Two serious red tides of toxic algae have been found in the Bohai Sea, the only inland sea in China, posing serious threat to fishery in the area, China's State Oceanic Administration (SOA) said in Beijing Tuesday.

One of the red tides that was found Friday near the mouth of the Yellow River, the second longest river in China, affected an area of 1,850 square kilometers, but diminished to 1,200 square kilometers the next day, said Chen Lianzeng, deputy director of SOA.

"A large number of remains of mosquitoes and flies could be seen floating on the surface of the affected water, but there is no sign of massive deaths of shellfish," he said.

Another red tide witnessed near Tianjin, the major port city in north China, was much larger, he said, adding that the affected area was 3,200 square kilometers when it was found Saturday.

"The red tides are continuing and could expand in the coming days," Chen said.

SOA has issued an urgent circular, urging localities around Bohai to closely monitor the tides and ensure that all the shellfish and other seafood be toxin-free before they are allowed into the market.

China in recent years has been witnessing rising occurrences of red tide, which was a result of worsening human and industrial pollution of sea water and consequently the deteriorating oceanic ecology. In return, the situation created ideal conditions for the toxic algae to prosper.

Since the 1980s, red tides have struck the Bohai Sea over 40 times, causing economic losses worth several billion yuan, as the sea has become a major pollutant absorber in north China.

The East Sea is another one that has been increasingly affected by harmful algae bloom. Recent SOA figures indicated that in May, 34 red tides were recorded in China's coastal waters, of which 31 occurred in the East Sea, affecting an area of more than 10,000 square kilometers.

Last year, a red tide of toxic algae hit China 119 times, 40 times more than in 2002, affecting approximately 14,000 square kilometers.

To better monitor the occurrence of harmful algae blooms, China has set up 33 surveillance zones along the country's coastline, and accurate predictions of red tides have been provided to the public.

"The key to winning the battle against red tide is to improve marine environment," said Ma Deyi, director of National Marine Environment Monitoring Center under SOA.

He called for more effective measures to reduce the amount of the land-based pollutants into the sea, including industrial wastewater and nitrogen from agricultural fertilizers.

Source: Xinhua