A new study of fish stocks around the world found that while 63 percent of commercial species have been fished to perilously low levels, many species have rebounded when fishing pressure is scaled back. The study, which included University of Washington scientists, is the most comprehensive look at fish stocks yet.

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When a study two years ago warned that commercial fisheries could be wiped out in 40 years, University of Washington biologist Ray Hilborn got out his flamethrower and blasted what he called a “mind-boggling stupid” conclusion.

The other side fired back, and for a while it looked like a full-fledged fish war would break out between scientists who forecast doom and those who see reason for hope.

Then the groups started talking to each other.

The result is a new analysis published Thursday in the journal Science that provides the most comprehensive look at fish stocks around the world. While the researchers found 63 percent of commercial species have been fished to perilously low levels, they also report that many species have rebounded when fishing pressure is scaled back.

“The bad news is that this analysis confirms there is an increasing trend toward species collapse in fisheries,” said Boris Worm, a marine ecologist at Dalhousie University in Halifax, Canada. Worm was the lead author of the 2006 study that predicted marine harvests would peter out by 2048.

Now he believes the situation might not be quite that grim by midcentury. The new analysis shows that it is possible to rebuild ecosystems, and that future collapses can be avoided if nations act wisely.

If he makes it to 2048 — he’ll be 79 years old — Worm said he hopes to host a seafood party.

But the scientists cautioned that there’s little monitoring of the 75 percent of the world’s seafood catch that comes from the developing world. As wealthy nations tighten fishing regulations, industrial fleets shift to Africa, Southeast Asia and South America. “This is going to cause a lot of … stock collapses in the coming decades,” said co-author Tim McClanahan, of the Wildlife Conservation Society in Kenya.

Worm and Hilborn launched their collaboration after debating each other on an NPR radio program. “We realized we actually shared as much in perspective as we differed,” said Hilborn, who was familiar with thriving fisheries through his work in Alaska. Working with 19 other experts from around the world, the researcher spent two years analyzing 10 major fishing regions from California to Australia.

Whereas Worm’s earlier study relied only on catch data, the team factored in population surveys, statistical analyses and models that examine the way fish species interact in ecosystems.

“I think they’ve done an excellent job of using the best information they can find … and I think the conclusions are much more robust,” said Steve Murawski, chief scientist for the National Marine Fisheries Service.

The study found the healthiest fish populations in Alaska and New Zealand. The other ecosystems had been seriously overfished in the past, but stricter rules have reduced harvests and are leading to recovery in five areas, including the Northeastern United States, Iceland and Southern Australia. Scallops are at record abundance in New England, and haddock populations are at their highest levels since 1930, Hilborn pointed out.

Fisheries managers learned from past mistakes, said Jim Cowan, a fisheries biologist at Louisiana State University who was not an author on the new study. “There are more fisheries in the world that are recovering now than are declining,” he said.

The improvements were achieved through measures that include limits on the number of fishing boats, quotas for individual fishermen, nets that allow vulnerable fish species to escape and the establishment of protected areas where fishing is off-limits.

Cutbacks have been painful for fishermen, but in the long term, fishing communities and ecosystems both benefit, Hilborn said.

In some areas, harvests still need to be cut by half if fish species are to remain healthy, Worm said.

Eastern Canada offers a cautionary example of what happens when protections are implemented too late. Fishing levels were slashed in the mid-1990s as stocks crashed, but so far, none of the commercial species is bouncing back, Worm said.

“There actually is a point … beyond which it may become very difficult or impossible to recover.”

Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com