24 U. S. BUREAU OF FISHERIES 



the environmental conditions. Three sections were studied espe- 

 cially to determine the difference in physical factors and how these 

 are reflected in growth. 



The onset of spawning was observed and studied at Cordova for 

 the first time. The water was colder than on the Washington coast 

 when spawning began, but the same relative change in temperature 

 appears to incite the action. Discharge of eggs begins slowly and 

 becomes more rapid after one day, but spawning never takes place 

 as rapidly as it does in Washington. No information has been received 

 about the set that resulted from the 1925 spawning, but usually there 

 are fewer young in Alaska than on the Washington beds. 



When the field work was performed in 1924 it was noticed that 

 razor clams in various localities seemed to become sexually mature 

 at a common size rather than at a common age. In working up these 

 data, therefore, the influence of size and age on sexual maturity was 

 especially observed, and in addition the relation between size and 

 age was determined for various localities. 



As razor clams in Washington grow approximately twice as fast 

 as do those in Alaska, it is of economic importance to determine 

 whether they really become spawners in one-half the time. It was 

 found that the older clams average a smaller size at maturity than 

 the younger ones. Specimens from Washington matured in less than 

 half the time required by those from Cordova, but the Cordova 

 specimens averaged more than one-half centimeter smaller in size. 

 Figures from all the beds showed that 1 centimeter in size was 

 approximately equal to 10 years in age in sexual maturity. 



Proportional measurements of razor clams from beds in California, 

 Oregon, Washington, British Columbia, and Alaska indicate that the 

 economically important forms all belong to a single species rather 

 than to several, as asserted by some systematists. 



A report was published in 1925 covering the results of the inves- 

 tigations made in 1923 and 1924. 



SCALLOPS 



Because of a sudden great reduction in the number of scallops, 

 the Fisheries Commission Board of North Carolina requested the 

 bureau to make an investigation, and J. S. Gutsell was assigned to 

 the work. 



The scallop fishery occupies an important place among the fishery 

 industries of the State and is an extremely important one among 

 those of Carteret County, to which it is confined. In recent years 

 it has approximated in financial importance the oyster industry of 

 the entire State, with an annual value of nearly $250,000. 



A survey made by the Fisheries Commission Board during the 

 summer of 1924 was reported to have revealed an unusually great and 

 widespread abundance of scallops. A later survey, following unprec- 

 edentedly heavy rains, showed almost complete mortality except 

 over unaffected areas in lower Bogue Sound. The scallop fishery 

 confirmed these findings, revealing scallops in great abundance wher- 

 ever they are found at all. Although direct evidence is lacking, there 

 seems to be no reason to doubt that unusually low salinities result- 

 ing from abnormal rains caused the mortality. 



