Survival, Immune response, Growth, Size at age, Artificial selection, Triploidy induction, Oncorhynchus tshawytscha
The production of sterile triploid salmon for aquaculture is an effective strategy to minimize potential environmental risks and increase productivity. However, the efficacy of heat-versus pressure-based induction protocols and the effect of treatment and genotype on fitness related traits have rarely been examined in the same study. In this study, the effect of treatment, family and the treatment-by-family interaction on freshwater survival, growth and immune function was examined in full-sib groups of diploid and heat- and pressure-shock induced triploid chinook salmon (Oncorhynchus tshawytscha) from five families. Heat and pressure were equally effective at inducing triploidy, and few differences between the two treatment groups in survival, growth and antibody response to intraperitoneal Listonella anguillarum (formerly Vibrio) vaccination were observed. While triploids had lower survival and poorer performance than diploids, significant differences occurred mainly during the early stages of development. Survival was mainly influenced by treatment (heat-shock, pressure-shock) and family (genotype), while growth characteristics and the immune response to vaccination were mainly influenced by family. Significant treatment-by-family interaction effects were also found; however, they explained a relatively low proportion of the total variation in survival and growth, but a large proportion of the variation in immune response. An extended effect of heat-shock treatment on survival was present even after the onset of exogenous feeding. Despite the presence of significant interaction effects, consistent performance ranking among families was generally evident, regardless of ploidy or treatment. Since substantial family effects were observed for most of the performance variables, selection applied to diploid broodstock will be part of an effective strategy for improvement of triploid offspring performance.
Johnson, Rachel M.; Shrimpton, J. Mark; Heath, John W.; and Heath, Daniel D.. (2004). Family, induction (heat- and pressure-shock) and interaction effects on the performance of diploid and triploid chinook salmon (Oncorhynchus tshawytscha). Aquaculture, 234, 123-142.
Available for download on Sunday, January 01, 2119