A SECOND GENERATION OF ARTIFI- 

 CIALLY REARED FRESH- WATER 

 MUSSELS* 



By Dr. A. D. Howard, Fairport, Iowa. 



At the annual meeting of this Society in 1914, I pre- 

 sented the resultsf of a method devised for rearing early 

 stages of fresh-water pearl mussels. Subsequent re- 

 sults indicate that the method with modifications is 

 equally favorable for later stages in the life history. The 

 means employed was a floating crate containing baskets 

 of sufficient size to hold the infected fish and made of 

 small enough mesh to retain the microscopic mussels as 

 they escaped from their hosts. 



The crate, supported by floats, was placed in the river 

 (the Mississippi) in a good current. A crate thus held 

 at the surface, in addition to other advantages, accommo- 

 dates itself to any rise or fall of the river, is convenient 

 of access, and removes the young mussel from many ene- 

 mies on the bottom. 



For the early stages, the baskets consisted of a frame- 

 work of galvanized iron or wood, attached to a base of 

 the same material. On the frame was stretched copper 

 cloth of one hundred mesh to the inch. As the mussels 

 increased in size, it seemed desirable to use netting of 

 larger mesh for the baskets in order to permit a freer 

 circulation of water. 



At the end of the first season, period of growth 5 

 months, the maximum growth was a length of 32 mm., 

 an average of 25.5 mm. which far exceeded the highest 

 previous record for growth under observation, viz. that 

 by Herbers, who obtained a growth of 3.13 mm. in Ano- 



*Contributions from the U. S. F. Biological Station, Fairport, Iowa. 

 Published by permission of Commissioner of Fisheries. 



f Howard, A. D., 1914. A New Record in Rearing Freshwater Pearl 

 Mussels. Trans. American Fisheries Soc, December, 1914. 



