OYSTER BOTTOMS IN MATAGORDA BAY. 59 



gorda Bay depend upon the maintenance of some considerable con- 

 nection between the gulf and the bay in, that region. The present 

 low salinity is absolutely prohibitive of the production of market- 

 able oysters. 



Between Dressing Point and Raymond Landing Shoals the bay, 

 from the standpoint of density, may be divided into two portions 

 by a line running through the middle. Northwest of this line the 

 average density between March 20 and April 6 was 1.0030 and south- 

 east of the line during the same period the average was 1.0048, over 

 50 per cent higher. As this was at a time when the standard obser- 

 vations on the Fish. Harris showed a marked decline of 50 or GO 

 degrees, it is not improbable, though by no means certain, that earlier 

 in the season, during January, February, and the first half of March, 

 the water on the southeast side of the bay had a density of at least 

 about 1.0060 or 1.0070, quite sufficient for the production of market- 

 able oysters, though not 0} 7 sters of the best quality as regards flavor. 



Between the uppermost of the Raymond Landing Shoals and Dog 

 Island Reef there was the same difference between the two sides of 

 the bay from April 7 to April 12, when the local observations were 

 made, the average density of the northwest half of the bay being 

 1.0012 and that along the southeast shore 1.0038. These observations 

 were made at a time when the general salinity of the bay was low, as 

 is shown by the Fish Hatch observations, and what has been said in 

 regard to probable higher salinity earlier in the season above Ray- 

 mond Landing Shoals is equally applicable here. Proximity to the 

 discharge from the Colorado River, however, must always keep the 

 density unsuitably low on the northwest shore. There never have 

 been any oysters there and there never will be so long as the mouth 

 of the river maintains its present position. 



Below Dog Island it is convenient for the purposes of consideration 

 of the densities to divide the bay into three longituclirial zones, one 

 near each shore and the other in the middle. When the depth exceeds 

 5 or 6 feet there is almost invariably a difference in density between 

 the bottom and surface strata, the fresher water from streams and 

 rainfall tending to float above the more saline water coming in from 

 the sea. As the survey's observations were all made at a fixed dis- 

 tance of about 14 inches above the bottom, it follows that the water 

 specimens from the shallow water alongshore were taken at a point 

 much nearer the surface than those made in the middle of the bay. 



In the region between Dog Island and Mad Island reefs the aver- 

 age densities for the northwest shore, middle, and southeast shore 

 were 1.0024, 1.0078, and 1.0094, respectively. These readings show 

 the influence of the discharge from the Colorado, which, passing 

 mainly through Dog Island channel, near the northern end of the 

 reef, tends to lower the densities in the northwest and middle zones. 



