Sarah McCarthy Trophic performance of Oncorhynchus mykiss along forest gradients in the South Fork...

Sarah McCarthy

Trophic performance of Trophic performance of Oncorhynchus mykissOncorhynchus mykiss along along forest gradients in the South forest gradients in the South Fork Trinity River watershedFork Trinity River watershed

UNIVERSITY OF WASHINGTON

South Fork Trinity RiverSouth Fork Trinity River

Photo courtesy of J. Duda

• Klamath River tributary• Trinity River dam: 1962• South Fork Trinity

undammed• Klamath Mountains

Province steelhead ESU unlisted

What factors control O. mykiss production in CA?• Temperature Effects• Prey Quality• Feeding Rate

Use bioenergetics modeling to identify effect of season, age, forest cover, and temperature on O. mykiss consumption and growth efficiency (GE).

ObjectivesObjectives

Study Design

• 9 streams

• 3 forest cover categories

• 2 temperature regimes

Study Design

Conifer-coolN=1

Conifer-warmN=2

Mixed-coolN=1

Mixed-warmN=2

Hardwood-coolN=3

N/A

FISH GROWTH

Bioenergetics Model

CONSUMPTION

THERMAL EXPERIENCE

DIET COMPOSITION

PREDATOR ENERGY DENSITY

PREY ENERGY DENSITY

C = G + M + W

Proportion of maximum consumption (p): C/Cmax

G/C = Growth

efficiency (GE)

Model Inputs

• Stream Temperature(constant temperature monitoring)

• Prey Quality(invertebrate drift sampling)

• O. mykiss Growth Measurements

• O. mykiss Diet Composition

Fish Sampling

• Electrofished 9 streams

during June, August, and

October 2003



October 2003

• Measured length & weight

Fish Sampling



October 2003


• Collected scales

Fish Sampling



October 2003


• Collected scales

• Collected stomach contents

Fish Sampling

Weight Trajectories

Fish Sampling

Age 2

June August October0

10

20

30

40

50Age 1

Month

June August October0

5

10

15

20Age 0

June August October

Wei

gh

t (g

)

0

1

2

3

4

5Conifer-coolConifer-warmMixed-coolMixed-warmHardwood-cool

Conifer-cool highest weight, but all groups had slow growth

Warm streams had sharpest growth increase

Hardwood-cool and conifer-cool grew most

Diet Composition

Prey items:

• Immature aquatic sources:– Aquatic larvae (Diptera, Coleoptera, Trichoptera, etc)

– Aquatic nymphs (Ephemeroptera, Plecoptera, etc)

– Aquatic other (Gastropoda, Isopoda, Crustacea, Acarina, Ostracoda, etc)

• Adult invertebrates: – Aquatic (Ephemeroptera, Plecoptera, Trichoptera, Diptera)

– Terrestrial (Coleoptera, Hymenoptera, Araneae)

Diet Composition

•Contribution of adult insects increased with age

Aquatic larvaeAquatic nymphsOtherAquatic adultsTerrestrial adults

Conifer-cool

Month

Jun Aug Oct Jun Aug Oct Jun Aug Oct

Die

t P

rop

ort

ion

s

0.00

0.25

0.50

0.75

1.00

Age 0 Age 1 Age 2

Diets varied by season and age

Age 0

Age 0

Age 1

Age 1

Age 2

Age 2

12 11 16 5 2 2 1 5 2 26 23 16 8 14 66 2

14 19 7 3 2 6 1 8 28 22 25 11 12 6 8 4

3 16 15 10 17 21 10 21 22

Conifer-warm

Month

Jun Aug Oct Jun Aug Oct Jun Aug Oct

Die

t P

rop

ort

ion

s

0.00

0.25

0.50

0.75

1.00


Conifer-cool

Month

Jun Aug Oct Jun Aug Oct Jun Aug Oct 0.00

0.25

0.50

0.75

1.00

Mixed-warm

Month

Jun Aug Oct Jun Aug Oct Jun Aug Oct D

iet

Pro

po

rtio

ns

0.00

0.25

0.50

0.75

1.00

Mixed-cool

Month

Jun Aug Oct Jun Aug Oct Jun Aug

Die

t P

rop

ort

ion

s

0.00

0.25

0.50

0.75

1.00

Hardwood-cool

Month

Jun Aug Oct Jun Aug Oct Jun Aug Oct 0.00

0.25

0.50

0.75

1.00

• Low proportion of maximum consumption (avg=0.25)

