Comparison of survival, gene expression and plasma biochemistry between genetic lines of rainbow trout reared under either laboratory or net pen aquaculture conditions.

Genetic variation for disease resistance is present in salmonid fish; however, the molecular basis and impact of environmental conditions is poorly understood. At the U.S. National Center for Cool and Cold Water Aquaculture, a line of rainbow trout has been selected with increased innate resistance against bacterial cold water disease caused by Flavobacterium psychrophilum (Fp). After five generations of selection, the resistant line (ARS-Fp-R) exhibits over 60 percentage points higher survival compared to a reference susceptible line. The goal of this project is to compare survival, gene expression and plasma biochemistry between the ARS-Fp-R line and several commercial trout strains reared under either controlled laboratory rearing conditions or at a commercial net-pen facility located on the Columbia River. Gill and spleen samples were collected at 8 timepoints corresponding to critical transitions in water temperatures at the farm-site. Differences in gene expression and plasma biochemistry between genetic lines and rearing environments are described.