172 American Fisheries Society. 



is necessary that it attach itself almost immediately to a 

 host fish by clamping its tiny valves to the gills of the fish. 

 (Only one of the commercial mussels becomes parasitic on 

 the fins of fishes.) The larval mussel has no power of 

 locomotion, so unless conditions are very favorable it will 

 fail to meet with a host fish and will fall to the bottom and 

 perish. The greatest loss of mussel life under natural con- 

 ditions is due to the failure of the larval mussel to connect 

 with its host fish. Artificial infection of fishes bring the 

 mussel and its host fish together. 



After the land-locked fishes have been rescued and taken 

 to the open waters, such suitable host fishes as are available 

 are placed in clearing tubs preparatory to the infection. A 

 ripe female mussel is then opened and the larval mussels 

 from her gill pouches released in the tub with the fishes and 

 the water gently stirred. The myriads of larval mussels 

 held temporarily in suspension give the water the appear- 

 ance of being milky and the tiny larval mussels constantly 

 open and close their valves in their attempts to attach them- 

 selves to the fishes. As the fishes pass the water through 

 their gills in process of breathing, the larval mussels are 

 carried againt their gills with the water and they readily 

 attach themselves. After the infection has been effected, 

 the fishes are released in the open water with a positive and 

 correct infection of larval mussels. 



If the juvenile mussel drops on favorable bottom, and is 

 not destroyed or devoured by enemies, it grows and matures 

 in from three to five years and is suitable for use in the 

 manufacture of pearl buttons in from four to seven years, 

 depending upon the species of mussel and its environment. 



Discussion. 



Dr. Osburn : To what extent are the fish that are of no particular 

 use for any other purpose available for mussel growth? 



Mr. Canfield: The most striking instance of that kind is found 

 in the common river gar, which, I believe, is of no commercial value 

 and is usually thrown out when caught in the commercial fisherman's 

 net. This gar is the only known host fish for one of the highest priced 

 commercial mussels that we have. Another instance is that of the 

 river herring, sometimes called the skipjack, which carries the nigger- 

 iead mussel, one of the important commercial varieties. 



Mr. Avery : Would it not be interesting if we could hear something 

 nore about the different varieties of fish that are hosts to the various 

 kinds of mussels? 



Mr. Canfield: The United States biological station at Fairport 

 ha? worked out very definitely the various host fishes of all the com- 



