Spatial scales of homing and the efficacy of hatchery supplementation of wild populations

Northwest Fisheries Science CenterNational Marine Fisheries Service

Seattle, Washington

Project # 35012

Significance to Regional ProgramsMainstem/Systemwide Artificial Production Program summary:

“Studies of hatchery effects on straying (homing and imprinting) are needed to manage straying rates of hatchery adults and assess the effects of straying on wild populations and stream productivity”

(BPA Gap Analysis: “Needing immediate implementation” for both BIOP and FWP)

RPA 184 Evaluate Hatchery Reforms

- “employ hatchery practices that reduce unwanted straying of hatchery fish”

- “assess frequency and magnitude of … interactions between wild and hatchery fish”

- “test the efficacy of acclimation sites for imprinting and homing to target areas and

the interactions and ecological overlap of hatchery fish with wild populations.”

RPA 182: Determine the reproductive success of hatchery fish - “ identify temporal and spatial distribution of [hatchery] spawners” relative to wild fish.

RPA 107 Identify causes of unaccounted losses of migrating adults.

Hatchery Supplementation of Wild Salmon: Yakima River

•Extensive tagging and monitoring

•Pre-supplementation data

•Minimal hatchery influence

•Multi-agency cooperation

•Accessible

•Ecological, chemical and geomorphological diversity

Cle Elum Hatchery

Acclimation site(Easton)

Acclimation site(Jack Creek)

Acclimation site(Clark Flat)

YKFP Spring chinook supplementation research program

• Wild broodstock collected at Roza Dam

•Reared at Cle Elum Hatchery 16 months until smolting•Transfer to acclimation sites and volitional release

•All fish: site-specific CWTs, eye tags; 5-10% pit tag

•Returning hatchery adults spawn naturally/redd surveys

Objectives

1) Identify and compare the fine spatial and temporal patterns of homing and spawning of wild and YKFP supplementation salmon relative to the Cle Elum hatchery, acclimation sites, and historical and current spawning reaches.

2) Describe and compare the prespawning migratory behaviors (e.g. exploring, proving, holding) and spawning site selection of homing wild and YKFP supplementation fish from each of the acclimation sites using radiotelemetry.

3) Characterize the site-specific physiological changes that occur in the olfactory system during imprinting to different acclimation sites to assess imprinting success.

Objective 1. Spatial and temporal patterns of homing and spawning of wild and supplemented salmon

Ho : Carcass distribution is not dependent on site of acclimation and release

-distributions relative to acclimation site-nearest-neighbor analysis for clustering-differences in temporal distribution (spawn timing)-migratory history

Ho : Carcass distribution is not different for wild and hatchery fish

H0: Carcass distribution of wild fish does not differ from pre-supplementation

H0: Patterns of redd distribution and clustering does not change over the spawning season or between years

Objective 1. Spatial and temporal patterns of homing and spawning of wild and supplemented salmon

Methods

Weekly comprehensive surveys of entire upper Yakima Basin

Carcasses-GPS location (3 m accuracy); date-hatchery/wild-male/female; jack, precocious-length-tag location, recovery-egg retention; disease

Redds-Yakama biologists survey and flag (color coded by date)

all redds in upper Yakima- GPS mapping of all redds in the upper Yakima at end of spawning season

Cle Elum Hatchery

Acclimation site(Easton)

Acclimation site(Jack Creek)

Acclimation site(Clark Flat)

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11

20002001

Redd distribution

% o

f T

ota

l R

edd

s

1 2 3 4 5 6

Easton (Dam to I-90)

Clark Flat (Teanaway to Thorpe)

Hatchery-unidentifiedWild

0

10

20

30

40

50

60

70

Number of

carcasses

1. Dam to I-902. I-90 to Twin Bridges3. Twin Bridges to S. Cle Elum4. S. Cle Elum to Teanaway5. Teanaway to Thorpe6. Thorpe to KOA

Distribution of Hatchery and Wild Spawners

Acclimation site/Origin

Reach where carcass was recovered

Temporal patterns of Redd distributions

Temporal patterns of Redd distributions

Temporal patterns of Redd distributions

Objective 2. Describe and compare the pre-spawning migratory behaviors (e.g. exploring, proving, holding) using radiotelemetry

H0: Prespawning movements of salmon released from

different sites do not differ

H0: Prespawning movements of wild/hatchery salmon do not differ

H0: Prespawning movements of wild fish do not change

after supplementation

-Radiotelemetry: 25 fish/treatment

-Fixed-site receivers

-Standardized surveys with portable receiver

-GPS mapping

-Comparison to pre-supplementation radiotelemetry

Objective 3. Characterize physiological changes that occur in the olfactory system during imprinting

H0: Olfactory sensitivity to specific odorants/water sources does not differ in fish reared and released from different sites

-EOG analysis of Cle Elum hatchery and acclimation site smolts

-Chemical analysis of hatchery/acclimation waters

-Molecular analysis of olfactory rosettes