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Interior Columbia Basin TRT Draft Viability Criteria June, 2005 ESU & Population Levels.

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Presentation on theme: "Interior Columbia Basin TRT Draft Viability Criteria June, 2005 ESU & Population Levels."— Presentation transcript:

1 Interior Columbia Basin TRT Draft Viability Criteria June, 2005 ESU & Population Levels

2 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

3 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?) What are the basic TRT technical tasks?

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

5 Population Level VSP Guidelines identify four basic components to consider: –Abundance –Productivity –Spatial Structure –Diversity

6 Abundance/Productivity Criteria Population 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)

7 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.

8 Viability Curve: Basic Principles Hockey Stick: Conservative Model

9 Abundance/Productivity Criteria Population 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


11 Assessing Abundance & Productivity Status Population 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

12 Spatial Structure/Diversity Criteria Two interrelated categories –Maintaining natural structure – spawning aggregations, spatial relationships –Maintaining Natural Variation

13 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

14 Diversity Criteria Population 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



17 –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

18 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

19 Integrating Across SSD Criteria Population 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

20 VVV VVV Spatial Structure/Diversity RISK Very Low Low Moderate High Very Low (<1%) Low <5% Moderate <25% HIGH Abundance & Productivity RISK Criteria: Distribution, Life history/genetics Supporting processes Assessing Population Viability: Integrating Across VSP Criteria ICTRT DRAFT (May 2005) Criteria: Recent Abundance And Productivity vs Viability Curve V = Viable population DRAFT DRAFT DRAFT DRAFT

21 Major TRT considerations regarding how many and which: 1)Catastrophic risk 2)Diversity 2)Metapopulation Dynamics Major policy consideration: Flexibility National Marine Fisheries Service How Many and Which Populations?

22 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.

23 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.

24 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.

25 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

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

27 Mid-Columbia Steelhead: Major Population Groupings & Populations 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 Yakima Basin Group Satus Cr. Toppenish Cr. Naches R. Upper Yakima R.. Columbia Plateau Group Umatilla R. Touchet R. Walla Walla R. Willow Cr


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