It was a big run in 2004 for yearling spring Chinook and steelhead juveniles migrating out of the Snake River system. However, due to poor in-river conditions with low flows and little spill provided at dams during the spring, most of the spring juvenile fish were transported by barge to below Bonneville Dam.
"During the peak of this year's migration, river conditions were only slightly better than they were during the 2001 drought year," Bill Muir of NOAA Fisheries told the Technical Management Team (TMT) during its annual Year-in-Review meeting last week.
Muir said that resulted in lower than average passage survival for fish that were not transported. In fact, 2004 results are showing the lowest in-river survival since 2001.
Steelhead were especially hard hit, as they were in 2001, particularly in the reach between Lower Monumental Dam on the Snake River and McNary Dam on the Columbia River where predation took a huge toll on the young fish, Muir said.
At the end of each year, TMT reviews weather, river conditions and juvenile and adult migration statistics in light of in-season decisions the group makes during the operating year. This year TMT met in an all-day session Nov. 10 to hear about the most recent studies and predictions.
All the reports can be found linked to the Nov.10 TMT agenda at www.nwd-wc.usace.army.mil/tmt/agendas/2004/1110.html
Although 2004 did not see the highest adult salmon migration in recent years, returns were again considered good, with most runs beating forecasts. Only upriver spring Chinook fell short of the forecasted 360,700 returns, with 193,800 showing up at the mouth of the Columbia River. The highest return in recent years was in 2001 when about 400,000 spring fish crowded Columbia River waters. Next year's spring Chinook preliminary forecast is for 200,000 to 300,000 fish, said Cindy LeFleur of the Washington Department of Fish and Wildlife.
The Snake River yearling spring Chinook migration was large and tightly compressed, boosted by 12.5 million hatchery fish, said Jerry McCann of the Fish Passage Center. He added that wild fish tended to migrate a little earlier than hatchery juveniles. However, by the time some in-river yearling Chinook reached Lower Monumental Dam on the Snake River, up to 87 percent of the total run had already been put in barges.
Compared to past years, a higher percentage of steelhead this year saw the inside of a barge, with 96 percent of the steelhead transported out of the Snake system. The total steelhead run consisted of about 7.8 million wild and about 8.3 million hatchery juveniles.
How well the fish left in the river survived through reaches of the Snake and Columbia rivers was the topic of a presentation by Muir. His findings showed a loss of 18.4 percent of the steelhead still in the river between Lower Monumental and McNary dams. That, he said, was due to predation by the Caspian tern population on Crescent Island, located at the confluence of the Snake and Columbia rivers. The loss in 2001 due to predation from terns nesting at the island was 21 percent.
"It's the same size population (of terns) as there has been over the last dozen years," Muir said. "But the birds seem to be more efficient and more steelhead are lost."
Spill was not provided at Lower Granite and Little Goose dams from April 24 to the end of May and at Lower Monumental from May 14 to the end of May. As a result, survival for yearling spring Chinook was 39.5 percent between Lower Granite Dam and Bonneville Dam. Muir said the survival for steelhead was unknown because biologists are unable to count steelhead at Bonneville Dam due to an inability to detect fish at the dam's corner collector, Muir said.
Scott Bettin of the Bonneville Power Administration confirmed that the PIT tag detector at the corner collector is not working and that it may need to be shut down for a few days for repairs.
However, Muir said, survival in the upper reaches for steelhead was consistently lower than survival for yearling Chinook, and it got worse lower in the river system. Between John Day and McNary steelhead survival was 46.5 percent, while yearling Chinook survival was 80.9 percent. Lower Monumental to McNary survival was 81.8 percent for Chinook and 51.9 percent for steelhead. Little Goose to Lower Monumental survival was 87.5 percent for Chinook and 82 percent for steelhead. Lower Granite to Little Goose survival was 92.3 for Chinook and 86 percent for steelhead.
Salmon returning to the river from the ocean fared better, as did sport, commercial and tribal treaty fishers. Of the 193,800 adult upriver spring Chinook that returned, sport fishers took 23,700, commercial fishers 24,000 and treaty fishers harvested 17,400.
The summer Chinook forecast was for a return of 104,800 fish, but the actual return fell a little short, according to LeFleur, at 93,800. The best of the more recent years was 2002 when 130,000 fish returned. Of this year's return to the mouth of the Columbia River, sport fishers took 1,100 fish, commercial fishers harvested 200 and treaty fishers harvested 8,700.
It was a huge run of fall Chinook, LeFleur said, with 793,200 returning fish, much higher than the predicted 634,900 fish. Of those, 34,100 went to sport fishers, 39,600 to commercial fishers, and 125,900 to treaty fishers. Of the fall Chinook run, 367,700 were upriver bright fall Chinook (287,000 were forecast), 109,300 were mid-Columbia River brights (88,800 forecasted) and Spring Creek Hatchery returns tallied 183,000 (150,000 forecasted).
Some 124,000 sockeye returned. Nearly all were wild fish (80,700 forecasted). Some 700 went to commercial fishers, 4,700 to treaty fishers and 5,700 were taken in the Lake Wenatchee sport fishery.
Technical Management Team: (www.nwd-wc.usace.army.mil/tmt)