friend or foe? influence of resident trout on steelhead production in the yakima basin
DESCRIPTION
Friend or Foe? Influence of Resident Trout on Steelhead Production in the Yakima Basin. Ian Courter Cramer Fish Sciences. David Child. Acknowledgements. David Child, DC Consulting Jim Hobbs, UC Davis Chris Frederiksen , YN Joe Blodget , YN Dave Fast, YN Shadia Duery , CFS - PowerPoint PPT PresentationTRANSCRIPT
Friend or Foe? Influence of Resident Trout on Steelhead
Production in the Yakima Basin
Ian CourterCramer Fish Sciences
David Child
AcknowledgementsDavid Child, DC Consulting
Jim Hobbs, UC Davis
Chris Frederiksen, YN
Joe Blodget, YN
Dave Fast, YN
Shadia Duery, CFSJay Vaughan, CFS
Tommy Garrison, CFSSteve Cramer, CFS
Funding
Yakima Basin Joint Board
Background
• Use existing data to determine whether resident rainbow trout contribute to the upper Yakima Basin steelhead population
• Construct a steelhead population dynamics model that accounted for conspecific resident rainbow trout
Spawn Timing Resident Spawners Anadromous Spawners
RM
RF
AM
AF
Assortative Mating
Egg ProductionRF RM AF AM
Cross-Ecotype ExchangeResident female
fecundityAnadromous female
fecundity
Model Validation
1992 1994 1996 1998 2000 2002 2004 2006
Ste
elh
ea
d S
pa
wn
er
Ab
un
da
nc
e
0
50
100
150
200
250
300
350Observed Predicted (default parameterization)Predicted (no Rf smolt production)
SAR
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16
Pro
po
rtio
n S
teel
hea
d D
eriv
ed
fro
m R
fxR
m
0.0
0.2
0.4
0.6
0.8
1.0
Photo Credit David Child
Hypotheses
A significant number (≥10%) of resident rainbow trout offspring migrate to the ocean and return as adult steelhead.
Microns
0 500 1000 1500 2000 2500 3000
87S
r : 86
Sr
0.703
0.704
0.705
0.706
0.707
0.708
0.709
Microns
0 500 1000 1500 2000 2500 3000
87S
r : 86
Sr
0.703
0.704
0.705
0.706
0.707
0.708
0.709
0.710
Photo Credit Frank Thrower
Ste
elhe
ad R
esili
ence
Resident A
bundance
Resident C
ontribution Rate
Steelhead Abundance
ConclusionsO. mykiss populations in the Yakima Basin are
partially anadromous, and significant numbers of offspring from resident trout adopt an anadromous life-history.
17% resident maternal origin 30% or more have at least one resident parent
steelhead population viability and recovery is dependent on existence of a robust resident trout cohort, which highlights the importance of jointly managing freshwater and anadromous life-histories as units of the same population.