2005 Subyearling Migration
Fish Passage Center
Overview – summer migration
• Court ordered summer spill occurred from June 20 to August 31, 2005
• Question was posed to FPC if any response could be determined for the juvenile migrants
• No specific studies related to spill were conducted in 2005. RT studies were conducted, but did not address reach survival of juvenile migrants.
• PIT tags data were available from production marking, as well as wild fish marking and various studies (transportation, hatchery operations)
Historic Data Set• PIT tags available included: production/acclimation
fish, wild chinook and research/surrogate fish.• Reach survival estimates (LGR to McN) possible
since 1998. This was partly due to increases in the numbers of tags released and PIT tag recapture location at JDA.
• Typical hydrograph – high flows occur in late May-early June – with subsequent decreasing trend.
• Summer spill prior to 2005, if spill occurred, was during late high flow periods or during periods of excess market capacity (2002).
Daily Avg Q Little Goose 1998 to 2005
0
50
100
150
200
250
5/1 5/8 5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 7/10 7/17 7/24 7/31
Sp
ill
(Kc
fs)
1998 1999 2000 2001 2002 2003 2004 2005
1998 to 2005 Conditions
0
20
40
60
80
100
98 99 00 01 02 03 04 05
Year
Kcf
s o
r #
day
s
FLOW (5/20-8/31) FLOW (6/20-8/31) Days spill after 6/20
Preliminary Analyis• Used available PIT-tags – conduct temporal analyses
similar to those conducted with yearling migrants • 2 groups separated as much as possible into
before/after spill began on June 20• Estimated LGR to MCN survival of two groups• Assigned exposure indices for environmental variables• Compared 2005 to patterns observed in other recent
past years • Originally compared back to 2001
Survival LGR to McN for Subyearling Chinook before and during summer spill in
2005 with 90% CI’s
0.0
0.2
0.4
0.6
0.8
1.0
5/20 to 6/12 6/17 to 7/15
Dates detected at LGR
Su
rviv
al
Survival for Subyearling Chinook LGR to McN 2001 to 2005 with 90% CI’s
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
2001 2002 2003 2004 2005
Group 1 Group 2
Updates to Preliminary Analysis
• Use shorter time intervals to better match reach survivals to environmental conditions
• Adds distinct pre-6/20 (at LGS-IHR), transitional, post 6/20 groups
• Expanded to include 1998 to 2000 migration years• Used weighted regression (inverse variance)• Introduces higher variability in survival estimates
due to lower sample sizes
Lower Granite Detection date ranges for Survival Groups
Update Groups GRJ Dates Prel. Groups
1 5/20-6/02 5/20 – 6/16
2 6/03-6/16
3 6/17-6/30 6/17 – 7/15
4 7/01-7/14
Percent Post LGR Detects of Fall Chinook seen as Yearlings downstream of LGR – 7 d moving average
Index of increasing holdover rates by mid-July
0
0.1
0.2
0.3
0.4
0.5
0.6
6/14 6/24 7/4 7/14 7/24 8/3 8/13 8/23 9/2
Date Detected at LGR
Per
cen
t Y
earl
ing
Det
ecti
on
s
my_2000 my_2001 my_2002 my_2003
Environmental Variables
• Assigned Flow, Spill, Temperature variables for each group through each reach segment (LGR to LGS, LGS to LMN, LMN to IHR, IHR to MCN)
• Averaged env. variable using two-week moving “window” based on median travel time for each detection group
• Then averaged these assigned variables for an exposure index related to reach survivals
Detection Group date range compared to Avg Total Q at Little Goose Dam
0
50
100
150
200
250
5/1 5/8 5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 7/10 7/17 7/24 7/31
Sp
ill (
Kcf
s)
1998 1999 2000 2001 2002 2003 2004 2005
1 2 43
