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Idaho's Wild Steelhead Show
from 2001's Drought-Plagued Migtration

by Bill Rudolph
NW Fishletter, November 10, 2003

Idaho's wild steelhead may have weathered the 2001 drought year in relatively fine style thanks to the all-out fish barging program put in place to get the fish past federal dams in the Columbia and Snake basins on their way to the ocean.

More than 6,000 wild 'B-run' steelhead have returned to Idaho this fall from the 2001 migration, along with about 20,000 hatchery B's, according to NOAA Fisheries biologists who sample the run every week at Lower Granite Dam. The run was listed for protection under the Endangered Species Act in 1997.

Most B-run steelhead spend two years in the ocean, while the majority of A run fish only forage for one year at sea before returning to fresh water. So many hatchery A's have returned from the 2002 migration that Idaho Fish and Game is trapping excess steelhead at Oxbow Hatchery below Hells Canyon dams, a barrier to further migration, and trucking them up to the Boise River for release, giving local residents a chance to eat steelhead this Thanksgiving instead of turkey.

Some had predicted the Idaho runs would teeter towards extinction despite the barging effort in 2001. "One will only have to wait until the adult returns start coming back from this year's migration to be reminded how grave the situation is for the salmon stocks in the Snake River," said Sharon Kiefer, IDFG's anadromous fish manager, back in March 2001.

Early last year, fish managers were still singing the same tune. Fish Passage Center head Michele DeHart wrote to federal biologists, saying, "Research has shown considerable interaction between flow and survival in the estuary. Despite the high proportion of Snake River fish transported from the 2001 out-migration it is unlikely that significant numbers of adults will return from this migration year because of the estuarine conditions."

Just last week, an IDFG press release that reported on the pre-Thanksgiving hatchery steelhead bonanza noted that "because 2001 was a poor runoff year, these larger steelhead will likely make up only a small portion of this year's steelhead run." Overall hatchery and wild steelhead numbers added up to about 175,000 fish this year, with about 44,000 in the wild category (some A-run fish are wild, too.). In 2002, nearly 220,000 steelhead were counted at the dam.

The 6,500 or so wild B-run steelhead returning to Idaho over the past two months is nearly twice the average return from 1995-1999, though much less than the previous year's run when about 32,000 wild B fish reached Bonneville Dam.

The returning fish have vindicated the federal agencies, who decided to go for mass barging in 2001 when they were faced with the second-worst water year in modern memory. More than 90 percent of the juvenile spring chinook (more than 4 million) and steelhead (6.7 million) were given a free ride in barges that environmentalists used to call "steel coffins," down rivers plagued with some of the lowest flows on record, flows so low they spelled disaster for the few fish left to migrate in them.

Only about 4 percent of the steelhead that stayed in the river in 2001 made it all the way past Bonneville Dam. But it wasn't simply low flows that crippled the inriver migration. A tern colony near Pasco consumed about 15 percent of them that year. By June, when waters began warming, most of the steelhead left likely quit migrating altogether and hung out in reservoirs, a phenomenon known as "residualization." Sports fishermen found a surprisingly good rainbow trout fishery in the lower Snake that year, most likely due to the residualized migrants from Idaho.

But the poor inriver survivals for juvenile salmon and steelhead migrating in 2001 have given flow augmentation proponents more ammunition in the endless debate over adding more water to aid fish migrations.

Last March, the Columbia Basin Fish and Wildlife Authority made a presentation to a National Academy of Sciences panel charged with studying flow and fish survival issues in the Columbia Basin. They cited PIT-tag data from 2001 as evidence of poor smolt-to-adult survivals, but their analysis never mentioned that most of the PIT-tagged fish were purposefully routed to migrate inriver, while more than 90 percent of the chinook and steelhead coming out of Idaho that year were barged.

NOAA Fisheries' Jerry Harmon, who leads the technical crew that monitors fish passage at Lower Granite Dam, said most PIT-tagged salmon were put in the river because they expected inriver survivals too be pretty low and wanted to make sure they could obtain enough data from those migrants to complete a rigorous analysis of flow and survival that year.

The 4 percent inriver survival rate for 2001 steelhead estimated from that strategy contrasts sharply with the 31-percent survival rate estimated for 2003 migrants, who migrated in a pretty much normal water year.

Related Page:
Only 3 Sockeye Return to ID's Sawtooths by Bill Rudolph, NW Fishletter, 11/10/3
Survival of Downstream Migration by National Marine Fisheries Service, 12/21/00
Count the Fish from the Fish Passage Center

Bill Rudolph
Idaho's Wild Steelhead Show from 2001's Drought-Plagued Migtration
NW Fishletter, November 10, 2003

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