006 
BULLETIN OF THE BUREAU OF FISHERIES 
GROWTH, AGE AT MATURITY, AND LENGTH OF LIFE (ANNUAL 
GROWTH LINE) 
Although scallops from various areas have been collected and measured, the 
material from which was obtained the data chiefly used in the study of growth rate, 
age at sexual and commercial ma- 
No. 
turity, and length of life, was secured 
from the Pivers Island bed close to 
the laboratory. This was a desir- 
able selection because of its ready 
accessibility and because during 
the first summer it offered the only 
known ample supply. An unfailing 
natural bed so close at hand has 
proved highly desirable, lacking 
only freedom from molestation by 
man 6 to be nearly perfect. 
Collections of scallops for meas- 
urement were made twice monthly 
over a large portion of the time. Of 
the scallops of considerable size, the 
attempt was made to secure a hun- 
dred . Therefore the number of these 
taken, unless markedly below that 
number, is not indicative of abun- 
dance. On the other hand, by the 
fall of 1926 collections for small 
scallops, which, as previously noted, 
not only dwell amidst vegetation 
but also attach themselves to it by 
means of the byssus, generally were 
made by raking a tubful of eelgrass. 
Numbers of these, therefore, are in- 
dicative of abundance. (See Tables 
4 and 5.) One collection, as here 
considered, generally was made on 
1 day, rarely on 2 or 3 days, and 
with an elapsed time of not over 4 
days. In no instance is a size fre- 
quency curve a composite of two 
collections, as here defined. 
The series of size-frequency 
curves (Figs. 23 and 24) show the 
year classes present and their ap- 
pearance, growth, and disappearance. At the first of the year two classes are present 
in abundance, one composed of small individuals varying much as to size, the other of 
mm. S 10 5 Z0 5 30 S 40 S SO 5 (O S 70 560 5 50 5 100 S/0 S 
Figure 24.— Length-frequency curves based on one collection at Pivers 
Island, for eaeh month of the second half of 1927 (5-millimeter group- 
ings). (See Table 4) 
s In the summer of 1926 a portion of these flats was set aside by the State to be excluded from commercial scalloping. Unfor- 
tunately, it has seemed impracticable to prevent serious molestation. 
