REPORT OF COMMISSIONERS OF INLAND FISHERIES. 31 



tion can be referred back still further to two general conditions : 

 1st, the position of the individual clams as regards comfortable 

 surroundings, and 2nd, of more importance, the position in rela- 

 tion to the abundance of food-supply. In certain localities, and 

 at certain depths of water, the average food-supply is greater than 

 at others. Moreover, the longer the water covers the clams, the 

 longer time they can feed ; for they derive all of their food from 

 the water, and can take it only when they are submerged. Other 

 conditions being the same, clams grow more slowly near the high- 

 water mark. Without taking into account the extreme variation, 

 the one-year-old specimens vary between three-quarters of an 

 inch and two inches in length. 



Contrary to the opinion ordinarily held, the clams reach sexual 

 maturity and breed during the first year of their life. 



In regard to the natural enemies of the clam, it is doubtless im- 

 possible to enumerate them all. Of the eggs laid, probably great 

 numbers perish without being fertilized. Of the enormous num- 

 ber which reach the swimming stage of development, it is certain 

 that only relatively few are successful in burrowing. During these 

 early stages, not only are they preyed upon by innumerable small 

 predaceous animals, but the chances of perishing by falling upon 

 unfavorable ground where they are smothered by the silt, or where 

 they cannot burrow on account of the rocks are equal to, if not 

 greater, than their chances of falling upon good ground. When 

 they begin to burrow they are subject to the attacks of the crabs, 

 eels, star-fish, and probably many other enemies ; and those which 

 attain a somewhat greater age are continually being dug out of 

 their burrows by man, and thus exposed to the attacks of fishes and 

 all other enemies, even if they are not actually carried away by the 

 clam-diggers. There is some evidence that in certain parts of the 

 Bay the red water has worked havoc among the clams, as 

 mentioned in the last report. It is probable, however, that the 

 excessive and indiscriminate digging is largely responsible for the 

 decrease in the clam product of the Bay. 



The clam gets, its food-supply from the sea-water, which is 