0.0

0.2

0.4

0.6

0.8

1.0

5 10 15 20 25

Temperature (°C)

Sp

ecif

ic r

ate

(g/g

/d) Cmax

• Summer

temps:

14-18°C

Consu

mpt

ion

Respiration

Bioenergetics Modeling

C = G + M + W

Simulation Day

100 200 300 400 500 600 700

Field Temperature

0 100 200 300 400 500 600 700

Wei

gh

t (g

)

0

5

10

15

20

Field TemperatureAug

Jun

Jun

Oct

Oct

Aug

Aug

Aug

Jun

Jun

Oct

Oct

Aug

Barker CreekCool (3.1 - 14.4oC)

Carrier GulchWarm (1.3 - 18.4oC)

Simulating Increased Summer Temperature Effects

Most growth occurs during winter/spring

Age 0 Age 0Age 1 Age 1Age 2 Age 2

Simulation Day

100 200 300 400 500 600 700

Field TemperatureTemperature +2oC

0 100 200 300 400 500 600 700

Wei

gh

t (g

)

0

5

10

15

20

Field TemperatureTemperature +2oC

Aug

Jun

Jun

Oct

Oct

Aug

Aug

Aug

Jun

Jun

Oct

Oct

Aug

Barker CreekCool (3.1 - 14.4oC)

Carrier GulchWarm (1.3 - 18.4oC)

Simulating Increased Summer Temperature Effects

With 2oC temperature increase, O. mykiss required to grow more over winter.

5.4% 8.9%

11.5%

18.8%

SummarySummary• Increased consumption of

adult insects with age and season

• Higher consumption of adult invertebrates in conifer-cool category

• Decreased or negative growth during late summer

• Low feeding rates throughout summer

• Decreased summer growth after 2oC temperature increase


SummarySummary• Increased consumption of adult

insects with age and season

• Higher consumption of adult invertebrates in conifer-cool category

• Decreased or negative growth during late summer

• Low feeding rates throughout summer

• Decreased summer growth after 2oC temperature increase


Conclusions

Isn’t summer the “growing season”?

– O. mykiss may be food-limited across the watershed

– Heightens concern for effects of interannual variability and/or climate shifts

– Implications for other steelhead stocks in CA• high temperatures exacerbated by low prey supply

• even minor shifts in temperature or food supply could push population further into negative growth patterns

– Recommend extending study to neighboring populations

Acknowledgements

USGS:

Jeffrey Duda, C. Ostberg, Dr. R. Reisenbichler, Dr. S. Rubin, K. Larsen, S. Dufrene, L. Pascoe, C. Chambers, C. Galitsky, J. Steinbacher

UW School of Aquatic and Fishery Sciences:

Dr. C. Grue, Dr. L. Conquest, V. Blackhurst, E. Chia, D. O’Donnell, A. Van Mason, A. Lind, C. Sergeant, S. Damm, J. Matilla, E. Duffy, A.

Cross, J. Moss, M. Mazur, N. Overman, S. Wang, E. Schoen

USFS Redwood Sciences Laboratory, Arcata, CA:

Dr. H. Welsh, G. Hodgson, Dr. B. Harvey

USFS Ranger Station, Hayfork, CA:

J. Lang, J. Fitzgerald

UNIVERSITY OF WASHINGTON

Graduate committee: Dr. David Beauchamp, Dr. John Emlen, Dr. Thomas Quinn

Effects of Food and Temperature Effects of Food and Temperature on Growth Energeticson Growth Energetics

0.0

0.2

0.4

0.6

0.8

1.0

5 10 15 20 25

Temperature (°C)

Sp

ecif

ic r

ate

(g/g

/d)

C max

Consu

mpt

ion:

Respiration

25% Cmax

Consumption rate reduction = reduced optimal temperature for growth and growth potential.

