Council Hears Presentation onby CBB Staff
No matter how you look it, fish counters at Columbia and Snake river have earned their pay over the past three years as salmon and steelhead numbers have swelled to unprecedented levels.
The overall chinook counts at Bonneville Dam (including spring, summer and fall species) were the highest in history in 2001, 2002 and 2003, says Bruce Suzumoto, special projects manager for the Northwest Power and Conservation Council.
During this week's Council meeting at the Coeur d'Alene Resort, Suzumoto presented a perspective on "Recent Trends in Adult Returns to the Columbia Basin" from the view of fish counters at Bonneville, McNary, Lower Granite dams.
The trend graphs assembled by Suzumoto date back, in Bonneville's case, to 1938. That's when the first dam, Bonneville again, was built on the Columbia-Snake mainstem. His conclusions focus, however, on the most recent decade when many species' numbers have risen from perilous lows to unanticipated heights.
The NPCC biologist qualified his report as a narrowly focused look at those trends. It employs a number of graphs "that plot the number of fish at a particular dam by species," he told the Council. That reveals overall species trends, a composite of various populations age classes within each species. Suzumoto, and Washington Councilor Larry Cassidy, noted that not all populations have enjoyed the same meteoric trend and some indeed have experienced declines.
Nor do the graphs acknowledge the fact that numerous human activities have affected those trends. The populations of fish returning now are dominated by hatchery produced fish, as much as 80 percent, Suzumoto said.
Reduced harvests in the ocean and improvements in freshwater spawning and rearing habitat and hydrosystem passage have also helped bolster populations. In-river harvest is also greatly reduced since the first listing of wild salmon stocks in the early 1990s.
But improved feeding conditions in those areas of the Pacific Ocean where Columbia basin salmon and steelhead are believed to grow to adulthood is probably the biggest single reason for the surge.
Through Oct. 31, 918,071 chinook salmon had been counted crossing Bonneville Dam, according to information compiled by the Fish Passage Center from Corps of Engineer dam counts. That is more than twice the average annual count for the most recent 10 years at Bonneville -- 397,878 fish.
Steelhead counted at Bonneville in 2003 thus far totaled 361,518, compared to the 10-year average of 278,729. Coho totaled 125,275 in 2003, compared to the 10-year average of 59,304.
Only the sockeye count at Bonneville, 39,291, is lower than the 10-year average (46,748).
And while the runs are dominated by hatchery fish, wild steelhead trends charted by Suzumoto also show high recent counts. The wild steelhead counts at Bonneville Dam were stuck in the 20,000 to 40,000 range from 1993 into 1998. But the past three years have all exceeded 110,000 with a peak of about 150,000 two years ago. Counts at Lower Granite and Wells showed similar trends.
"This is good news for the Northwest," Council Chair Judi Danielson said. "The ocean, where the fish spend most of their lives, has turned in favor of Columbia Basin stocks in recent years, and our efforts to improve the freshwater spawning and rearing habitat appear to be contributing, as well."
"It seems that good ocean conditions and good freshwater habitat yield good returns. But ocean conditions are variable, and we can't control them," she said. "What we can do, though, is keep up the work in the freshwater habitat. Then, when the ocean is less favorable the fish still will have an adequate place to come home to."
The Suzumoto presentation shows that the gains of recent years are even more striking when compared to returns during the mid-1990s, when many of the species' runs declined. Spring chinook counts at Bonneville averaged 297,346 fish from 2001-2003. That is a 10-fold increase from the 1994-96 average of 29,770.
At Lower Granite Dam, the last of eight dams on the lower Columbia and Snake Rivers that spring chinook cross on their way to spawn in Idaho, Washington or Oregon, the annual average for the years 2001 through 2003 is 110,370 fish, compared to an annual average of just 3,478 for the years 1994-1996, almost 32 times as many fish.
The counts used in Suzumoto's comparison are of adult fish only and do not include jacks, which also were well above the 10-year averages in 2003. Jacks are immature fish that return after one year in the ocean; their numbers are considered a reliable indicator of the size of the next year's runs when the higher percentage of that year class return to the Columbia basin to spawn.
"That's a good indication of what's coming next," Suzumoto said.
Suzumoto presentation: www.nwcouncil.org/news/2003_11/3.pdf
Fish Passage Center: www.fpc.org
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