MB Civic

By ELISABETH ROSENTHAL

SUCURAJ, Croatia — Two decades ago, the channels that separate the Adriatic Islands here were brimming with giant bluefin tuna, a species so plentiful that tourists used to climb ladders by the sea to watch the schools swim by.

Today, these majestic predators are rarely if ever caught. “You have to work a lot harder to catch fish of any kind,” said Lubomir Petricivic, a fisherman who recently opened a restaurant in the harbor here. “Tuna? Impossible. We don’t have any; we can’t get it.”

The tuna population in the Mediterranean is nearing extinction, a new World Wildlife Fund report concludes, with catches down 80 percent over the past few years, even for high-tech trawlers that now comb remote corners of the sea in search of the hard-to-find fish.

“This is past the alarm stage,” said Simon Cripps, director of the global marine program at the World Wildlife Fund, who compares the situation to strip mining. “We are seeing a complete collapse of the tuna population. It could disappear and never come back.” The group is urging the European Union to impose an immediate fishing moratorium until the international body that regulates tuna catches meets in Dubrovnik, Croatia, in November.

Many edible fish stocks in the Mediterranean and its extension, the Adriatic, have sharply declined in the past decade because of pollution and intensive fishing, including crayfish and John Dory, according to the United Nations Food and Agriculture Organization.

In Croatia, much of the fish eaten at seaside resorts is imported from as far away as the United States.

But it is the bluefin tuna that is in crisis, thanks to a new and lucrative European network of fishing and fish farming companies that provide the prized fish to sushi and sashimi markets in Japan.

With tuna prices going as high as $15 a pound in Tokyo, European trawlers fish for tuna aggressively and illegally, far exceeding international quotas meant to protect the species, scientists said. Compounding the problem is the recent development of tuna fattening farms in Croatia, Spain, Turkey and other Mediterranean countries.

Now, even small juvenile tuna, captured in the few corners of the Mediterranean where the species still breeds or even from the Atlantic, can be brought to the vast underwater cages that line the Croatian coast, where they are fed for months or years until they are ready for market.

And so, though few tuna are in Croatia’s seas and none are in its restaurants, tuna is one of this country’s most lucrative food exports. One hundred percent of Croatia’s tuna is farm-fattened, ending up as toro — precious, fatty raw tuna.

Officially, the International Commission for the Conservation of Atlantic Tunas, or Iccat, restricts tuna catches across the Mediterranean to 32,000 tons to ensure the survival of the species. But the new W.W.F. report says that current fishing levels are 50 percent beyond that, because of “illegal, unregulated and unreported production.”

Because of the small size of fish being harvested for farms, “farming is being used to bypass attempts at regulation,” Dr. Cripps said.

Croatia regulates commercial trawling in its waters to protect local fisheries, with laws so restrictive that many local fisherman have quit. Abandoned fishing boats dot the coastline.

It is difficult for the relatively poor Croatian fisherman to compete in tuna fishing anyway, because hunting the species now requires long trips and expensive technology.

In the Mediterranean, high-tech tuna boats from countries like France, Italy and Spain use sonar and airplane spotters to find schools in the remaining tuna grounds, off Cyprus, Egypt and Libya.

But Croatia, with its vast pristine coastline, turns out to be a perfect place for fattening farms. Started less than a decade ago, they now employ hundreds of Croatians, 95 percent of them former fishermen.

Accurate population statistics on the fast and migratory fish are difficult to compile, and catches are self-reported, all of which presents a confusing picture at best. Numbers from fishing vessel surveys do not match scientific estimates, which do not match national reports or export tallies, according to the F.A.O.

But the anecdotal evidence of the tuna’s decline is alarming.

A ship owned by the environmental group Greenpeace spent a week recently trailing French, Italian and Spanish tuna boats in the far reaches of the Mediterranean with plans to confront a trawler engaged in illegal fishing; the crew’s hopes were stymied because it discovered that the trawlers had been unable to find a single tuna to catch.

“We went out trying to find trouble and what we found was a fishery on the brink of collapse,” said Karli Thomas, who was on the boat. “This industry has a limited shelf life.”

“Significant negative changes” have occurred in the fish stocks of the Adriatic because of overfishing, said Dr. Nedo Vrgoc of the Institute of Oceanography and Fisheries in Split, Croatia, with a particularly steep reduction in long-lived fish species like rays, John Dory and anglerfish.

Because of intense regulation of coastal waters and Croatia’s poorly equipped fleet, the situation is relatively better near Croatia than in the open Adriatic or the full Mediterranean, Dr. Vrgoc said.

“The open Adriatic is exposed to exploitation of the better equipped and several times more numerous Italian fishing fleet,” he said, and “there is almost no regulation.”

Tuna farms are licensed by the government and must conduct an environmental impact study, he said.

The huge thrice-a-day feeding frenzies on the farms put pressure on local fish stocks since the “food” is often bought from local fishermen, and the waste produced in the aftermath of the meals can lead to pollution.