Kathryn Kostow Oregon Department of Fish and Wildlife A Demonstration of Modified Selection Pressures in a Steelhead Hatchery Program on the Hood River, Oregon Red Fish Blue Fish Hatchery 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 Typical Hatchery Program Whatever changes Wild Fish into Hatchery 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 West Fork Punchbowl Falls Hood River Distribution of Wild Winter Steelhead Wild Summer Steelhead Hatchery Release Sites Smolt Traps Adult Trap

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

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 Hatchery New Hatchery Average length (mm) * ** Direct Acclimated Wild Fish Tributaries, Mainstem Acclimated New Hatchery Fish, Mainstem Length (similar results for Weight)

0% 2% 4% 6% 8% 10% 12% 14% Length (mm) Percentage of sample Length (similar results for Weight) Wild Fish in the Tributaries Notice the peak(s) and the variance in the distributions

0% 2% 4% 6% 8% 10% 12% 14% Length (mm) Percentage of sample Wild Fish in the Mainstem Length (similar results for Weight)

Length (mm) Percentage of sample Acclimated New Hatchery Fish in the Mainstem Length (similar results for Weight)

Wild Fish Old Hatchery New Hatchery Average length (mm) * ** Direct Acclimated Wild Fish, Mainstem Acclimated New Hatchery Fish, At Release, Mainstem Old Hatchery Fish, Mainstem Length (similar results for Weight)

0% 2% 4% 6% 8% 10% 12% 14% 16% Length (mm) Percentage of sample Length (similar results for Weight) Wild Fish In the Mainstem Acclimated New Hatchery Fish at Release Acclimated New Hatchery Fish in the Mainstem Old Hatchery Fish in the Mainstem Acclimated New Hatchery Fish were already different than Wild Fish at release During out-migration they became More hatchery - like

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% New and old hatchery, adults Wild, tributary smolt trap Wild, mainstem smolt trap Wild, adults Ages of juveniles Percentage of sample A few in all wild fish samples Fresh Water Age Measured from Scales Release and Smolting Rearing Out-migrating Smolting Rearing, Out-migration and Smolting

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 Salt Water Age and Total Age Smaller N e

Wild Fish Old Hatchery New Hatchery Average length (mm) Direct Acclimated Length Wild fish were different sizes because they were different ages All the hatchery fish were 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-Mar 6-Apr 21-Apr 6-May 21-May 5-Jun 20-Jun 5-Jul 20-Jul 4-Aug 19-Aug 3-Sep 18-Sep 3-Oct 18-Oct 2-Nov Date of out-migration Percentage of sample Hatchery and Wild fish out-migration peaked in the spring Wild fish continued to out-migrate in the fall What did wild fish do from Nov. through Mar.? Date of capture at the mainstem smolt trap

Feb 10-Mar25-Mar 9-Apr 24-Apr 9-May 24-May 8-Jun 23-Jun 8-Jul 23-Jul 7-Aug 22-Aug 6-Sep 21-Sep 6-Oct 21-Oct 5-Nov 20-Nov Wild, tributaries Wild, mainstem Day of out-migration Daily average length at out-migration Ages 0 - 3

Wild, tributaries Wild, mainstem New Hatchery, tributaries and mainstem Day of out-migration Daily average length at out-migration 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. Environment Genotypes

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 / parent Number of adults / parent Selection Pressures Comparisons of Egg-to-smolt survival Smolt-to-adult survival Egg-to-adult survival

Survival Comparisons of Studies of relative Reproductive Success: Both Wild and Hatchery parents spawn in a stream

Survival Comparisons 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 Wild Winter Steelhead Wild Summer Steelhead Percentage survival Why would the wild winter 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 spawning New Hatchery Fish in the population; 78% to 88% natural spawning Old Hatchery Fish in the population;

Egg-to-smolt survival 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock * * * Percentage survival Wild fish lived in the River under strong natural selection and had LOW Egg-to-smolt survival Hatchery fish were protected in the hatchery and had HIGH Egg-to-smolt survival Natural selection is relaxed Genetic Load is Increased

Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock Number of smolts / parent (All differences are significant) The Old Hatchery Fish produced the most smolts/parent

0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock Smolt-to-adult survival Percentage survival * * * * Both the Hatchery and Wild fish are in the stream or ocean under natural selection. Survival of Hatchery Fish was relatively LOW. The survival of the Acclimated New Hatchery Fish was lowest of all

0% 0.1% 0.2% 0.3% 0.4% 0.5% 0.6% 0.7% 0.8% 0.9% 1% Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock Egg-to-adult survival Percentage survival * *

Number of adults / parent Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock Number of adults / parent * *

Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock Number of adults / parent * * “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% Length (mm) The Hatchery Fish became Less Like the Wild Fish It was not just that smaller fish do poorer, since the wild fish were the smallest of all and had the best survival

How many times did we detect that the New Hatchery stock was being changed by Selection? % 20% 30% 40% 50% 60% 70% 80% 90% Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock Percentage survival Natural Selection was Relaxed in captivity But 30% to 40% of the fish were Selected Against in the captive environment. This promoted Adaptation to the captive environment. 3.

How many times did we detect that the New Hatchery stock was being changed by Selection? 4. 0% 1% 2% 3% 4% 5% 6% 7% 8% 9% 10% Wild Winter Steelhead Wild Summer Steelhead New Hatchery Stock Direct Acclimated Old Hatchery Stock Percentage survival 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.