8 PROTECTION OF FRESH-WATER MUSSELS. 



critical period in their life history, after which they must be left to 

 continue the struggle for existence by their own efforts. 



We therefore plan to work in such a way that, even with the 

 liberal discount that nature Avill surely apply to our returns, there 

 may be left a real measure of benefit gained without undue cost. 

 Many of the young will be lost from falling upon unsuitable bot- 

 toms and from many other unfavorable conditions, such as confront 

 every young mussel in nature with more or less frequency. "VYe would 

 like to remove all of the unfortunate conditions productive of loss, 

 both to the mussels that we put out and to those that are propagated 

 entirely by natural means; but this, of course, is not possible. 

 There are, however, artificial conditions which do injury to the 

 younger mussels, and it is both desirable and practicable to prevent 

 such damage as far as can be done reasonably. 



RESUI.TS DEPENDENT UPON PROTECTION. 



In the regular fishery for mussels the beds are continually dragged 

 over with rakes, tongs, crowfoot hooks, or dredges. It is inevitable 

 that the young mussels will suffer to some extent from this process. 

 It is quite unnecessary, however, for the " infant " mussels, many of 

 them too small for any use at all and many more too small for any 

 economical or proper use in manufacture, to be entirely removed 

 from the beds. Mussels are thus uselessly destroyed that might be 

 left to grow to a size at which they would be both commercially 

 valuable and properly usable; meantime, too, they might take their 

 natural part in the reproduction of the species. 



Furthermore, it would be desirable to leave portions of the rivers 

 entirely undisturbed by the operations of shelling during periods of 

 some years. This would accomplish a double object — it would leave 

 the best conditions for the natural reproduction of the remnant of 

 the old stock and for the growth of the young mussels and at the 

 same time it would create a series of reserves in which artificial 

 propagation could be carried on with the best conditions for maxi- 

 mum results. In such closed regions the young mussels would have 

 to contend against only the normal unfavorable conditions which 

 all mussels have ever had to withstand, without an added toll of 

 destruction being taken by the direct and indirect effect of the opera- 

 tions of men. 



The simple " closing " of a depleted region, if the exhaustion has 

 not proceeded too far, may be expected to lead to sure betterment, 

 and even in time, if the closure were for a very long period, to a 

 restoration of the former condition when mussels were so richly 

 abundant. It will be advisable, however, to supplement natural 

 processes by the methods of artificial propagation in order that the 



