22 THE SCALLOP FISHERY 



(5) What temperature is most favorable for spawning? 



In confinement scallops have been observed to throw spawn at all 

 temperatures from 68 to 84 P., although above 76 F. was most 

 favorable. Great variation is found, as every scallop is a distinct 

 individual and the eggs vary in degree of maturity. One scallop gave 

 off its sex elements at a temperature of 68 F. in fifteen minutes after 

 being placed in the aquarium, while at 78 F. one spawned in three 

 minutes and others took hours. Under natural conditions the spa\vning 

 season begins when the water reaches 61% F. As a rule high tempera- 

 tures are most conducive for spawning. 



(6) At what age does a scallop first spawn? 



The extreme rapidity of growth makes it possible for the scallop to 

 spawn when exactly one year old. With the clam, spawning occasionally 

 occurs at the age of one year, with the quahaug only in very exceptional 

 cases, but with the scallop the most important reproductive period, and 

 the only one of practical value, comes at this early age. This fact is 

 explained by the short life of the scallop, from twenty to twenty-six 

 months, as compared with the many years of the clam and quahaug. 



(7) Is there a second spawning season? 



For the majority of scallops there is only one spawning season. Na- 

 ture has so regulated that less than 25 per cent, attain a length of life 

 of two years. In the few scallops which pass the two-year mark, eggs 

 and spermatozoa apparently develop normally, and if the animal lives 

 through the season it produces offspring for the second time in its life. 

 These two-year-old scallops are larger, and the ovaries and testes are of 

 correspondingly greater size. Two-year-old scallops are occasionally 

 found in small beds, but large numbers are by no means of common 

 occurrence. In the protected waters of the Powder Hole two-year-old 

 specimens were frequently found. During the summer of 1909 a com- 

 paratively large number of the set of 1907 were found. This set was 

 peculiar for its slow growth and small size, the two-year-old animals 

 being about the size of normal one-year-old scallops. The spawning 

 of this set was perfectly normal during the second season, and the sex 

 products could in no way be distinguished from those of yearlings. 

 Although it is possible for scallops to spawn a second time, provided 

 they pass the two-year limit, their economic importance is slight, owing 

 to the small per cent, which survive so long. The first spawning season 

 must, therefore, be considered the only practical one in legislation for 

 the welfare of the scallop fishery. 



This fact proves that all scallops under one year old must be pro- 

 tected, as these furnish practically all the spawn for the following 

 year. Only scallops under this age need protection. If the scallop 

 under this age is amply protected, the law has done all in its power to 

 insure the future of this profitable industry. It does no harm to capture 

 scallops over one year old; in fact, it would result in economic loss if 



