Race Is On To Discover Vaccine To Save Salmon

Jan Burian is determined to stop a killer. As Director of Molecular Biology at Microtek International Ltd. in Victoria, British Columbia, Canada, he is trying to save the lives of thousands of coho salmon infected with a deadly bacterium. Since 1989, when researchers first isolated the pathogen piscirickettsia salmonis in coho salmon commercially raised in southern Chile, the bacterium and the rickettsial (SRS) diseases it causes have been observed in several diverse fish species. It has been found in British Columbia, Chile, Norway, Ireland and Taiwan, at both fresh and salt water fish farms. Death rates from this fastidious, intracellular microorganism reach as high as 90 percent at certain sites, striking a devastating blow to commercial hatcheries and fish species.

While SRS diseases impact a broad geographic area, most research has concentrated on the aquaculture community in Chile where all salmonid species are affected by the pathogen. The highest death rates occur in coho salmon cultured in sea water netpens. Infected fish begin to die off six to twelve weeks after being transferred to fresh water, with death rates peaking in the fall and rising again the next spring.