Experts speculate on cause of massive fish deaths off Kwun Tong

Mass kill a mystery as clean-up continues and a putrid stench fills the air

PUBLISHED : Sunday, 12 July, 2015, 6:04am
UPDATED : Sunday, 12 July, 2015, 6:04am

Thousands of dead fish were floating off the Kwun Tong Typhoon Shelter yesterday, stinking to high heaven and startling passers-by and nearby residents.

The unsightly scene recalls the thousands of dead fish drifting in waters between Peng Chau and Discovery Bay in April.

In the current case, the Marine Department said it received a report at about 7am and sent three vessels to the area.

"About 2,000kg of dead fish have been taken away so far. The cleaning work is still ongoing," a department spokesman said in the afternoon.

He said no oil spillage could be detected, but did not explain the cause of the phenomenon.

The morbid scene was near the Kai Tak Cruise Terminal, which opened two years ago.

One passer-by said: "They stink really bad. There is also a lot of rubbish floating in the water." Others covered their noses as they hastened past the shelter.

Professor Chan King-ming, director of Chinese University's environmental science programme, believed the mass deaths could be the result of an algal bloom. He said the increasingly warm weather favoured the growth of algae. "During the day, algae make use of sunlight for photosynthesis. But at night, they take in oxygen from the water," he said.

The fish could have died of oxygen starvation, Chan said.

Another possible reason, he said, was that mud from construction projects nearby had entered the waters through the Kai Tak nullah.

The mud would also take away marine oxygen while facilitating the growth of bacteria, he said.

Ichthyological Society chairman Chong Dee-hwa, who visited the pier, had another postulation. He told Cable TV that last week's Typhoon Linfa might have loosened toxins accumulated at the bottom of the nullah, poisoning the fish.

Green Sense chief executive Roy Tam Hoi-pong, meanwhile, believed the fish deaths had to do with global warming.

"From my observations, we had one of the hottest Junes in the history of Hong Kong," Tam said.

"Global warming is becoming increasingly serious. Hongkongers are not aware of that because many are worried only about the stock market these days."

He said mass deaths of fish had been occurring in many parts of the world.

Last month, Australian authorities launched an investigation to determine the cause of the thousands of fish deaths in Tasmania, the Australian Broadcasting Corporation reported.