Radio Script
1998

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Salmon May Move North If Climate Warms
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STORY: When Canadian researcher David Welch began studying salmon survival in the North Pacific Ocean, he expected to find salmon throughout the sea. But the further south he went--the warmer the ocean became--the fewer salmon he found. As he moved into waters roughly the same latitude as northern California, he didn't find any salmon at all.

WELCH: "We've got about 21,000 days of fishing at sea over a 40-year period. For every species of salmon, they get to a certain temperature and they just stop. We've almost never caught a salmon south of those temperatures in warmer waters."

If salmon are that sensitive to temperature, Welch wondered: what would happen to salmon if current models about how the global climate might warm came to pass? Under those models, the amount of the greenhouse gas--carbon dioxide--in the earth's atmosphere is expected to double during the next 50 years. That in turn would cause the North Pacific Ocean to warm by as much as 6 degrees Fahrenheit. If the models prove correct, Welch says the colder water that salmon prefer would no longer be found in the North Pacific.

WELCH: "We found that the temperatures didn't even exist in the Pacific Ocean. They were up in the Bering Sea. That would mean everybody's salmon--Canadian, Alaskan, Washington, Oregon, Japanese, and Russian--might not be in the Pacific Ocean at all for much of their lifespan."

Of course, Welch's predictions depend to a great extent on just how much the North Pacific Ocean actually warms up. Scientists caution that the models used to predict climate change are imperfect. Still, scientists generally agree that David Welch is on to something. Last year's El Nino brought warmer ocean conditions to the North Pacific, and fewer salmon returned to their spawning grounds throughout the North Pacific. Milo Adkison is a fisheries professor at the University of Alaska Fairbanks.

ADKISON: "This scenario is plausible and very worrying. The reason it's worrisome is if you get global warming then the habitat disappears. We could lose large populations of salmon."

Still, don't look for salmon to change their migration patterns overnight. Welch says warming of the ocean will be a gradual event and that salmon will probably return to their traditional spawning grounds for many years to come. But he says fishery managers need to understand and consider how a changing ocean will affect salmon populations.

OUTRO: For Arctic Science Journeys, this is Doug Schneider, reporting from Fairbanks, Alaska.