Concerned residents have spotted hundreds of dead fish floating in the harbour at the V&A Waterfront over the last few days. This is, however not a cause for panic, marine experts say. In fact, it is a natural process that occurs every year.
An increase in mackerel numbers in the marina has caused depletion of oxygen as they compete with the existing mullet population for resources, Brett Glasby, Wildlife Management Programme Coordinator at the Two Oceans Aquarium’s Education Foundation told Cape Town Etc on Monday, March 29.
The lack of oxygen, due to algae and mysid bloom, causes a mass die-off in mullets every year. The dead fish in turn lead to an influx in natural predators like seagulls and seals, who can feed on them and this helps to clear away many of the fish.
And no, Glasby says, eating dead fish is not toxic for these predators, who are brilliantly adapted and can tuck in without getting sick.
The V&A Waterfront provides resources such as staff and sweeper boats to assist the Aquarium with the removal of the rest of the dead fish.
They get flushed from the marina systematically, returning oxygen and nutrients to the water and sustaining the breeding of the fish in the area.
Take a look at the current situation: