Federal Energy Regulatory CommissionHydroelectric Operations

Wild Rainbow (Redband) Trout

Redband Spawning and Population Study Elements

• Hydrology Review

• Spawning Patch Inventory of the Study Area

• Physical Characterization of Spawning Patches

• Hydrodynamic Characterization of Spawning Patches

• Biological Spawning Characterization

• Effective Spawning/Incubation Habitat Relationships

• Redband Trout Abundance Estimates (ten years)

Study Reach and Patch Inventory (2009)

Substrate Characterization

Survey Patch Area and Elevation

Survey Water Elevations

Redband Trout Spawning Period 2010

April 1 - 7

April 8 - 14

April 15 -

21

April 22 -

28

April 29 - May 5

May 6 - 12

0

2

4

6

8

10

12

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Number of Redds Observed Average Daily Discharge

Date

Num

ber o

f Red

ds O

bser

ved

Ave

rage

Dai

ly D

isch

arge

(cfs

)

Spawning Survey (2010)

Spawning Areas Mapped

Observed Redband Trout Depth and Velocity Frequency

0 1 2 3 4 5 6 7 80

5

10

15

20

25

30

35

40

45

50

Velocity (ft/s) Depth (ft)

Feet or Feet/Sec

Freq

uenc

y

Artificial Redds for Intra-gravel Survival

Trout Fry Survival

Cumulative Spawning Plot Area

0 2000 4000 6000 8000 10000 12000 140000

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

Discharge (cfs)

Tota

l Pat

ch A

rea

(ft^2

)

Results 2010

• 58 Gravel Patches

• Deeper Spawning: Ave. 3.5’, Max. Over 5 Feet

• 148 Redds Counted in 2010 (130 in 2003)

• Appears There is Good Intra-Gravel Survival

• Habitat Over a Range of Flows

• Effective Spawning and Incubation Habitat Tables

Mark-Recapture Population Estimate

Results

• Tagged Over 800 Redbands in 2010

• Estimated Over 1,300 Ten Inch Fish in 2010

• Tagged Over 650 Redbands in 2011

• Estimated Over 1,400 Ten Inch Fish in 2011

• Tagged Over 455 Redbands in 2012

• Estimate Over 1,050 Ten Inch Fish in 2012

Effective Spawning and Incubation Habitat

Fork Length (mm)

0 50 100 150 200 250 300 350 400 450 500

Prop

ortio

n of

the

catc

h (%

)

0

1

2

3

4

5

6

7Age 0 Age 1 Age 2 Age 3 Age 4 Age 5 Age 6

Length and Age Frequency

Tim Vore509.495.8612tim.vore@avistacorp.com

Credits: West Fork Environmental, Cardno Entrix, WDFW