A Toxic Solution : SCIENCE FILE / An exploration of issues and trends affecting science, medicine and the environment : The growing use of cyanide to stun and catch tropical fish is killing off coral reefs, researchers say. Divers are using the poison to meet the demand from restaurants.

A diver slips into the crystalline waters off Southeast Asia. Spotting a highly prized fish--worth $80 a pound in Hong Kong restaurants--he sprays the rainbow-colored reef with a milky liquid from a squirt bottle.

Almost instantly, dozens of smaller, less-coveted fish die as the diver nabs his large prey--live--and moves onto another section of the sea floor. Within days or weeks, a once- vibrant coral reef can turn into a ghostly white skeleton, and in extreme cases become almost devoid of life.

Many of the world’s most spectacular and remote coral reefs are turning into piles of rubble from tons of cyanide that fishermen are squirting--or in some cases dumping--on shallow reefs to stun and catch live fish for Asian restaurants, according to a report by an Australian reef ecologist and a New Zealand fisheries economist.

For the first time, the research documents the increasing demand for live tropical fish in overseas restaurants and the rapid expansion of large operations using cyanide to catch them.

Export of live reef fish to Asian restaurants is a $1-billion industry. Affluent gourmets in Hong Kong and China will pay four to eight times more for a tropical fish if it is displayed alive in a tank moments before it is served at their table, according to the researchers. One delicacy, humphead wrasse lips, fetches over $200 per plate.

An estimated 150 to 400 tons of cyanide are now used annually by fishermen in the Philippines in a practice that began in the mid-1980s on a much smaller scale to collect fish for aquariums, according to one international group that monitors the trade. The poison is used to drive large fish from the reef, but the aftermath often is scores of smaller, dead fish and a barren reef that takes decades to recover.

“This is the ecological equivalent underwater to clear-cutting a forest,” Robert Johannes, the report’s principle researcher and author, said in a recent interview. “It becomes an underwater graveyard.”

The cyanide--the same potent poison used in gas chamber executions--jeopardizes a sensitive underwater resource already injured worldwide by numerous man-made dangers, from raw sewage to clumsy scuba divers and boaters.

“Most Americans cherish the notion of being able to visit a Pacific paradise, and at the rate [the reefs] are disappearing, there won’t be many to visit anymore,” said Johannes, a reef ecologist from Tasmania and a Pew Fellow in environmental research who has spent years in Southeast Asian and Pacific villages tracking fishing practices.

Live reef fishing spans “a range equivalent to about one-quarter of the Earth’s circumference--from the Maldives in the western Indian Ocean to the Solomon Islands and Australia in the Pacific,” according to the report.

Although cyanide use has been documented in only part of that range--mostly the Philippines, Indonesia and Palau--fish populations there have been so decimated by the practice that the fishermen are moving their operations to the even more remote Papua New Guinea and Solomon Islands near Fiji, the researchers said.

“The region’s most remote and pristine reefs are among the industry’s most tempting targets,” says the report, which was funded by a South Pacific government fisheries forum, the Nature Conservancy and the Pew Scholarship in Conservation and the Environment.

Cyanide fishing appears to pose not only an ecological problem but a social and an economic one because the food and incomes of poor fishing villages are being decimated by larger, wealthier foreign fishing operations, especially from Hong Kong.

Some operations are so large that their specially designed boats can hold 24,000 live fish in water tanks and employ as many as 20 divers. Each diver can average nine fish a day, and uses roughly a liter of cyanide solution to catch three fish, Johannes said. The targeted fish are usually large enough to be stunned, but remain alive, although smaller ones on the reef often are killed immediately by the cyanide.

Philippine-based marine biologist John McManus reported seeing a 55-gallon drum of cyanide emptied from one motorboat, while another source told Johannes that he saw a line of fishermen each pumping cyanide into the water from five-gallon buckets.

“That was really shocking,” Johannes said. “It’s uncommon, but it’s not rare.”

