Favourite Malaysian dishes such as fish head curry and clay pot prawns may soon be off the menu as thousands of fishermen refuse to go to sea in protest against new rules on net sizes. The decision by about 28,000 west coast fishermen - nearly all ethnic Chinese - is causing mayhem in the usually calm seafood trade, with shortages emerging after the protest started on Saturday. Prices of prawns, crabs and favourite fish like red snapper and white pomfret have shot up by 30 per cent to 80 per cent. Seafood restaurateurs, meanwhile, are getting desperate. 'I might have to import fish head from Thailand,' said Bala Chandran, owner of B-Sentral restaurant. The dispute centres on the 19mm mesh-size nets the fishermen use. The government wants them to switch to 38.8mm nets to protect the nursery grounds of juvenile prawns and fish and help restock the coastal waters. Environmentalists have long demanded a ban on 19mm nets and enactment of other stringent measures to stop overfishing and destruction of the coastal ecosystem. The new rule was enacted in 1985 but was not enforced for political considerations. But enforcement finally started on January 1. 'Fishermen must accept the fact that the government will not back down,' Agriculture and Fishery Minister Muhyiddin Yassin said. Since January 1 the ministry has only issued fishing permits for boats using the 38.8mm nets, thus preventing those with 19mm nets from putting out to sea. The ruling does not apply to fishermen in the east facing the South China Sea, most of whom are Malays, because they use small boats and do not trawl the seas. According to the Chinese daily Nanyang Siang Pau, the striking fishermen supply 30 per cent of the country's annual landing of 1.5 million tonnes of seafood.