THE OYSTER INDUSTRY OF GEORGIA. 2G9 



Brunswick and elsewhere, is attributable to the salinity of the water, and that the 

 American oyster can not endure constant submersion in water of great density at the 

 South, and that the mere specific gravity does not affect the set. The theories advanced 

 explaining the absence of a set in deep water at the South are as follows: 



1. The extreme density of the water preventing the swimming embryos from sink- 

 ills: at the fixative stage. 



2. The extreme softness and film-covered character of the bottom preventing the 

 oyster from fixing. 



3. The suspension of slowly depositing silt in the deeper water, whose clogging 

 action is fatal to the delicate respiration of the microscopic young. 



4. Changes in the composition of the oyster-bed water, either in its salts or food 

 constituents, at different levels. 



Dr. Bashford Dean remarks in "The Physical and Biological Characteristics of 

 the Natural Oyster Grounds of South Carolina" that "if the first theory be correct, 

 spat in no instance should be found in deep water of high specific gravity," and that 

 "spat has been sparingly found affixed to deep-water shells, but we must admit that 

 it may have been attached before the host itself dropped into deeper water." 



When the shells we had planted in water not anywbere less tban 20 feet deep were 

 examined, a slight set had undoubtedly occurred, and but for the exceedingly warm 

 winter and early spring, which induced the mother oysters to emit their spawn very 

 early, it would have been heavier. In fact, we first attributed our failure entirely to 

 this fact. But in every instance the young oysters, all less than one-eighth of an inch 

 in diameter, were dead. The upper shells were intact, but could be brushed off by the 

 slightest touch. Previous fixation could not have occurred in our case, for all the 

 shells were 8 or 10 years old, and time and rough handling must have removed all 

 such young oysters before the shells were deposited. If a set occurs at the North in 

 consequence merely of the ability of the spawn to sink at its fixative stage, and does 

 not do so at the South in water of exactly the same specific gravity, then the inevitable 

 conclusion follows that the spawn of all northern oysters is heavier than that of all 

 southern oysters of the same species. 



Dr. Dean also says that as the water becomes fresher the oysters, with spat of 

 undeniably recent attachment, as in the North, should be found in favorable localities 

 covering the bottom; and, accordingly, as the water becomes less salt the raccoon 

 ledges should gradually and entirely disappear. He says : 



This does not maintain. Notwithstanding the water becomes fresher in character, deep beds of 

 single oysters do not become common in an increasing ratio. Such as are found rarely have spat 

 attached, and in every way appear still to represent the dropped-off raccoons. As the water becomes 

 less dense raccoon ledges do not disappear. Oyster ledges occur in Winyaw Bay, where the specific 

 gravity of the water is as low as 1-010. 



Now, as has been stated, coon oysters dropped from the ledges and constantly 

 submerged in water of high density perish, and while there does not seem to be any 

 reason why coon ledges should not be able to form in water of low density under 

 favorable circumstances of freedom from silt and the presence of collectors on the 

 shore, the fact is undeniable that they do generally diminish as the water becomes 

 fresher in rivers receiving a large amount of fresh water, and that the oysters improve 

 in quality as the density declines. This obtains in the rivers of Georgia, and natural 

 beds independent of coon reinforcement have remained self-sustaining in the fresher 



