Some scientists had speculated that the destructive "by-catch" of unwanted species in the South Pacific would not be as bad as that in the North Pacific, where the controversy over drift nets and the slaughter of dolphins and whales started.
But Michael Hagler, a Greenpeace official based in Auckland, said in a recent interview that the data collected between New Zealand and Australia in the Tasman Sea indicates that the by-catch is just as significant in the South Pacific.
"We expected to find that," said Hagler, head of the Greenpeace monitoring expedition. "We knew that drift nets are indiscriminate and deadly. They virtually catch and kill everything that enters the nets. If you know whales and dolphins are out there, you know they are going to get caught."
John McCoy, manager of fisheries research for the New Zealand government, said observations by New Zealand officials were consistent with those of Greenpeace.
"There were dolphins caught," he said. "There certainly is a by-catch. It would seem desirable in any case to reduce the catch of unwanted things in those nets - if they have to use them at all."
Calling drift netting "abhorrent," New Zealand Prime Minister Geoffrey Palmer announced a ban in May 1989 on the fishing technique within New Zealand's economic zone.
New Zealand and 19 other South Pacific nations adopted a legal convention in November banning drift netting in their territorial waters.
The United Nations also passed a resolution last year sponsored by the United States and Fiji calling for a moratorium on drift net fishing in the South Pacific by 1991 and a worldwide ban in 1992.
The South Pacific countries were most concerned about the depletion of albacore tuna stocks by fishermen using drift nets, with some scientists predicting that those stocks could collapse within two years if the catch remained as high as it was during the 1988-89 season.
Using an underwater "light torpedo" to illuminate the drift nets, which are typically set at night, Greenpeace divers and officials, who monitored the catch on the surface as the nets were hauled in, counted 1,419 tuna, five sunfish, six sharks, seven billfish, seven dolphins and 31 miscellaneous species, mostly Ray's bream. The catch was monitored on 10 consecutive nights in January in almost 80 miles of nets.
From that data, an Auckland environmental consulting firm developed catch rates per kilometer for each of the species and applied those catch rates to the total length of nets - about 500 miles - set each night by the 20-boat fleet in the Tasman.
"A drift net fleet of 20 boats working the Tasman Sea for three months during the 1989-90 season was predicted, therefore, to have caught some 900,000 tuna, 2,700 sunfish, 3,500 sharks, 6,300 billfish, 4,600 dolphins and 13,800 Ray's bream," according to a Greenpeace report.
Since there were another 20 drift net boats fishing waters in the South Pacific on the other side of New Zealand at the same time, Hagler said, it is conceivable that the actual catch on both sides of New Zealand could have been twice as high.
Hagler said that Greenpeace observers saw - and managed to save - only one whale, a rare southern bottlenose, during the monitoring expidition. But he said that the drift net fishermen were setting their nets in the Tasman Sea during the migration season for sperm whales.
"It's a gauntlet that these whales have to run," Hagler said, noting that Greenpeace oberserver had seen numerous sperm whales in the Tasman during the expidition. More likely, he said, some of them ended up in the nets - though Greenpeace monitors did not see any.
Hagler also said that in monitoring the by-catch, Greenpeace observed an ''immoral" practice by drift net fishermen of even throwing back much of the tuna caught.
Since the fish are caught by the gills when they swim into the nets, most are too damaged to live when they are thrown back.
"They throw back in some cases the majority of tuna they have caught
because it doesn't meet a certain standard," Hagler said.
The first drift net fishermen arrived in the South Pacific from Taiwan and Japan in 1987.
By late 1988, according to a report by the New Zealand government, at least 35 drift net boats were discovered in the Tasman Sea while another 130 were thought to be fishing the water east of New Zealand.
Under intense international pressure, both Japan and Taiwan agreed to limit their drift net fleets to 20 boats each during the 1989-90 season, which began in November and continued through January.
The data gathered by Greenpeace, according to its report, "supports reports that this fishing practice is directly responsible for an unacceptable number of marine mammal deaths in the Tasman Sea, and that it presents a hazard to non-target animals such as sharks and sunfish."