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Simulation study on genetic progress in a closed fish population
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Genetic and environmental sources of variation for survival and body size during freshwater rearing of Atlantic salmon Jonas Jonasson Institute ofFreshwater Fisheries, Box 5252, 125 Reykjavik, Iceland
A research program in salmon ranching in Iceland was started in 1987 to study genetic variation in return frequency to the site of release of smolts. Results from the freshwater period are presented. Brood stock of Atlantic salmon (Salmo salar) were taken from five stocks in Iceland in 1987 and 1988 and mated in a hierarchical fashion of one male to three females to produce a total of 298 families over the two year-classes. After fertilization, the eggs from each family were reared in separate egg trays; first feeding fry were reared in separate tanks. Survival from the eyed-egg stage to 12 weeks after first feeding was recorded for each family. Individual weight and length were recorded on a sample of fish from each family 190 days after first feeding. Significant differences between stocks were found for survival, length and weight in both yearclasses (P< 0.05 ) . Significant phenotypic correlations were observed between egg size and survival, weight and length (0.23,0.23 and 0.22 respectively). Estimates of heritabilities, based on sire variance component estimates for the total material, were: for survival, 0.04; weight, 0.20; and length, 0.20. Heritability estimates for dam component were 0.34 for survival, 0.39 for weight and 0.40 for length. The genetic correlation estimates were 0.3 I& 0.26 for survival and weight, 0.39 + 0.26 for survival and length, and 0.98 k 0.01 between weight and length.
Simulation study on genetic progress in a closed fish population L. Siitonen and I. Stranden Department ofAnimal Breeding, Agricultural Research Centre, SF-31600 Jokionen. Finland
Monte Carlo simulation has been developed to investigate genetic progress and rate of inbreeding under different conditions of population size, selection intensity and association between traits in the aggregate genotype. The traits included are growth over three sequential periods and age at sexual maturity. An infinitesimal model is used to generate the correlated traits. For growth, selection is carried out at multiple stages and it was based on the estimated breeding values of individuals calculated using a BLUP animal model. Some selection can be done on the basis of the degree of sexual maturity to prevent change in the mature age. The genetic correlation between growth and age at sexual maturity is assumed to be negative.
Genetic and environmental sources of variation for survival and body size during freshwater rearing of Atlantic salmon Jonas Jonasson Institute ofFreshwater Fisheries, Box 5252, 125 Reykjavik, Iceland
A research program in salmon ranching in Iceland was started in 1987 to study genetic variation in return frequency to the site of release of smolts. Results from the freshwater period are presented. Brood stock of Atlantic salmon (Salmo salar) were taken from five stocks in Iceland in 1987 and 1988 and mated in a hierarchical fashion of one male to three females to produce a total of 298 families over the two year-classes. After fertilization, the eggs from each family were reared in separate egg trays; first feeding fry were reared in separate tanks. Survival from the eyed-egg stage to 12 weeks after first feeding was recorded for each family. Individual weight and length were recorded on a sample of fish from each family 190 days after first feeding. Significant differences between stocks were found for survival, length and weight in both yearclasses (P< 0.05 ) . Significant phenotypic correlations were observed between egg size and survival, weight and length (0.23,0.23 and 0.22 respectively). Estimates of heritabilities, based on sire variance component estimates for the total material, were: for survival, 0.04; weight, 0.20; and length, 0.20. Heritability estimates for dam component were 0.34 for survival, 0.39 for weight and 0.40 for length. The genetic correlation estimates were 0.3 I& 0.26 for survival and weight, 0.39 + 0.26 for survival and length, and 0.98 k 0.01 between weight and length.
Simulation study on genetic progress in a closed fish population L. Siitonen and I. Stranden Department ofAnimal Breeding, Agricultural Research Centre, SF-31600 Jokionen. Finland
Monte Carlo simulation has been developed to investigate genetic progress and rate of inbreeding under different conditions of population size, selection intensity and association between traits in the aggregate genotype. The traits included are growth over three sequential periods and age at sexual maturity. An infinitesimal model is used to generate the correlated traits. For growth, selection is carried out at multiple stages and it was based on the estimated breeding values of individuals calculated using a BLUP animal model. Some selection can be done on the basis of the degree of sexual maturity to prevent change in the mature age. The genetic correlation between growth and age at sexual maturity is assumed to be negative.