Comparing Current and Desired Status: Gaps Analysis

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Comparing Current and Desired Status Gaps
Analysis

• Brief overview ICTRT Viability Criteria
• Abundance/Productivity Gaps Concepts and
  Calculations
• Considering Uncertainties future environmental
  conditions, continued direct hydro survival
  improvements.
• Results Summaries Snake Basin Chinook and
  Steelhead

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General TRT Tasks

• Define goals
• Population identification
• Viability criteria (ESU population levels)
• Example ESU Scenarios
• How far do we have to go to get there?
• Current status assessment
• Defining gap between status and goal
• Choosing and implementing actions
• Limiting factors analyses
• Evaluating the effect of proposed actions

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TRT Hierarchical Criteria
ESU
ESU Status
Stratum/Geographic Unit/Major Population Group
Status
Stratum 2
Stratum 3
Stratum 1
Pop Status
Pop Attributes
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ICTRT Viability Criteria

• ESU level criteria
• Major Population Groupings
• Minimum number of viable populations in each
• Major life history patterns represented
• Historical population size representation
• Population Level Criteria
• Abundance/Productivity
• Spatial Structure/Diversity

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What Are the ICTRT Criteria Designed For?

• Providing benchmarks for
• Setting planning goals and objectives
• Starting point for delisting criteria, recovery
  goals
• Assessing the current viability of an ESU
• Formulating protection and/or recovery strategies
• Designing monitoring/evaluation efforts
• To assess changes in population status,
  contributions from recovery and/or protection
  efforts

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Purpose of MPG Criteria

• General VSP recommendation An ESU needs multiple
  spatially distinct and diverse populations to be
  viable.
• 1) To protect against catastrophic loss of any
  one population.
• 2) To ensure maintenance of long-term
  meta-population processes
• 3) To ensure that AMONG population diversity is
  maintained

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Snake River Spring Summer Chinook Major
Population Groupings Populations
Upper Salmon R. Group Lemhi R.
Pahsimeroi R. North Fk Panther Cr
Valley Cr. Yankee Fk East Fk Upper
Salmon Upper Salmon tribs.
South Fork Salmon Group South Fork East
Fork/Johnson Cr. Secesh R.
Lower Snake Tribs Group Tucannon R. Asotin R.
Middle Salmon R. Group Big Cr. Bear
Valley Marsh Cr . Sulphur Cr. Loon Cr.
Camas Cr. Chamberlain Cr. Upper Mainstem
tribs Lower Mainstem tribs
Grand Ronde/Imnaha Group Imnaha R. Big
Sheep Cr. Wenaha R. Minam R.
Lostine/Wallowa R. Catherine Cr. Upper
Grand Ronde
Clearwater (Ext.)
Above Hells Canyon (Ext)
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Figure E-2
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Population LevelAbundance/Productivity Criteria

• Abundance should be high enough that
• In combination with intrinsic productivity,
  declines to critically low levels would be
  unlikely assuming recent patterns of
  environmental variability
• Compensatory processes provide resilience to the
  effects of short-term perturbations
• Subpopulation structure is maintained (e.g.,
  multiple spawning patches, etc)
• Status estimates should consider statistical
  uncertainties

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Parameters contributing to risk (Abundance
Productivity)
trend
Variance ( autocorrelation)
abundance
N
time
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Population Level Spatial Structure and Diversity

• Three interrelated categories
• Structure spawning aggregations, spatial
  relationships
• Maintaining Natural Variation
• Habitats and Natural Processes

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Integrating Across SSD Criteria

• Simple Weighted scoring
• A population would be rated at HIGH risk if
• Average rating across spatial distribution
  criteria is HIGH RISK or
• Rating for life history or direct genetic
  criteria at HIGH Risk or
• Average rating across Life history, genetics,
  habitat and selectivity criteria is HIGH

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Assessing Population Viability Integrating
Across VSP Criteria

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ICTRT Viability Curves

• Expressed in terms of a simple hockey stick model
  (can generate curves for other functions)
• Used a constant Quasi-extinction risk level of 50
  spawners
• Incorporated minimum abundance thresholds
  (function of historical spawning area of the
  population)
• Modeling includes average age structure,
  estimated autocorrelation/variance in brood year
  productivity rates

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Viability Curve Basic PrinciplesIntrinsic
Productivity
At Capacity
Below Capacity
Next Generation Spawners
RaSmax
RaS
Replacement 1 spawner for every 1 parent spawner
Parent Spawners
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Population Size Thresholds

• Populations with fewer than 500 individuals are
  at higher risk for inbreeding depression and a
  variety of other genetic and demographic
  concerns.
• Increased thresholds for larger populations
  promote the full range of abundance/ productivity
  objectives.
• Avoid Allee affects
• Ensure compensatory processes
• Provide for spawning in multiple sub-areas

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Viability Curve
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Wenatchee River
Current abundance productivity

• Comparison to Viability Curve
• Abundance 10-year geomean Natural Origin
  Returns
• Productivity Geomean of spawner to spawner
  return rates most recent 20 years, parent
  escapements below 75 of the threshold. Indexed
  to annual marine survivals to improve estimate of
  rate under average conditions.
• Conclusion Wenatchee Spring Chinook population
  is at HIGH RISK based on current abundance and
  productivity. The point estimate for abundance
  and productivity is below the 25 risk curve.

