Table 10.— Comparative susceptibilities of various Salmonidae 



Salmo trutta 



Salmo salar 

 sebago 



Salve linus 

 fontinalis 



Salmo trutta 



Salmo salar salar 

 and Salmo truttae 

 (sea trout, Europe) 

 Salmo trutta 



Salvelinus 

 fontinalis 



Salmo gairdnerii Salmo gairdnerii Salmo gairdnerii Salmo gairdnerii 



P\irunculosis 

 Coiranittee 1931. 



Furunculosis 

 Committee 1933. 



Furunculosis 

 Committee 1935- 



Davis 19-^6. 



Salmo gairdnerii 



Salmo salar salar Salmo truttae 

 (grilse) and 

 Sa,lmo truttae 

 (highly susceptible 

 experimentally), Salmo trutta 



Salmo trutta and 



Salvelinus 



fontinalis 



(particularly 



susceptible). 



Salmo clarkii 



Salmo gairdnerii 



The Furunculosis Committee (1933) found that in experiments in 

 which trout were exposed to infection by contact and by contaminated 

 food or water, individual fish of the same species exhibited great 

 variation in susceptibility. Some resisted infection completely., others 

 developed the carrier state (see below) and ultimately died of active 

 disease after a variable period. Still others developed the "subacute 

 disease" with external furunculous lesions, and again others died 

 rapidly of a general infection mthout localized lesions. 



Influence of A ge 



That susceptibility increases with age, which has been found in 

 Europe (Plehn 1924-, Blake and Clark 1931), has not been the experience 

 in the United States vAiere f ingerlings and yearlings frequently suffer 



38 



