ood news for fish fanciers here and abroad. All but wiped out by pollution, over - fishing and loss of habitat, fresh trout and salmon are reappearing in supermarkets everywhere. Jumbo prawns, once something we only dreamed of eating, have become almost commonplace on restaurant menus. Soft - shelled crab, formerly a seasonal delicacy, is now available and increasingly popular year around. And there are signs that abalone, a famously scrumptious mollusc, might be poised to make a re-appearance at affordable prices.

Why? Aquaculture, long talked about as a potential solution to many of the world's food problems, has finally become a reality, currently accounting for 20 percent of all aquatic life consumed. Thailand, with its long coastline and abundant water resources, is a major player in the world of aquaculture and, since 1991, has been the world's largest producer of farmed shrimp. Furthermore, with a government eager to see more export income along the lines of the 100 billion baht that shrimp farming produced in 2000, appears likely to play an even bigger role in the future. Whether or not this is desirable, however, is another matter.

Shrimp farming, in particular, has proved a mixed blessing for the Kingdom. The income has been welcome, but the ecological damage has arguably been a disaster. The ponds used to raise the shrimp — usually tiger prawns — have often been built in or near mangrove swamps, leading to physical and ecological destruction of large areas of this valuable and irreplaceable resource. Pollution from the ponds has often had a devastating effect on the water of nearby areas, causing the destruction of valuable sources of food and other resources.

Aquaculture has been hailed as a sustainable way to use the world's resources, but this has often not been the case with Thailand's shrimp farms. Shrimp ponds are typically used for about four years and then abandoned because pollutants prevent them from being used any longer to raise shrimp. Abandoned ponds scar the landscape all over Thailand. Unfit for raising shrimp, neither may their polluted soil be used for traditional farming.

Although slow to react, the government does now recognize that significant environmental hazards accompany shrimp farming. In keeping with Food and Agriculture Organization (FAO) guidelines, it has established a voluntary code of conduct designed to ensure sustainable farming. The Department of Fisheries has also established regulations controlling pollution and the quality of shrimp produced. But some argue the regulations are poorly enforced, and that they apply primarily to large farms — those least likely to be causing problems in the first place.

Soft - shelled crab has recently been added to the list of cultured seafoods exported by the Thais. Ranong Province, 200 kilometres north of Phuket, is the centre of production. Soft-shelled crabs have long been an expensive treat popular on the eastern seaboard of North America and around Venice, Italy. But they're only available in these areas for the short season when they lose their hard shells. Limited supplies and the fact they must be captured by commercial fishermen mean they are always costly.

The soft-shelled crab eaten in North America and Italy is a "blue swimmer", but Thais have learned to raise mud crab species in ponds. As soon as the crab loses its shell, the farmer pops it into a plastic container and flash freezes it. Voila! Soft-shelled crab without the expense of fishing and the uncertainty of whether or not it will have a soft shell when captured. Some people say the mud crab tastes slightly different, but the proof of the pudding lies in the fact significant quantities of it are now exported to Chesapeake Bay, Maryland — the area where soft-shelled blue swimmers are held in highest esteem.

Although culturing soft-shelled crabs poses some of the same environmental threats as shrimp farming, these animals illustrate one of the reasons mangrove swamps need to be preserved. The commercial mud crabs aren't really cultured. They're captured when small — before natural predators have radically reduced their numbers — in mangrove swamps. They are then introduced to the "farms", where they're kept until they lose their hard shells. In other words, without the swamps, there would be no baby mud crabs and no soft - shelled crab for the table. Sadly for Thailand, one of the reasons Ranong is a centre for soft-shelled crab production is its proximity to Myanmar, a country where extensive mangrove swamps still survive.

Soft - shelled crab is available at most of Phuket's finer restaurants. The always popular Kan Eang, on Chalong Bay, has served it in a variety of ways for years. It's especially delicious deep fried or stir-fried with black pepper.

Perhaps the most exciting event in recent Thai aquaculture occurred right here on Phuket. Dr Sitthisak Muangsin, a veterinarian educated at Bangkok's Chulalongkorn University, is raising abalone at his Abalone Farm & Seafood Restaurant on Koh Sirey, a tiny island right next to Phuket Town. Once one of the most treasured of seafoods, this mollusc has become so rare that prices put it beyond the reach of everyone except those with Bill Gates - sized pocketbooks.

Abalones are farmed in other parts of the world, but farming costs make them almost as expensive as the wild version. Dr Sitthisak has not only solved the technical problems involved in raising abalone, he has also found two Asian species that grow quickly and yield large amounts of edible flesh. This allows him to sell his product at prices well below those charged for abalone obtained in the wild and at prices below those charged by abalone farmers in other parts of the world.

Right now, most of Sitthisak's abalone is shipped live by air to Taiwan and Japan. Next year, he hopes to expand production by selling small cultured abalones to local farmers who will then keep them in ponds until they're large enough for export. If this move proves successful, abalone fanciers everywhere will be eternally grateful, as it will be a major step forward in making the delicious mollusc more readily available and at prices almost everyone can afford. If you've never tried abalone, drop by the Abalone Farm & Restaurant on Koh Sirey. Discover for yourself what all the excitement's about.

In addition to high profile seafood produced primarily for export, Thai farmers grow large amounts of freshwater fish for domestic consumption. Although a recent addition to the Thai diet, Nile River tilapia is now the most popular species. These fish reproduce at a prodigious rate, grow quickly and are immune to many of the diseases associated with cultured fish. Tilapia production has been spurred by research conducted by His Majesty the King's projects. This fish species has become a favourite with Thais and is providing badly needed protein for people in rural areas.

Other freshwater species raised in significant amounts include catfish and pla chon, a fascinating creature often called "snakehead fish" or "serpent's head fish" in English. Unlike tilapia, these hardy fish are often raised in drainage areas and rice paddies, providing farmers with badly needed additional income. Both are available on Phuket, and are often overlooked by tourists bent upon eating only Phuket's famous seafood.

Catfish can be found at roadside stands and small restaurants specializing in food from Isarn, the northeastern part of the country. Pla chon are often coated in rock salt, stuffed with lemongrass and grilled at roadside barbecues. Dipped in a piquant sauce, the delicate white flesh makes for excellent eating — so good, in fact, that it's also beginning to appear on the menus of some of the Kingdom's upmarket seafood restaurants.