1. Maternal Life-History Type and Natal Rearing Origin of Adult Steelhead in the Yakima Basin
David Child
DC Consulting, L.L.C.
Ian Courter
Cramer Fish Sciences

2. Yakima Basin Joint Board
Acknowledgements
Joe Blodgett, YN
Dave Fast, YN
Jim Hobbs, UC Davis
Shadia Duery, CFS
Jay Vaughan, CFS
Tommy Garrison, CFS
Steve Cramer, CFS
Funding
Yakima Basin Joint Board

3. Photo Credit Eric Anderson

4. Hypotheses
A significant number (≥10%) of resident rainbow trout offspring migrate to the ocean and return as adult steelhead.

7. Otolith strontium isotope geochemistry
Natural abundance of
stronitum isotopes
Radiogenic Decay
87Rb
87Sr
t1/2 = 48.8 B yr
87Sr = 7%
/86Sr = 10%
= 0.7…
Plasma mass spectrometer
icpms.ucdavis.edu
otolithlab.ucdavis.edu
Credit: J. Hobbs

8. Microns
500
1000
1500
2000
2500
3000 87
Sr : 86 Sr
0.703
0.704
0.705
0.706
0.707
0.708
0.709

9. Microns
500
1000
1500
2000
2500
3000 87
Sr : 86 Sr
0.703
0.704
0.705
0.706
0.707
0.708
0.709
0.710

12. The upper basin may be more influential than previously thought
Conclusions
O. mykiss populations in the Yakima Basin are partially anadromous, and significant numbers of offspring from resident trout are adopting an anadromous life-history.
17% resident maternal origin
30% or more have at least one resident parent
The upper basin may be more influential than previously thought
Management implications?
17% resident offspring 12

13. Plans for 2011
Collect additional water samples in Satus Creek, Toppenish Creek, and Lower Yakima River.
Collect a representative sample of the entire kelt emigration
Develop additional validation tests

14. Questions/Comments
Photo Credit Frank Thrower 14

18. Natal Core 87 Sr: 86 Sr Freshwater Rearing 0.704 0.705 0.706 0.707
0.708
0.709
0.710
Freshwater Rearing
0.703