SPAWNING AND SETTING OF OYSTERS 
69 
The records of Offatts Bayou water are shown in Figure 10, while those of the 
water at Deer Islands and East Bay are given in Figures 11 and 12. In the bayou 
during March and up until about the middle of April the salinity was 21 to 22 parts 
per thousand. It then fell slightly (fig. 10) to about 18 parts per thousand, slowly 
rising to 21 parts per thousand at the middle of May, before falling sharply to around 
14 parts per thousand at the end of the month. Early in June it fell to 8 parts per 
thousand, and at the end of August it steadily rose to about 24 parts per thousand. 
Records for Deer Islands were not made until June (fig. 11) but after this time the 
Figure 11. — Showing records of salinity and pH of surface water and intensity of oyster larva at Deer Islands 
from May to August, inclusive. After August 20 setting was occurring but counts were not made 
salinity variations were essentially similar to those in the bayou save that, due to 
the larger size of West Bay and the free sweep of winds and tides, there is greater 
fluctuation. Early in June the salinity was below 4 parts per thousand and the 
water was almost fresh. In East Bay few tests were made, and these were as low 
as 2 parts per thousand in June. (Fig. 12.) 
A more detailed description of the salinity variations is made in the section on 
setting. 
The pH of the water, both in the bayou and in West Bay, appears to be char- 
acteristically between 8.1 and 8.4. Readings were found to agree closely when 
different indicators were employed. During the time that tests were made the 
