Columbia River Salmon Runs Plentiful Now,
by Matthew Preusch
In some Northwest streams, it seems like a return to the storied days when it was said salmon ran so thick you could walk across their backs.
Record numbers of coho have returned to the Columbia River in recent years, and this year forecasters predict the same for spring chinook. But it's not time to pop the champagne corks and declare victory in the nation's most expensive wildlife restoration venture.
The reason: Most scientists agree much of the thanks for the recent runs, in addition to improved river conditions and more hatchery fish, goes to favorable circumstances in the ocean where the salmon mature after being born in fresh water.
"It looks like the abundance of adult salmon that we see come back to the rivers appears to be set or at least strongly regulated by their early ocean experience," said Nate Mantua, a climate scientist and fisheries researcher at the University of Washington.
If the Pacific has been a cornucopia, it can just as easily flip to an environment with all the bounty of a vegan butcher shop. Signs are showing it already has.
"The ocean conditions suggest that we'll have low returns in 2010" for coho, said Bill Peterson, an oceanographer with the National Oceanic and Atmospheric Administration, based in Newport. The same could be true for the chinook that will return in 2011, but that's less clear.
If runs plummet again, it will test the degree to which changes at hydropower dams, scores of restoration projects and billions of federal dollars are helping to turn Northwest salmon, the pink-fleshed lifeblood of Northwest rivers, away from the path to extinction.
"It's not a matter of if, but when, we are going to return to an extended period of poor ocean conditions," said Howard Schaller, head of Columbia River fish programs for the U.S. Fish and Wildlife Service. "And that's when we'll really see if these actions we're taking are going to encourage the resiliency this species needs to persist in the long term."
Scientists have recognized for decades that swings in salmon returns correspond to changing conditions in the ocean, but what exactly is happening at sea and how that affects fish has remained something of a mystery.
But researchers like NOAA's Peterson continue to pull back the curtain.
His latest maxim: "It all boils down to what kind of copepods are off the coast of Oregon right now."
Copepods are tiny crustaceans a few millimeters long, part of the complex food web that juvenile salmon join when they enter the ocean from the Columbia River.
For the last 15 years, Peterson and his colleagues have regularly trawled the Pacific with dragnets to see what kind of copepods it holds. If the copepods are a larger sort full of energy-rich molecules called lipids, indicating the water off the coast is moving down from Alaska, that corresponds with lots of food for the young salmon. If the copepods are the smaller type riding warm currents up from California, the opposite is true.
Either way, the copepods' numbers depend on the arrival of nutrient rich water that swells up from the ocean floor, as it did in abundance in 2008.
"Those big copepods were just thick out here in 2008," when conditions were the best for fish since scientists started taking the measurements in 1996, Peterson said.
Related to that were favorable swings in cyclical climate events such as El Nino and the Pacific decadal oscillation, a close relative of El Nino that plays out over longer time frames.
"Changes in El Nino and the PDO influence the ocean conditions," Mantua said.
In the latter half of last year, both El Nino and the PDO switched to warm phases, which typically leads to conditions unfavorable for fish. The food web became less productive. Juvenile fish emerging into the ocean from their trek down the Columbia River were less likely to survive.
"Expectations for returns of coho in 2010 are considerably lower due to warm sea-surface conditions throughout August 2009 and low catches of coho salmon in our June and September surveys," a recent NOAA forecast said.
Even as more attention is focused on the ocean, salmon advocates and others continue to argue over how to manage the fresh water systems where the fish are born and return to spawn after their time at sea.
"The ocean definitely influences salmon productivity and survival, but if you look at it in terms of salmon recovery, what are you going to do about it?" the wildlife service's Schaller said.
In recent years, coho, chinook and steelhead have been returning at some of the highest numbers since the construction of federal dams beginning in the 1930s. Those changed the once-wild Columbia and Snake rivers into a series of slackwater lakes useful for barging goods but unfriendly to salmon.
The salmon that took advantage of good ocean conditions of late also benefited from recent increases in the amount of water flowing over those dams - an action ordered by a federal judge - as well as pumped-up production of hatchery salmon, aggressive reintroduction efforts and improved habitat in freshwater areas.
"Whether the ocean is good or bad, fish have to reach the ocean alive and in good condition," said Michele DeHart of the federal Fish Passage Center.
A federal judge in Portland is reviewing the Obama administration's plan to run the region's power-producing dam without further imperiling salmon. That plan relies heavily on the idea that improving fresh water habitat will lead to increases in the numbers of salmon.
And federal fish managers point to the recent high returns as evidence that their efforts are making a difference.
"People are trying to get it right, as best they can," Peterson said. "But the Columbia is never going to be like the Columbia as it was."
Despite the recent good returns, over a dozen runs of salmon and steelhead remain on the federal list of protected species. None are expected to come off the list anytime soon.
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