Because the quantities of cyanide that collect in the live fish are small, the chemical is believed to pose little toxic risk to people who consume them.

A reef, however, is much more vulnerable to the poisoning.

Cyanide kills the multihued algae that grow on a reef, bleaching it and then causing its coral tissue to rot and become overgrown with dark scum. The reef’s vibrant hues are gone. The brightly colored fish vanish. And the turquoise waters often turn murky.

According to newly conducted laboratory tests, the damage begins at potencies of cyanide many times lower than Johannes found in fishermen’s bottles.

Tests by University of Guam researcher Robert Richmond show that coral began to bleach within four hours, and 90% was dead within four days, after exposure to four parts cyanide per thousand parts water. It started to die after three weeks at a much lower dose of one part per 10 million. The typical dose in a diver’s squirt bottle is 20 parts per thousand--thousands of times greater potency than the lowest concentration shown to kill reefs, Johannes said.

He acknowledges that there is no scientific data detailing how many miles of reef have died, because it would take years to perform extensive underwater dives. But he says all the anecdotal, biological and economic evidence he collected points to what appears to be a disturbing amount of damage linked to cyanide.

Among the most alarming findings, he said, are fishermen’s descriptions of the rapid depletion of once-thriving fisheries--some within a year’s time--and the 25,000 tons of live fish exported annually to Hong Kong. Included in the project were interviews Johannes conducted with more than 100 fishermen in about 30 villages.

One Filipino fisherman who worked with a large cyanide fishing crew for 1 1/2 years told Johannes that about 80% of the reefs that were healthy off his island in the early 1980s are now dead.

“The fish importers give Indonesia another three to five years before its reefs are in a similar state,” the report says. “By unfortunate coincidence, the coral reefs of these two countries constitute the very center of the world’s marine biological diversity.”

This week, Indonesia’s environmental minister met with officials from surrounding nations to discuss global solutions to the fisheries depletion described in the report.

Reef fishing need not be outlawed, Johannes said, just controlled. If local villages rather than national governments were granted the right to outlaw foreign operations, they would have incentive to preserve their reefs by enforcing a cyanide ban and fishing in a sustainable way, he said.

“Many fishermen are initially against the use of cyanide,” he said, “but after a while, they find themselves forced into it so they can compete” with foreign operations.

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Poisoned Reefs

The lucrative business of harvesting reef fish has depleted many of the Earth’s most bountiful marine waters. Most damaging is the fairly new but widespread practice of spraying cyanide on coral reefs to harvest the fish. Eastern Indonesia and the Philippines are home to the world’s richest coral reefs, but cyanide bleaches them, killing algae and fish and rotting the reef itself. In recent years, the technique seems to be spreading to even more remote reefs in Palau and perhaps Papua New Guinea.

This map plots the harvesting of reef fish that began off China in 1968, using traditional hooks and lines. But as fish become depleted there, fishermen started to move to more remote islands in the 1970s, and turned to the use of cyanide to accelerate their catch in the early to mid- 1980s.

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1. 1968: Pratas Islands / China: Fisheries depleted.

2. 1970: South China Sea: Fisheries depleted.

3. 1975: Philippines: Extensive use of cyanide since 1982. Fish stocks severly depleted.

4. 1984: Palau: Cyanide fishing documented. Major spawning areas depleted.

5. 1989: Indonesia: Fish stocks greatly depleted. Major use of cyanide reported.

6. 1991: Papua New Guinea: No proven use of cyanide yet, but anecdotal reports are surfacing.

7. 1993: Great Barrier Reef: Hook and line fishing. No known cyanide use because of crackdown by Australian government.

8. 1994: Maldives: No proven use of cyanide, but some depletion noticed within past year.

9. 1994: Solomon Islands: No live reef fishing yet, but Australian and Hong Kong firms have bid to start it.

Source: October, 1995 report by ROBERT JOHANNES and MICHAEL RIEPEN