The main problem with the technique is that it is indiscriminate, according to its foes.

Tuna and swordfish are the most common targets, but the lines also snag as many as 4.4 million sea turtles, bullfish, sharks, marine mammals and seabirds every year, according to a study of the practice conducted for Costa Rica by Robert Ovetz of the California-based Sea Turtle Restoration Project.

One of the hardest-hit creatures is the migratory leatherback sea turtle, whose numbers in the Pacific have declined by 95 percent since 1980, according to Ovetz.

Scientists warn the leatherback could disappear in five to 30 years unless fishing techniques are altered.

Because it is migratory, traveling thousands of miles (km) every year to nest, international action is required to save it, according to the study.

The question of sustainable fishing practices will be one of several controversial practices on the agenda next week when delegates from 148 nations meet at UN headquarters in New York for consultations on oceans and marine law.

The conference will also focus on trash in the ocean and how to discourage dumping.

Longline fishing is practiced by vessels from many nations including the United States, Japan, Taiwan, Spain and other Asian and Latin American nations.

The value of its take at dockside is estimated at $4 billion to $5 billion a year.

Supporting Costa Rica's stand, 1,007 scientists from 97 countries have signed a letter to meeting participants urging decisive UN action to ban all fishing techniques that menace the leatherback "until such activities can be conducted without harm to the species."

Also backing the initiative are 281 private organizations from 62 countries.