"As the fourth largest country in world fish production, Indonesia is a fisheries giant. Yet ... Indonesian marine fisheries resources are close to fully exploited and a significant number in all areas are over-exploited," she said.

Williams, a former director general of the international WorldFish Center, said the number of fishers was still increasing in most Southeast Asian countries despite a trend since the 1980s to close frontiers due to territorial claims and overfishing.

In the Gulf of Thailand, the density of fish had declined by 86 percent from 1961 to 1991, while between 1966 and 1994 the catch per hour in the Gulf by trawlers fell more than sevenfold.

In Vietnam, a new fishing power and a rising source of imports by Australia, the total catch between 1981 and 1999 only doubled despite a tripling of capacity of the fishing fleet -- a sure sign that fishing was reaching capacity, she said.

In the Gulf of Tonkin, where Vietnam shares resources with China, the record was even worse with fish catch per hour in 1997 only a quarter of that in 1985.

"In the Philippines, most marine fisheries were overexploited by the 1980s, with catch rates as low as 10 percent of rates when these areas were lightly fished," she said.

Williams said Southeast Asian fisheries were serviced by a plethora of regional bodies and agreements, but few acted effectively on illegal fishing and shared stock management.

At the same time, illegal fishing was "dynamic, creative, clever and usually one step ahead of authorities".

A Southeast Asian government may issue a single fishing licence only to find it being used by four different boats, she said. In Indonesia, foreign fishing vessels, often Chinese in joint-ventures, operated on the "margins of legality" in a geographically vast archipelago.