Blue-sac disease in Lake Ontario lake trout

Egg lots from individual females of Seneca strain lake trout (Salvelinus namaycush), captured from Lake Ontario and incubated at 7°–9°C, showed a very high incidence of blue-sac disease and associated mortality. Losses were shown to be female dependent. Some of the eggs were found to be infected by a myxobacterium (Cytophaga sp.) that may have been transmitted to the fry through the egg and/or sperm. This myxobacterial infection may have been related to the blue-sac disease observed in some egg lots. Incubation at 1.7°–3.0° C significantly reduced the incidence of blue-sac disease and mortality in the replicated egg lots.