226 
BULLETIN OF THE BUREAU OE FISHEEIES 
Table 7. — Cordova: Size of clams in different stages of maturity 
Length in centimeters 
Age 
3 
4 
5 
6 
Imi 
Imj 
M 
Imi 
Im] 
M 
M 
M 
7.0 - 
3 
8 
17 
23 
12 
3 
7.5 _ -- 
1 
5 
5 
6 
1 
8.0 - 
1 
8.5- - 
1 
1 
1 
1 
2 
27 
45 
14 
9.0 -_ 
1 
9.5.-.- 
6 
33 
18 
6 
10.39 
3 
2 
3 
1 
4 
10.50 
1 
1 
10.0 
2 
1 
10.5.- - 
11.0- 
Medians.-- - 
8. 60 
9. 50 
10.75 
8. 80 
9. 67 
9.67 
Medians (total) 
8. 70 
9.87 
10 
06 
It must be I'emembered that each year class here used had a separate origin. 
The annual variation that exists may account for the apparently large number of 
5-year clams that were not fully mature. In the vicinity of Cordova clams are 
taken from several beds, upon which the rate of growth is not equal, and the 
_ — 
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r 
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rlOO 
■40 
-20 
Age in Years 
Fig. 17. — Sliowlng the percentage of all clams mature at each age. For example, at Cordova 
of all clams 4 years of age 36.5 per cent were mature, while at Swlckshak 85 per cent were 
mature at the same age 
selection of some of the material used may have caused this discrepancy. AU 
clams more than 5 years old are completely mature and spawn every year. 
Figures obtained from 308 clams taken on Swickshak Beach gave more regular 
results. All 2-year-old clams were immature, but the following year over 40 per 
cent had passed out of this stage, 15 per cent becoming completely mature. In the 
fourth-year class 7 per cent were immature, while those in the second stage of 
