8 OYSTER BOTTOMS OF MISSISSIPPI SOUND, ALA. 



This furnishes an exact statement of the condition of the bed at 

 the spot, which can be platted on the chart with error m position of 

 not more than a few yards. From the data obtained a close estimate 

 may be formed of the number of bushels of oysters and shells per 

 acre in the vicinity of the examination, and, by multiplying the 

 observations, for the bed as a whole. In the course of the survey 

 775 observations were made at various places, principally on the nat- 

 ural rocks, but some on the barren bottoms also. 



In estimating the productiveness of the bottoms it appeared desir- 

 able to use the method employed m Delaware Bay ° rather than that 

 followed in the James River survey. 



Where tongs are used exclusively a bed with a given quantity of 

 oysters lying in shoal water is more valuable commercially than one 

 with the same quantity of oysters in deep water, owing to the fact 

 that the labor of the tonger is more efficient on the former. As has 

 been pointed out, the area covered by a "grab" decreases with the 

 depth, other factors being the same; and, moreover, the deeper the 

 water the greater is the labor involved in making the grab and the 

 smaller is the number of grabs which can be made in a given time. 

 Where, however, the depth is practically uniform and shoal, as in the 

 region treated in this report, it is unnecessarily refined and laborious 

 to make such allowance for depth, and it is nearly as accurate and 

 satisfactory to rate the bottoms in accordance with an arbitrary 

 standard. 



The classification adopted in this report is as follows: 



Depleted bottom Less than 25 bushels per acre. 



Very scattering growth Between 25 and 75 bushels per acre. 



Scattering growth Between 75 and 150 bushels per acre. 



Dense growth Over 150 bushels per acre. 



In tliis classification no oysters less than 3 inches in length are 

 considered, as the rating is made solely in respect to what are assumed 

 to be marketable. It may therefore occur that bottom covered by 

 an enormous growth of small oysters may be regarded, both in the 

 text and on the chart, as depleted on account of the few large oysters 

 which it bears. A reference to the tables which accompany the 

 description of each bed will show cases of this kind. "Depleted 

 bottom" is in a measure an unfortunate term, as it implies that it 

 has retrograded in productiveness, whereas in reality in many cases 

 it may be barren bottom gradually changing to productive. The 

 term is employed to designate a definite present condition without 

 regard to the past, and is retained despite its false implication, 

 because no better has been suggested. 



a Condition and Extent of the Natural Oyster Beds of Delaware. By H. F. Moore, assistant, United 

 States Bureau of Fisheries. Bureau of Fisheries Document No. 745, 1911. 



