Though protected, they are allowed to be caught by anglers because of hatchery production programs. In the acute form, hemorrhages are found in the fins, tail muscles, gills, and internal organs. In more chronic forms focal areas of swelling, hemorrhage and tissue necrosis develop in the muscles. Liquefactive necrosis occurs in the spleen and kidney. Diagnosis is made by isolating a pure culture of the organism.
Avoidance is the most effective prevention because A. salmonicida is an obligatory fish pathogen.
The salmon was postulated to be the source of the epizootic. Frogs are commonly infected with A. hydrophila , not A. salmonicida .