The effects of climate change on the Atlantic salmon's (Salmo salar) immunological response to infectious salmon anemia (ISAv)

Infectious salmon anemia is a reportable disease in Canadian aquaculture that severely affects the health of Atlantic salmon and results in millions of dollars in economic losses each year. With ocean temperatures continuing to rise due to global climate change, the industry has to discover ways to adapt and deal with the impacts the changing environment can have on immunological robustness of cultured fish. In this study, approximately 120 fish from each of 20 full or half-sib families were divided and cohoused in 38 different tanks. Half of the tanks were then acclimatized and maintained at 10°C (95-100% oxygen saturation), while the other half were acclimatized and maintained at 20°C (and 80-85% oxygen saturation). Donor Atlantic salmon were IP-injected with an ISAv isolate (HPR4) with a virulence of TCID50 of 1x105/ml. One week after the injection, 6 donor fish were added to each study tank (ratio of 1:7, donor to naïve cohabitants). Mortalities were observed over the course of the study and percent mortality was calculated. A difference in survivorship was seen across the different temperatures and families. The three families with the highest mortalities (most susceptible), and the three families with the lowest mortalities (most resistant) were assessed for their antiviral responses using relative immune gene expression. Differences in anti-viral responses will be discussed with respect to relative resistance/susceptibility across family and the impact on temperature on these responses.