Kathryn Kostow

1
Red Fish Blue Fish Hatchery Fish Wild Fish
A Demonstration of Modified Selection
Pressures in a Steelhead Hatchery Program on the
Hood River, Oregon
Kathryn Kostow Oregon Department of Fish and
Wildlife
2
The Argument
Hatchery Fish are genetically different than
Wild Fish
3
But all Hatchery Fish start as Wild Fish.
So how could they be different? Do they
change? How? Why?
4
Hood River Steelhead (summer and winter runs)
Columbia River
Portland
Hood River
Mt. Hood
A 5-year study to detect what makes Wild Fish
change into Hatchery Fish
5
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.
6
Typical Hatchery Program
Whatever changes Wild Fish into Hatchery Fish
probably happens here
7
This study compared juvenile Phenotypes and
Survival (Survival is a way to look at Selection
Pressures)
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.
Wild Fish Were naturally produced summer and
winter steelhead juveniles
Old Hatchery Stock A domestic, non-local
summer steelhead stock established in the 1950s
8
Powerdale Dam
Punchbowl Falls
West Fork
East Fork
Hood River
Mt. Hood
9
Comparisons of juvenile phenotypes
Length Weight Age at out-migration Age at
smolting Saltwater age Total age Generation
time Time of out-migration Other behavior
observations
10
Comparisons of juvenile phenotypes
Measured fish
11
Acclimated New Hatchery Fish, Mainstem
Wild Fish Tributaries, Mainstem



Acclimated
Wild Fish
New Hatchery
Length (similar results for Weight)
12
14
Wild Fish in the Tributaries
12
10
8
Percentage of sample
6
4
2
0
30
45
60
75
90
105
120
135
150
165
180
195
210
225
240
255
270
285
300
Length (mm)
Length (similar results for Weight)
13
14
12
Wild Fish in the Mainstem
10
8
Percentage of sample
6
4
2
0
30
45
60
75
90
105
120
135
150
165
180
195
210
225
240
255
270
285
300
Length (mm)
Length (similar results for Weight)
14
Acclimated New Hatchery Fish in the Mainstem
Percentage of sample
Length (mm)
Length (similar results for Weight)
15
Acclimated New Hatchery Fish, At Release, Mainstem
Old Hatchery Fish, Mainstem



Wild Fish, Mainstem
Acclimated
Direct
Wild Fish
Old Hatchery
New Hatchery
Length (similar results for Weight)
16
16
Acclimated New Hatchery Fish in the Mainstem
14
Old Hatchery Fish in the Mainstem
12
Acclimated New Hatchery Fish at Release
10
Wild Fish In the Mainstem
8
Percentage of sample
6
4
2
0
Length (mm)
Length (similar results for Weight)
17
Fresh Water Age
Measured from Scales
100
90
80
New and old hatchery, adults
Wild, tributary smolt trap
70
Wild, mainstem smolt trap
60
Wild, adults
Percentage of sample
50
40
30
A few in all wild fish samples
20
10
0
0
1
2
3
4
Ages of juveniles
Release and Smolting
Rearing, Out-migration and Smolting
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Salt Water Age and Total Age
Wild Fish, New Hatchery Fish and Old Hatchery
Fish all 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
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Wild fish were different sizes because they were
different ages
These smaller wild fish were often older than
these bigger hatchery fish
All the hatchery fish were the same age
20
Time of hatchery fish releases
Hatchery and Wild fish out-migration peaked in
the spring
Date of capture at the mainstem smolt trap
Wild fish continued to out-migrate in the fall
21
(No Transcript)
22
300
250
200
Daily average length at out-migration
150
100
Ages 0 - 3
50
0
8-Jul
8-Jun
23-Jul
6-Oct
9-Apr
9-May
23-Jun
7-Aug
6-Sep
5-Nov
24-Feb
10-Mar
25-Mar
24-Apr
24-May
22-Aug
21-Sep
21-Oct
20-Nov
Day of out-migration
Wild, tributaries
Wild, mainstem
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Age 1
Daily average length at out-migration
Day of out-migration
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Conclusions about Phenotypes
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.
The New Hatchery Fish were produced by the same
pool of parents as the Wild Fish.
Genotypes
plus the produce
Phenotypes.
Environment
The New Hatchery Fish and the Wild Fish looked
and behaved differently because they grew up in
different environments.
25
Revisit our Lesson in Genetics
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.
26
Selection Pressures
Survival
Comparisons of
Egg-to-smolt survival Smolt-to-adult
survival Egg-to-adult survival
Number of smolts / parent Number of adults /
parent
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Survival
Comparisons of
Studies of relative Reproductive Success Both
Wild and Hatchery parents spawn in a stream
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Survival
Comparisons of
In this study, some parents were selected to
spawn in a hatchery while others were left to
spawn in the stream
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Egg-to-smolt survival
Why would the wild winter and summer steelhead
have such different egg-to-smolt survivals?
Percentage survival
30
Natural selection is relaxed
Egg-to-smolt survival
Hatchery fish were protected in the hatchery and
had HIGH Egg-to-smolt survival
Genetic Load is Increased


