UBC Theses and Dissertations
Genetic parameters and breeding plans for Pacific salmon Winkelman, Anne
The general objective of this study was to obtain background information needed for the development of a breeding program for the commercial production of Pacific salmonids. The data consisted of preharvest (end of freshwater rearing and after 9 and 22 months of saltwater rearing) and harvest (29 months of saltwater rearing) weight and length measurements from chinook (Oncorhynchus tshawytscha) and harvest weight and length measurements (approximately 17 months of saltwater rearing) of coho (Q. kisutch). The work entailed estimation of genetic parameters for the traits measured as well as the development of methodology for the genetic analysis of data collected under actual fish farming conditions. The statistical model used for the analyses was the animal model that incorporated the additive genetic relationships among animals and, depending on the analysis, the dominance genetic or full-sib family effects. The heritabilities of preharvest weight and length measurements in chinook ranged from 0.24 to 0.39. Heritabilities for harvest weight and length in chinook, measured after 29 months of saltwater rearing were 0.27 and 0.29, respectively. In coho, the heritabilities of the harvest weight and length were 0.38 and 0.51. The dominance genetic effects associated with a full-sib family could be separated from the conmion environmental effect of family tank only in preharvest weight and length measurements in the chinook. For these traits, dominance genetic variance, expressed as a ratio of the phenotypic variance, ranged from 0.08 to 0.26. For all other traits of the chinook and coho, the common environmental effect associated with full-sib family was confounded with the nonadditive genetic effects. The variance associated with the full-sib family effect, as a fraction of the phenotypic variance, ranged from 0.05 to 0.07. Selection on BLUP of breeding value was simulated with levels of the common environmental effect associated with full-sib family of 0.0, 0.075 and 0.15. In the absence of a common environmental effect, selection on BLUP of breeding value resulted in 8-14% greater response after 9 generations than phenotypic selection. In the presence of the effect, selection on BLUP of breeding value resulted in 0.7% to 5% greater response than selection on phenotype.
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