54 U, S. BUKKAU OF FISHERIES 



The oysters artificially propagated by the bureau diirino; the 

 summer of 1923 were placed on suitable inshore beds at Milford, 

 and up to August 1, 1924, they had attained an average growth of 

 21/4 inches. It is expected that b}^ the fall of 1925 they will make 

 excellent half -shell stock. 



Experiments were also conducted with the soft clam, Mya are- 

 nan'a, and over 8,000 were artificially propagated and grown in one 

 of the hatchery troughs until sufficiently large to be placed in the 

 harbor. The larva? of the soft clam are much larger than those of 

 the oyster, and during the short free-swimming period and subse- 

 quent " setting " stage are more vigorous and better able to take care 

 of themselves. 



The relationship between water temperature and occurrence and 

 distribution of oyster larvse in Great South Bay was studied by 

 J. S. Outsell. Evidence was obtained that the small larvae appear 

 in the water quickly following a rise in temperature. Later in the 

 summer, however, the larvae disappeared abruptly and almost com- 

 pletely from the bay without forming a set. Their disappearance 

 coincided with the appearance of a great number of ctenophores, 

 which are known to feed on the larvae of bivalve mollusks. 



ALASKA CLAMS 



During the summer of 1924 Dr. F. W. Weymouth, of Stanford 

 University, and H. C. McMillin, scientific assistant, spent nine 

 weeks in the field, from July 1 to September 3. The razor-clam beds 

 in the vicinity of ConloA a were twice visited (once early and again 

 later in the season), and some time was spent on the beds near 

 Kukak in Shelikof Straits. Incidental observations were made on 

 other mollusks, chiefly "butter clams" (Saxidomus), and on the 

 crab and shrimp forming the basis of the fisheries of Petersburg 

 and Wrangeil. Mr. McMillin later visited the razor-clam beds on 

 the Washington coast and the " butter clam " beds on some parts of 

 Puget Sound. 



These observations and a review of the data for this and the pre- 

 vious season have shown the annual ring method of age determina- 

 tion to be reliable, and have given a mass of age and size records 

 from which satisfactory norms for growth in the commercially 

 important districts (Washington, Cordova, and Shelikof Straits) 

 have been determined. 



Further observations made by McMillin on the Washington coast 

 have given interesting data on the time of spawning and its relation 

 to water temperature. Material obtained through the cooi)eration of 

 Alaskan canners has permitted the approximate determination of 

 the spawning season here, which is less sharply marked and occurs 

 later than on the Washington coast. Extensive data showing tiie 

 relation of length and age to sexual maturity have been worked out, 

 making it possible to determine the effect of the size limit upon the 

 breeding reserve. 



On tlie basis of these findings a size limit of 4i/, inches has been 

 placed on all Alaskan beds. Those in the vicinity of Cordova are 

 now greatly overfished and it is hoped that this regulation will limit 

 the pack to an amount which the beds can sustain; if not, more 

 stringent size limits will be proposed. 



