Cape Town - V&A Waterfront says its Marine Wildlife Management team is removing the hundreds of dead fish seen floating in the water over the past week.
V&A Waterfront spokesperson Donald Kau said every year mullet breed in the basin, and this year the number was quite high.
“We also saw a large school of mackerel entering the harbour, and the high volume of fish obviously impacted on the levels of oxygen in the water, causing the fish to die.
“The dead fish are a great source of food for the Cape fur seals and the sea gulls, hence the heightened activity of marine life in the harbour.
“It is also confirmed that the school of mackerel was followed by a pair of humpback whales, so the harbour basin literally had a ‘system overload’,” said Kau.
“The marine and harbour team see this kind of activity every year and when it happens they mitigate the reduced oxygen by opening the lock and flushing the bay with the water from the canals. This gets done up to six times a day. They indicated that one sometimes sees similar events at estuaries, and it’s a very ‘natural occurrence’.
“The mullet return every year to breed and their numbers are being monitored,” he said.
No links have been established between the dead fish at the V&A Waterfront and the pufferfish washouts experienced in recent weeks.
The Department of Environment, Forestry and Fisheries last week linked washouts and mortalities of pufferfish on various parts of the coast of Elands Bay to north of the Olifants River estuary, in the port of Cape Town and in False Bay, to current deep-water conditions, saying this was probably driving fish and shellfish into the warmer, shallower and more oxygen-rich nearshore.