Red tide spreads, but officials decline to alert fish farmers
Agriculture and fisheries officials came under fire yesterday for not releasing a city-wide warning to fish farmers after a huge red tide spread through Hong Kong waters.
The extensive accumulation of algae, discovered at five southern island beaches, is believed to be the biggest since 1998, when the worst red tides in history killed 90 per cent of Hong Kong's farmed fish.
The algae, Cochlodinium sp, is the same one that formed a red tide at Ma Wan on Friday. It is non-toxic but in concentrations like that found yesterday it can deprive fish of oxygen.
A red tide expert urged the government to issue a city-wide alert because the algae could be spread by impending heavy rain.
But the Agriculture, Fisheries and Conservation Department said there was no need for such a notification.
The red tide was first discovered at Repulse Bay, South Bay, Middle Bay and Chung Hom Kok beaches at around 10am. Deep Water Bay nearby was affected a few hours later.
Lifeguards raised red flags at all five beaches and used loudspeakers to advise swimmers not to enter the water. At Repulse Bay, a swimmer coming out of the water said it had an odd smell.
The department, which confirmed the species from water samples, said it had notified fish farmers on Lamma Island, the nearest to the southern beaches, and asked them to report any fish deaths.
But the spokesman insisted there was no need to notify all fish farmers.
He said red tides were common, but the number had fallen from 41 in 2005 to 14 last year. From January to June 1 this year, six had been found.
Red tide expert Ho Kin-chung of the Open University of Hong Kong urged the department to inform all fish farmers as the red tide may spread 'all over Hong Kong' if the heavy rains forecast for later this week come to pass.
He said red tides caused by regional water pollution had been on the rise in recent years.
That was reflected in the increased number discovered in southern waters and Ma Wan, which lie in the channel from the highly polluted Pearl River Delta, Dr Ho said. Heavy rain in the past few days could have brought into Hong Kong waters the delta's polluting nutrients, which stimulate the growth of algae and caused the latest red tide, helped by the hot weather, which also speeds up the algae's growth.
Man Chi-sum, chief executive officer of the environmental group Green Power, said the department had underestimated the problem, adding he was worried that more fish farms will be affected.
'The department should notify all fish farms so that they can be better prepared, such as getting some oxygen pumps in hand to get fresh air into the water to help fish breathe,' Dr Man said.
Legislator Wong Yung-kan, who represents the agriculture and fisheries sector, also criticised the department. 'Even if the species is non-poisonous, it will use up oxygen in the water and kill the fish,' he said.
