2005 Rural Labour Migration in China Challenges for Policies CAAS UNESCO
2005 Subyearling Migration
description
Transcript of 2005 Subyearling Migration
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2005 Subyearling Migration
Fish Passage Center
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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)
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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).
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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.
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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.