# Presentation: 034863

## Catastrophes and Recovery Goals

## The Question: 

- What is the number and distribution of populations needed for a sustainable ESU?

## Spatial Scale

- Population (as per VSP)
- reproductive isolation
- independent demographics and intrinsic extinction risk
- ESUs may contain multiple populations

## The laundry list of catastrophes

- Weather (draughts, floods)
- Oil Spills / Shipping Risks
- Landslides / Mass Wasting
- Epidemics
- Dam/Water Diversion Failure
- Major mistakes in harvest
- Chemical contamination
- Volcanoes
- Earthquakes
- Fires

## Major Challenges

- Predict the frequency, spatial extent and severity of potential catastrophic events
- Establish the link between the event and salmon survival or behavior
- Translate impacts on salmon into population and ESU level extinction risk

## Example: Southern Sea Otter

- Ralls et al. 1996
- Oil Spill considered most serious threat
- Extensive modeling potential of oil spill
- Related spill probabilities to number of contacted otters
- Estimated mortality per contact from Exxon Valdez data

## Simulated

- California
- Oil Spills

## Probable Otter Oil Contacts

## Major Oil Spills in Washington

- Spills >10,000 gallons over 14 year period.
- (State of Washington Dept. of Ecology)

## Effect of Oil on Pink Salmon in Prince William Sound

- (Bue et al. 1997)

## Increase in Sediment following 1970 Fire in Entiat River, WA (Helvey, 1980)

- Increase in Sediment following 1970 Fire in Entiat River, WA (Helvey, 1980)

## Slide 12

## Slide 13

## What counts as a catastrophe?

## SimSalmon

*N**x* = Number at time *x*
*R**x* = Spawners produced per Spawner at time *x*
*     **R* is a stochastic variable with a lognormally
-      distribution that can be estimated from data
*A**i* = Fraction that mature at age *i*

## More Bits on SimSalmon...

- Extinction:
- If Nt < Depensataion Threshold, Rt =0
- The population is extinct if *N* = 0 for a number of years in a row equal to the maximum age at maturation.
- Density Dependence
- Simple Ceiling
- If *N**t* > *K*, then *N**t* = *K*

## SimSalmon Calculation

## Sample Data Set

- Snake River Fall Chinook
- (PATH 1999)

## Sample Trajectory

## Question For SimSalmon

- What is the affect of losing an entire year class on extinction risk?

## Initial population Size

## Simulation Conditions

- Distribution of R
- Lognormal, mean = 1, variance = 1.72
- Depensation threshold = 10
- Age distribution

## Results

## Extinction in 40 Years

## Major Challenges

- Predict the frequency, spatial extent and severity of potential catastrophic events
- Establish the link between the event and salmon survival or behavior
- Translate impacts on salmon into population and ESU level extinction risk

## Dams in the Lower Columbia

## ESU Viability Guidelines

- ESUs should contain multiple populations.
- Populations in an ESU should be geographically widespread.
- Populations should be geographically close to each other.
- Populations should not all share common catastrophic risks.
- Populations that display diverse life-histories and phenotypes should be maintained.
- Some populations should exceed VSP guidelines.
- Evaluations of ESU status should take into account uncertainty about ESU-level processes.** **

## Final Thoughts

- Catastrophes can be the largest risk.
- Catastrophic risk will not be eliminated and needs to be incorporated into large scale recovery plans.
- Collaboration across many disciplines will be required.