Weather Clouds Salmon Horizons Global Warming Spurs Downward Spiral In Ocean, Land Conditions

The greatest threat to Pacific Northwest salmon may be global warming, despite the best conservation efforts.

Scientists gathered for the 78th annual meeting of the Pacific Division of the American Association for the Advancement of Science said the short-term outlook for the already-depleted migratory fish was poor because it has been difficult to revive salmon runs under normal weather conditions, let alone a massive climate shift.

“In the past we always emphasized hatcheries, dams and fishing pressure as the only important factors in salmon conservation, but that was shortsighted. This problem involved environmental changes literally Pacific Rim in scope,” said Daniel Bottom, salmon conservation manager for the Oregon State University Center for the Analysis of Environmental Change.

The survival of the fish depends on a complicated mix of factors that includes ocean currents and upwelling that pushes nutrients closer to the surface, the overall food supply, inland temperatures, snowpacks and stream flows.

A small shift in temperature could reduce the Pacific Northwest snowpack and result in wetter winters and drier summers. A light snowpack would mean rain would quickly run off mountainsides in winter and there would be little melting snow in summer to provide water when skies turn dry.

“That could be very stressful to some populations of salmon,” Bottom said.

He and other researchers have identified what appears to be a significant turning point in 1976, marking a long, downward spiral in ocean conditions and onshore weather patterns salmon need to thrive.

In the two decades since then, a low-pressure system that forms over the Aleutian Islands each winter has been more intense than usual, enhancing salmon fisheries in Alaska and British Columbia while Pacific Northwest fisheries declined.

The appearance of another El Nino ocean warming this year raises more questions about links to a changing global climate, Bottom said.

Salmon are a cold water fish that range over most of the North Pacific, from the Northwest to Alaska, Japan and Russia.

A global climate shift would affect salmon on both sides of the Pacific, said Xanthippe Augerot, an Oregon State University researcher who works with Russian scientists and fisheries managers.

She and her colleague, Sergey F. Zolotukhin of the Pacific Fisheries Management Institute in Vladivostok, Russia, note that salmon have a more natural habitat in the Russian Far East because there are few hydroelectric dams, unlike the Pacific Northwest.

But poaching - mostly for the eggs that make expensive caviar - and environmental pollution from gold and coal mining threaten some Russian salmon populations.

Fishery managers in Russia also are forced to sell licenses to catch salmon to fund their research programs because of the massive financial problems the country still faces in the transition from a planned communist economy, Augerot said.

Stan Gregory, an Oregon State fish and wildlife professor, called for establishing an international database on salmon that all governments and researchers could share.