One of China's major provincial fishing grounds, east China's Zhejiang Province, has been warned to expect more red tides (algal blooms) this year.

"Red tides are predicted for the province's offshore waters as early as late April," said an official surnamed Zhang with the provincial oceanographic and fishing authority.

Red tides are usually algae and protozoa that kill fish and other marine life either by releasing lethal toxins or by taking up most of the oxygen in the water. They can do great harm to fishing and aquaculture industries.

Red tides normally break out during the three hottest months in Zhejiang - May, June and July.

The fishing and aquaculture industries in the province's famous fishing grounds, such as Zhoushan fishing zone, Xiangshan Bay and the offshore waters of Taizhou, have been urged to enhance their vigilance against red tides.

"Losses due to red tides can be reduced through measures such as promptly adjusting the density of farmed marine life according to changes in accumulated nutrients in the water," said Zhang.

"We strongly recommend local people engaged in fishing and aquaculture listen to relevant forecasts and tailor their activities accordingly."

The forecasts will be issued by the local oceanographic authority and be based on data collected by a specialized red tide monitoring and warning system. The system was introduced as part of the State Oceanographic Administration's decades-long campaign against the algae menace.

Zhejiang Province plans to achieve a total output value from its marine industries of around 20 billion yuan (US$2.4 billion) this year, accounting for 7.5 per cent of the province's gross domestic product.

But to reach this goal, as well as a grander target of 10 percent by the year 2007, Yu Guohui, an esteemed expert in oceanographic studies, urged the province to better protect its marine environment.

He said excessive fishing, large-scale engineering construction and the huge amount of residential and industrial sewage discharged into the sea have seriously damaged the one-time marine "paradise."

The more frequent red tides in the province were a sign of the damage done, Yu said.

(China Daily April 24, 2003)