GROWTH AND AGE AT MATURITY OF THE PACIFIC RAZOR CLAM 209 
northwestern Washington. There is no available information on spawning on the 
Vancouver Island and Graham Island beds in Canada. 
While visiting the canneries and beaches of Alaska, as many observations as 
possible were made on the condition of the clams at various times. During the 
season several cannery men preserved specimens in formalin at stated intervals. 
These specimens were collected and examined further to determine the amount of 
reproductive material in the gonads during each part of the season. In this Avay 
it is possible to fix approximately the spawning season for each section from which 
specimens were obtained. 
Spawning records for the vicinity of Cordova are very incomplete. The ob- 
servations made on preserved material and the examination of clams on the 
beds indicate that spawning started soon after July 1, 1924. On July 13 but 2 
per cent of the clams showed they had recently spawned out, 10 per cent had full 
gonads of such consistency as to indicate no active spawning, and the remainder 
(88 per cent) showed various degrees of incomplete spawning. On August 15, 
when over 400 specimens were examined, but 2 per cent carried any appreciable 
amount of spawn, 28 per cent showed the presence of a small amount of repro- 
ductive material, and 70 per cent were completely spawned out. 
The two records cited above were taken over a month apart. They give a fair 
example of what is found to exist generally in Alaska. There is no short com- 
mon spawning season, as is found on the Washington beaches, but rather a gradual 
changing over in the condition of the clams, from those in midsummer with large, 
full gonads to the thin, spent ones in early fall. The process takes over a month, 
although it is probable that any particular individual may cast its entire spawn 
more quickly. 
Similar conditions are found to exist elsewhere in Alaska. Near Chisik Island 
in Cook Inlet observations were made during the summer of 1923. The clams ap- 
peared fullest, or "fat," in late July. Evidently spawning started between July 
25 and 30. After August 1 it proceeded more rapidly and continued as long as 
specimens were obtained. On September 25 a few showed the presence of a very 
small amount of reproductive material, but it is doubtful if any spawn was beino- 
cast. 
The figures from Swickshak Beach for 1923 and 1924 show that the clams de- 
velop reproductive material rapidly in early May. By July 1 they are quite full 
and they start spawning between July 20 and 25, but proceed most rapidly after 
August 1. They appear to spawn out somewhat more rapidly than on either the 
Cook Inlet or Cordova beaches. Before September 1 spawning was completed. 
RELATION OF WATER TEMPERATURE TO SPAWNING 
From the excellent work of Dr. Thurlow C. Nelson (1921) it is apparent that 
the water temperature is closely correlated to the spawning of the oyster. A 
critical temperature of 21° C. (70° F.) has been found, below w^hich oysters will 
Hot spawn. Above 21° C. spawning will take place more rapidly as the tem- 
perature increases. It is further stated that due to continued cold weather, wliere 
the water has failed to reach the critical temperature for any length of time the 
eggs will not be cast, but rather be resorbed by the oyster. 
