|Application of selective breeding to commercial trout production (Abstract)|
Gall, A.E. (1989). Application of selective breeding to commercial trout production (Abstract), in: De Pauw, N. et al. (Ed.) Aquaculture: a biotechnology in progress: volume 1. pp. 525
In: De Pauw, N. et al. (Ed.) (1989). Aquaculture: a biotechnology in progress: volume 1. European Aquaculture Society: Bredene, Belgium. ISBN 90-71625-03-6. 1-592 pp., more
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|Document type: Conference paper|
Five generations (10 years) of selective breeding involving two replicates (year classes) for each of two, age-2 spawning rainbow trout broodstocks (RTH and RTS), were completed between 1976 and 1986. The selected populations consisted of from 5 000 to 7 500 age-2 fish each generation and each stock was selected for increased egg size, number of eggs per female at age-2 and body weight at 1 yr of age. The RTH stock was also selected for early-fall spawning. No control populations were maintained for this commercial project, so the response observed is due to both genetic and environmental improvement. Selection for early-season fall spawning in the RTH stock resulted in an average response ot 12.5 days per generation moving average spawning date from September 17 to August 8. The response in the number of eggs per female averaged 10.9% and 9.3%.yr-1 for the two RTH year classes,and 11.9% and 13%.yr-1 for the two RTS year classes. There was no change in egg size for three of the four year classes; the RTS even-year class showed an improvement of 1.4%.yr-1. The results indicate that the selection pressure for egg size was adequate to yield a positive response but was sufficient to prevent the decline in egg size expected from a doubling of the number of eggs per female. Analysis of yearling weight has not been completed, but the correlated response in the post-spawning weight of females was 4.0% and 4.5%.yr-1 for RTH and 13.8% and 11.2%.yr-1 tor RTS. for the odd- and even-year classes, respectively.