13 



the external et)nditi()iis were sueh as to allow, if not assure, the 

 development of the embryos. 



During the two weeks from the 6th to the 21st of June tlie 

 oysters in the lower part of the pass were spawniui^ actively, 

 and all the clean shells on the reefs below Leesburg became cov- 

 ered with a good set of spat. The average number of spat on 

 each one hundred shells from the different reefs was as follows : 



TABLE 3. 



No. of spat 

 Location of reef. per shell. 



One-quarter mile below Leesburg 3fi 



One-half mile below Leesburg 97 



Lighthouse Reef »b 132 



While all the clean shells below Leesburg, both on the 

 natural reefs and in cages, showed a good set of spat, none of 

 the shells in the upper part of the pass or in St. John Bayou 

 were found with spat attached, although, as has been previously 

 mentioned, the physical conditions were suitable for the growth 

 of. young oysters. 



The ab.sence of any spat on shells from the reefs in this 

 part of the pass Avhen conditions Avere favorable for their growth 

 lends support to the conclusion reached as a result of tonging 

 on these beds, namely, that there were no living oysters even in 

 the deepest water at the upper part of the pass. This point has 

 an important bearing on the question of the distance that spats 

 may travel before the time of their attachment, as will be dis- 

 cussed farther on in this report. 



The spawning activities of the oysters ceased with the be- 

 ginning of the period of fresh water on June 21, or at least all 

 setting of spat ceased, and no further catch of spat occurred 

 until late in the fall. During the first tw^o weeks of this second 

 period of freshet most of the young oysters had succumbed to 

 the effects of the fresh water or had been covered up by the 

 srdiment, so that during the summer very few spats could be 

 found, and those only on the deepest reefs. 



