PRODUCTION AND COLLECTION OP SEED OYSTERS 
233 
vals at Shell Point. In spite of the scarcity of oyster larvae the setting on this bar, 
as will be shown later, was very abundant, varying from 40,000 to 67,000 per bushel 
of shells. Throughout the spawning season the number of the larvae collected in 
various sections of the bay amounted to 146 found in 49 samples. (This figure does 
not include 43 larvae collected in 68 samples taken on July 17.) 
Table 18 . — Occurrence of oyster larvse in 'plankton at Shell Point, Onset Harbor, from June 29 until 
August 3, 1928 
Date 
Time 
Tem- 
pera- 
ture 
° C. 
Number 
of larvae 
in 50 
liters 
Date 
Time 
Tem- 
pera- 
ture 
° C. 
Number 
of larvae 
in 50 
liters 
Date 
Time 
Tem- 
pera- 
ture 
° C. 
Number 
of larvae 
in 50 
liters 
July 12 
23.8 
July 
21 
21.8 
2 
July 2 
13 
9.54 a. in 
22.8 
23 
9.50 a. m 
21.7 
3 
11.45 a. m. . 
25.5 
16 
9.30 a. m _ . . 
22.6 
9 
24 
8.25 a. m. . . 
22.0 
5 
2.15 p. m... 
24.0 
17 
10.11 a. m. . 
24. 1 
2 
25 
1.06 p. in. .. 
24.8 
9 
6 
21. 3 
18 
1.45 p. m. 
20. 1 
9 
26 
21. 9 
8 
20.4 
2 
19 
10.40 a. m_ - 
23. 1 
Aug. 
2 
22.0 
9 
22.7 
20 
12.03 p. m.. 
24.2 
1 
3 
24. 1 
10 
8.50 a. m. .. 
22.8 
2 
A study of the relation between the occurrence of larvae in plankton and the 
stage of the tide was made on July 17 at the station located at the end of the shelled 
area off Shell Point. Observations, consisting in taking quantitative plankton 
samples from top and bottom, continued without interruption from high slack water 
at 6.25 a. m. until the beginning of ebb at 6.45 p. m. One can notice from an examina- 
tion of Table 19 that few oyster larvse were found only during the morning ebb tide. 
Unfortunately, the small number of larvae found in plankton samples makes it im- 
possible to draw a definite conclusion regarding the relation between their behavior 
and the stage of the tide. 
Table 19 . — Occurrence of oyster larvse in plankton at different stages of tide on July, 1928, Shell Point 
Bar 1 
Time 
Tide 
Number of larvae in 50 liters 
Number of larvae in 50 liters 
Straight hinge 
Umbo 
Time 
Tide 
Straight hinge 
Umbo 
Sur- 
face 
Bot- 
tom 
Sur- 
face 
Bot- 
tom 
Sur- 
face 
Bot- 
tom 
Sur- 
face 
Bot- 
tom 
Ebb 
2 
0 
0 
0 
8.40 a. m 
Ebb. 
3 
1 
1 
1 
6.40 a. m 
do 
3 
0 
0 
3 
9 a. m... 
do 
3 
0 
0 
0 
7 a. m . 
do __ 
3 
0 
3 
0 
9.20 a. m 
do 
0 
0 
0 
o 
7.20 a. m 
do 
2 
0 
1 
0 
9.40 a. m 
Low slack... 
0 
0 
0 
0 
0 
0 
0 
0 
10 a. m _ . _ 
do__ . 
0 
0 
o 
o 
4 
2 
1 
1 
10.20 a. m 
Flood 
0 
o 
o 
o 
8.20 a. m. 
do 
3 
2 
1 
2 
10.40 a. m 
do 
0 
0 
0 
0 
1 No oyster larvae were found in 48 samples taken at 20-minute intervals from 11 a. m., until 6.40 p. m. 
An attempt to study horizontal distribution of the larvae in a limited area of the 
bay was made on July 30; plankton samples were taken from the surface, middle 
zone, and bottom at seven stations along the line between Shell Point and the point 
on the southern shore of the bay. (Fig. 15.) The result of the observations, pre- 
sented in Table 20, show that there was a slight concentration of the oyster larvae 
in the vicinity of Shell Point. 
