Rintamakikinnunen, P., Bernardet, J.F., Bloigu, A.-1997
Aquaculture, 149 (1-2) : 1-14
Abstract:
Atlantic salmon (Salmo salar), sea trout (S. trutta m. trutta) and brown trout (S. trutta m. lacustris) at four fish farms in northern Finland were examined in 1988-1992 for external lesions with filamentous bacteria. Phenotypic tests demonstrated that most of these bacteria were very similar to Flavobacterium johnsoniae. In two cases Flavobacterium columnare was isolated also. A total of 247 tanks (cases) with fish having external lesions containing filamentous bacteria were found, 57.5% of which contained only filamentous bacteria, while the rest had simultaneous non filamentous bacterial or parasitic infection. In 31.6% of the cases more than 5% of the fish died in the course of the disease, but in 39.7% of the cases no mortality occurred or it was below 1%. The disease symptoms occurred on either the gills, jaws, skin, fins or tail, or on different combinations of these. Logistic regression analysis was used to assess the significance of the site of the symptoms, fish species, fish age, rearing density, other simultaneous infections, water temperature and the farm for fish mortality in the cases with filamentous bacteria. The results indicated that water temperature, fish species, gill or jaw erosion and the farm itself had the greatest effects on mortality.
(Univ. Ooulu, Dept. Biol., POB 333, FIN-90571 Oulu, Finland)
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