Increased resistance of triploid rainbow trout × coho salmon hybrids to infectious hematopoietic necrosis virus

Triploid hybridization improved viability of the hybrid cross, increased relative resistance to IHN virus challenge, and may provide a useful method for the interspecific transfer of desired characters into commercial fish stocks.

Abstract

Diploid and heat-induced triploid treatment groups of rainbow trout (Salmo gairdneri), coho salmon (Oncorhynchus kisutch), and reciprocal hybrid crosses were produced and monitored for survival and growth through early life stages. Survival to the fry stage showed a significant increase in the triploid rainbow trout female × coho salmon male hybrids relative to the diploid hybrid group. At a mean weight of 0.65 g all groups were administered a standardized static bath challenge with Leong Type 2 virulent IHN virus. The triploid rainbow trout female × coho salmon male hybrids showed a significant increase in IHN resistance when compared to pure-species rainbow trout groups. Early growth results suggest a poorer growth rate for the triploid hybrid. Triploid hybridization improved viability of the hybrid cross, increased relative resistance to IHN virus challenge, and may provide a useful method for the interspecific transfer of desired characters into commercial fish stocks.