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Warm Ocean Conditions Affect Salmon Returns by Steve Benson, Express Staff Writer Idaho Mountain Express, August 31, 2005

It's no secret that dams kill salmon.

It's also no secret that those dams are probably not going away anytime soon.

Meanwhile, salmon face another, lesser-known enemy that can not be controlled--a warming ocean.

Whether a natural cycle or yet another impact of global warming, the problem has only compounded the effects of the dams, eight of which greet the salmon between Idaho and the Pacific Ocean along the lower Snake and Columbia rivers.

"If the ocean doesn't behave, we're going to have to move quickly," Bert Bowler, the native fisheries director of Idaho Rivers United, said at the 6th Annual Sawtooth Salmon Festival in Stanley last weekend.

That issue, along with a host of others, took center stage at the festival, which attracted activists, Shoshone-Bannock tribal members, Idaho Department of Fish and Game biologists, U.S. Forest Service representatives, and ordinary citizens.

Bowler believes that removing the four dams on the lower Snake River--Ice Harbor, Lower Monumental, Little Goose and Lower Granite--would not only save Idaho's salmon but provide an economic boost for the region. Federal projects aimed to help salmon navigate the dams are expected to cost about $6 billion over the next 10 years.

"There are 101 reasons to take down the dams," Bowler said. "The salmon are just one."

But recognizing that it will be a long uphill battle with an uncertain ending, Bowler wonders if time is running out.

For the fourth straight year, spring and summer Chinook returns have been far below expectations. As of this week, just over 32,000 spring and summer chinook had passed Lower Granite Dam in eastern Washington. The easternmost of the Lower Snake's four dams, Lower Granite is considered the gateway for Idaho's spawning salmon and is the site used by Fish and Game to calculate returns to the state.

As of last weekend, only four (now six) sockeye salmon had returned to their namesake, Redfish Lake, to spawn.

Historically, 2 million chinook returned annually to spawn in Idaho's waters, and 30,000 sockeye made the journey to Redfish Lake, south of Stanley.

In 2001, about 150,000 chinook passed Lower Granite into Idaho, a record in the dam era. But optimism among salmon advocates quickly turned to concerned bewilderment as those numbers plummeted by about half the following year.

Scientists believe the decline can be directly linked to ocean conditions, specifically upwelling--or a lack thereof.

As described by Nate Mantua, a research scientist with the Climate Impact Groups and a professor with the School of Marine Affairs at the University of Washington, upwelling is a an annual oceanic occurrence which is vital to the survival and development of young salmon, or smolt.

As the salmon spill out of the Columbia River into the Pacific Ocean in April and May, when they're about a year and half old, they need vast quantities of cold, nutrient and food rich water for rapid development. Upwelling draws such water from the depths and deposits it near the coast.

The phenomenon is an annual occurrence, but its timing is less predictable. Some years it arrives in April--the ideal time for smolts--others as late as July or August. This year, the upwelling didn't occur until July, when ocean temperatures off the coast of Oregon dropped 18 degrees in two weeks.

"It was plenty cold, but the question is did it come soon enough to save those juvenile fish?" Mantua said. "My guess is we're not going to see good numbers of coho and chinook in the Columbia Basin (for the next couple of years) because of upwelling.

Mantua added that the favorable years between 1999 and 2001 helped salmon populations recover from the brink of extinction.

"Now we have some years where we might get pushed back down to disturbing levels," he said.

Upwelling provides cold water and plentiful food for the smolt, but it also provides protection. In the absence of upwelling, the warmer waters support predators that can decimate the young salmon. Mantua said he's heard of cases where mackerel wiped out an entire stock of chinook smolt in one season.

"That class of fish was gone," he said.

What's troubling is the upwelling cycle. While Mantua said it's difficult to predict upwelling, there are studies that suggest the phenomenon operates in 20 to 30-year cycles.

"To a degree we can look at the history of upwelling for the last 100 years and say 'Yeah, there are 20 to 30 year periods that have good conditions," Mantua said. Studies indicate that from 1946 to 1976, upwelling was generally favorable. And from 1977 to 1998, most years were unfavorable.

So when salmon returns spiked in 2001, there was optimism that the upwelling cycle was entering another 20-year period of favorable conditions. Those hopes were dashed a year later, and Mantua said there are too many variables, including climate change, to count on a favorable lengthy cycle returning.

"It's not something I'd bet much money on, we just don't know what makes the climate tick," he said. "Even if we didn't have global warming, we still have a very limited ability to predict the future."

Salmon have existed for millions of years, using their superior adaptability to survive ice ages. But they may have finally met their match.

"Long term habitat degradation and loss of abundance has not been reversed and continues to be the big issue ... and these year to year climate changes can either mitigate it or make it a lot worse," Mantua said. "In 2001, salmon made a remarkable comeback, but how many times can we knock them down and expect them to come back up?"

Related Pages:
Expert Changes His Mind: Dams Should Come Down by Rocky Barker, Idaho Statesman, 8/9/5