interior columbia basin trt draft viability criteria june, 2005 esu & population levels

Interior Columbia Basin TRTDraft Viability Criteria

June, 2005

ESU & Population Levels

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

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?

TRT Hierarchical Criteria

Pop Attributes

Pop Status

Stratum/Geographic Unit/Major Population Group Status

ESU Status ESU

Stratum 1 Stratum 2 Stratum 3

Population Level

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

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)

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.

Viability Curve: Basic PrinciplesHockey Stick: Conservative Model

Spring ChinookViability Curves (Hockey Stick)

1.0 1.2 1.4 1.6 1.8 2.0 2.20

250

500

750

1000

70:30

1600260036004600

Hi Risk

Low Risk

Mean R/S

Sta

rtin

g P

opul

atio

n S

ize

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

Spring/Summer Chinook: Natural Origin Smolt to Adult Return Rates (Referenced to Lower Granite Run Size)

0.0%0.5%1.0%1.5%2.0%2.5%3.0%3.5%4.0%4.5%5.0%

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Brood Year

LGR

Smol

t to

Adul

t Su

rviv

al (S

AR)

Williams CSS/Petrosky Average 1978- Avg.

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

Spatial Structure/Diversity Criteria

• Two interrelated categories– Maintaining natural structure – spawning

aggregations, spatial relationships

– Maintaining Natural Variation

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

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

#

Entiat River

#

Mad River

Enitiat RiverSpring Chinook MSAs

Branch

>1.25km Weighted "moving window"

Major Spawning Area

<100000m2 (non-MSA)

>=100000m2 (MSA)

0 5 10 Miles

0 5 10 Kilometers

#

Vansycle Canyon

#

Woodward Canyon

#

Mill Creek

#

South Fork Walla Walla River

#

North Fork Walla Walla River

#

Pine Creek

#

Dry Creek

#

Spring Valley Creek

#

Spring Creek

# Cottonwood Creek

#

Dry Creek

#

Couse Creek

#

Little Dry Creek

#

Blue Creek

non-MSA

branch

MSA

Walla Walla RiverSummer Steelhead MSAs

0 10 20 Miles

0 10 20 Kilometers

– 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

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

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

V V V

V V V

Spatial Structure/Diversity RISK

Very Low Low Moderate High

Very Low(<1%)

Low<5%

Moderate<25%

HIGH

Abundance & Productivity RISK

Criteria: Distribution, Life history/geneticsSupporting processes

Assessing Population Viability: Integrating Across VSP CriteriaICTRT DRAFT (May 2005)

Criteria:Recent AbundanceAnd ProductivityvsViability Curve

V = Viable population

DRAFT DRAFT DRAFT DRAFT

Major TRT considerations regarding “how many and which”:

1) Catastrophic risk2) Diversity2) Metapopulation Dynamics

Major policy consideration:Flexibility

NationalMarine

FisheriesService

How Many and Which Populations?

NationalMarine

FisheriesService

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.

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.

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.

What are the major groupings within Interior ESU’s?

• Based on:– Genetics,

-- life history patterns, – large scale variations in major environmental

factors• EPA ecoregions• Elevation, temperature & precipitation

Snake River Spring Summer Chinook Major Population Groupings & Populations

Lower Snake Tribs Group

Tucannon R.Asotin R.

South Fork Salmon Group

South ForkEast Fork/Johnson Cr.

Secesh R.

Grand Ronde/Imnaha GroupImnaha R. Big Sheep Cr.Wenaha R. Minam R.

Lostine/Wallowa R.Catherine Cr.

Upper Grand Ronde

Middle Salmon R. GroupBig Cr. Bear ValleyMarsh Cr . Sulphur Cr.Loon Cr. Camas Cr.

Chamberlain Cr.Upper Mainstem & tribsLower Mainstem & tribs

Upper Salmon R. Group

Lemhi R. Pahsimeroi R.North Fk Panther Cr Valley Cr. Yankee Fk

East Fk Upper SalmonUpper Salmon tribs.

Above Hells Canyon

(Ext)

Clearwater(Ext.)

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 DaySouth Fk John Day

Middle Fork John DayNorth 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

Middle Columbia Steelhead ESUSpawning Elevation Ranges (Intrinsic)

MC

FIF

-s

MC

RO

C-s

MC

WS

A-s

DR

ES

T-s

MC

KLI-

s

DR

WS

T-s

WW

MA

I-s

WW

TO

U-s

MC

UM

A-s

YR

TO

S-s

YR

UM

A-s

YR

NA

C-s

JDLM

T-s

JDM

FJ-

s

JDU

MA

-s

JDN

FJ-

s

JDS

FJ-

s0

200

400

600

800

1000

1200

1400

1600

1800

Populations

Ele

vati

on

(m

)