OYSTEB BOTTOMS IN MATAGORDA BAY. 55 



when feeding — all vital considerations to the oyster culturist. Unless 

 it be kept clean of even thin deposits of sediment and slime, which 

 would stifle the tiny oyster when it settles down, the material de- 

 posited for the purpose of obtaining a set of spat is soon rendered 

 useless and the planter loses both his material and the labor involved 

 in distributing it. If there be no currents to waft the tiivy oyster 

 fry from the neighboring natural or planted beds of spawning oys- 

 ter.^ it is necessary to distribute brood oysters with the cultch, which 

 entails additional expense while the chance of obtaining a good 

 strike is materially reduced. And finally, unless they be enormously 

 laden with food organisms, as in the artificial inclosnres or claires 

 used by the French, dead or slack waters will not produce fat oysters. 

 Excepting the reef channels and taking all factors into considera- 

 tion, the currents are most constant and strongest in that portion of 

 the bay lying along the peninsula shore below Tiger Island. In the 

 upper part of the bay the free ebb and flow r of the lunar tides is re- 

 tarded more or less by the barrier of Dog Island Reef, but below 

 Tiger Island they have unrestricted sweep in the deeper water of 

 the southeastern side of the bay, while the}^ are impeded on the oppo- 

 site side by shoaler water and the projecting reefs. The same 

 factors operate to promote in the same locality a freer circulation of 

 the water under the influence of the winds, and finally all of the 

 water derived from the streams, the major portion of which is dis- 

 charged just above Dog Island, finds its way to the sea through the 

 lower bay mainly along the peninsula shore, toward which it is de- 

 flected by Dog Island and Shell Island reefs. So far, therefore, as 

 one may be influenced by the important matter of currents, the choice 

 of location for oyster culture will be directed toward this part of 

 the bay, for here flows not only most of the water passing from the 

 sea to the upper bay, and of the still heavier discharge from the 

 upper bay toward the sea, but also such movements as operate to raise 

 or depress the level locally below 7 Dog Island Reef, whether under 

 lunar or meteorological influence. Other factors being equal, the 

 advantages in the matter of current velocities are decisive. 



TEMPERATURE. 



Two series of water-temperature observations were made during 

 the survey, one consisting . of tridaily records at the anchorage of 

 the Fish Hawk, beginning January 1, 1905, and ending May 12, 1905, 

 and the other consisting of 120 observations scattered at more or less 

 uniform intervals, both in time and space, over the entire bay above 

 Half Moon Light, between March 4 and April 28, 1905. In all cases 

 these readings represent the temperature of the water at a distance 

 of 14 inches from the bottom, irrespective of depth. 



