1 / 4   The annual sardine run, the biggest migration of marine wildlife on the plant, started in March this year. The dolphins swam at high speeds of up to 15 knots, chasing the sardines through Algoa Bay, until they eventually tired out and formed a so-called bait ball, a mass of fish up to 100 meters in diameter, which hovers just under the surface of the sea. /VCG Photo

2 / 4   The fish try to form a huge mass to survive attacks from their predators./VCG Photo

3 / 4   However, the dolphins form a spiral trap. This confuses and traps the sardines, preventing them from escaping. /VCG Photo

4 / 4   Photographers Sike and Rainer Schimpf, experts at documenting the migration of marine wildlife, followed the large pod of dolphins that were tracking the sardines in Port Elizabeth, South Africa. /VCG Photo