Between May and July, millions of small silver fish commonly known as sardines, travel in huge shoals from the cold Atlantic waters of Cape Point to the warmer Indian waters of the northern Eastern Cape and southern KwaZulu-Natal. This is called the sardine run or the greatest shoal on earth.
What makes this migration special?
Many species of fish migrate during different times of the year but the migration of sardines is different. The shoal of sardines is generally more than 7 km long, 1.5 km wide and 30 meters deep. This huge size makes the sardine run more interesting than most because it is visible by satellites in space.
The arrival of such an influx of sardines attracts countless predators that are hungry to feast. The two species of predators that are the first to locate the shoals are Cape gannet, a large white seabird with a yellowish head, and the common dolphin. These two species work together in separating the shoal into what is known as bait-balls. This makes other predators and humans aware of the sardine action.
Humans look forward to the sardine run and come down to the sea with their nets hoping to catch sardines as they enter shallow water in search for food.
One can achieve the best experience of the sardine run in the sea. For this reason, scuba divers and underwater photographers flock to the coast during this occasion. Much of the action can also be seen from above the waves, for those who want to experience the sardine run without getting themselves wet.
Why does the sardine run happen?
There are various research hypotheses regarding to why the sardine run takes place. However, some of these hypotheses are contradictory because the ecology of the sardine run is poorly understood. A recent interpretation of the cause is that the sardine run is a seasonal reproductive immigration of sardines. The sardines that migrate up the coast are doing so to lay eggs. Therefore, the sardines that survive predators deposit their eggs in the warm coast. These eggs drift back all the way to Algulhas Bank (the region where the Atlantic and Indian oceans meet) where they hatch the following year.
South Africa’s annual sardine run has been delayed lately and there have been cases where it hasn’t happened at all. According to an article published in 2019 by University of Witwatersrand scientists who tracked South Africa’s sardine run over 66 years, sardines arrived off the coast of Durban at a rate of 1.3 days later per decade.
Why is the sardine run important for South Africans?
The sardine run delay should be a concern for South Africans because the sardine run is economically important to the country.
A large number of tourists travel from around the world to South Africa for shark and dolphin sightings, in addition to the sardine run. Some local tour operators from the Eastern Cape coastal towns offer expedition tours to both the international and South African divers who want to explore the sardine run underwater. The sardine run is regarded as one of the major tourist attractions in KwaZulu-Natal between May and July.
In addition to tourism, the sardine run provides great fishing opportunities. If the sardine run cannot be positively anticipated or doesn’t occur at all, commercial fishermen will be subjected to high profit losses.
The delay in the sardine run also has a negative effect on the marine food chain. Predators such as the common dolphins and sharks, which prey on sardines, experience food shortages.
Large shoals of sardines were already sighted off the coast of Port Elizabeth in late April this year. The sea is expected to be overrun by fishermen during this year’s annual sardine run as many have been affected by the Covid-19 level 5 lockdown. The South African government transitioned the lockdown from level 5 to level 4 on 1 May 2020 and, in doing so, allowed essential fishing operations to resume.
The sardine run is one of the most spectacular wildlife events on earth. With millions of sardines scattering around, dolphins whipping about the surface and whales lunging to feed, it is certainly a site to behold. It’s important that we look after our environment or else this magnificent sighting could be a thing of the past.
Learn about why the sea is salty here
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