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In this presentation, I will highlight the potential to selectively breed fish for resistance to disease and focus on areas where future research is required. In doing so, I have divided the presentation into four sections, loosely resembling the development of a selective breeding program: (1) Definition of the breeding objective, (2) Estimates of heritabilities and genetic correlations, (3) Identification of suitable selection criteria, and (4) Implementation of the breeding program. I will point out that breeding objectives are rarely, if ever, defined for fish. Before effective breeding programs for resistance are implemented, breeding objectives, which incorporate resistance to disease, should be defined. I will show that the few heritability estimates available for fish indicate a real possibility of breeding for resistance. However, further heritability estimates are required for resistance to many diseases, together with estimates of genetic correlations between resistances to different diseases. I will show that there are a number of potential selection criteria available by which to select fish for resistance, although the suitability of each of these criteria has yet to be determined. Finally, I will point out that the most effective way for the fish industry to breed for resistance to disease is to establish a central breeding station(s), from which fish bred for resistance are distributed to individual fish producers. These points highlight the vast potential to selectively breed fish for resistance to disease. With research attention directed towards key areas, successful breeding programs for resistance to disease can be developed and implemented by the fish industry.

Mark Henryon is a Senior Scientist within the Department of Animal Breeding and Genetics at the Danish Institute of Agricultural Sciences. He is currently developing selective breeding programs for fish and pigs, where resistance to disease as a of the trait of interest.

Contact details: Mark.Henryon@agrsci.dk