1984 Volume 19 Issue 2 Pages 75-80
Coho salmon (O. kisutch) reared in a freshwater pond were transported by ship from Wakayama Prefecture to Otsuchi Bay, Iwate Prefecture, in November 1979. The fish were immediately transferred to a pen for marine culture in seawater, and mortality was observed. The cumulative mortality after ten days was approximately 80 percent.
On examination of the diseased fish, Aeromonas salmonicida was considered to be the causative agent of the extensive mortality, but a mixed infection with Vibrio anguillarum was observed in a few cases. We tried to determine the origin of this disease. A. salmonicida was isolated from freshwater cultured coho salmon remaining in Wakayama, and relatively high agglutination titer for the organism was detected in their sera. It was concluded from this that A. salmonicida is probably carried by freshwater cultured fish and can be transmitted during the transport.
The results of this study suggest that it needs to control furunculosis throughout the stage of freshwater culture and to reduce physiological stress as much as posible during transport of salmon to the marine culture site.
