Anieri-can Fisheries Society. 83 



beg to remind you, does not consist essentially in a knowledge of 

 the Latin names of fishes or the minute anatomy of an insect. 

 Such things are not to be despised, but they are only aids and 

 means to something of greater importance ; and a man may pos- 

 sess either or 1)oth of them and yet be less scientific than a 

 huml)le layman who holds his eyes and his mind open for the 

 acquisition of new facts, and faithfully restrains his opinions 

 from crystallizing on any half-knowledge. 



I think that the im|)ortance of this subject is generally under- 

 estimated. It is not impossible that many fish cultural opera- 

 tions have been brought to naught by the action of unrecognized 

 diseases: nor that definite diseases have been the cause of many 

 of those great fluctuations in the numbers of wild fishes that his- 

 tory has recorded. 



Hardly any of the gTeat commercial fishes have escaped fluc- 

 tuations, either general or local, which have been of great 

 moment to mankind. Not only to the fresh-water and anadrom- 

 ous species, but to those of the ocean, will this statement apply. 

 For instance, the sudden disappearance of the tile fish some years 

 ago from the grounds where it had been abundant, followed after 

 years by its reappearance; the fluctuations of herring on the 

 coast of Sweden; of the blue fish and menhaden on the coast of 

 ISTew England. Some of these phenomena may be accounted for 

 in other ways, but the tendency of discovery is in the direction of 

 some destructive enemy or disease to account for very sudden de- 

 crease of species. 



An official report lying before me gives a list of 104 different 

 diseases from which human deaths occurred in the state of Maine 

 ■during the seven years from 1892 to 1898. Is there any inherent 

 reason why fishes should not have as many diseases as men? 

 Observation has already gone far enough to indicate the probable 

 existence of a very considerable number of diseases among the 

 fishes we cultivate. At the Craig Brook Station of the United 

 States Fish Commissioii there have been observed perhaps a 

 dozen different diseases affecting salmon and trout, the majority 

 ■of which still await sufficient study to warrant us in naming them 

 or assigning definite causes. A rough list of them, not pretend- 

 ing to be complete or exact, is as follows : 



