Federal fish managers say the recovery of wild Snake River fall chinook appears promising, with 50,000 or more wild and hatchery fish returning annually in recent years well distributed across the lower Snake and the Clearwater rivers.
But if the public wants to recover the chinook where they used to spawn in the Snake River in Southern Idaho all the way to Twin Falls, some form of fish passage around the three Hells Canyon dams will have to be developed, NOAA Fisheries officials said Monday.
NOAA released a proposed recovery plan for Snake River fall chinook salmon Tuesday. Fall chinook are the only stock of Snake River salmon that biologists say may be able to be recovered without major improvements in the migration corridor through eight dams on the Snake and Columbia rivers. But scientists said in the plan that recent improvements in wild salmon abundance may not be sustainable.
The fish were nearly sent into extinction by the building of the Hells Canyon Complex of dams by Idaho Power in the 1950s and ’60s, which closed off 80 to 85 percent of the streams that made up its spawning habitat. But the chinook has been brought back in less than 25 years.
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The effort involved Idaho Power, the Nez Perce tribe, state and federal fisheries officials and the Bonneville Power Administration. Nez Perce fisheries officials planted hatchery Snake River fall chinook in many tributaries and has increased the number of fish. Idaho Power stabilized flows below its dams in the fall and the spring to help spawning.
The 75,846 native and hatchery-born fall chinook counted at Lower Granite Dam in 2013 went to just 15 percent of their historic habitat.
“Salmon recovery is a community effort that takes good science and a regional commitment,” said Will Stelle, West Coast regional administrator of NOAA Fisheries. “The improvements we’ve seen in Snake River fall chinook in recent years demonstrate the strength of that commitment, and the recovery plan provides a guide to carry that through to full recovery of the species.”
Once more than a half-million fall chinook returned to the Snake and its tributaries all the way into Nevada. But more than a century of farming, mining and other development and the cutoff of its habitat by dams.
Just 78 wild fall chinook returned to Lower Granite Dam on the Snake in 1990. Biologists counted 20,222 wild fall chinook in 2013.
The recovery plan includes a series of potential options for recovering fall Chinook and open to public comment for 60 days. NOAA Fisheries will consider comments and develop a final plan for release in 2016.
Fall chinook are adapting to their very altered environment and climate change. Usually, fall chinook hatch in the spring. The smolts, just inches long, enter the ocean a few months later. But as many as a fourth of these chinook are staying put in the river for at least a year — either at the mouth of the Clearwater River or further downstream in the Columbia — before heading to sea.
The chinook that delay their migration are about eight times as likely to make it back to their spawning grounds as adults than the traditional migrating fall chinook.