Steve Cramer Casey Justice

Ian Courter

Environmental drivers of steelhead abundance in partially anadromous Oncorhynchus mykiss populations

Key Characters in the Plot

Project Objectives

• Determine how environmental factors drive productivity of resident and anadromous O. mykiss ecotypes

Test this understanding:• Can the functional relationships of O. mykiss

productivity to environmental factors predict the observed distribution of the two ecotypes in the Yakima Basin?

Examples of Resident Rainbow Streams

within the Anadromous Fish ZonesAugust

Basin Flow (cfs)

Temperature

McKenzie 2,600 54o F

Metolius 1,400 46o F

Upper Yakima 3,600 60o F

Upper Sacramento

10,000 55o F

Mainstem Teanaway

Teanaway and Yakima River confluence

Yakima River Temperatures

30

40

50

60

70

80

Average T

em

peratu

re (

F)

JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC

Month

Yakima R @ Umtanum (Rb)Yakima R @ Prosser (Sthd)

Yakima Basin

Rainbow And Steelhead Intermix And Produce Both Types

• Interbreeding of Rb x St is observed

• Genetics show similarity by basin, not by ecotype

• Breeding studies show each type produces some of the other

• Sr/Ca ratio in otoliths of spawners confirms cross parentage

Focal Point Depth and Velocity. From Everest and Chapman 1972

0

0.2

0.4

0.6

0.8

1

1.2

0 1 2 3 4 5 6 7

Depth (ft)

Pro

bab

le S

uit

abil

ity

fry

juvenile

adult

Depth Suitability for O. mykiss

0

0.2

0.4

0.6

0.8

1

1.2

0 1 2 3 4 5Velocity (fps)

Pro

ba

ble

Su

ita

bil

ity

fry

juvenile

adult

Velocity Suitability for O. mykiss

From Grant and Kramer (1990)

Fork Length (mm)

0 50 100 150 200 250 300 350 400

Ter

rito

ry S

ize

(m²)

0

2

4

6

8

10

12

14

16 Fry Juvenile Adult

Flow (cfs)

0 500 1000 1500 2000

Fry

cap

acit

y

0

10000

20000

30000

40000

50000

60000

Juve

nil

e an

d a

du

lt c

apac

ity

0

1000

2000

3000

4000

FryJuvenileAdult

Territory Needed for a Steelhead Cohort

0

100

200

300

400

500

600

700

800

Fry 0+ Parr 1+ Parr

Life Stage

Num

ber

in

Coh

ort

-

20

40

60

80

100

120

140

160

Ter

rito

ry R

equi

red

(m̂2)

Fish Territory

From Rand et al. (1993) and Mangel and

Sattherthwaite (2008).

Modeling Growth in FreshwaterGrowth = anabolic gains – catabolic losses

Factors influencing growth:

1) Temperature

2) Food availability

Stream temperature (°C)

0 5 10 15 20 25

Gro

wth

(g

/day

)

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

Mainstem Growth

0

100

200

300

400

500

6002

6-J

un

24

-Se

p

23

-De

c

23

-Ma

r

21

-Ju

n

19

-Se

p

18

-De

c

17

-Ma

r

15

-Ju

n

13

-Se

p

12

-De

c

12

-Ma

r

10

-Ju

n

8-S

ep

7-D

ec

7-M

ar

5-J

un

3-S

ep

2-D

ec

2-M

ar

31

-Ma

y

29

-Au

g

27

-No

v

Time since emergence

Fo

rk le

ng

th (

mm

)

Age-0 Age-1 Age-2 Age-3 Age-4 Age-5

Spawning27-Mar

Emergence26-Jun

Growth of PIT-tagged Wild SteelheadRecaptured 1 yr after Tagging

Keifer et al. 2004

Salmon & ClearwaterRiver tributaries

Relationship Between Temperature & Trout Biomass

Salt River Basin (Isaak and Hubert 2004) L

og

10(B

iom

as

s)+

1

2

1

05 10 15

Mean Stream Temperature (oC)

MWAT (oC)

12-14 14.1-16 16.1-18 18.1-20 20.1-22 22.1-24 24.1+

Mea

n c

oh

o d

ensi

ty (

no

./m

2 )

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Juvenile Coho Density vs. Temperature 260 Oregon Coast Sample Sites

Extended Bar shows 2 Standard Errors

0.0

0.2

0.4

0.6

0.8

1.0

12 14 16 18 20 22 24 26

Conclusions

• Channel size, flow and temperature are key factors that determine carrying capacity for resident fish over 250 mm, and may determine which of the two ecotypes will dominate

• Data are available in the Yakima Basin to predict how carrying capacity for O. mykiss will be affected by flow, temperature, and channel morphology

• We can test how well we understand the factors driving life history of O. mykiss by: – Using what we understand to build a life cycle model for O.

mykiss– Plug in actual values for habitat and environmental factors,– Compare how the predicted and observed distributions of

the two ecotypes match

Growth is a Key Driver

• Growth determines size at age

• Size determines the area of habitat occupied

• Size at age determines winter survival in freshwater

• Size at smolting determines ocean survival

Hypothesis

Variation in flow conditions influence the distribution of the two ecotypes across subbasins

Substantial declines in summer discharge will reduce carrying capacity for adult resident fish and promote a migratory life-history strategy

Hypothesis

Over-winter Survival

Fork length (mm)

60 80 100 120 140 160 180 200 220

Ove

r-w

inte

r su

rviv

al N

ov-

Feb

(%

)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Smith and Griffith (1994)

Adjusted curve

Length at emigration (mm)

100 125 150 175 200 225 250 275 300

Mar

ine

surv

ival

sca

lar

(% o

f m

ax)

0

20

40

60

80

100

120

Data from Ward and Slaney (1989)

Marine Survival

Rearing capacity = Habitat Area (m2) / Territory size (m2)

0.0 0.5 1.0 1.5 2.0

# o

f O

bse

rvati

ons

0

200

400

600

800

1000 Cum

ula

tive F

requency0.0

0.2

0.4

0.6

0.8

1.0

Depth (m) (Upper Bound)

0.0 0.5 1.0 1.5 2.0

# o

f O

bse

rvati

ons

0

500

1000

1500

2000

2500 Cum

ula

tive F

requency0.0

0.2

0.4

0.6

0.8

1.0Riffles

Pools

7 Basins528 km5,886 pools

4,900 riffles

Atlas of Pacific Salmon (2005)

Tributary Growth

0

50

100

150

200

250

300

350

4001

3-J

ul

11

-Oct

9-J

an

9-A

pr

8-J

ul

6-O

ct

4-J

an

3-A

pr

2-J

ul

30

-Se

p

29

-De

c

29

-Ma

r

27

-Ju

n

25

-Se

p

24

-De

c

24

-Ma

r

Time since emergence (months)

Pre

dic

ted

fo

rk le

ng

th (

mm

)

Age-0 Age-1 Age-2 Age-3

Spawning date3-Apr

Emergence13-Jul