DESTRUCTIVE FISHING Fishers in Southeast Asia have adapted to market demands by using specialized, often destructive, fishing techniques such as poison fishing and blast fishing. Each of these methods contributes to overfishing of economically important fish and may cause the unintended exploitation of countless other species, fundamentally changing the marine ecology of the region. Poison Fishing Traditional communities throughout the region have long used natural poisons to capture fish. However, these practices were typically small-scale and had only incidental consequences. Today, poison fishing is far more damaging. The commercial use of poisons to capture live reef fish began in the Philippines in the 1960s and soon spread to Indonesia, Vietnam, and parts of Malaysia. Poison fishing typically employs sodium cyanide, a deadly broad-spectrum poison. Crushed into plastic squirt bottles and applied to reefs by divers, the poison acts as an anesthetic, stunning fish and making them easier to capture. Unfortunately, other fish are damaged, killed, or left exposed to predation as the poison stuns them. Corals are also affected. Initial exposure can cause effects ranging from slight to full coral bleaching, and repeated applications of cyanide may cause coral death. Poisons are the predominant method used to obtain high-value live reef fish in Southeast Asia. The full extent of poison fishing is unknown because it targets some of the most pristine and isolated coral reefs, where observations are limited. (See Box 5) Governments and nongovernmental organizations in the region are working to combat poison fishing, which is illegal in most countries in Southeast Asia. However, poison fishing remains a widespread problem in Indonesia and Vietnam, where laws have been difficult to enforce. Blast Fishing Although outlawed throughout Southeast Asia, blast fishing is practiced regularly in most countries in the region. During World War II, Japan and the Allied powers left behind thousands of unexploded shells, littering the waters of Southeast Asia and the Western Pacific. In the past, these shells were repacked with explosives to make bombs for fishing. Today, fishers no longer employ World War II era shells but instead use dynamite or grenades. They also fill empty beer or soda bottles with potassium nitrate, an artificial fertilizer, and pebbles, topping them with a commercial fuse or blasting cap. The bombs kill most fish nearby by bursting their gas-filled swim bladders. Although some fish float to the surface, many sink and are not retrieved. Bombs can cost US1 -2 to construct but may bring in a catch with a market value of US15-40-' The effects of blast fishing can be devastating to both reefs and people. Prematurely exploding bombs have led to lost limbs and lives. Depending upon the distance from the substrate at the time of explosion, a typical I -kg beer bottle bomb can leave a crater of rubble 1-2 m in diameter The extent and severity of damage to reefs often depends on the amount and type of explosive, the depth of the water, and the distance to stands of corals. Regularly bombed reefs frequently exhibit 50-80 percent coral mortality" In a few areas, community-based education programs and active community management are helping to change fishing practices at local levels' Use of explosives on a coral reef destroys the reef structure, and can leave a crater of rubble several meters wide. Local conditions, including nutrient and sediment levels, presence of herbivores, and the availability of coral larvae, affect whether the reef will recover. < 28