Effects of Food and Temperature Effects of Food and Temperature on Growth Energeticson Growth Energetics

0.0

0.2

0.4

0.6

0.8

1.0

10 15 20 25

Temperature (°C)

Sp

ecif

ic r

ate

(g/g

/d)

Cmax

Consu

mpt

ion

Respiration

5

25% Cmax

Gro

wth

(g

/(g

*d))

Temperature (°C)

0.0

0.4

0.6

0.8

0.2 25% Cmax

100% Cmax

5 10 15 20 25

Absolute growth very low when costs associated with metabolism and waste are accounted for.

Physical Stream Characteristics

Stream Temperature• Temperature loggers deployed

April-October 2003

• Temperature recorded every 20 minutes

• Avg daily temp >17°C = warm

• Avg daily temp <17°C = cool

June October

Warm

Tem

per

atu

re (

C)

0

5

10

15

Conifer Mixed

Cool

Day

0 50 100 150 200 250 300 3500

5

10

15

ConiferMixedHardwood

Prey Sampling

Drift Composition• Drift samplers deployed before dusk; collected after dawn

• Evaluated relative proportion of invertebrate drift

• Invertebrates used for bomb calorimetry

Relative Prey SupplyDrift Composition• Higher volume of

immature aquatic invertebrates

• Higher prey supply in hardwood-cool

flow

Stream bottom

Conifer-warm

Month

April June August October

Ave

rag

e in

vert

ebra

te b

iovo

lum

e/d

ay

0.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

2.25

Mixed-warm

Month

April June AugustOctober

Ave

rag

e in

vert

ebra

te b

iovo

lum

e/d

ay

0.0

0.5

1.0

1.5

2.0

Conifer-cool

Month

April June August October0.0

0.5

1.0

1.5

2.0


Mixed-cool

Month

April June August October

Ave

rag

e in

vert

ebra

te b

iovo

lum

e (m

L/h

)

0.0

0.5

1.0

1.5

2.0

Hardwood-cool

Month

April June AugustOctober0.0

0.5

1.0

1.5

2.0

• Drift sampler bias

Cumulative Consumption

Ditch Gulchwarm

Jun-Aug Aug-Oct Jun-Aug Aug-Oct Jun-Aug

Carrier Gulchwarm

Simulation Period/Age

Jun-Aug Aug-Oct Jun-Aug Aug-Oct

Co

nsu

mp

tio

n (

g)

Barker Creekcool

Jun-Aug Aug-Oct Jun-Aug Aug-Oct Jun-Aug Aug-Oct

Co

nsu

mp

tio

n (

g)

0

25

50

75

100

125

Aquatic larvaeAquatic nymphsOtherAquatic adultsTerrestrial insects

Age 0 Age 0Age 0Age 1 Age 1 Age 1Age 2 Age 2 Age 2

Conifer

GE = Growth/Consumption

2.9 - 8.9% -2.3 – 9.7% -7.3 – 7.2%

Lower growth efficiencies during late summer

West Twin Creekwarm


Potato Creekwarm



Co

nsu

mp

tio

n (

g)

Chanchellula Creekcool

Jun-Aug Aug-Oct Jun-Aug Aug-Oct Jun-Aug

Co

nsu

mp

tio

n (

g)

0

25

50

75

100

125

Aquatic LarvaeAquatic NymphsOtherAquatic AdultsTerrestrial Adults


Mixed



-1.1 – 11% -42 – 15.2% -3.8 – 15.4%


Underwood Creekcool


Olsen Creekcool



Co

nsu

mp

tio

n (

g)

Monroe Creekcool


Co

nsu

mp

tio

n (

g)

0

25

50

75

100

125

Aquatic LarvaeAquatic NymphsOtherAquatic AdultsTerrestrial Adults


Hardwood



3.7 – 7.1% -2.7 – 13.2% -12.2 – 15.9%


Sarah McCarthy Trophic performance of Oncorhynchus mykiss along forest gradients in the South Fork...

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