Now that death sentences have been imposed by a mainland court on 13 pirates who hijacked the Hong Kong-owned Cheung Son and murdered, or attempted to murder, 23 crewmen, other gangs involved in this heinous crime are put on notice that they, too, could pay the ultimate price for their murderous activities if caught in Chinese waters. The sentences are the first positive sign that the mainland is prepared to crack down on the pirate gangs who roam the South China Sea. Provincial authorities caused an outcry in international maritime circles this year when they released 16 pirates suspected of involvement in the hijacking of the MV Tenyu, claiming they were legitimate crewmen. They included two Indonesians allegedly involved in a notorious 1995 hijacking near Vietnam when 30 masked men armed with M-16 assault rifles, pistols and knives seized the bulk carrier and set its crew adrift in rafts without food or water. The decision to free the Tenyu gang - detained when the ship turned up repainted and renamed in Jiangsu province with its $15 million cargo of aluminium ingots missing - came months after Beijing publicly pledged at an International Maritime Organisation meeting to hold the men until a full investigation was completed. The previous year, security officials on Hainan Island released a gang who hijacked and terrorised the crew of a fuel carrier, the Petro Ranger. Piracy has become so widespread in the waters off China that local fishermen fear for their lives when they put to sea. Their concerns may be misplaced, since today's well-equipped international piracy syndicates are after far richer pickings. But these buccaneers have made all forms of sailing a perilous undertaking. They are a growing menace throughout Asia, well informed about maritime law and aware of countries where they cannot be prosecuted unless the crime occurs in national territorial waters, and who do not have extradition treaties to return suspects back to the scene of their crimes. They also prefer to operate in regions where they can bribe their way to safety, and where they feel at liberty to plunder and kill with impunity. Although loopholes in the law can be plugged by adopting existing conventions, international maritime organisations stress it requires the will of governments and the co-operation of shippers before the seas can be made safe. Increased patrols in the South China Sea would give due warning to hijack gangs that Beijing is determined to ensure all shipping has safe passage in these waters. Naval protection would drive the message home, establishing the mainland as a safe haven for seafarers, but a dangerous place for pirates.