Development of IPN Resistant Commercial Rainbow Trout Stocks

It is estimated that 3 billion rainbow trout eggs were required to produce the world farmed harvest in 1994. The majority of these fish are reared in areas where infectious pancreatic necrosis (IPN) virus is endemic. Unfortunately, mortalities are highest before the fish are fully immunocompetent, making vaccination a less effective tool in disease prevention. Increasing the natural resistance of trout through genetic selection is the only feasible method for increasing productivity in the commercial sector and increasing survivability for fish destined for the natural resource. Many animal husbandry industries have been successful in breeding disease resistant strains. Although only limited selected breeding for disease resistance in salmonids has been performed, evidence exists for the heritability of resistance to several disease agents, including IPN. This proposal seeks to use quantitative genetics to select for a domesticated strain of rainbow trout with substantial resistance to IPN. Phase I is designed to standardize a quantitative IPN challenge system and make a preliminary assessment of the variability of response to virus challenge between selected crosses of rainbow trout. Phase II will be aimed at conducting family selection for disease resistance.