007 further to 50 sharks (41.3% released).
This dramatic reduction in catches has been achieved not only by improved monitoring but also by removing the nets slightly earlier than was previously the case and by keeping them out of the water until all indications suggest that the Sardine Run is over. However, this temporary removal of the nets has implications for the tourist industry. The KwaZulu-Natal coast enjoys some of its best weather at this time of year and the Sardine Run coincides with the winter school holidays. Pressure to return the nets to the water prematurely has been eased by the introduction of "discretionary bathing" . Until the mid-1990s the removal of nets resulted in a complete ban on bathing. More recently, however, a number of local authorities have agreed to "discretionary bathing" , in which signs are erected that state that the nets have been removed from the sea because of the Sardine Run but that bathers may enter the water at their own risk. In KwaZulu-Natal winter is a lower risk period for shark attacks than summer but if there is sardine activity in the immediate vicinity of a particular beach, local life guards will advise bathers of this.
The Board will continue to do everything in its power to continue to keep catches as low as possible but nature is unpredictable and keeping ahead of the sardines and associated predators represents an annual challenge for the organisation.
The Sardine Run and tourism
Each year Hibiscus Coast Tourism has run a focused marketing campaign entitled "The Greatest Shoal On Earth", using information provided by the KZNSB and with financial support from Tourism KwaZulu-Natal. A number of high profile television documentaries, including the BBC's Blue Planet series, have featured the Run, as have prestigious magazines such as National Geographic. In 2004, 93 000 calls were made to the KZN Sharks Board/East Coast Radio Sardine Run Hotline (083 9139495) to find out the whereabouts of the sardine shoals. The Hotline is updated regularly throughout the duration of the Run by KZNSB staff. Members of the public flock to the beaches to watch the seine netting of sardine shoals. Tour operators, launching from centres such as Shelly Beach, take people out to see the sardines and their attendant sharks, gannets and common dolphins. Air flips are available from Margate Airport. Groups of sport divers from around the world plan trips to South Africa specifically to see the Run off the coasts of both KwaZulu-Natal and the Wild Coast (Eastern Cape). The tourism industry of KwaZulu-Natal is starting to capitalise on this spectacular natural phenomenon that takes place on our doorstep each year.