Wild fish lived in the River under strong natural
selection and had LOW Egg-to-smolt survival

Percentage survival
Wild Winter Steelhead
Wild Summer Steelhead
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Number of smolts / parent
The Old Hatchery Fish produced the most
smolts/parent
1400
(All differences are significant)
1200
1000
800
Number of smolts / parent
600
400
200
0
32
Smolt-to-adult survival
Both the Hatchery and Wild fish are in the
stream or ocean under natural selection. Survival
of Hatchery Fish was relatively LOW.
10
9
8
The survival of the Acclimated New Hatchery
Fish was lowest of all
7
6
5
Percentage survival
4
3
2
1
0
Wild Winter Steelhead
Wild Summer Steelhead
New Hatchery Stock
33
Egg-to-adult survival
1

0.9
0.8

0.7
0.6
Percentage survival
0.5
0.4
0.3
0.2
0.1
0
Acclimated
Direct
Old Hatchery Stock
Wild Winter Steelhead
Wild Summer Steelhead
New Hatchery Stock
34
Number of adults / parent
35
If a parent got picked to spawn in the
hatchery it contributed a LOT more offspring to
the next generation
Number of adults / parent
Genetic Swamping (Ryman Laikre Effect)
18
16
14
12
10
Number of adults / parent
8
6
4
2
0
Acclimated
Direct
Old Hatchery Stock
Wild Winter Steelhead
Wild Summer Steelhead
New Hatchery Stock
36
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
37
How many times did we detect that the New
Hatchery stock was being changed by Selection?
1.
The Hatchery Fish became Less Like the Wild Fish
14
12
It was not just that smaller fish do poorer,
since the wild fish were the smallest of all and
had the best survival
10
8
6
4
2
0
45
60
75
90
30
105
120
135
150
165
180
195
210
225
240
255
270
285
300
Length (mm)
38
How many times did we detect that the New
Hatchery stock was being changed by Selection?
But 30 to 40 of the fish were Selected
Against in the captive environment. This
promoted Adaptation to the captive environment.
3.
2.
Natural Selection was Relaxed in captivity
Percentage survival
Wild Winter Steelhead
Wild Summer Steelhead
39
How many times did we detect that the New
Hatchery stock was being changed by Selection?
10
4.
Hatchery fish were Selected Against in the
natural environment
9
8
7
6
5
Percentage survival
4
3
2
1
0
Wild Winter Steelhead
Wild Summer Steelhead
New Hatchery Stock
40
Acclimation in a semi-natural environment DID
NOT make the New Hatchery Fish more similar to
Wild Fish.
41
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
42
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.
Questions?
The End