CLAM AND SCALLOP INDUSTRIES 623 



6 Rate of growth. In developing methods of culture, nothing 

 could concern us more than the rate of growth. The oyster reaches 

 a marketable size in three or four years. In other important respects 

 we find that clam production is much easier than oyster culture. 

 It requires little labor and less capital. But what about the length 

 of time required for clams to reach a marketable size? 



We may answer with much certainty that it is not more than half 

 as long a period as in the case of the oyster. We make the statement 

 in a general way. Under varying conditions, an oyster or a clam 

 may grow fast or slowly. There has been a general belief that this 

 variation in oyster growth is a matter of food. The belief is probably 

 well founded. Very little is known of the relation existing between 

 growth and the food supply in marine animals. Much recently ac- 

 quired evidence shows that, to a certain limit, which is a wide one, 

 the clam's growth increases with an increase in the amount of food. 

 Its position in reference to water currents, then, has much to do with 

 the rate of growth. However, it is perfectly safe to say that, on 

 an average, clams increase in volume twice as fast as do oysters. 



Recently many experiments have been made under various con- 

 ditions, showing just how rapid this increase actually is in My a. 

 We may cite a single example, not at all an extreme one, in which 

 a clam half an inch long became one and a half inches long in two 

 (summer) months. Under specially favorable conditions, clams 

 probably may reach a fair marketable size in one year from the 

 time when their life begins:; while clams which have lived for two 

 years, in almost any clam beach, if not too closely crowded, should 

 certainly be large enough to bring high prices. 



7 Legislation. Culture methods, we must conclude, are in them- 

 selves simple and easy of application. There should be no difficulty 

 in reclaiming depleted flats, if indeed they may not be made to yield 

 more than when in the most flourishing natural state. At the very 

 least, ground still productive should be prevented from becoming 

 barren. 



But there is one serious difficulty which threatens to defeat all 

 efforts at clam culture. That is in regard to the control of clam 

 ground. I have elsewhere discussed this matter, attempting to show 



