An Aberrant Strain of the Bacterial Fish Pathogen Aeromonas salmonicida Isolated from a Marine Host, the Sablefish (Anoplopoma fimbria), and from Two Species of Cultured Pacific Salmon

Abstract

Biochemically unique strains of the causative bacterium (Aeromonas salmonicida) of furunculosis in fish are described. The strains were first isolated from a marine host, the sablefish, Anoplopoma fimbria, and later, from sockeye (Oncorhynchus nerka) and chum (Oncorhynchus keta) salmon. The strains were essentially identical, and although always isolated from diseased fish cultured in sea or brackish water, they behaved like typical freshwater bacteria.The outbreaks of furunculosis in local fish-culture facilities were rare events that are thought to have resulted from import of the pathogen in wild carrier fish. In the case of the sablefish that was captured at sea shortly before its death, the infection appears to represent the first instance of spontaneous furunculosis in a marine fish.