84 



THE SCALLOP FISHERY 



discernible to the naked eye.) Stragglers can be found weeks before 

 and after, due to the length of the spawning season. 



The rate of growth of the young scallop is affected by the same 

 natural conditions as the adult. Between the sizes of 1 and 15 milli- 

 meters, the average gain per day is 0.5 of a millimeter (about %o of an 

 inch). As the scallop increases in size the actual growth becomes less. 



The habit of attachment is of great importance to the scallop, not 

 only occasionally saving it from destruction on foul bottom, but raising 

 it in a position where the little animal can obtain a better food supply, 

 thereby favoring its growth. Eel grass from its abundance proves the 

 most common place of attachment, but is often detrimental to growth 

 by shutting off the circulation of water. In comparing the growth of 

 small scallops in eel grass and outside, the eel-grass scallops show a 

 slower growth. 



In summarizing the growth of the young scallop the following points 

 are important: (1) the actual growth begins only with the first shell 

 formation; (2) the time of set varies in regard to (a) locality, and 

 (6) year; (3) the growth up to 15 millimeters averages %o of an inch 

 per day; (4) growth becomes less and less as scallop increases in size 

 beyond the 15 millimeter mark; (5) power of attachment aids growth; 

 (6) conditions governing growth are the same as for adult; (7) 

 growth of the young is faster than for yearling scallops, both in (a) 

 actual gain, and (b) in volume. 



Growth of the Average Massachusetts Scallop. Owing to the varia- 

 tion in the growth of the scallop in the different localities, it is difficult 

 to strike more than an approximate average for the size of the yearly 

 sets and the typical Massachusetts scallop. Two classes of scallops are 

 found, (1) the shallow -water or eel-grass scallop, and (2) the deep-water 

 or channel variety. The following tables are compiled from the average 

 growth in the different localities for a period of three years. The height 

 of the scallops is given in millimeters, 25.4 millimeters being equivalent 

 to 1 inch. 



The Average Scallop. 



