Plans to hold a trial blast yesterday as part of a scheme to build a sewage treatment plant in Sham Tseng were called off after about 60 fishing boats sailed into the waters in protest. A five-month project to blast a trench in the rocky seabed to accommodate a 160-metre sewage outfall pipe for the $438 million plant was due to begin immediately if the trial was successful. Democratic Party legislator Albert Chan Wai-yip said the Government should commission an independent expert to review how much damage the blast would cause the fishing industry. There are 83 fish farms in the area with stocks worth $30 million. A spokesman for the Drainage Department said the trial was called off for safety reasons and had not yet been rescheduled, adding academics would study the impact of the blast.