Principal Investigators:

Fred R. Monzyk Jeremy D. Romer

Ryan EmigThomas A. Friesen

Oregon Department of Fish and WildlifeCorvallis Research Lab

Corvallis, Oregon

Most juvenile Chinook enter reservoirs in spring as fry (mean FL=35 mm).

Subyearlings use nearshore habitat in the spring

Move offshore into deeper water in the summer

Return to surface in the fall

Month

July August September October November December

Dep

th (m

)

0

5

10

15

20

20132012

Lookout Point

Vertical Distribution

Spring

Summer

Fall

Where are they???

Lookout Point

Information needed for designing downstream passage

Evaluated longitudinal distribution (HoR to Dam) of subyearlings in the spring 2011-2014.• Cougar, Detroit, Foster, Lookout Point (LOP)

In 2014, evaluated longitudinal distribution in the summer and fall (pilot effort in fall 2013).• LOP only

Spring Nearshore nets set throughout reservoirs

• 3 months in spring (Mar-Jun)• Checked daily• Cumulative distribution by res length

2x2x3’ box trap w/ 5-m lead net

Summer and Fall Gill nets set in 6 areas of LOP (all with steep slopes) Set 45-65’ deep in summer (Jul-Aug ) and surface in fall (Oct-Nov) Compared catch between areas w/ Kruskal-Wallis test (α=0.05)

(hatchery and natural origin)

• Subyearlings more abundant near HoR, except at Foster

Percent distance to dam

0 20 40 60 80 100

Cum

ulat

ive

prop

ortio

n

0.0

0.2

0.4

0.6

0.8

1.0

Cougar 2012 Cougar 2013 Cougar 2014 Foster 2013 Foster 2014 Lookout 2013 Lookout 2014

DamHoR

South Santiam Arm

Spring

• Subyearlings disperse further into reservoir each month

Percent distance to dam

0 20 40 60 80 100

Cum

ulat

ive

prop

ortio

n

0.0

0.2

0.4

0.6

0.8

1.0

AprMayJun

HoR Dam

Cougar Reservoir -2014

Spring

6

1

2

4

3

5

Lookout Point 2014 (viewed another way)

Divided reservoirinto 6 areas forcomparison tosummer and fallcatch

Area

A6A5A4A3A2A1

Chi

nook

cat

ch

0

20

40

60

80

Spring

1 2 3 4 5 6Dam HoR

Spring

Hatchery

Reservoir area

A1 A2 A3 A4 A5

Hat

cher

y-or

igin

Chi

nook

0

5

10

15

20

25

30Natural

A1 A2 A3 A4 A5

Nat

ural

-orig

in C

hino

ok0

5

10

15

20

25

30

z zy y y

A6

Toowarm

A6

Reservoir area

Bimodal distribution –subyearlings at dam and near HoR

Toowarm

23% of A5 hatchery catch comprised of forebay release group38% of A1 hatchery catch comprised of HoR release group

Milling?

Dam HoR Dam HoR

Chi

nook

cat

ch

Summer

Reservoir area Reservoir area

Dam

Warm/shallow water

Conceptual model of movement patterns that would cause bimodal distributions

Summer

Reservoir area

A1 A2 A3 A4 A5

Nat

ural

-orig

inCh

inoo

k ca

tch

0

2

4

6

8

10 Natural

Reservoir area

A1 A2 A3 A4 A5

Hat

cher

y-or

ign

Chi

nook

cat

ch

0

2

4

6

8

10 Hatchery

A6

Dry Dry

A6

• Subyearlings moved towards dam• Distribution developed before outflows increased

z z y y y y

Fall

Chi

nook

cat

ch

Dam Dam HoRHoR

Lookout Point Fall Discharge

Date

06-Oct 13-Oct 20-Oct 27-Oct 03-Nov 10-Nov 17-Nov 24-Nov

Dis

char

ge (C

FS)

0

2000

4000

6000

8000

10000

Inflow Outflow

14-21 October(before increase in flows)

Reservoir area

A1 A2 A3 A4 A5

Natu

ral-o

rigin

Chi

nook

cat

ch

0

1

2

3

4

5

6

• Distribution pattern developed prior todischarge increases

• Consistent with downstream movement to overwintering habitat

Fall

Distribution shifted from HoR to Dam from spring to fall

Bimodal summer distribution• Traversing, milling at barrier behavior??

Fall distribution consistent with downstream movement to overwintering habitat observed for unimpounded populations

Greg TaylorChad HelmsDoug GarlettsTodd PierceNat EricksonRich Piaskowski

Jeff ZillerKelly Reis

The ‘Reservoir Dogs’Khoury HickmanChris AbbesGreg GilhamAndrew NordickMeghan Horne-BrineJohn ElliottKevin StertzRyan FlahertyJD Hansen

Questions?