Historical Review

1
Historical Review

• Fish Migration Data

2
Two Management Approaches Spill for Fish Passage

• Planning dates
• Percent passage dates

3
Planning Date Advantage

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

4
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

5
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

6
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

7
Present Sampling and Marking Do Not Support the
Percent Passage Approach

• Mark groups do not represent the entire passage
  distribution
• Marking constraints
• Sampling constraints

8
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

9
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

10
The Historic Data1985-2003

• 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

11
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 (1994-2003), 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.

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Summer Migrants Snake RiverRun-at-large

• The 1991-2003 average 95 passage date at Lower
  Granite was Sept. 3
• The 1991-2003 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)

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Marked Snake Basin Subyearlings

• In 7 of 13 years (1991-2003) 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
  (1991-1998) marked fish showed a much earlier
  passage date.

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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 1995-2001 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.

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Mid-Columbia Summer Migrants

• Unclipped subyearling chinook at Rock Island from
  1997-2003 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

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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
Year Snake River Basin Snake River Basin Snake River Basin Mid-columbia River Basin Mid-columbia River Basin Mid-columbia River Basin Mid-columbia River Basin
Year ClearwaterRiver () Snake River () Tucannon River () Yakima River () Hanford Reach () Rock Island Dam () Wells Hatchery ()
1998 28.6 18.7 1.2 3.3 0.0 53.1 1.8
1999 (0 fish) 42.3 No tags 30.7 2.4 64.9 14.1
2000 (0 fish) 8.8 6.9 2.9 16.3 64.0 20.3
2001 (0 fish) 33.4 33.3 0.0 17.2 71.7 37.7
2002 (0 fish) 12.7 2.0 No tags No tags 57.2 5.1
2003 (3 fish) 12.5 No tags No tags 0.0 28.6 1.0
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Percentage of Subyearling Wild Chinook Migrants
Observed at John Day Dam During August
Year Yakima River Hanford Reach
1998 19.6 2.3
1999 20.0 9.2
2000 20.8 44.7
2001 4.5 66.7
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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.

26
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.

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Cont.

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