Historical Review Fish Migration Data

Two Management Approaches Spill for Fish Passage Planning dates Percent passage dates

Planning Date Advantage Certainty in planning and implementing hydro system operations Eliminates controversy and conflict regarding spill management Implemented within present data collection systems

Planning Date Disadvantage Late migrating stocks receive less spill protection Does not adjust to variability in passage distribution and timing Does not incorporate travel time

Advantage of Fixed Percent Passage Potential to extend protection to later migrating stocks which extend beyond the present planning dates Potential economic benefit if percent passage date occurs prior to the present planning date

Disadvantage of Percent Passage Date Uncertainty in planning, difficult to predict Present data collection system does not support this management approach Using run-at-large weights protection to hatchery releases Present mark groups do not support this management approach

Present Sampling and Marking Do Not Support the Percent Passage Approach Mark groups do not represent the entire passage distribution Marking constraints Sampling constraints

Cont. Requires more extensive marking of specific stocks to fully represent the migration May require later end date of sampling Additional PIT tag marking required of index groups

Using Run-at-large, Weights Protection to Hatchery Releases Run-at-large dates are determined by large production releases upstream of the project Protection of upstream origin or weaker stocks is diminished at downstream sites

The Historic Data Run-at-large Timing and distribution data is highly influenced by large hatchery releases Present marking and monitoring does not allow the differentiation between hatchery and wild stocks in the run-at-large Percentiles based upon the run-at-large timing do not accurately represent the wild passage distribution

Spring Migrants For wild PIT tagged yearling chinook from the Salmon and Clearwater basins, the 10 year average 95% detection date occurred after the June 20 planned end of spring spill in the lower Snake River. For Salmon River stocks in 6 out of the 10 years analyzed ( ), 7% to 16% occurred after June 20. For Clearwater wild yearling chinook in 9 of 10 years, 6% to 23% of detections occurred after June 20.

Summer Migrants Snake River Run-at-large The average 95% passage date at Lower Granite was Sept. 3 The average cumulative passage index that occurred after August 31 at Ice Harbor was 11.6% The 95% passage date at Ice Harbor occurred after August 31 in 9 of 13 years (based on Lower Granite plus travel time)

Marked Snake Basin Subyearlings In 7 of 13 years ( ) greater than 5% of passage occurred at Ice Harbor after August 31, August 15 at Lower Granite Dam. Marked subyearling chinook may not represent the wild run at large. In 5 of the 8 years of data ( ) marked fish showed a much earlier passage date.

Lower Columbia Summer Migrants The 95% passage date of the summer migration at McNary is largely influenced by the present hatchery release schedules for Ringold and Priest Rapids (Aug. 6 –19) For the wild Hanford reach groups which are PIT tagged in early June, 95% passage occurs on July 26. There is no tag data for the middle and late portion of this population.

Mid-Columbia Summer Migrants Unclipped subyearling chinook at Rock Island from average 95% passage date at McNary is Sept. 16 In 3 of 7 years of data 95% passage occurred at MCN (7%-21%) and BON (10%-27%) after August 31

Year Snake River BasinMid-columbia River Basin Clearwater River (%) Snake River (%) Tucannon River (%) Yakima River (%) Hanford Reach (%) Rock Island Dam (%) Wells Hatchery (%) (0 fish)42.3No tags (0 fish) (0 fish) (0 fish) No tags (3 fish)12.5No tags Percentage of annual PIT tag detections occurring in August at McNary Dam for subyearling chinook originating in the Snake R. and Mid-Columbia R. basins

Percentage of Subyearling Wild Chinook Migrants Observed at John Day Dam During August YearYakima RiverHanford Reach

General Impressions Significant modifications are required to sampling programs to facilitate the percent passage management approach. Expansion of mark groups are required for all species to support the percent passage approach.

Cont. On average 95% passage date for subyearling chinook at Lower Granite Dam extends past the planning date. By terminating spill at Ice Harbor on August 31, only the passage distribution through August 15 at Lower Granite is provided spill protection.

Cont. On average wild Mid-Columbia stocks extend beyond the planning date at McNary Dam.