The Sardine Run
The South African sardine, also known as the pilchard (Sardinops sagax), is usually found in huge shoals in the upper layers of the ocean (epipelagic zone). Pilchards, like anchovies and herrings, are small, primitive fish belonging to the group of fish known as the clupeoids. Although each fish is small, collectively they make up about 23% of the world’s fish catch, making them very important economically. Pilchards are cold water species and are usually associated with areas that exhibit cold upwellings (the movement of deeper, cooler, nutrient-rich water into shallow coastal areas). Pilchards are commonly found in enormous shoals on the west coasts of California, Peru/Chile, Japan, Australia and, of course, South Africa.
COMMON NAME: pilchard / South African sardine
Pilchards are short lived, fast growing fish that reach a length of about 23cm in two years. Most pilchards do not live for much longer than three years and may grow up to 0.60mm per day. Pilchards are sequential spawners with a prolonged breeding season through spring and summer (September to February), and most reach sexual maturity at about 19cm. Pilchards are highly fecund, producing many thousands of eggs per female. These eggs are simply released into the water, fertilised and the larvae abandoned to an almost certain death. Only two larvae need to survive (one male and one female) for the pilchard population to remain stable; all the others form part of the food web of the ocean. The movement of the larvae has been well researched and it appears that, after spawning takes place on the Agulhas banks, the larvae are transported northwards, along the West Coast. Although conditions are very harsh for the larvae, which can barely swim, the current systems in the area enable them to aggregate into small groups which gradually expand as more and more larvae are attracted. After metamorphosing into juvenile fish, pilchards are ready to return to their spawning grounds, thereby completing their life cycle.
Pilchards are primarily filter feeders, straining zoo- and phytoplankton (minute plants and animals) from the water, using their modified gill rakers as sieves. Juvenile pilchards feed primarily on copepods (minute crustaceans), while adults are opportunistic, omnivorous feeders. Pilchards are eaten, in turn, by many larger predators. From gamefish to birds, marine mammals to humans, all want their share.
In the large pelagic fishery off the Western Cape coast, about 100 000t of pilchards are caught annually. Each night, depending on the weather and season, a fleet of purse-seiners sets out from harbours along the South and West Coasts. Once a shoal of pilchards has been located, huge purse-seine nets are used to encircle it. The fish are then drawn up alongside the vessel before being pumped on board. Depending on the quality of the fish, the catch may be canned or reduced to fishmeal. This fishery employs thousands of people in the Western Cape and is, therefore, very important to many coastal communities in the area. In the Eastern Cape, about 4000t are caught annually while the catch is about 700t in KwaZulu-Natal (KZN) waters.
In South Africa, pilchards live in temperate coastal and shelf waters, ranging from northern Namibia to KZN. It is their movement into the waters of KZN that results in the well known “sardine run”.
THE SARDINE RUN
The sardine run is an annual phenomenon that occurs during the winter months when large shoals of pilchards enter KZN waters from the cooler Cape waters. The great bulk of South Africa’s pilchard stock is found distributed between the Agulhas Bank (off the Cape South Coast) and the West Coast. Each winter, however, a small proportion of the stock expands its range eastwards and moves up the Wild Coast and into southern KZN waters. A narrow band of cooler water exists here in winter, between the coast and the warm Agulhas Current. It is this band of cooler water that enables pilchards to move northwards up the east coast. Although some of the pilchards are in a spawning condition and do spawn in KZN waters, it is unlikely that the “sardine run” represents a spawning migration. And, although higher concentrations of copepods occur off KZN during the winter months, this does not appear to be a feeding migration. Conditions for both spawning and feeding probably remain more favourable on the Agulhas Bank. The migration appears to be related to an extension of the environmental conditions that are suitable for pilchards.
The sardine run is known to attract a large number of piscivorous predators, including gamefish such as shad (elf), garrick (leervis) and geelbek, and sharks, such as copper, dusky, blacktip and spinner sharks. Sea birds, such as Cape gannets, cormorants and the occasional penguin; and marine mammals such as Cape fur seals and dolphins, all pursue the pilchards into the warmer waters of KZN. In fact, the appearance of common dolphins along the KZN south coast is closely associated with the arrival of the sardine run. 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 sight of birds diving onto the shimmering shoals of pilchards, while gamefish and dolphins attack them from below - all determined to make the most of the short lived feast - is a truly amazing spectacle.
During the sardine run, commercial fishing for pilchards in KZN is 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. Certain wind and current conditions may force the pilchards very close to the beach, where they can easily be caught using baskets, hand nets or even skirts! In fact, when pilchards are beaching "anything goes" and it is not uncommon to see grandmothers competing with teenagers for ‘their’ share of the feast.
Pilchards are an integral component of the marine ecosystems along the coast of South Africa and are of considerable economic and social importance. The sardine run is a spectacular, natural, annual phenomenon that visitors to the KZN south coast in winter may be fortunate to witness.
Shad, The Commercial Fishing Industry
CoastCare (Department of Environmental Affairs and Tourism)
Private Bag X2, RoggeBaai 8012
The KwaZulu-Natal Nature Conservation Service
P.O. Box 13053, Cascades, Pietermaritzberg 3200. Tel: +27(0)31 845 1999
Oceanographic Research Institute, Sea World, Sea World Education Centre
P.O. Box 10712, MarineParade 4056. Tel: +27(0)31 3373536, Fax: +27(0)31 337 2132
Natal Sharks Board
Private Bag X2, Umhlanga Rocks 4320. Tel: +27(0)31 566 1001
Payne, A.I.L., Crawford, R.J.M. & Van Dalsen, A.P. 1989. Oceans of Life off Southern Africa. Vlaeberg Publishers, Cape Town.