12 



oysters are densely cro^vded, it is probable tbat the water is 

 strained by a number of different ones as it passes over the reef, 

 making the number of food organisms captured by each oyster 

 comparatively small. The currents are always swifter some dis- 

 tance above than close to the bottom, so that the chance of the 

 food content of the water being depleted is less. In times of 

 freshet the more saline water from the gulf reaches the jetty 

 oysters before it reaches those farther up in the pass ; and where 

 the current begins to run down again the water becomes fresh 

 here later than over the other reefs, so that the period when 

 conditions are suitable for feeding is more prolonged. 



. The fact that the .jetty oysters begin a period of freshet in 

 better condition than those on the I'eefs has proOa'oly a marked 

 relation to their abilij^^ to withstand these conditions for a 

 longer period than their less fortunate neighbors. 



EFFECT OF THE FRESHET ON THE BEGINNING AND 

 DURATION OF THE BREEDING SEASON. 



Although under normal conditions the breeding season of 

 the oyster begins in Louisiana waters some time during x\pril 

 or in the early part of May, no spat could be found on shells in 

 the pass previous to June 6th, Avhich date marked the beginning 

 C'f a period of two weeks when the water in the pass was brack- 

 ish ; although for some weeks previous to this date artificial fer- 

 tilization of the eggs had show^n that the sexual products of the 

 oysters from all the reefs were ripe. Whether the oysters ha^i 

 been throwing out eggs and sperms previous to this date, ^me 

 absence of spat is to be accounted for by the fact that on ac- 

 count of the prevalence of fresh water the embryos were unable 

 to develop, or whether the matured sexual products Avere re- 

 taiiied by the adults until the physical conditions should become 

 sncli as to make possible the development of the young, is a 

 ({uestion to which a definite answer cannot at present be given. 

 However, the unusual prolongation of the breeding season into 

 the late fall, when a set of spat was secured at a season when 

 oysters are^spa^ming only sporadically, lends support to the 

 belief that the spawning activities were limited to times when 



