[2] Council Hears Hot Fish Predictions
Last year, federal scientists saw more baby spring chinook off the mouth of the Columbia than any other year since they've been keeping track.
NOAA Fisheries scientist John Ferguson presented the good news at the March meeting of the Northwest Power and Conservation Council in Boise.
Ferguson said ocean conditions are about as productive as they have ever seen, and his agency expects large spring chinook runs over the next three years.
Results from 2008 ocean trawl surveys have led the NMFS Science Center in Seattle to predict that about 40,000 spring chinook jacks should return to Bonneville Dam this year. That's nearly twice as many as anybody has seen in recent years, and could signal a spring run in 2010 far larger than any seen in the past decade.
With about 19,000 jacks counted at Bonneville last year, the feds estimate that the 2009 spring run could be around 340,000 fish. Harvest managers have it pegged closer to 300,000.
On March 10, Ferguson also reported that the PDO [Pacific Decadal Oscillation] is still strongly negative, with a cold ocean and few storms. He said southern copepod species are around, but the northern varieties, which are much more nutritious for young salmon, are already dominant, just like last year.
Ferguson quoted NOAA oceanographer Bill Peterson about the current conditions: "The pump is primed and ready to go."
But the future may not be so rosy, Ferguson cautioned. Ocean variability--the flip-flops between good and poor conditions for juvenile salmon--seem to be increasing, and the ocean itself is predicted to be getting warmer.
However, for the time being, most salmon runs in the Columbia Basin are climbing, and good sockeye runs are predicted for both the upper Columbia and the Snake.
IDFG biologist Paul Klein said the number of last year's sockeye jacks at Lower Granite Dam may point to even better adult returns this year than in 2008, when about 900 adults and jacks were counted there.
He was afraid to speculate about the size of this year's run because of the uncertain relationship between sockeye jacks and adults returning the following year. But he said in 2000, when 300 adults made it to the dam (the previous high), seven jacks were seen the year before.
However, 150 jacks were counted last year. Klein said the lack of data keeps biologists from developing a relationship between jack numbers and adults, but he expected this year's sockeye return to be at least as good as last year's and possibly higher.
That is good news for the most endangered run in the basin, which has only been kept from winking out because of an expensive, captive broodstock program.
NOAA scientist John Williams reported that juvenile inriver spring chinook survival through the hydro system averaged about 46 percent in 2008, with steelhead at about 48 percent. That's a few percent higher than preliminary numbers released late last year, but down from the past two years, when spring chinook survival was 60 percent or better, and steelhead averaged around 40 percent.
Williams also presented evidence that in years with low spill and high transport of juvenile fish, fewer fish in the river results in lower survival, since predators are likely to take a higher number of young salmonids when their numbers are less. He said inriver survival would have been higher if non-tagged bypassed fish had been returned to the river, instead of being barged.
With increasing spill, like that which occurred in the past few years, he said inriver survival increases, since more smolts in the river are reducing an individual's vulnerability to predation.
His ultimate conclusion is that direct or indirect effects of spill may not improve smolt-to-adult survival for the population because the cumulative effect must offset the effect of transporting fewer steelhead, since steelhead always seem to survive better to adulthood if transported.
The Corps of Engineers' Mike Langsley and Marvin Shutters presented the council with the results of the most up-to-date acoustic tag data of smolt survival between Bonneville Dam and the ocean.
They said that spring chinook smolts averaged about 79-percent survival in 2008, while fall chinook survival averaged 83 percent through the estuary, significantly better than in 2006 and 2007.
The largest losses appear to be in the bottom 35 kilometers (22 miles) of the river for springers, and the bottom 50 kilometers (31 miles) for the young falls. At this time, there is no explanation why more fish seem to die near the mouth of the river.
If the Corps' data are correct, fish mortality in the estuary is about twice that of the hydro system per distance traveled (For presentations, click here for the Council's March agenda). -B. R.
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