Fishermen Barred From Using Explosives on Dolphins

In a victory for environmentalists, the National Marine Fisheries Service has moved to prohibit tuna fishermen from detonating percussion bombs near dolphins swimming with schools of tuna.

The new prohibition, which takes effect Sunday, covers the 26-boat U.S. tuna fleet, representing about 20% of the world’s Pacific tuna fleet. The U.S. fleet, based in San Diego, fishes in the eastern Pacific from Southern California to Chile.

Foreign tuna ships will have 180 days to voluntarily comply with the prohibition or face an import ban on their fish.

An estimated 100,000 dolphins are killed each year in the eastern Pacific when they are caught in tuna nets. Environmentalists say they believe a “significant number” will be saved by the ban on percussion bombs.

But officials of the National Marine Fisheries Service said the main benefit will be sparing many dolphins from injuries, especially to their hearing.

E. Charles Fullerton, regional director of the Fisheries Service in Los Angeles, said dolphins use their hearing as “underwater radar. We really don’t know what the total effect (of hearing loss) could be but it could impair them from hunting for food.”

Biologist David Phillips, director of the San Francisco-based Earth Island Institute, added that with the ban, “hundreds of thousands of dolphins won’t be subjected to deafening blasts. Their sound is way more important than our sight is to us. A deaf dolphin is as good as a dead dolphin.”

Officials of the San Diego-based American Tunaboat Assn. could not be reached for comment on the ban, but Fullerton said the rule is not expected to reduce the tuna catch. He noted that fewer than 10 of the U.S. fleet’s 26 boats now use the explosives.

According to reports from government observers on U.S. tuna boats and the Earth Island Institute, many fishermen have relied on the explosive devices, known as “seal bombs,” in catching tuna.

Each bomb, which Fullerton said has the explosive power of an old-fashioned cherry bomb, contains no more than 40 grains of explosives. But Phillips said some tuna boats have been known to use explosives manufactured in Mexico, Panama and Costa Rica that are twice as powerful.

A just-completed Fisheries Service study found that dolphins suffered injuries when even the lighter-impact devices were detonated within 1 1/2 feet of them.

Biologist Phillips said in a telephone interview Tuesday that tuna fishermen typically locate the tuna by watching for surface-skimming dolphins, which travel with large yellowfin tuna.

Once spotted, the dolphins are slowed down and rounded up with the use of the seal bombs, which are hurled from helicopters, speedboats and from the deck of the tuna ship as the net is drawn in. The bombs disorient and frighten the dolphins, causing them to swim closer together for safety and allowing the fishermen to put a net around them and the tuna.

The Fisheries Service said an average of 200 bombs are used for each netting.

Once the tuna are trapped, more bombs are used to chase the dolphins to an open end of the net so that they can escape.

In 1988, Congress amended the Marine Mammal Protection Act to prohibit more powerful explosive devices in tuna fishing operations, but it exempted seal bombs pending a study of their effects on marine mammals.

Congress authorized the continued use of the devices only if the fisheries study found they would not kill or injure dolphins.

The ban will become final in 30 days after a period to accept public comment.