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Fisheries Issues in the News
Wednesday 30 June 1999
Salmon use sun, familiar smells as guide back to birthplace
They're back again. Hundreds of silvery Puget Sound salmon, soon to be thousands, leaping up local streams and fish ladders and posing for snapshots behind the underwater window at the Ballard locks.
Despite their newfound status as endangered species, there will be plenty of salmon to astound tourists and natives, who once again will consider the salmon's saga and ask: How do they do that?
How does a Puget Sound fish traverse thousands of miles of ocean, yet return faithfully to its native river and stream to spawn? How does it distinguish between one river and the next? How does this seemingly primitive creature exhibit navigational abilities that rival man's most-sophisticated technology?
The short answer: Nobody knows.
But scientists are working on it. And now the question may be more timely than ever, since that homing mechanism is what determines the genetic differences between one run of salmon and the next - and between one that is endangered and another that is not.
Decades of research, much of it at the University of Washington, appears to be zeroing in on the salmon's navigational process - or processes, because it appears there is more than one.
This according to Tom Quinn, who has spent 20 years trying to unravel the mysteries of the salmon's homeward migration.
From his corner office at the UW School of Fisheries, Quinn looks over Portage Bay and the artificial rearing pond and concrete fish ladder that have been the scene of salmon research for half a century. It was here, in the early 1950s, that scientists demonstrated the extraordinary homing instincts of the Pacific salmon.
The experiment went like this: Juvenile coho salmon from Soos Creek were moved to two alternate sites - the university and the Issaquah hatchery - then marked and released into the lakes, where they migrated to the ocean for two or more years. "When they returned as adults," Quinn says, "UW fish returned to the UW, Issaquah fish returned to Issaquah, and none returned to Soos Creek."
This established that the salmon's navigational impulse is primarily learned, not inherited, Quinn explains. If the trait had been inherited, the fish would have been drawn back to Soos Creek.
Lost with a plugged-up nose
The navigational process appears to have at least two stages. At the beginning and end of the salmon's life, it is primarily "olfactory"; that is, the fish smell their native stream.
This, too, has been established by experiments, Quinn says. Salmon from a specific run were captured, blinded and released again; they still found their way home. But fish from the same run whose noses were plugged became lost.
Streams differ in chemical composition, Quinn explains. Each has its own unique mix of minerals, plants and chemical scents, which might not be detectable to humans but make a big difference to fish.
Salmon appear to learn the odor of their stream very soon after hatching. Each fish becomes "imprinted" with the distinct smell of its native stream. "It is spontaneous learning," Quinn explains. "There is no reward, no punishment, no reinforcement, positive or negative."
The fish then go to sea. The creature will not need the odor information until its return migration, one-to-three years later. But the memory persists. As the fish approaches its home territory, it will begin picking up traces of its native stream. Molecules of water will pass into the fish's olfactory "capsules," nostrillike openings in front of the eyes, and past sensory tissues which detect the distinct odor of the home stream.
The scent need not be natural. In another UW experiment, water in the salmon-rearing pond was tainted with artificial chemicals before the juvenile salmon were released. Years later, the returning fish were drawn to the artificially tainted fish ladder.
And, just as the fish detects the scent of its native stream, it also detects the absence of that scent. Research on the Columbia River shows returning fish will take wrong turns into tributaries and travel briefly upstream. Most, however, correct their mistake, backtrack to the main river and resume the upriver migration in search of their birthplace.
More recent research suggests that for some salmon there is more than one imprinting. Lake Washington sockeye, for example, stop along the way both downstream and upstream to feed or rest. The pauses are so routine that they must be programmed, Quinn says. This sequence of imprints might be triggered by hormones, which increase during the salmon's upstream journey, Quinn says.
Either way, the homing instinct is nearly perfect. Of the fish that survive in the ocean, about 98 percent will find their way home to spawn. But even the 2 percent or so that stray serve a critical biological function. They expand the domain of the species.
If not for these errant fish, Puget Sound would have no salmon. Some 12,000 years ago, Western Washington was encased in ice up to a mile thick. As the glaciers retreated, they carved a new topography, a process that continues today.
Salmon had to start over again. Repopulating Puget Sound required at least two stray salmon, a male and female, from distant runs that were not glaciated. Ever so gradually, those occasional strays gained a finhold in one river, then another. As a result, the oldest Puget Sound salmon runs are a few thousand years old - a mere wink of an eye in evolutionary time.
Something else at work
If smell leads salmon to their stream, it certainly does not work in the ocean, scientists say. Even if a fish could detect the scent of a single stream from hundreds of miles out at sea, it could not determine which direction it came from. Something else is at work out there.
