kathryn kostow oregon department of fish and wildlife a demonstration of modified selection...

Kathryn KostowOregon Department of Fish and Wildlife

A Demonstration of Modified Selection Pressuresin a Steelhead Hatchery Program

on the Hood River, Oregon

Red Fish Blue FishHatchery Fish Wild Fish

The Argument:

Hatchery Fish are genetically different than

Wild Fish

But all Hatchery Fish start as Wild Fish.

So how could they be different?Do they change?

How? Why?

Hood River Steelhead(summer and winter runs)

Portland

Mt. Hood

Hood River

Columbia River

A 5-year study to detect what makes Wild Fish change into

Hatchery Fish

A Quick Lesson in Genetics:

Fish inherit Genotypes from their Parents.

Genotypes plus the Environment produce Phenotypes.

Phenotypes are the way the fish looks and behaves.

Selection Pressures act on Phenotypes to determine which fish live and breed and which fish die

without leaving offspring.

Selection Pressures acting on Phenotypes determine which Genotypes get inherited by the Next

Generation.

Over time, this process produces Genetic Change.

Smolts to adults

Spawning, rearing from eggs to smolts

TypicalHatcheryProgram

Whatever changes Wild Fish intoHatchery Fish probably happens here

This study compared juvenile Phenotypes and Survival

(Survival is a way to look at Selection Pressures)

Wild Fish: Were naturally – produced summer and winter steelhead juveniles;

Old Hatchery Stock: A domestic, non-local summer steelhead stock established in

the 1950s

New Hatchery Stock: A local winter steelhead stock established in the 1990s.

The parents were wild fish that were taken into the hatchery and spawned.

For three years of the study, this stock was acclimated in a “semi-natural”

environment that was supposed to make the fish “more wild-like”.

Powerdale Dam

East Fork

WestFork

Punchbowl Falls

Hood River

Distribution of

Wild Winter Steelhead

Wild Summer Steelhead

Hatchery Release Sites

Smolt Traps

Adult Trap

Comparisons of juvenile phenotypes:

LengthWeightAge at out-migrationAge at smoltingSaltwater ageTotal ageGeneration timeTime of out-migrationOther behavior observations

Comparisons of juvenile phenotypes:

Measured fish:

Just prior to release (hatchery fish),

In the tributary traps (~3,000 fish)

In the adult trap

In the mainstem trap (~5,250 fish)

Wild Fish Old HatcheryNew Hatchery

0

50

100

150

200

250A

vera

ge

len

gth

(m

m)

* * *

Direct Acclimated

Wild FishTributaries,Mainstem

AcclimatedNew Hatchery Fish,

Mainstem

Length (similar results for Weight)

0%

2%

4%

6%

8%

10%

12%

14%30 45 60 75 90

105

120

135

150

165

180

195

210

225

240

255

270

285

300

Length (mm)

Per

cen

tag

e o

f sa

mp

le


Wild Fish in the Tributaries

Notice the peak(s) and the variance in the distributions

0%

2%

4%

6%

8%

10%

12%

14%30 45 60 75 90

105

120

135

150

165

180

195

210

225

240

255

270

285

300

Length (mm)

Per

cen

tag

e o

f sa

mp

le Wild Fish inthe Mainstem


0%

2%

4%

6%

8%

10%

12%

14%30 45 60 75 90

105

120

135

150

165

180

195

210

225

240

255

270

285

300

Length (mm)

Per

cen

tag

e o

f sa

mp

leAcclimatedNew HatcheryFish in the Mainstem



0

50

100

150

200

250A

vera

ge

len

gth

(m

m)

* * *

Direct Acclimated

Wild Fish,Mainstem

Acclimated NewHatchery Fish,

At Release,Mainstem

Old Hatchery Fish,Mainstem


0%

2%

4%

6%

8%

10%

12%

14%

16%

30

45

60

75

90

10

5

12

0

13

5

15

0

16

5

18

0

19

5

21

0

22

5

24

0

25

5

27

0

28

5

30

0

Length (mm)

Per

cen

tag

e o

f sa

mp

le


Wild FishIn the Mainstem

AcclimatedNew Hatchery Fish at Release

AcclimatedNew Hatchery Fish in the Mainstem

Old HatcheryFish in the Mainstem

Acclimated NewHatchery Fish werealready different than Wild Fish at release

During out-migrationthey became

More hatchery - like

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4

New and old hatchery, adults

Wild, tributary smolt trap

Wild, mainstem smolt trap

Wild, adults

Ages of juveniles

Per

cen

tag

e o

f sa

mp

le

A few in all wild fish samples

Fresh Water Age

Measured from Scales

Release and Smolting

Rearing

Out-migratingSmolting

Rearing, Out-migration and Smolting

Wild Fish, New Hatchery Fish and Old Hatchery Fishall had similar salt water age distributions

