54 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



a large scale, and yet, if narrow furrows are cut in the ground, a 

 large quantity can be planted in a few hours. 



THE RATE OF GROWTH AND AGE AT MATURITY. 



In a consideration of clam culture, of the propagation of clams on 

 public shores, or of restrictive legislation, it is of importance to know 

 the rate of growth of the clam, and the age at which it may reason- 

 ably be expected to reach a marketable size. This was one of the first 

 questions which the commission undertook to solve; for in regard to 

 it, even among professional clam diggers, there existed a wide differ- 

 ence of opinion. The problem turned out to be less simple than it 

 might seem at first, mainly from the fact, which was soon learned, that 

 the rate of growth varies extremely according to different conditions. 



The main spawning season is about June, and the clams ordinarily 

 reach sexual maturity and begin to spawn in one year. They be- 

 come a marketable size, that is about three inches in length, in from 

 eighteen months to two years, if they are given fairly favorable con- 

 ditions. In Narragansett Bay, however, they are not intentionally 

 allowed to reach this size, but are dug and sent to market or to the 

 clambakes as soon as they are a year old, and often before. At 

 some of the popular clambakes great quantities of clams are daily 

 served which are not as large as some specimens which we know to 

 be less than four months old. 



Methods of Determining the Rate of Growth.- — To ascertain the 

 rate of growth, various methods have been employed. Individual 

 specimens have been isolated in flower pots and land tiles which 

 were set into the ground; enclosures of various sorts have been 

 planted with clams, all of approximately the same size; the set of 

 a particular season has been kept under constant observation with- 

 out transplanting; and large areas of ground, half an acre or more 

 in extent, have been planted in various places. 



During the last year a new and excellent method of indelibly mark- 

 ing the shell was devised, which serves as a record of the growth 

 of individual clams wherever they are planted. The so-called rings 



