CONDITIONS REGULATING THE GROWTH OF 

 THE CLAM (Mya Aretiaria). 



By David L. Belding, 



Biologist of the Massachusetts Department of 



Fisheries and Game. 



It is with some hesitation that I submit for your con- 

 sideration an old, though interesting, subject; but I 

 desire to approach it from a viewpoint slightly different 

 from that taken by previous writers. I desire briefly to 

 outline the more important natural conditions which reg- 

 ulate the growth of lamellibranch mollusks, using the soft 

 clam (Mya arenaria) as an illustration. In the future 

 the tidal flats of Massachusetts will undoubtedly be cov- 

 ered with numerous clam farms. Therefore, from a 

 practical standpoint, a knowledge of the conditions which 

 influence clam growth will be of value to the culturist 

 in the selection and development of his grant. 



In the tidal waters clams are present in abundance on 

 some flats, in scattering quantities on others and in many 

 sections entirely absent. The reason is that certain defi- 

 nite conditions are essential for a favorable environment. 

 There is no more convincing illustration of the influence 

 of environment upon the life of a clam than the effects 

 of the surroundings upon the rate of growth. Chief 

 among these natural forces may be enumerated current, 

 tide, soil, depth and salinity of the water, so closely inter- 

 woven that their separate action cannot always be clearly 

 demonstrated. Any discussion of these conditions, which 

 form a favorable or unfavorable environment, involves 

 their separate treatment; but it should be understood 

 that there are few, if any, instances where the pure un- 

 complicated action of a single natural condition can be 

 obtained. These factors naturally fall into three main 

 groups: (1) the circulation of the water or the current; 

 (2) the condition of the water; and (3) the character 

 of the soil. 



Current. — The most important factor in clam growth 

 is a good current, not necessarily an exceedingly swift 



