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.