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 FMetolius 1,400 46o FUpper Yakima 3,600 60o FUpper Sacramento

10,000 55o F

Mainstem Teanaway

Teanaway and Yakima River confluence

Yakima River Temperatures

30

40

50

60

70

80

Ave

rage

Tem

pera

ture

(F)

JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDECMonth

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)

Prob

able

Sui

tabi

lity

fryjuvenileadult

Depth Suitability for O. mykiss

0

0.2

0.4

0.6

0.8

1

1.2

0 1 2 3 4 5Velocity (fps)

Prob

able

Sui

tabi

lity

fryjuvenileadult

Velocity Suitability for O. mykiss

From Grant and Kramer (1990)

Fork Length (mm)

0 50 100 150 200 250 300 350 400

Terr

itory

Siz

e (m

²)

0

2

4

6

8

10

12

14

16 Fry Juvenile Adult

Flow (cfs)

0 500 1000 1500 2000

Fry

capa

city

0

10000

20000

30000

40000

50000

60000

Juve

nile

and

adu

lt ca

paci

ty

0

1000

2000

3000

4000

FryJuvenileAdult

Territory Needed for a Steelhead Cohort

0100200300400500600700800

Fry 0+ Parr 1+ ParrLife Stage

Num

ber

in C

ohor

t

-20406080100120140160

Terr

itor

y Re

quir

ed

(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/d

ay)

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

Mainstem Growth

0

100

200

300

400

500

60026

-Jun

24-S

ep23

-Dec

23-M

ar21

-Jun

19-S

ep18

-Dec

17-M

ar15

-Jun

13-S

ep12

-Dec

12-M

ar10

-Jun

8-S

ep7-

Dec

7-M

ar5-

Jun

3-S

ep2-

Dec

2-M

ar31

-May

29-A

ug27

-Nov

Time since emergence

Fork

leng

th (m

m)

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) Lo

g 10(B

iom

ass)

+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 co

ho d

ensi

ty (n

o./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 sur

viva

l Nov

-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 max

)

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

bser

vatio

ns

0

200

400

600

800

1000 Cumulative Frequency0.0

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

bser

vatio

ns

0

500

1000

1500

2000

2500 Cumulative Frequency0.0

0.2

0.4

0.6

0.8

1.0Riffles

Pools7 Basins528 km5,886 pools

4,900 riffles

Atlas of Pacific Salmon (2005)

Tributary Growth

0

50

100

150

200

250

300

350

40013

-Jul

11-O

ct

9-Ja

n

9-A

pr

8-Ju

l

6-O

ct

4-Ja

n

3-A

pr

2-Ju

l

30-S

ep

29-D

ec

29-M

ar

27-J

un

25-S

ep

24-D

ec

24-M

ar

Time since emergence (months)

Pred

icte

d fo

rk le

ngth

(mm

)

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

Spawning date3-Apr

Emergence13-Jul