Coker. — Fresh-water Mussels 43 



now extends from the Dakotas to Tennessee, and from 

 Minnesota to Louisiana. 



In the course of this brief development of the fishery, 

 two significant observations have been made. One is 

 that an exhausted bed will recuperate, given a sufficient 

 period of rest, if the bed has not been too thoroughly 

 depleted. The other is that the quality of shells yielded 

 by a mussel bed is often distinctly improved after the 

 first years of working. Certain streams in Arkansas, 

 for example, are said to have first produced a rather un- 

 desirable shell, old, thick and coarse; but after a little 

 time a smaller shell of prime quality came to predomin- 

 ate in the catches, and these were unexcelled by those 

 from any part of the country. 



Formerly it was supposed that the commercial shells 

 were of excessively slow growth, requiring 12 years or 

 more to reach maturity. We now know that there are 

 slowly growing species and fast growing species. Some 

 may indeed require 8 or 10 years to reach a proper size, 

 but others of equal commercial importance attain a mar- 

 ketable size in four or five years. 



Our mussel resources are potentially self-perpetuating, 

 given a reasonable opportunity and practicable assistance. 

 The mussel industry is not dependent for temporary pros- 

 perity upon the eradication of its material basis. It is 

 perfectly feasible to have an important mussel fishery 

 enduring as long as the demand for mussels continues, 

 and that demand, as we have seen, is, humanly speaking, 

 a permanent one. 



It does not follow that the shell resources cannot be 

 exhausted either locally or as a whole. Since the mussels 

 are living forms dependent for reproduction upon the 

 maintenance of a stock sufficient for casting the seed of 

 successive generations, it is obvious that they cannot 

 withstand an entirely heedless onslaught. The perpetua- 

 tion of the resources is consistent with their utilization, 

 but it is quite dependent upon the adoption of a rational 

 policy of conservation. 



