Effect of triploidy on growth and ionoregulatory performance in ocean-type Chinook salmon: A quantitative genetics approach
The use of triploid salmon for aquaculture is attractive as they do not mature sexually, limiting losses associated with poor flesh quality in mature fish and posing less genetic risk to wild stocks if they escape. Inconsistent survival and growth performance in triploid fish, however, has limited their implementation. In our study, ocean-type Chinook salmon (Oncorhynchus tshawytscha) were bred using replicated 3 x 3 factorial mating designs to create 18 families to test whether triploidization resulted in changes in growth and ionoregulation performance in freshwater and seawater. Eggs were pressure shocked after fertilization to create triploid offspring in a subset of each family. In spring, freshwater fish were sampled for size and gill Na+, K+- ATPase activity. Plasma chloride and cortisol were measured following a 24-h saltwater challenge. Growth performance was monitored for a further four months following transfer to sea water. We found significant effects of ploidy and sire (paternal effect) on smolt weight, as well as on gill Na+, K+-ATPase activity, although the latter did not correspond with performance in a 24-h saltwater challenge. Following four months of ocean growth, diploid animals were consistently larger, with greater circulating levels of insulin-like growth factor-1 than triploid sibs, although specific growth rates did not differ. Conversely, gill Na+, K+-ATPase activity at that time was significantly higher in triploid than diploid fish. When the phenotypic variance for the various traits was partitioned, triploids exhibited significantly greater additive genetic variance and maternal effects across all traits relative to diploid fish - indicating that gene dosage effects were primarily additive. The strong family effect indicates that genotype has a substantial role in determining the effects of ploidy manipulation on ionoregulatory and growth performance in Chinook salmon. (c) 2011 Elsevier B.V. All rights reserved.
Shrimpton, J. M.; Heath, J. W.; Devlin, R. H.; and Heath, Daniel D.. (2012). Effect of triploidy on growth and ionoregulatory performance in ocean-type Chinook salmon: A quantitative genetics approach. Aquaculture, 362, 248-254.