THE CATFISH AS A HOST FOR FRESH- WATER 



MUSSELS 



By A. D. Howard 



The rapid growth of the pearl-button industry, with its 

 increasing demand for shells of the fresh-water mussel, has 

 already made it evident that this natural resource is not un- 

 limited and that even a practical extinction is possible. In 

 recognition of this situation the U. S. Bureau of Fisheries 

 has carried on for several years an extensive investigation 

 of methods of artificial propagation. 



The interesting relation of parasite to host between the 

 Unionidse and fishes has long been known. An exami- 

 nation of fishes caught at random plainly indicates that in 

 nature the number of mussels successfully finding a host is 

 comparatively small. Lefevre and Curtis* have demon- 

 strated that in certain cases a single fish may by artificial 

 means be induced to carry several thousand more mussels 

 than it would under ordinary circumstances in nature. 

 Thus large numbers of the young mussels which otherwise 

 would sink to the bottom and die are carried through the 

 most critical period in their life history. The method of 

 infection is as follows: 



Young mussels or glochidia produced to the number of 

 many thousands by each female mussel, are taken from the 

 gills of the latter and placed in a receptacle with the fish to 

 be infected. The myriads of glochidia thus distributed in 

 suspension through the water, passing constantly through 

 the gills of the fish, become attached to the filaments of the 

 gills or in some cases fasten externally upon the fins. As 

 soon as they become attached there is a reaction of the tis- 

 sues of the fish, in the nature of an hypertrophy of the ex- 



*Lefevre, G., and Curtis, W. C. : 12 Studies on the Reproduction 

 and Artificial Propagation of the Fresh-water Mussels. Bull. Bureau 

 of Fisheries, Vol. 30, 1910. 