Detection Group date range compared to Avg Spill Q at Little Goose Dam
0
20
40
60
80
100
120
5/1 5/8 5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 7/10 7/17 7/24 7/31
Sp
ill (
Kcf
s)
1998 1999 2000 2001 2002 2003 2004 2005
1 432
Detection Group date range compared to Avg Temp C at Little Goose Dam
10
12
14
16
18
20
5/1 5/8 5/15 5/22 5/29 6/5 6/12 6/19 6/26 7/3 7/10 7/17 7/24 7/31
Sp
ill (
Kcf
s)
1998 1999 2000 2001 2002 2003 2004 2005
321
Subyearling Survival 1998 to 2005 Lower Granite Tailwater to McNary Tailwater
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1998 1999 2000 2001 2002 2003 2004 2005
Su
rviv
al L
GR
to
McN
(95
% C
I)
5/20-6/2 6/3-6/16 6/17-6/30 7/01-7/14
Subyearling Chinook Survival versus Avg Spill Percent Lower Granite Tailwater to McNary Tailwater
0
0.2
0.4
0.6
0.8
1
1.2
0 0.1 0.2 0.3 0.4 0.5 0.6
Avg Spill (Percent) LGS, LMN, IHR, MCN
Su
rviv
al L
GR
to
MC
N
Weighted Regression 1998 1999 2000 2001 2002 2003 2004 2005
y=0.31613 + 0.95695X
adj R2 = 0.48
Subyearling Chinook Survival versus Avg Total Discharge Lower Granite Tailwater to McNary Tailwater
0
0.2
0.4
0.6
0.8
1
1.2
40 60 80 100 120 140 160 180
Avg Total Discharge (KCFS) LGS, LMN, IHR, MCN
Su
rviv
al L
GR
to
MC
N
Weighted Regression 1998 1999 2000 2001 2002 2003 2004 2005
y=0.1954 + 0.0038X
adj R2 = 0.52
Subyearling Chinook Survival versus Avg Temperature Lower Granite Tailwater to McNary Tailwater
0
0.2
0.4
0.6
0.8
1
1.2
13 14 15 16 17 18 19 20 21 22
Avg Temperature (C) LGS, LMN, IHR, MCN
Su
rviv
al L
GR
to
MC
N
Weighted Regression 1998 1999 2000 2001 2002 2003 2004 2005
y=1.6062 - 0.0593X
adj R2 = 0.56
Subyearling Chinook Survival versus Median Travel Time Lower Granite Dam to McNary Dam
0
0.2
0.4
0.6
0.8
1
1.2
10 15 20 25 30 35 40 45
Median Travel Time LGR to MCN (d)
Su
rviv
al L
GR
to
MC
N
Weighted Regression 1998 1999 2000 2001 2002 2003 2004 2005
y=0.7872 - 0.01458X
adj R2 = 0.43
Correlation Matrix Subyearling Data 1998 to 2005
SURVIVAL AVSPLPCT AVGFLOW AVTEMPC
SURVIVAL 1
AVSPLPCT 0.71 1
AVGFLOW 0.74 0.66 1
AVTEMPC -0.76 -0.59 -0.82 1
Multivariate Analysis
• Tested for significant interactions between main effects (flow, spill, temperature)
• No significant interactions detectable but variability and low sample size make multivariate approach tenuous
• Backward Stepwise regression AvgFlow removed from model
• Final Model N=26, adj mult R2= 0.651
Effect Coefficient Std Error Std Coef Tolerance t P(2Tail)
CONSTANT 1.14803 0.23617 0 4.86099 0.00007
SPILLPCT 0.5393 0.19793 0.39827 0.65352 2.72474 0.01208
AVTEMPC -0.04094 0.01142 -0.52399 0.65352 -3.58481 0.00157
Conclusions
• Relations between survival and flow, temperature and spill were significant based on weighted linear regression at p < 0.01
• Stepwise regression resulted in Spill and Temp remaining in model; flow and temp variables were highly correlated; interactions could not be fully assessed
• Trend of survival in most years since 1998 was higher early decreasing throughout the period reflecting annual patterns in flow, spill and temperature.
Conclusions• The notable exceptions were 2001 and 2005. The
2001 estimates were low throughout the extreme drought year. However, the 2005 survival estimates showed a distinctly different trend with higher survival observed for the later time period.
• Given the relatively low flows and relatively warm temperature, the change in survival pattern in 2005 was likely due to the provision of spill.
• Similarly, travel time estimates were shorter than expected for the late group in 2005, based on flow levels that occurred in that time 2005.