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Catastrophes and Recovery Goals

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.

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Catastrophes and Recovery Goals

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  1. Catastrophes and Recovery Goals

  2. The Question: • What is the number and distribution of populations needed for a sustainable ESU?

  3. Spatial Scale • Population (as per VSP) • reproductive isolation • independent demographics and intrinsic extinction risk • ESUs may contain multiple populations

  4. 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

  5. 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

  6. 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

  7. Simulated California Oil Spills

  8. Probable Otter Oil Contacts

  9. Major Oil Spills in Washington Spills >10,000 gallons over 14 year period. (State of Washington Dept. of Ecology)

  10. Effect of Oil on Pink Salmon in Prince William Sound (Bue et al. 1997)

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

  12. What counts as a catastrophe?

  13. SimSalmon Nx = Number at time x Rx = Spawners produced per Spawner at time x R is a stochastic variable with a lognormally distribution that can be estimated from data Ai = Fraction that mature at age i

  14. 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 Nt > K, then Nt = K

  15. SimSalmon Calculation

  16. Sample Data Set Snake River Fall Chinook (PATH 1999)

  17. Sample Trajectory

  18. Question For SimSalmon • What is the affect of losing an entire year class on extinction risk?

  19. Initial population Size

  20. Simulation Conditions • Distribution of R • Lognormal, mean = 1, variance = 1.72 • Depensation threshold = 10 • Age distribution

  21. Results

  22. Extinction in 40 Years

  23. 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

  24. Dams in the Lower Columbia

  25. 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.

  26. 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.

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