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Ecology and salmon related articles

2001: A Bad Year
for Salmon, Steelhead Juveniles

by Mike O'Bryant
Columbia Basin Bulletin - October 5, 2001

Some of the lowest river flows on record, coupled with no spill, or reduced spill provided too late at Columbia Basin dams to move the main body of juvenile migrants downstream, resulted this spring and summer in lower than ever in-river survival for juvenile salmon and steelhead.

By anyone's spin, it was a bad year for salmon and steelhead juveniles.

Of yearling spring/summer chinook not barged through the gauntlet of dams from Lower Granite Dam on the Snake River to Bonneville Dam on the mainstem Columbia River, only 23 percent survived.

Average system survival from 1995 to 2000 for those fish through that stretch of river has been roughly 43 percent, and was 49 percent in 2000.

Steelhead fared much worse at 4 percent, considerably off the historic 46 percent survival rate and 39 percent survival in 2000.

About 80 percent of juveniles in the Snake River were barged, according to Jim Ruff of the National Marine Fisheries Service.

Survival of subyearling chinook through three mid-Columbia dams also dropped to the lowest on record, with a 55 percent survival rate. Survival in 2000 was 83 percent.

Finally, survival for steelhead in the mid-Columbia dropped from the 2000 level of 66 percent to 19 percent.

In a summary of this year's juvenile salmon migration that she said is preliminary, Margaret Filardo of the Fish Passage Center, told the multi-agency Implementation Team this week that near record low runoff volume and emergency power operations "combined to produce the poorest migration conditions we've seen."

As she summarized her report, Filardo provided little in the way of good news:

With the second lowest water volume runoff on record at only 58 million-acre feet, spring and summer river flows this year seldom reached the target levels set by the NMFS BiOp. Spring flows at Lower Granite Dam peaked just above the 80,000 cubic feet per second target for only several days in May, but averaged only 49 kcfs. Flows at McNary Dam never reached the 220 kcfs target; instead they hovered around 126 kcfs. Summer flows at Lower Granite averaged 25 kcfs, far below the 50 kcfs BiOp target. McNary summer flows averaged 91 kcfs, also far below its target of 200 kcfs.

Even with these low flows, water temperatures seldom rose to lethal levels, primarily due to the use of colder water released from Dworshak reservoir.

Filardo said that the run timing of both subyearling chinook and steelhead was later due to the low flows and that the duration of the run was shorter. She also found some of the slowest travel times on record.

"These are some of the longest travel times we've seen," Filardo said. "We always get a wide range of travel times, but they've never been as long."

Her information showed average historic travel times for chinook between Lower Granite and McNary in the 7- to 15-day range, but this year those times ranged from 12 to 28 days. McNary to Bonneville travel time is general about 6 days, but this year times ranged from 6 to 13 days. Steelhead travel times were similar, but travel between McNary and Bonneville for steelhead was particularly shocking, according to Howard Schaller of the U.S. Fish and Wildlife Service.

"Even the fastest travel time for steelhead this year was slower than the longest time recorded before," he said. "That's very unusual to have all fish later." It may also be one of the reasons steelhead in-river survival was so poor, he added.

Travel time through the mid-Columbia stretch of river showed similar results, with chinook taking 15 to over 30 days to travel from Rock Island Dam to McNary, while historic travel time has been 10 to 15 days. Steelhead travel time was about the same, but historically it has been around 6 days.

This year spill was non-existent at Snake River projects and only limited spill was provided by the Bonneville Power Administration for spring and summer due to a declared power emergency. McNary spilled on alternating days between May 25 and June 15. When not spilling, juveniles were collected and barged downstream. John Day also spilled during that period. Spill was provided at The Dalles and Bonneville dams May 16 to June 15 and July 24 to August 31. All spill was at less than BiOp levels.

"Unfortunately, spill was kind of out of sync with fish passage," Filardo said. "Most fish were past when spill began. I am not suggesting that we missed totally. I'm just suggesting that spill should be spread out over the entire season."

For example, the steelhead run peaked at McNary the week of May 13, but spill didn't begin until May 25. Most of the steelhead run had passed both McNary and John Day dams when spill began. At Bonneville, the steelhead run built from mid-April and peaked May 13, which is when spill began. Passage of subyearling chinook showed similar patterns.

The last of the bad news from Filardo was the increase this year in stranded emerging chinook at Hanford Reach below Priest Rapids Dam. Filardo said that significant variation in flow at Priest Rapids resulted in stranding mortality estimated at 1, 628,878 fish. That's up from 72,362 last year and 125,695 in 1999.

This year's data did confirm a positive relationship between spill and in-river survival and a relationship between flow and passage, said Filardo. Using PIT-tagged fish from mid-Columbia projects, biologists found that yearling chinook survival from the McNary Dam tailrace to the John Day Dam tailrace increased from 79 percent to 90 percent when spill began. Steelhead survival increased from 31 percent to 38 percent (steelhead passage was later than chinook when temperatures were warmer and flow lower, which could account for their lower survival).

Filardo said that this year's results point out that even during low flow times, there is a significant benefit from spill and also the results confirm that the spill periods called for in NMFS' BiOp are correct.

Passage at Lower Granite Dam this spring spiked along with spikes in flow levels. A rain event in late April resulted in an increase in both yearling chinook and steelhead passage and a warming trend in mid-May produced similar results.

Filardo's presentation can be found beginning next week on the Fish Passage Center web site. Ruff said the information will be compiled and given to the federal executives. They have tentatively set Oct. 19 for their next meeting.

Link information:
Implementation Team
National Marine Fisheries Service
Fish Passage Center

Mike O'Bryant
2001: A Bad Year for Salmon, Steelhead Juveniles
Columbia Basin Bulletin, October 5, 2001

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