infecting tlie others, and even possible that the diseased fish might recover, 

 though in the hatchery I have never seen any fish recover from the dis- 

 ease, nor have I noted any immunity among the survivors of an epidemic. 

 Mk. Titcomb : Is it not true in most instances v^'here there are diseased 

 fish that if you liberate them when not too far gone so they have natural 

 conditions and a free run, a large proportion of them will recover? 



Dr. Belding : If we are not contaminating new waters the thing to do 

 is to put out the fish and let nature take its course. I do not know the 

 origin of that disease but it has been found in 25 rivers in Bavaria, and 

 in this country is prevalent in New Jersey and New York. It is not limited 

 to the trout or salmon family, since many salt and fresh water species 

 are susceptible to artificial inoculation. I have not found this disease in 

 salt water fish, under natural conditions, but believe it may exist. Cir- 

 cumstantial evidence indicates that this epidemic was started by feeding 

 whiting. Low vitality would render the fish more susceptible to the dis- 

 ease, but I believe that the strongest hatchery trout would in time suc- 

 cumb to this virulent disease. For instance, the landlocked salmon are 

 more, and rainbow trout less, susceptible than the brook trout. Both the 

 rainbow trout and the brown trout are more resistant to disease generally. 

 Mr. Titcomb: We might say that all our trout, under these intensive 

 conditions which are not quite norma), would naturally be more susceptible 

 than they would be in wild waters. 



Dr. Belding : Naturally, the disease would spread by contact infection 

 more easily at the hatcheries. About 40 per cent of the diseased fish show 

 local lesions in the form of external abscesses and ulcers. The peritoneum 

 is also affected in certain cases and a thin bloody fluid exudes from the 

 vent. In crowded pools other fish are constantly in contact with this in- 

 fectious material. So far as I know no animals except fish are susceptible 

 to this particular disease which evidently spreads through the water from 

 fish to fish and occurs in the wild state. It is possible that at some time 

 this was a harmless bacterium which later acquired pathogenic properties 

 for fish. The bacterium which we isolated at the Sandwich hatchery was 

 first called Bacterium salmonicida in 1894 by Emmerich and Weibel in 

 Bavaria, and Bacterium truttw in 1904 by Marsh in the United States. 



Mb. Titcomb: Do you think this disease can be connected with 

 pollution? 



Dr. Belding : I do not. The earlier investigators believed it was due 

 to water polluted with organic materials from barnyards, not the chemical 

 trade waste pollution of today, but later observations have completely dis- 

 proved this idea. 



Mr. J. M. Crampton, New Haven, Conn. : At our hatchery last spring 

 we had 100,000 two-inch trout which died at the rate of about 10,000 a day 

 until all were gone. Their eyes were protruding and they were transparent. 

 The water temperature was 56° F. and Professor Rutger of Yale University 

 said it was as fine as any spring water he had examined. Those who 

 furnished the liver and melts fed to the fish declared them fit for table 

 use. The minute we put the fish into another spring, or tank from another 

 spring, they died more quickly than those held in the original trough. We 

 salted the springs and did everything we could think of to save them, but 

 they all died in about 10 days. I have since heard that there is not a State 



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