The New and Old Hatchery fish had identical total ages. Both of them were a younger total age and had a less variable age distribution than Wild Fish

Both Hatchery stocks had a shorter generation time than Wild Fish

Salt Water Age and Total Age

Smaller Ne


0

50

100

150

200

250

Ave

rag

e l

eng

th (

mm

)

Direct Acclimated

Length

Wild fish weredifferent sizesbecause they were different ages

All the hatchery fishwere the same age

These smaller wild fish were often older than these bigger

hatchery fish

0%

2%

4%

6%

8%

10%

12%

14%

16%

Time of hatchery fish

releases

22-M

ar

6-A

pr

21-A

pr

6-M

ay

21-M

ay

5-Ju

n

20-J

un

5-Ju

l

20-J

ul

4-A

ug

19-A

ug

3-S

ep

18-S

ep

3-O

ct

18-O

ct

2-N

ov

Date of out-migration

Per

cen

tag

e o

f sa

mp

leHatchery and Wild fishout-migration peaked in the spring

Wild fish continuedto out-migrate in the fall

What did wild fish do from

Nov. through Mar.?

Date of capture at the mainstem smolt trap

0

50

100

150

200

250

300

24

-Fe

b

10

-Ma

r

25

-Ma

r

9-A

pr

24

-Ap

r

9-M

ay

24

-Ma

y

8-J

un

23

-Ju

n

8-J

ul

23

-Ju

l

7-A

ug

22

-Au

g

6-S

ep

21

-Se

p

6-O

ct

21

-Oc

t

5-N

ov

20

-No

v

Wild, tributaries Day of capture

Da

ily

av

era

ge

le

ng

th a

t c

ap

ture

Ages 0 - 3

0

50

100

150

200

250

300

24

-Fe

b

10

-Ma

r

25

-Ma

r

9-A

pr

24

-Ap

r

9-M

ay

24

-Ma

y

8-J

un

23

-Ju

n

8-J

ul

23

-Ju

l

7-A

ug

22

-Au

g

6-S

ep

21

-Se

p

6-O

ct

21

-Oc

t

5-N

ov

20

-No

v

Wild, tributariesWild, mainstem

Day of out-migration

Da

ily a

ve

rag

e l

en

gth

at

ou

t-m

igra

tio

n

Ages 0 - 3

0

50

100

150

200

250

300

24

-Fe

b

10

-Ma

r

25

-Ma

r

9-A

pr

24

-Ap

r

9-M

ay

24

-Ma

y

8-J

un

23

-Ju

n

8-J

ul

23

-Ju

l

7-A

ug

22

-Au

g

6-S

ep

21

-Se

p

6-O

ct

21

-Oc

t

5-N

ov

20

-No

v

Wild, tributariesWild, mainstemNew Hatchery, tributaries and mainstem

Day of out-migration

Da

ily a

ve

rag

e l

en

gth

at

ou

t-m

igra

tio

n

Age 1

The New Hatchery Fish were different than Wild Fish at every phenotype measured, except salt water age.

The New Hatchery Fish were similar to the Old Hatchery Fish, and they became even more like them as they out-migrated.

Conclusions about Phenotypes:

The New Hatchery Fish were produced by the same pool of parents as the Wild Fish.

The New Hatchery Fish and the Wild Fish looked and behaved differently because they grew up in different environments.

plus the produce Phenotypes. EnvironmentGenotypes

Selection Pressures act on Phenotypes to determine whether a fish lives and breeds, or dies

without producing offspring.

Selection Pressures acting on Phenotypes determines which Genotypes get inherited by the Next

Generation.

Over time, this process produces Genetic Change.

Since the Wild Fish and the New Hatchery Fish have different Phenotypes, perhaps Selection

Pressures affect them differently.

If Selection Pressures affect them differently, over time they will become genetically different.

Revisit our Lesson in Genetics:

Survival

Number of smolts / parentNumber of adults / parent

Selection PressuresComparisons of

Egg-to-smolt survivalSmolt-to-adult survivalEgg-to-adult survival

SurvivalComparisons of

Studies of relativeReproductive Success:

Both Wild and Hatchery parentsspawn in a stream

SurvivalComparisons of

In this study, some parents were selected to spawn in a hatchery while others were left to spawn in the stream

0%

0.5%

1%

1.5%

2%

2.5%

3%

3.5%

Egg-to-smolt survival

WildWinter

Steelhead

WildSummer

Steelhead

Per

cen

tag

e su

rviv

al

Why would the wildwinter and summer

steelhead have such different egg-to-smolt

survivals?

