Council Members get Good News from Ocean Research Updateby Bill Rudolph
NW Fishletter, June 27, 2002
At their June 15 meeting in Eugene, OR, Power Planning Council members got a respite from discussions on the future of the mainstem amendment process to hear what's going on in the part of the world that's just beyond the mouth of the Columbia River. NMFS scientists, participating in a joint effort with several universities, shared their findings on the effects of the estuary and near-ocean environment on fish survival.
The researchers are also concentrating on the Columbia River plume, an area off the coast where the river mixes with the ocean, creating a special environment that scientists think is beneficial for salmon. The plume, which extends seaward for many miles, is the subject of much speculation over its potential benefits for fish.
The latest hydro BiOp mentions the plume as a potential beneficiary of the hydro system's flow augmentation, since more flow makes for a larger plume. A larger plume, in turn, may create a larger space for juvenile salmon to feed, scientists have hypothesized.
Since the plume is generally more turbid than the surrounding ocean, it could also serve as a refuge from predators. And since it's less salty than surrounding waters, back eddies and boundaries are created, which tend to concentrate the plankton and crab larvae that young salmon feed on before they get serious about migrating to sea.
First the good news. NMFS scientist Bill Peterson gave the Council a primer on ocean conditions, which have vastly improved off the Northwest coast over the past few years. Conditions there are still great for salmon, said Peterson, despite the low river flows and small plume from last year's drought.
He said the improvement is part of a 50- to 60-year overall cycle of the North Pacific weather circulation pattern. Every 20 years or so, the climate regime shifts gears, putting Alaska and the West Coast in a seesaw of salmon productivity. When fishing is great in Alaska, it's lousy down south. Now, the opposite seems to be true. Scientists have dubbed this pattern the Pacific Decadal Oscillation [PDO].
Peterson said an Aleutian low-pressure area that's normally far north in the Bering Sea has moved south since July 1998, causing the ocean current that flows east from Japan to move farther south as well. When the current is in this position, scientists think more of the highly productive northern water gets shunted south and improves conditions for plankton growth off the West Coast and British Columbia. Evidence for this cycle has been gleaned from fish scales found in sediment cores going back to the fifth century AD, Peterson said.
Scientists have suspected that conditions in the estuary and plume may have reduced salmon survival since the hydro system has been in place, largely because of less sediment transport and lower spring flows. Now they are trying to quantify those effects.
NMFS scientist Ed Casillas showed the council satellite images that how the Columbia River plume contributes to productivity by boosting chlorophyll levels in the nearby ocean. This is the first step to increasing the types of zooplankton commonly found in the stomachs of juvenile salmon. Casillas said trawl surveys have found that salmon were concentrated near the frontal edges of the plume. By developing models that represent the linkages in the near-ocean habitat, Casillas said scientists will be able to evaluate how both natural effects--like climate and oceanography--and human factors--like river flows and channel deepening--impact the availability of salmon habitat.
The plume seems especially important for coastal coho populations because those fish tend to spend more time in the area than spring chinook before migrating north and out to sea. Peterson's research off Newport, OR, has found that zooplankton growth has improved over the past few years, which has helped boost coho stocks from miserably low numbers a few years ago, when only about 2 percent survived to return. He predicted 10 percent returns of coho salmon this fall, based on plankton.
Other models are also optimistic, Peterson said. One that's based on bait fish numbers also predicts a 10 percent return for coho. Yet another model developed by scientists at NMFS in Seattle and the University of Washington predicts an 8 percent return based on a correlation of water temperature, the date when spring winds shift from south to north, and plankton growth.
But there's a rub. "With a negative PDO [that's good for fish], we've got lots of prey, lots of things to eat, lots of bait fish; we've got an early spring transition," Peterson said. "Everything's perfect for the fish. But we caught very few fish last June, the jack counts were very, very low, and the fish we caught were small. So something happened last June..." Based on the fish caught in June, Peterson said only 2.5 percent are expected to return, about the same prediction from the jack return.
Part of the puzzle is the fact that last year was one of the driest winters on record, he said. "The fish got out into the plume and they found the plume to be very, very small--you're packing millions of fish into a really small area--and I'm suggesting that they probably never got to the ocean, so to speak," Peterson said. "They got into the plume, and they're there for weeks to months, getting used to the ocean and feeding and things. I think what happened was the plume wasn't big enough for the coho for this past year." But with flows in the Columbia River at less than half of normal last year, Peterson noted that these years have been uncommon.
"We're all hopeful that when the fish come back this fall," said Peterson, "it will either be a really high number, or really low, so we can kind of know that one of these actions is the correct one. It'll be 5 percent, you can bet on it, then we won't have any idea."
What did Council members think about the NMFS research? "It's a first step," said Montana's new face on the council, John Hines. Hines said he hoped that NMFS could eventually incorporate their results into real-time operations for the hydro system. "In any case," he said, "some council members [read: Idaho and Montana] feel we must be sure we have flexibility in shaping the mainstem amendment process to incorporate changes in mainstem operations."
Hines said the council's program could be written with the BiOp as baseline for operations, as long as there were language included to allow for changes with new science. The council was scheduled to have a mainstem plan ready for public review by the end of the June meeting, but council members' continued wordsmithing of staff drafts over the flow augmentation issue will keep the document from being finished until next month.
"The BiOp is not written in stone," Hines said. Other council members, like Oregon's Eric Bloch, feel the group's mainstem process should stay out of any conflict over BiOp operational issues and current operations that augment flows in spring and summer to aid fish passage, a strategy with little scientific support.
With the four council members from Idaho and Montana expected to vote together, a single vote from one of Washington's members could carry a proposal that might clash with the BiOp. Washington council member Tom Karier has already expressed interest in further evaluation of the current flow augmentation strategy.
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