A COMPARISON OF THE SUSCEPTIBILITY OF SALVELINUS-ALPINUS AND SALMO-SALAR-OUANANICHE TO PROLIFERATIVE KIDNEY-DISEASE

In 1986 Arctic charr (Salvelinus alpinus) parr being reared at the Marine Sciences Research Laboratory in St. John's, Nfld., Canada suffered mortality due to proliferative kidney disease (PKD). Other salmonids reared under the same conditions did not suffer any mortality. This led us to hypothesize that the charr had not been exposed to the PKX organism and therefore had not developed a resistance to the disease. We set up an experiment to compare the susceptibility of Arctic charr and landlocked Atlantic salmon (Salmo salar ouananiche) to the PKX organism. Approximately 8 weeks after water temperature had reached 12-degrees-C the mortality of Arctic charr began to increase and remained high during the period of high water temperature (> 12-degrees-C). No increase in mortality of ouananiche was observed. Histopathological diagnosis determined that PKD was the cause of the high mortality of charr. No PKX was found in the ouananiche samples or among charr taken when water temperatures were below 12-degrees-C. Our results show that charr, in contrast to ouananiche, have not developed a resistance to PKD. The pattern of the disease was very similar to that reported for rainbow trout.