SPAWNING AND SETTING OF OLYMPIA OYSTERS 
479 
season. It appears to have been a common idea that only by planting cultcb in time 
for the initial setting could a good catch be obtained. In 1931 this was certainly not 
the case. The larvae continued to set in small numbers up until about the middle 
of October. 
Either dike 5 or dike 1 (Olympia Oyster Co.) was used for experimentation during 
all five seasons. The former is at a level of about 1.5 feet above the zero tide, while 
the latter has a height of about 3.5 feet. Both grounds are considered as excellent 
seed-catching areas. According to the results obtained in these experiments the 2 
grounds are almost equally favorable. As may be seen in table 21 the number of 
spat caught on bags of shells which were in the water at the same time is almost iden- 
tical for the two 
dikes. Considering 
only those bags 
which were in the 
dikes during the 
same periods, the 
total number of 
spat caught was 
137,074 in dike 5, 
and 13 6,581 in 
dike 1. 
-Average number of spat caught daily per bag of shells on two grounds in Oyster Bay, 
1932. Each bag was in the water for 7 days. Range of tide is also shown. 
SEASON OF 1932 < 
In 1932 the sys- s 
tern of carrying on 
two overlapping 
series of bags of 
shells for each 
ground was put into 
effect. Although 
involving the count- figure 24 . 
ing of spat on a 
great many more shells the results well justify the effort because of the increased 
accuracy obtained, permitting more exact determination of the times of maximum and 
minimum frequency of setting. Complete counts were made of two series and on 
sample bags of another (table 22). No spat were found until June 26, although daily 
observations were made. After this date setting continued until the middle of 
October, a total period of over 3% months. 
Represented graphically (fig. 24) the more numerous samples make an excellent 
picture of setting activity. Dike S (Steele ground) is about 2 miles down the bay 
from dike 1 and is removed from the larger area in which most of the beds are located. 
The total number of larvae caught is therefore considerably less than on grounds up 
the bay. There are two distinct major periods of setting having their maxima during 
the first few days of July and near the end of August respectively. The graphs repre- 
senting the two grounds are substantially alike with respect to the times of the maxima 
and minima and differ only in the total number of spat caught at any time. As was 
found in the previous year the season consists of two distinct setting periods, with the 
maxima in the present case approximately 8 weeks apart. 
