Abstract

Baltic salmon brood fish were investigated for the presence of Flavobacterium psychrophilum in the kidney, spleen, brain and sexual products (ovarian fluid, unfertilised eggs and milt). Samples for bacteriology were taken at capture, when the fish were ascending their native river to spawn, and after a period of captivity in indoor pools, at stripping. During captivity, abnormal wiggling behaviour was recorded in some of the fish. Bacterial samples were taken to determine if F. psychrophilum had any role in the aetiology of the condition. Furthermore, the presence of F. psychrophilum on egg surfaces during incubation was investigated. F. psychrophilum was isolated from internal organs and/or sexual products in 7 out of 50 (14.0%) fish sampled at capture and 63 out of 272 (23.2%) fish sampled at stripping. The bacteria was isolated from either spleen or gonads in 2 out of 19 (10.5%) fish with abnormal wiggling behaviour but no bacteria was isolated from the brain. No F. psychrophilum was isolated from eggs at the eyed stage. Just before hatching, the bacterium was isolated from 5 out of 15 (33.3%) family groups. The present study shows that Baltic salmon brood fish are carriers of F. psychrophilum during their spawning migration. The presence of the bacteria in sexual products from both females and males indicates that transmission from the brood fish to the offspring should be considered an important route of infection.

Keywords

Flavobacterium psychrophilum; Baltic salmon; brood fish; eggs; milt; ovarian fluid

Published in

Diseases of Aquatic Organisms
1999, Volume: 37, number: 3, pages: 159-163
Publisher: INTER-RESEARCH

SLU Authors

• Ekman, Elisabet

  • Department of Pathology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Pathobiology
Fish and Aquacultural Science


Publication identifier

DOI: https://doi.org/10.3354/dao037159

Permanent link to this page (URI)

https://res.slu.se/id/publ/39757