1. Dave Pflug & Ed Connor Seattle City Light
Management and Recovery Implications of Wild/Hatchery Steelhead Interactions with a Large Complex Watershed - Skagit River, WA PART 2
Dave Pflug & Ed Connor
Seattle City Light

2. Hatchery Smolts Released in the Skagit River Basin: 1960-2010

3. Wild and Hatchery Steelhead Smolt Outmigration Timing in Skagit River
174,000 Hatchery Smolts Released Between May 11-22
Wild smolts began outmigrating in January in low numbers peaking in late May (May 27th) and continuing into late July (July 21st). Hatchery smolts were released from Marblemount Hatchery and Baker River trap. Hatchery fish began appearing within 2-3 days of release peaking June days post release. The last hatchery smolt captured left the river 38-days after the latest release date.

4. Wild versus Hatchery Steelhead Smolts Captured at Skagit Smolt Trap
If trap capture efficiencies are similar for wild and hatchery smolts the catch data suggests that hatchery smolt production exceeds wild production on an annual basis
WDFW operates a smolt trap at Mount Vernon to determine the annual abundance of juveniles leaving the watershed each year
Composed of a Screw and Scoop Trap
Annual steelhead smolt catch numbers range from 1,000 – 8,000 per year
Assuming similar trap efficiency hatchery smolts typically outnumber wild smolt

5. Skagit Steelhead Regression Model
Escapement
-0.19
0.39**
-0.13
PDO Index
0.56**
Skagit Steelhead
Return
0.32
- 0.43**
Peak Flow
0.44*
0.24
0.49**
Low Flow
Unexplained = 21%
* p < 0.01
** p < 0.001

6. Pacific Decadal Oscillation (PDO
University of Washington
Climate Impacts Group (CIG)

7. Skagit Steelhead Run Size versus PDO Index (1978-2009)
RSQ = 0.34
p < 0.01

8. Steelhead Abundance Trends in many Northern Puget Sound and Georgia Basin Rivers are Correlated

9. Skagit Steelhead Survival Index: 1945 - 2010

10. Smolt to Adult Return Trends for Skagit Hatchery Steelhead

11. Ocean Survival: Skagit Wild and Hatchery Steelhead

12. Freshwater and Ocean Survival Rates for Returning Skagit Steelhead

13. Modeled Population Productivity for Upper Skagit River Steelhead

14. Hatchery Steelhead Survival Rates versus Smolt Release Numbers

15. Are Skagit Steelhead Approaching a Critical Viability Threshold?

16. Implications of Current Freshwater and Ocean Conditions
Ocean survival rates of hatchery fish have dropped to about 0.1%
We are now experiencing record low FW and SW survival rates for wild Skagit steelhead
Worst steelhead “depression” since the 1940s
Even small impacts can have big effects under current FW and SW survival conditions

17. Summary Effects of hatchery programs need to be looked at closely
Genetic introgression
“Wasted” wild spawning
Increased competition and predation impacts
Reduced spatial and temporal diversity
“Allee Effects” need to be given increaseed scrutiny
Predator impacts in Skagit River and Puget Sound