Fishermen in more than 100 boats laid a siege to the Lamma Thermal Power Plant yesterday in protest against the newly built rock berm around its gas pipeline because it had reduced their catch considerably.

The fishermen, members of Hong Kong Fishery Alliance, blew horns and shouted slogans, demanding the removal of the berm. Later, they handed a petition to an official of Hongkong Electric Company (HKE), which owns the power plant.

The rock berm, or the "under-sea great wall" as the fishermen call it, has blocked currents and oxygen in the water around it, they alleged. Many of their nets were broken, too, after getting entangled in it.

Their catch had dropped by as much as 30 per cent, from about 10,000 to 7,000 catty a day, after the berm was completed in August, they said.

Therefore, HKE should remove the berm and pay HK$100,000 to 500,000 each to the 2,000 fishermen as compensation, they demanded.

Alliance chairman Keung Yin-man said the 18-kilometre-long, 3-metre-high and 80-metre-wide berm ran through the most productive fishing area of Hong Kong.

Though 10 meetings have been held between the alliance and the HKE since March, the company has not yet agreed on the amount of compensation.

HKE general manager (projects) Tso Che-man claimed that his company's environmental impact and risk assessments both had taken the fishermen's needs into consideration before the berm was given a final shape.

He said he understood the fishermen's worries but denied that the natural gas pipeline or the berm had anything to do with the reduced catch or environmental damage.

The 20-inch-wide pipeline is 92-kilometre long and runs up to Shenzhen, and was built after an environmental impact assessment and in accordance with the Environmental Ordinance 499, he said.

After the environmental impact assessment was completed, the company took some relief measures, such as keeping the pipeline as close as possible to Hong Kong waters' boundary.

Tso said HKE had used the most environmentally friendly method to build the pipeline to ensure that minimum harm was caused to the marine ecology.

According to the company's calculations, about 150,000 ocean liners pass through Lamma Channel every year. That's why experts had suggested that the pipeline be protected with extra rocks.

The pipeline is the only way the company can get natural gas for its power plant, Tso said. And if the berm was removed, it would damage the company's operation and its electricity supply.

He quoted the Environmental Protection Department as having said that water quality in the pipeline area had been normal since January.

The company has paid an ex gratia to the Lands Department, he said, without disclosing the amount, and was awaiting more objective data before paying any compensation to the fishermen.

HKE "has done the best of what could have been done", he said, and hoped the government could intervene and settle the issue as soon as possible.

The Agriculture, Fisheries and Conservation Department (AFCD) has already formed an inter-departmental task force to find out if HKE had fulfilled all the requirements for the project, a spokesman said. The task-force is to submit its results by next year.

It has been collecting fishermen's opinions for some time now, and would conduct a study to determine if the project had harmed the marine ecology and and/or the fishing industry.

But the AFCD has ruled playing an intermediary's role in the dispute between the fishermen and the company.

They should hold direct talks to decide the amount of compensation, the spokesman said. The department can provide the technical opinion, if and when needed.