Only 2-3% hatchery fish for 3 years; then for 2 years they had 43 to 51% natural spawningNew Hatchery Fish in the population;78% to 88%

natural spawningOld Hatchery Fish in the population;

Egg-to-smolt survival

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

WildWinter

Steelhead

WildSummer

Steelhead New Hatchery Stock

Direct Acclimated OldHatchery

Stock

* **

Per

cen

tag

e su

rviv

al

Wild fishlived in theRiver under strong natural selection and had LOWEgg-to-smoltsurvival

Hatchery fish wereprotected in the hatcheryand had HIGH Egg-to-smoltsurvival

Natural selection is relaxed

Genetic Load is Increased

0

200

400

600

800

1000

1200

1400

WildWinter

Steelhead

WildSummer

SteelheadNew Hatchery

Stock


Stock

Nu

mb

er o

f sm

olt

s /

par

ent

Number of smolts / parent

(All differences are significant)

The Old HatcheryFish produced the most smolts/parent

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

WildWinter

Steelhead

WildSummer


Stock


Stock

Smolt-to-adult survivalP

erce

nta

ge

surv

ival

* *

**

Both the Hatchery andWild fish are in the streamor ocean under natural selection. Survival of Hatchery Fish was relatively LOW.The survival of

the Acclimated New Hatchery Fishwas lowest of all

0%

0.1%

0.2%

0.3%

0.4%

0.5%

0.6%

0.7%

0.8%

0.9%

1%

WildWinter

Steelhead

WildSummer


Stock


Stock

Egg-to-adult survival

Per

cen

tag

e su

rviv

al

**

Number of adults / parent

0

2

4

6

8

10

12

14

16

18

WildWinter

Steelhead

WildSummer


Stock


Stock

Nu

mb

er o

f ad

ult

s /

par

ent * *

Number of adults / parent

0

2

4

6

8

10

12

14

16

18

WildWinter

Steelhead

WildSummer


Stock


Stock

Nu

mb

er o

f ad

ult

s /

par

ent * *

“Genetic Swamping”(“Ryman – Laikre Effect”)

If a parent got picked to spawn in the hatchery

it contributed a LOT more offspring to the next

generation

Conclusions about Survival:

Hatchery Fish had very high survival while they were protected in the hatchery

After release into streams, Hatchery Fish survived poorer than Wild Fish

Fish that spawned in the hatchery produced a LOT more offspring / parent than fish that spawned in streams

By every measure, the survivals of Hatchery and Wild fish were different

Therefore, the Selection Pressures affecting Hatchery and Wild fish were different

How many times did we detect that the New Hatchery stock was being changed by Selection?

1.

Smaller hatchery fish were Selected Against during out-migration

0%

2%

4%

6%

8%

10%

12%

14%30 45 60 75 90

105

120

135

150

165

180

195

210

225

240

255

270

285

300

Length (mm)

The Hatchery Fish became Less Like the Wild FishIt was not just that

smaller fish do poorer, since the wild fish were the smallest of all and had the best survival


2.

0

10%

20%

30%

40%

50%

60%

70%

80%

90%

WildWinter

Steelhead

WildSummer

Steelhead New Hatchery Stock


Stock

Per

cen

tag

e su

rviv

al NaturalSelectionwas Relaxedin captivity

But 30% to 40%of the fish wereSelected Againstin the captive environment.This promotedAdaptation to the captive environment.

3.


4.

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

WildWinter

Steelhead

WildSummer


Stock


Stock

Per

cen

tag

e su

rviv

al

Hatchery fish were Selected Against in the natural environment

**

**

Acclimation in a “semi-natural” environment DID NOT make the New Hatchery Fish “more similar” to Wild Fish.

Phenotypes

Survival

**

**

The results of this study demonstrate that the

New Hatchery Fish had Phenotypes and patterns

of Selection that were different than those of

Wild Fish but that were quite similar to those of

Old Hatchery Fish

In conclusion:

The New Hatchery stock is being changed from Wild Fish into an

Old Hatchery stock

The forces of change are strong, but we do not know how quickly the genetic changes will become significant in Hood River.

Other researchers have shown that after about five generations there are detectable genetic differences between Hatchery and Wild fish.

kathryn kostow oregon department of fish and wildlife a demonstration of modified selection...

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