Researchers have investigated numerous theories: minute differences in salinity, water temperatures or dissolved oxygen. Quinn's model, proposed in 1982 and now widely shared, suggests salmon use a combination of several devices:
-- An internal "map" of the North Pacific, based on Earth's magnetic field.
-- A celestial compass with a backup magnetic compass that might actually incorporate tiny magnetite crystals inside the salmon's brain.
-- An internal clock that enables the fish to determine its latitude based on the sun's position.
Lots of animals, from bees to gray whales, migrate over long distances, Quinn says. They use a variety of navigation techniques, but many appear to be learned. Birds, for instance, tend to follow their mothers. So do whales.
It seems that animals learn the transit of the sun across the sky and combine this information with an internal clock, Quinn explains. Migrating birds, kept in captivity, will at the appointed time begin to hop in the direction they yearn to fly.
But salmon are all first-time migraters. Since they die after spawning once, none gets a second chance. There is no old-timer to follow and no opportunity to learn by experience.
Quinn believes the fish are born with a biological template, a sort of magnetic sixth sense with which they learn celestial patterns - the paths of certain stars or of the sun at a given time of year.
"We don't know yet if salmon use the stars to navigate, but we have evidence that they use a sun compass," Quinn says. "If they have a clear day, they will follow the sky. But if the skies are cloudy, they revert to their backup device, which is the Earth's magnetic field."
To do that, they may actually use those tiny crystals of magnetite, which serve as tiny compass needles, to align themselves with the magnetic poles.
Far-fetched? Sharks detect magnetic fields electrically, including fields induced by their own own movement. Still, Quinn is cautious.
"All of this is still pretty speculative," Quinn says. "We're talking about an entire sensory system that we don't understand. But I think we're getting closer."
Like the salmon's journey itself, the mission is more than intellectual. Quinn believes that the more we learn about the salmon's navigational abilities, the more we learn about the capabilities of human beings.
He thinks of ancient Polynesians who navigated across thousands of miles of the South Pacific or Eskimos who traversed vast expanses of Arctic wilderness seemingly devoid of landmarks.
"We know that magnetic field detection is present in honeybees, sharks, bees, fish, even primitive organisms such as nudibranchs. So why not human beings?"
Tuesday 29 June 1999
Nature groups see WTO pact as threat
It's only fitting that, four months before World Trade Organization talks begin here in November, one of the battles already brewing is over one of the region's, and the world's, most precious and valuable resources: trees.
At issue are three primary concerns: The WTO plans to reduce global tariffs on forest products; existing regulations could be weakened or amended to enhance trade; and new laws could be introduced to allow companies the right to claim damages for environmental regulation.
The meeting came after environmentalists from around the world met for the last three days in Leavenworth to discuss the upcoming trade talks and their implications for the world's forests.
The WTO will hold its highest level meeting in Seattle Nov. 30 to Dec. 3 this year. The talks will attract top trade officials from the 135 countries who are members of the organization.
The four days of meetings are expected to draw between 5,000 and 7,000 trade officials, journalists and protesters to Seattle.
Victor Menotti, director of the San Francisco-based International Forum on Globalization Environment Program, said his organization would hold seminars in Seattle on Nov. 27 and 28 about the WTO and its practices; and Mark Westlund of Rainforest Action Network said his group will offer training sessions on how to become an activist.
Daniel Seligman, who focuses on international trade issues for the Sierra Club, said the potential WTO agreements are part of larger trend toward decisions that take control away from local governments and residents.
As another element to the trend, he cited Weyerhaeuser's recent acquisition of MacMillan Bloedel, one of Canada's largest forest-products companies.
"This purchase by Weyerhaeuser is an example of companies shopping for places where environmental laws are weaker," he said.
In response, Weyerhaeuser spokesman Bruce Amundson said that position "completely ignores the fact that we have had operations in Canada for 35 years. . . . We have been outstanding citizens in terms of our practices.
"Certainly the forest-products industry is much more global today; there are global players and to the extent that those companies are allowed to compete freely - we would be in favor of that."
Seligman also said he feared that WTO agreements would give companies the right to sue governments for losses incurred from environmental regulations.
"We are concerned that in the Pacific Northwest that efforts to protect salmon will reduce profit. We are afraid efforts in the WTO will allow them to sue in order to reduce losses from salmon habitat," he said.
The WTO was formed on Jan. 1, 1995. It has 133 member nations and 33 nations with observer status. The group settles trade disputes and sets agreements and monitors the trade policies of its member nations. WTO agreements set rules that its members must adhere by or face face punishments, including sanctions.
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