A tourist dreamscape has turned into a deathtrap at Cape Town’s Victoria & Alfred Waterfront marina, where a millionaires’ playground is under siege from tons of rotting fish.
This week, marina staff were preparing to flush their prestigious facility to dislodge a layer of decomposing horse mackerel lying beneath a flotilla of luxury powerboats and yachts.
The fish swam into the V&A harbour in a massive shoal in March during what was described as a rare natural phenomenon. They became trapped and died en masse after depleting the water’s oxygen.
• 200m - Litres of water in the V&A marina
• < 1% - Oxygen left in the water
— In Numbers
Almost three months later the fish are still on the marina bed, to the dismay of surrounding residents whose swanky apartments now have a view of a milky white chemical soup.
Boat owners are concerned about damage to their vessels, including several new leisure catamarans awaiting export. The situation has also affected the adjoining Two Oceans Aquarium, which used to draw water from the marina.<
The V&A is planning to oxygenate the marina artificially in an attempt to accelerate the decomposition process and allow the water to return to normal. It is also installing pumps to increase water circulation.
In a statement on its website, the V&A said the situation is the result of a chain reaction that probably started when whales chased the fish into the harbour. The unusual event coincided with an algal bloom that depleted the water’s oxygen levels.
“When the dead fish start to decompose, they remove even more oxygen from the water,” said the statement by the V&A’s marine and industrial executive head, Andre Blaine.
“Good bacteria is replaced by another bacteria that survives in very low-oxygen environments, and this starts a process that releases hydrogen sulphide. That’s the unpleasant odour you smell. It also changes the colour of the water.”
V&A spokesperson Donald Kau said experts and aquarium scientists are being consulted, and a marina official said pH test results showed there is no risk to boats in the marina.
Aquarium spokesperson Renée Leeuwner said it has shut its secondary intake pump from the marina. “Our main intake pump is close to Mandela Gateway, far enough from the V&A basin that water quality there is largely unaffected at present,” she said.
The colour of the dead zone prompted a comparison with tropical water on a popular news website: “We felt like we were in the Seychelles, nogal!” said the writer, a remark quickly shot down by boating commentators on social media.
Another commentator described the “green pungent water” as a boating liability “damaging anti-fouling coatings and even corroding stainless-steel fittings”.
A group working on a power boat in the marina this week told the Sunday Times they believed the water had eroded steel anodes attached to the keel to prevent corrosion.
A resident of the adjoining marina residential estate said her neighbours had to keep their doors closed for two weeks due to the fishy smell — which has since abated as the fish sank to the bottom.
Luxury boat broker Derrick Levy from Boating World South Africa said he could not run his vessels’ air-conditioners in the basin for fear that the water they use could cause damage. Another broker said he had lost clients who fled due to the smell.
The V&A is hoping to help establish Cape Town as a global superyacht repair and service hub and said it is investigating plans to develop a dedicated superyacht quay opposite the Table Bay Hotel.
Photographer Jean Tresfon, who took aerial photographs of the marina’s unusual appearance, said he witnessed the “insane scenario” when the fish entered the harbour.
“I was up in the air [in a gyrocopter]. There were huge rugby field-size shoals of fish with multiple whales and dolphins and seals feeding on them. So I’m not surprised that the fish went into the harbour.”
Cape Town marine biologist and Sea Search co-founder Simon Elwen said the abundance of sea life, while causing a temporary problem at the marina, is at least good news for the marine environment.
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