Oval /- 1 standard error Lines /- 2 standard
errors
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Observed A/P Gaps

• Quantitatively gauging the relative change in
  survival/capacity required to move a population
  from current status to alternative viability
  levels (e.g., 5 or 1 risk over 100 years).
• Expressed terms of return/spawner.
• Gaps can be reduced by improved survival at any
  life stage from parr to returning adult.
• Assume recent (post-1980) climate, hydropower
  system, hatchery and harvest influences
• For a given population, more formal limiting
  factors analyses should be used to evaluate the
  potential for change at any given life history
  stage.
• Caveat All four VSP parameters (abundance,
  productivity, spatial structure and diversity)
  contribute to population viability. The ICTRT
  uses a series of metrics to assess current risk
  with respect to these factors. Comprehensive risk
  assessments are included in population specific
  status reports.

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ICTRT Gaps Reports

• Two components
• Observed Gaps Generic assessment of a/p gaps for
  populations with sufficient abundance data series
• More detailed stochastic matrix modeling for
  selected populations with sufficient data
• Incorporates alternative climate scenarios
• Improvements to life stage survivals (e.g.,
  current vs historical hydro)
• Can incorporate more detailed (life stage
  specific) analyses of recovery strategies
• projected improvements in survival or effective
  capacity
• Matrix Model Populations
• Yearling Chinook Wenatchee, Marsh Cr., South
  Fork and Catherine Cr.
• Steelhead Umatilla River, Rapid River (subarea
  of Little Salmon River population).

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A/P Gaps

• Observed Gap Quantitative change required to
  meet ICTRT A/P viability criteria
• Simple Algebraic approach
• Starting Point Population Current Status draft
  abundance/productivity summaries. Calculated
  using data from 1978-1999(2001) brood years
• Most populations Shortest distance from point
  defined by current status (abundance
  productivity) to a selected risk curve.
• Alternative calculations for higher productivity
  populations capacity considerations

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A/P Gap
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Key Considerations

• Productivity affected by mortality and survival
  at all life stages.
• The gap analyses themselves do not identify or
  target a particular life stage A/P gaps can be
  addressed by improvement opportunities at any
  life stage.
• Gap calculations can be sensitive to assumptions
  regarding relative hatchery effectiveness when
  parent spawners have high proportions of hatchery
  origin fish.

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Considering Uncertainty

• Different ways to consider uncertainty
• Checking current status evaluate the impact on
  projected risks of directly incorporating
  uncertainty measure
• Gaps analyses point estimates of gap under a
  range of potential future climate/ocean scenarios
  
• Status assessment approach can be adapted to gaps
  

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Snake River Steelhead Populations

• Major Population Group Analyzed Base Gap(5
  Risk)
• Lower Snake 1 1.23
• Grande Ronde/Imnaha 7 of 9 1.04 (0.59 to 3.09)
• South Fork Salmon 6 of 8 0.45 (0.32 to
  1.33)
• Middle Fork Salmon 6 of 8 1.27 (0.65 to 1.70)
• Upper Salmon 7 of 9 1.07 (0.44 to 2.28)

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Results

• Snake Fall Chinook
• One of three historical populations extant,
  largest populations extirpated
• Considerations
• Strong upward trend in abundance in recent years
  BUT
• Relatively short time series of applicable A/P
  data
• Lack of data to calculate SAR, parr to smolt
  relationships
• Changes in exploitation and hydro/transport over
  time
• Increased presence of multiple life history
  patterns
• Observed Gaps dependent on time frame
• 5 Risk 0.01 to 0.28
• 1 Risk 0.07 to 0.47

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Modeling Alternative Futures

• Matrix modeling
• Alternative Future Environmental Scenarios
• Historical patterns (50-100 years)
• Recent patterns (25 Years)
• Direct hydro survival improvements
• Continuation of recent observed improvements
• Modifications from Zabel et al. 2006
• Population-specific (rather than ESU-level)
• Climate function relies on PDO, upwelling, SST
  and WTT

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Climate scenarios
Poor
Historic
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Insert fig 2 flowchart
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South Fork Chinook A/P Gap Example
Gap
Gap
Gap
Recent Hydro
Recent Hydro
Recent Hydro
Warm PDO Years
Base Environmental
Recent 60 Year
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Summary

• Base gaps for Snake River Spring/summer chinook
  populations range from 0.32 to greater than 3.00.
• Alternative climate assumptions can substantially
  affect the absolute value of gaps Assuming that
  the future would be more like longer term
  conditions reduces gaps by 60-70, assuming
  consistent poor survivals (like 1990s) increases
  gaps by about 20
• Survival increases required to meet the 1 risk
  level would be 1.3 to 1.5 times the levels needed
  to meet the 5 risk criteria.
• For most populations, the survival changes being
  modeled for hydrosystem actions alone would not
  be sufficient to meet ICTRT viability criteria.
• Next steps modeling projected survival benefits
  of strategies generated through regional recovery
  planning efforts.