The fate of a fish has the Pacific Northwest up in arms.

Nothing defines this region as much as its salmon, which were once so plentiful that Indians and early settlers could almost snatch them from rivers and streams with their hands. But after decades of decline, the federal government decided earlier this year that the salmon of Puget Sound and beyond are so threatened that they must be protected with extraordinary measures.

It is the first time that the Endangered Species Act is being imposed on metropolitan areas, and already there are signs that life across the Northwest may never be the same. The fight to save salmon could reshape the region's economy, limit development, curtail water recreation and maybe even play out in presidential politics.

Plans to expand shopping malls and build more suburban housing--the sprawling symbols of how robust the economy is here--are being reexamined if the projects brush too close to fragile salmon migration routes. Seattle is blocking construction of luxury waterfront houses and running newspaper ads that urge residents to stop using pesticides that harm fish habitats. Even an annual water skiing competition in suburban Seattle on Lake Ballinger has been canceled, out of concern that boat motors would damage water quality.

In the state legislature, lawmakers have just cut a deal with the timber industry for the sake of the fish. In exchange for millions of dollars in tax breaks, companies have agreed to limit logging near riverbanks because trees cool water in ways that help salmon spawn.

In Oregon, Gov. John A. Kitzhaber (D) has announced plans to destroy a few old dams to clear a better path for salmon and to spend $10 million restoring their habitats. The United States and Canada agreed last week on new quotas for salmon harvests and rebuilding fish stocks. Catholic bishops across the Northwest also just took the unusual step of issuing a pastoral letter calling for residents to make a commitment to improving the "spiritual vitality" of the Columbia River.

And all of that is only the beginning, officials say. Most local governments are still scrambling to resolve how their environmental and land use policies will have to change--and what the costs will be--because of the threat to salmon.

"Sometimes it seems like there are more salmon meetings going on right now than there are salmon," said Kathy Fletcher, the executive director of People for Puget Sound, a nonprofit conservation group based in Seattle.

The salmon debate is also beginning to cast a shadow over the race for president. It will largely be the job of the next White House to decide how toughly and how long the Endangered Species Act should be enforced here. And that in turn will have a powerful influence on how the region's mind-set and priorities may have to change. Political analysts say that in the Northwest, the fortunes of each party's presidential candidate could ride on views about salmon, for the fish have become symbols of larger debates here on everything from suburban sprawl to the rights of farmers and fishermen.

"We are all asking a fundamental question," said Tim Stearns, president of the advocacy group Save Our Wild Salmon. "What do we want our future to be?"

In a region filled with aggressive environmental groups, some communities are vowing to restrict growth, improve water quality, even to raise taxes. But there is no shortage of resistance to the salmon campaign, especially since the federal government is the driving force behind it.

State lawmakers just shelved a key part of Washington Gov. Gary Locke's (D) salmon recovery plan, his initiative to revamp laws on water use. Meanwhile, a coalition of business interests is suing the National Marine Fisheries Service, the federal agency at the heart of the salmon debate, to overturn the decision to list chinook salmon of Puget Sound as an endangered species.

In the eastern end of the state, farmers are furious with federal officials for banning them for months from pumping water from the Methow River, another salmon habitat. A few thousand people also turned out for a rally in support of dams recently. On a highway south of Seattle, a billboard even rails about "environmental communists."

"We don't want to see salmon disappear--we're Northwesterners," said Dean Boyer, a director of the Washington Farm Bureau, which represents 18,000 farmers. "But there has to be a middle ground to solving this issue. Right now our members are very afraid all of this is going to curtail their livelihoods."

Patrick McCourt, a builder in suburban Seattle, said that local governments are pressuring some developers to revise blueprints for projects that already have approval, such as a site for 50 new homes near the waterfront in Everett, Wash. "I guess we'll have to adapt," he said, "but there is absolutely no question that this is going to have a serious economic impact on all of us."

Skeptics call the decision to protect salmon with the Endangered Species Act an overreaction to a problem that could be addressed in other ways with far less disruption in the region. They advocate more restrictions on commercial harvesting of salmon and cracking down on predators that feast on the fish.

But others say the Northwest already has taken those steps, with little success, and has wasted too much time avoiding a hard truth: That everyday human habits, such as building roads and clearing trees near waterways, are most responsible for the harm being done to salmon.

"This will be a long and difficult path for the region," said Tim Ceis, the policy coordinator of the Endangered Species Act for King County, which includes much of metropolitan Seattle. "Around here, people seem to be recognizing that this is going to cause some pain, but they also see how it could improve their quality of life. In other parts of the state, they're digging in for a fight."

The Northwest has struggled for many years to protect salmon on their epic migration from rivers and streams to the ocean and then back to spawn.

Once it became clear that salmon runs were dwindling, officials initially adopted a strategy of conservation though chemistry: They began breeding millions of the fish in hatcheries and poured them into waterways. But the salmon still had to contend with the obstacles that man had placed along their migration routes.

Officials had an elaborate response for that too. They began loading millions of salmon on barges to get them past the dams. Then they even tried trucking them down highways to points along waterways where it was safer for the fish to be released to resume their journey. But the fish often proved to be less resilient than their wild, native counterparts. Some could not find a way back from the ocean.

Meanwhile, the region kept growing. And its salmon population kept plummeting toward extinction. Rivers in the Northwest that once had salmon runs exceeding 16 million fish barely reach 1 million these days.

The numbers are so low that federal officials say it is too risky even to let nature take its course any more. They are seeking permission from Congress to start shooting Puget Sound sea lions that have an insatiable appetite for the fish. The National Marine Fisheries Service already has shipped a few salmon-loving sea lions cross-country to Sea World in Florida.

The latest campaign for salmon represents a change in philosophy. It aims to confront the problem at a key source: human activities. But for that reason, many here doubt the region will make the sacrifices necessary to save the fish.

"I'm not confident at all yet," Stearns said. "We have a lot of industries in denial about the problem, and there is paranoia about the federal role."

Small but important examples of cooperation between some business and environmental leaders over the fate of salmon are emerging, however.

Along the Duwanish River in Seattle's busy industrial corridor, an estuary and a marsh channel that can serve as salmon habitats are blossoming out of what until recently were paved and fenced factory parking lots. Businesses are picking up the tab. Workers from a cement plant nearby are helping restore the sites to their natural origin. And the fish are slowly coming back.

Jacques White, a biologist who oversees the project, calls it a sign that all hope for salmon in the Northwest may not be lost.

"Ideas that were inconceivable in industrial areas a few years ago, people are taking seriously now," he said one afternoon as he walked along the river's edge checking progress at each site. "People realize we don't have the luxury of nibbling around the edges of this problem any more. And this is just the start."

CAPTION: FRAGILE MIGRATION (This graphic was not available)

CAPTION: Biologist Jacques White at the Duwanish River in downtown Seattle, where parking lots are being transformed into an estuary and marsh channel for salmon.