74 THE SCALLOP FISHERY 



CHAPTER V. GROWTH. 



The rate of growth of the scallop, besides being of popular interest 

 among the fishermen, has an important bearing on the development of 

 the fishery. Owing to its intimate connection with practical scallop 

 culture, a detailed study of the rate of growth comprised a large part of 

 the investigation. In addition to extending the knowledge of the fisher- 

 man and defining the proper relation of growth to protective legislation, 

 several facts of biological interest have been brought out by the experi- 

 ments, and although not at present of practical importance, they are 

 likewise included for the benefit of persons interested in the study of 

 the Mollusca. 



In the determination of the average growth of any shellfish it is diffi- 

 cult to make definite statements, as the natural conditions, which influ- 

 ence development, are varied. The rate of growth for one body of water 

 is different from the growth in other localities, unless the same condi- 

 tions are present, instances of which occur but rarely in nature. This 

 fact not only has rendered difficult the concise presentation of the sub- 

 ject, but also has necessitated a manifold duplication of the experimental 

 work in order to satisfactorily cover the conditions in Massachusetts 

 waters. Therefore, the reader must understand that the general figures 

 given in the following pages do not hold true for individual localities 

 and are but the averages for certain sections. 



Methods of Investigation. The natural conditions of the scallop 

 grounds in Massachusetts are dissimilar to the Rhode Island waters, 

 Buzzard's Bay being the only section at all approximating the conditions 

 in Narragansett Bay. These differences will be brought out later by a 

 comparison with the growth experiments of Risser (2) on the Narra- 

 gansett Bay scallops. The variety of conditions presented in the differ- 

 ent localities of Massachusetts necessitated an extensive series of 

 experiments, covering the same ground and in several instances with 

 results at variance with the observations of Risser. 



The opportunities for solving the rate of growth of the scallop under 

 a variety of natural conditions were especially favorable owing to the 

 diversity of the different scallop grounds. The average rate of growth 

 for the different sections in the State, as here presented, is the result 

 of three years' continued observations on sets of scallops under various 

 environments. Excellent facilities for detailed work on the growth and 

 length of life for a period of four years were afforded at Monomoy 

 Point in the nearly landlocked harbor, the Powder Hole, and a large 

 share of the experimental observations, many of which could never have 

 been obtained elsewhere, were made in this locality. Inclosed in a 

 natural aquarium, the scallops could be followed from birth to death 

 under conditions many of which were under the direct control of the 

 operator. 



