Scott WilliamsManager of ARI wet lab research facilities

Formerly Brood Operations Manager & Geneticist for Clear Springs Foods, Inc.

Clear Springs Foods’ Production• 22,000,000 lbs year • process 85,000 lbs/day• grow more than 60,000 lbs/day• approximately 60% of Idaho’s production

Vertical Integration of Trout Production

• Feed manufacturing• Brood operations• Farm production• Processing

– primary– value added

• Distribution• Marketing

Brood DivisionEgg Production & Research

•Egg Production:•Soda Springs 71.5 Million•Snake River Brood 8.1 Million

•Research:•Genetics of growth and survival traits•Trout reproduction

The Brood DivisionTwo facilities

–Buhl • Snake River canyon• Research facility• Selection site• Brood propagation site• 5% of egg production

–Soda Springs• Primary egg production site

Brood Divisionmovement of fish and eggs

Snake River Brood Station Soda Springs Brood Station

CSF farms

primary site of egg production

neomale productionbrood female selection & propagation

selection program

egg production

Snake River Farm Box Canyon Farm Crystal Springs Farm

Selection ProgramAnimal Model

Genetic merit based on:• Individual records• Family records

Selection Program• Primarily

• Growth rate• Indirectly for feed conversion rate

• Secondarily• Disease resistance

Size SelectionFamily and Within Family Selection

• 100 to 110 full-sib families per generation• 10 families per generation from randomly bred line• Families selection:

– Families with poor early survival were discarded– Families with high mean weights at 273 days were

saved• Within the selected families:

– pit tag top 15 to 20% of individuals within the largest families at 273 days

The Steps for Size Selection

• 40 days post-spawn, reduce to 600 individuals• 63 days, reduce to 100 individuals• 76 days, pool with another family in 100 gal tank• 138 days, each family is given unique clip/brand• 139 days, to raceway• 273 days, final measurement• 274 days, PIT tag the largest 10% of fish within the

families having the largest mean weights

Family and Within Family Selection for Size

• 100 to 110 full-sib families per generation• 10 families per generation from a randomly

bred non-selected (control) line• At 273 days

• Families with low mean weights are discarded• Top 10-15% of the individuals from the largest families

are PIT tagged

311333

403

508

604

236 219 224

353

406

0

100

200

300

400

500

600

700

1991* 1993* 1995* 1997 1999

gram

s/fis

h

selected control

Mean of Family Mean Weights at 273 Days Post-Fertilization

Odd year generation

294 342

461

643 669

216 236 217

437 450

0

100

200

300

400

500

600

700

800

1992* 1994* 1996 1998 2000

gram

s/fis

h

Increasing Family Mean Weights at 273 Days

CSF Control

I

Even year generation

Transfer of Genetic Improvement to the Farms

• Selected females join the ranks of the brood females after first spawn

• Amplification through use of selected females’ daughters become brood replacements

• Selected males are sires of brood replacement females

Brood Replacement Females• Progeny of 30 sires and 30 dams• Undergo mass selection• Produced in 15 lots per year• In the months of July through January• Spawn twice in natural photoperiod• Spawn two more times in light-control• Used for a total of four spawns

Rainbow Trout Egg Production• Maturation in 24 months

• Some females will mature precociously• Depending on stock, 50% of the males will mature

at 12 months• Photoperiod cues reproduction• Naturally spring spawners

• Wild stocks will spawn from Feb to June• Selective breeding of domesticated fish has

moved spawn time to fall - winter

Egg Productionmethods to affect egg availability

• Photoperiod manipulation of brood dams• Skeletal photoperiod

• 6 hours of light 18 hours of light 6 hours of light

• Thermal manipulation at incubation• Water chilled to slow or heated to speed development

• Hormonal control of reproduction• Exogenous hormone applications to synchronize

maturation• LHRHa implants

Current Culture Practicesmodifying populations for growth and carcass traits

Mono-sex culture• Sexual Dimorphism:

– growth rates– carcass confirmation

• Examples– Male culture

• Tilapia– Female culture

• Trout

• Triploid culture• 3N ploidy• Are sexually non-viable (99.9%)• Males will exhibit secondary sexual characteristics

Current Culture Practicesmodifying populations for growth and carcass traits

Production of Normal Diploids and Triploids

• Triploid culture• 3N ploidy• Are sexually non-viable (99.9%)• Males will exhibit secondary sexual characteristics

• Triploid mono-sex female populations• Will not undergo sexual maturation• Will be a uniform population• Will have improved growth rates over diploid female

population after 18 months

Current Culture Practicesmodifying populations for growth and carcass traits

Sex determination in rainbow trout

• Females are homogametic– Have two copies of the X chromosome (XX)

• Males are heterogametic– Have both an X and Y chromosome (XY)

• Male gametes (sperm) are sex determining– They will carry either an X or Y chromosome

The perfect population – (from a trout culturist perspective)

All female or Monosex femaleFirst Path-• Direct feminization of a mixed sex population

• Oral doses of estradiol• Population of XX and XY genotypes

• All female phenotypes• Problem

• Regulatory concerns with hormone use on food fish

Mono-Sex Female Population

Second Path through gynogenesis• Gynogenesis is an induced form of

parthenogenesis– e.g. “virgin birth” of Komodo dragons

• Diploid organism produced without the contribution of a male parent

• Forms a population of XX animals in trout• Gynogens are highly inbred

– Heterozygosity through crossing over during meiosis

Production of Haploids and Gynogens

Mono-Sex Female PopulationThird path - start with masculinized females• Direct masculinization of a mixed sex

population• Oral dose of methyltestosterone• Identify XX males (neomales)

• Progeny testing• Use morphology to separate neomales from genetic males

• Neomales become sires to mono-sex female population

Mono-Sex Female Population (commercial method)

• Generate female population through gynogenesis• Sex-reverse gynogens

• Gynogens become neomales (XX males)• Neomales are sires for all female offspring• Perpetuate female population by sex-reversing

offspring for sires of the next generation• Total elimination of the Y chromosome from the

population

Sex-Reversal and Mono-Sex Female Production