The sardine run in South Africa is a spectacular occurrence.
Sardines normally live in the cool waters of the southern and
western Cape, where they provide food for various predatory fish.
At the beginning of autumn, they gather in extraordinary
shoals and move northwards up the Mozambique Current to find warmer water in
which to spawn.
The migration takes six months and is extremely regular.
Along most of the Cape coast, the sardines keep well out to sea, but off Port
St. Johns, on the Wild Coast, counter currents bring them close to the shore.
Travelling in successive shoals, the sardines hug the
coastline for 250 kilometres. They complete their migration just south of
Durban, where they swing out to sea again, and the Mozambique current carries
them back to the Cape for the six months of spring and summer.
Each successive shoal of sardines of many millions of the
little fish, followed by a horde of predators, Cormorants, gannets and other sea
birds dive at them from overhead or rest on the water in overhead masses,
themselves a prey to sharks.
Game fish attack the fringes of the shoals, gorging on the
sardines but careful never to venture into the midst of the mass for fear of their
gills becoming clogged up. Ravenous local fish such as barracuda, kingfish,
prodigal son, queen fish, snoek, sharks, skates, and rays join predators, which
follow the shoals up from the Cape.
The spectacle of these passing shoals is remarkable. Anglers
crowd every vantage point. If a shoal has been driven far enough inshore by
weather or predators even housewives wade into the surf to scoop out the sardines
in buckets and aprons. Birds circle in thousands overhead and the surface of
the sea is churned up as though it is boiling. It takes about 30 days for the shoals
to pass. The size of the catches can be affected by various factors: rough seas
or a heavy swell can send the sardines deep below the surface where they will
escape their predators; high atmospheric
pressure gives them extra energy owing to the increase of oxygen in the water;
low barometric pressure makes them sluggish.
It is not known how many of the little fish complete the
return journey to the Cape in safety, but hundreds of millions must surely be
eaten on the way. Each female, however, lays about 100 000 eggs. Providing
that two from each female survive, the number of sardines will remain stable.
