Interior Columbia Basin TRT Draft Viability Criteria June, 2005

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Interior Columbia Basin TRTDraft Viability
CriteriaJune, 2005

• ESU Population Levels

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Outline

• General Approach to evaluating ESU viability
• Population criteria
• Abundance Productivity
• Spatial Structure Diversity
• Integrating these components for a population
• Higher Level
• MPG criteria and examples
• ESU level risk criteria

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What are the basic TRT technical tasks?

• NOAA asked TRTs to address this question in
  context of the following
• Identify historical populations
• Identify viability criteria for each population
• Identify guidelines for viable ESUs (how many and
  which populations?)

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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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Population Level

• VSP Guidelines identify four basic components to
  consider
• Abundance
• Productivity
• Spatial Structure
• Diversity

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Abundance/Productivity CriteriaPopulation Level

• Abundance refers to the average number of
  spawners in a population over a generation or
  more.
• Productivity (or population growth rate) refers
  to the performance of the population over time.
• 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
• Within population substructure is maintained
  (e.g., multiple spawning patches, etc)

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Viability Curve Approach

• Assume a simple, generic model Hockey stick is
  relatively conservative.
• Include a measure of year to year variability
  consistent with observations
• Select Risk objective e.g., less than 5 risk
  of quasi-extinction in 100 years.
• Quasi-extinction Extremely low level of
  escapement below which continued production is
  uncertain 50 spawners is current level
• Run model many times and define threshold
  combinations of Intrinsic Productivity and
  Average abundance associated with meeting risk
  objective.

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Viability Curve Basic PrinciplesHockey Stick
Conservative Model
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Abundance/Productivity CriteriaPopulation Level

• Adapting basic viability curves to reflect
  complex spatial structure and size for particular
  populations
• Using measure of historical intrinsic potential
  as index
• Relatively simple populations (e.g., Entiat
  spring chinook) used as standard.
• Complex, relatively large populations (e.g.,
  Wenatchee and Methow spring chinook or steelhead)
  would have potential for higher combinations of
  abundance and productivity, therefore lower risk

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Assessing Abundance Productivity
StatusPopulation Level

• Measuring against the Viability Curve
• Abundance Recent average across generation
• Intrinsic Productivity Difficult to directly
  measure
• Population Change Criteria sustained growth
  rate from low abundance
• Population growth rate over time
• Return per spawner metrics
• Curve fitting
• Directly incorporate estimates of uncertainty
  when comparing population status to viability
  curves
• Where feasible Augment adult return information
  with indices of juvenile productivity and smolt
  to adult survival

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Spatial Structure/Diversity Criteria

• Two interrelated categories
• Maintaining natural structure spawning
  aggregations, spatial relationships
• Maintaining Natural Variation

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Spatial Structure Criteria Population Level

• Spatial Structure refers to the geographic
  distribution of a population and the processes
  supporting that distribution.
• Basic rationale
• Multiple spawning reaches within a population
  provides protection against local catastrophic
  loss
• Some production areas may be inherently more
  productive than others potentially serving as
  sources to a broader range of areas after
  prolonged periods of low survival, etc.
• Multiple spawning areas provide greater
  opportunities for differentiation

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Diversity CriteriaPopulation Level

• Diversity the distribution of traits within and
  among populations of an ESU
• Three reasons for diversity criteria
• Allows a species to use a wide array of
  environments
• Protection against short term changes in habitat
• Provides the genetic material necessary to adapt
  to longer term changes in the environment

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• Spawning Range
• High Risk
• Small/Simple Populations Historical range
  reduced Absence of spawners from 50 or more of
  the historical distribution based on intrinsic
  potential analysis. OR
• Absence or major reduction from major habitat
  categories (e.g., upstream/downstream, tribs vs
  mainstem, ecoregions)
• Complex Populations Same as above OR
• Absence of spawners from 50 or more of
  historical Major Spawning Areas - MSAs

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Diversity Criteria Population Level

• Phenotypic Traits (morphological and life
  history)
• Loss of major life history strategies
• Reductions/changes in traits
• Genetic Characteristics
• Direct measures
• Influences of artificial production
• Population characteristics that suggest changes
  in diversity
• Gaps in spawning
• Spawner composition
• Selective effects of human activities
• Spawning distribution vs habitat types

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Integrating Across SSD CriteriaPopulation Level

• Simple Weighted scoring approach
• 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 ICTRT DRAFT (May 2005)
Spatial Structure/Diversity RISK
Criteria Distribution, Life
history/genetics Supporting processes
Very Low Low Moderate High
Abundance Productivity RISK
V V V
V V V


Very Low (lt1)
Criteria Recent Abundance And Productivity vs Via
bility Curve
Low lt5
Moderate lt25
HIGH
V Viable population
DRAFT DRAFT
DRAFT DRAFT
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National Marine Fisheries Service
How Many and Which Populations?

• Major TRT considerations regarding how many and
  which
• Catastrophic risk
• Diversity
• Metapopulation Dynamics
• Major policy consideration
• Flexibility

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National Marine Fisheries Service
How Many and Which Populations?

• General TRT approach to how many and which
• Partition each ESU into groups of populations
  based on genetic measures, major habitat patterns
  (e.g., eco-regions) and life history variations
  (Major Population Groupings or strata)
• Development of risk based ESU level criteria
  for deciding how many populations at what status
  within each stratum.

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ESU Level Criteria

• VSP Guidelines
• Consistent with historical setting, Multiple
  populations, some geographically widespread, some
  in close proximity to one another.
• All Populations within an ESU should not share
  the same catastrophic risk.
• Populations displaying diverse life
  histories/phenotypes should be maintained
• Some populations should exceed VSP guidelines.

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Proposed ESU Viability Criteria

• An MPG would have a high probability of
  persistence if
• At least one-half of the historical populations
  (minimum of 2) in each extant Major Grouping are
  meeting population viability criteria. (Major
  extirpated areas considered on a case by case
  basis.)
• High viability populations should include all
  major life history patterns and representative
  number of large/intermediate populations.
• At least one population in each extant strata
  should be rated at Very Low risk.
• The remaining extant populations are maintained
  i.e., not in immediate danger of extinction
• Note For some multi-population ESUs, there may
  be combinations of pop status across major
  groupings that could result in low risk without a
  requirement that all major groupings individually
  meet criteria case by case consideration.

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What are the major groupings within Interior
ESUs?

• Based on
• Genetics,
• -- life history patterns,
• large scale variations in major environmental
  factors
• EPA ecoregions
• Elevation, temperature precipitation

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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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Mid-Columbia Steelhead Major Population
Groupings Populations
Yakima Basin Group Satus Cr. Toppenish
Cr. Naches R. Upper Yakima R..
Eastern Cascades Group Deschutes (w) Deschutes
(E) Klickitat Rock Cr. Fifteen Mile Cr. White
Salmon (ext)
John Day Basin Group Lower John Day South Fk
John Day Middle Fork John Day North Fork John
Day Upper John Day
Columbia Plateau Group Umatilla R. Touchet
R. Walla Walla R. Willow Cr
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