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Ecology and salmon related articles

Chinook Run Forecasts High for Spring, Fall

by Jonathan Brinckman
The Oregonian, February 19, 2002

Biologists say the Columbia River fall chinook run will be one of the biggest in 60 years, outpacing last year's robust run of 544,000 by nearly 134,000 fish.

Combined with what also is expected to be another strong spring chinook run, the numbers are good news for the Columbia Basin's sport, tribal and commercial fisheries.

But biologists also are sounding a cautionary note about future chinook runs because this year's coho runs are expected to be down sharply -- hurt by the federal government's decision to put electricity generation before fish protection last year because of the drought and an energy shortage.

Coho generally spend only one to two years feeding in the ocean before returning to fresh water to spawn, while chinook usually spend two to four years at sea. This year's coho returns will be biologists' first indicator of how much the poor river conditions of last year might have hurt chinook runs.

A forecast released this month predicts that coho returns to the Columbia will be one-quarter of last year's total: 305,000, compared with 1.3 million.

The forecast for the spring chinook run is for 418,500 fish to enter the river this year. That would be the second-highest total since record-keeping began when Bonneville Dam was completed in 1938. The record was set last year when 508,000 fish entered the Columbia.

"People should enjoy the good chinook returns we have now, but they shouldn't get used to them," said Mike Matylewich, fisheries manager for the Columbia River Inter-Tribal Fish Commission, which represents four tribes with treaty rights to salmon. "Early indications are that returns in 2003 and 2004 will not be good."

Biologists were surprised by the large chinook runs last year, attributing them to a change in ocean conditions that brought colder water, which is higher in nutrients.

Last year's spring chinook run allowed fishery officials to open a spring sportfishing season on the Columbia for the first time since 1977. Tribes also were allowed to sell spring chinook caught in gill nets, something they had been unable to do for 25 years.

But mixed with this year's spring and fall chinook will be tens of thousands of immature chinook, called jacks, that left the Columbia in 2001. Biologists say the number of jacks, which spend a year or less in the ocean, is a reliable indicator of future adult returns.

If the chinook jack counts are low, it would mean chinook runs will be low in 2003 and 2004, despite favorable ocean conditions. Biologists cite two main reasons for potentially low runs in those years:

Young salmon migrating downriver to the ocean do best when they are carried quickly by fast, cool rivers. The drought last year reduced the flow of the Columbia to the second-lowest level since record-keeping began in 1929.

The federal salmon recovery plan requires the U.S. Army Corps of Engineers, which operates dams on the Columbia, to spill millions of gallons of water each spring and summer over the dams' spillways, rather than through power-generating turbines. That gives young salmon safer passage through the dams. But last year, the Bonneville Power Administration declared a power emergency and decided to send only 20 percent of that additional water over the spillways. The rest was sent through the spinning turbines, which can kill or injure young fish.

The first coho jacks returned to the Columbia River last fall, about six months after leaving as juveniles. Biologists said the jack count was surprisingly low, and it led to a forecast for lower coho returns and to fears that chinook also might have been hurt by the low flows and decreased spill.

"The coho news isn't so good," said Steve King, salmon manager for the Oregon Department of Fish and Wildlife. "This might be the first indication of a decline of salmon."

In addition, the National Oceanic and Atmospheric Administration's Climate Predication Center is warning that water temperatures in the tropical Pacific are rising, an indication that 2002 will be an El Nino year. The periodical weather phenomenon can change ocean currents off the Northwest, bringing warmer temperatures and reducing nutrients.

But Northwest scientists said they aren't alarmed by the El Nino warning, because the ocean off the Northwest appears to be starting a 20-year cycle of cooler-than-normal temperatures. That cycle probably will trump the effects of an El Nino and keep warm waters from reaching the Northwest, scientists said.

"Not every El Nino that develops in the tropics has a big impact on the coast of the Northwest," said Nathan Mantua, a research scientist at the University of Washington's Joint Institute for the Study of the Atmosphere and Oceans. "If history repeats itself, the odds favor a low chance of a big El Nino in the northwestern Pacific."

Jonathan Brinckman
Chinook Run Forecasts High for Spring, Fall
The Oregonian, February 19, 2002

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