Steelhead and Snow

1. Steelhead and Snow Linkages to Climate Change ?

2. Recruitment CurvesFact or Fiction?

3. Clues from Residuals

4. Possible Candidates • PDO • PNI • Stream flow • Others

5. Mountain Snowfall • A guess based on my experiences • Good skiing years = good fishing years

6. Data Sites for Snow Index Mount Rainier Crater Lake

7. Which Measurement?Seasonal Maximum Snow Depths Mt Rainier Crater Lake

8. Snow Depth Index and Residuals Snow Index

9. Evaluation of Crater Lk & Mt Rainier Snow Index (CRSI) • Spawner-Recruit time series for 26 populations of Oregon steelhead • Evaluated 4 environmental indices as variables • CRSI • CRF • nsPDO • nPNI • Attempted fit of B-H function w/ and w/o environmental variable • Comparison • Was model statistically significant ? • Which model had lowest AICc score ?

10. Four Environmental IndicesThe Last 80 Years

11. Fitting Recruitment Curves Overview Predictor Variable 1 Spawners Response Variable Recruits Predictor Variable 2 Environmental Index

12. Fitting Recruitment CurvesTiming / Lags Predictor Variable 1 Spawners Response Variable Recruits Predictor Variable 2 Environmental Index

13. Which Models Significant?

14. AICc “Best Model” Frequency nPNI nsPDO CRF 5 Populations CRSI 19 Populations

15. The Not So Cool PartDecreased Snow = Fewer Steelhead

16. Mountain Snow Levels are in Decline(from 1950 to present) • Source: Mote et al. 2003

17. Air Temperature is the Story(Willamette Valley 7-yr Running Avg) CRSI AirTemp

18. Temperature Increase to Continue Source: IPCC (2007)

19. Driven by Anthropogenic Factors Source: IPCC (2007)

20. Climate Change is Here • “The West’s snow resources are already declining as the climate warms ” • - Mote et al. (2003)

21. What Does this Mean for Steelhead ? • Smaller Populations • Higher Risk of Extinction • How Much Higher ?

22. Attempt to Quantify Extinction Risk • Snow trends as proxy for climate change effect • Forecast extinction risks with PVA • Tested three CRSI scenarios • Slight decline (8% per 100 yrs) • Moderate decline (15% per 100 yrs) • Large decline (34% per 100 yrs)

23. PVA Model Add Spawners Recruits CRSI Adjusted Recruits

24. Prob Extinct < 0.05 Prob Extinct < 0.05 to 0.25 Prob Extinct < 0.25 to 0.50 Prob Extinct < 0.50 to 0.80 Prob Extinct > 0.80 Slight Decline in CRSI

25. Prob Extinct < 0.05 Prob Extinct < 0.05 to 0.25 Prob Extinct < 0.25 to 0.50 Prob Extinct < 0.50 to 0.80 Prob Extinct > 0.80 Moderate Decline in CRSI

26. Prob Extinct < 0.05 Prob Extinct < 0.05 to 0.25 Prob Extinct < 0.25 to 0.50 Prob Extinct < 0.50 to 0.80 Prob Extinct > 0.80 Large Decline in CRSI

27. Grim Predictions At least 50% of populations vulnerable to extinction

28. Implication for Fish ManagersCrafting a Response Extreme Response #1 Extreme Response #2

29. A More Measured Response • Accept that steelhead are in a evolutionary race against a rapidly changing environment • Losing the race = extinction • Management response should be: • Eliminate impediments to natural process of genetic adaptation • Support regional, national, and international actions to lessen and slow the impact of climate change

30. Natural Evolutionary ProcessesPart 1 – Get all Pieces in Full Play • Enable full expression of species diversity • Functional populations across species range • Function distribution across diverse habitats within a population’s range • Resident life history strategy • Repeat spawner life history strategy • Older age smolts • Maximize abundance of wild spawners to help retain genetic diversity

31. Natural Evolutionary ProcessesPart 2 – Don’t put Adaptive Gains at Risk • Limit use of hatchery fish • Genetic (regardless of broodstock origin) • Ecological • Expect phenotypic changes that depart from the historical condition, for example • More resident fish • Smaller fish • Different out-migration timing • Different return timing • Do not try to counteract these changes

32. Natural Evolutionary ProcessesPart 3 – Change Definition of Success • Steelhead management paradigm shift • Old – Abundance, productivity, and fishery utilization goals • New - Facilitation of rapid evolutionary change • Evidence of population response will be much slower and more difficult to detect • Determination if management strategy is a success will not occur in our lifetimes.

33. Summary • Mountain snowpack is linked to climatic factors that effect steelhead survival and recruitment • Climate change will greatly increase the vulnerability of steelhead populations to extinction • Facilitating the evolutionary process of population adaptation to climate change should be the primary focus of steelhead management in the future

34. Questions ?

36. 36 populations of steelhead, coho, and spring chinook

37. Preview • Demonstrate an association between variations in mountain snowpack and steelhead recruitment performance • Quantify an increase in extinction risk due to climate change based on linkages with snowpack • Suggest that facilitating the evolutionary process of population adaptation to climate change should be the primary focus of steelhead management in the future

38. Summary of Evaluation Approach • General Model Recruits = (Beverton-Holt Equation) * exp(c * Indx) • Examined 29 variations of model per population • Evaluation • Was model statistically significant ? • Which model had lowest AICc score ?

39. Pretty Cool!

40. CRSI Reflects this Decline

41. Air Temperature the Last 1300 Years From 2007 IPCC Technical Summary Report

43. Major Extinction Events