Page:Popular Science Monthly Volume 20.djvu/42

32 of the sound is shoal, and these shoals covered with oysters scattered singly and in small groups, or existing in large, well-defined beds. Several small creeks empty their waters into this sound, and one large river, the Pocomoke, discharges into it also. The majority of the beds were found on the eastern side of the sound, and the largest were about the middle and near the mouths of the creeks. The beds in both sounds were located and defined during the summer of 1878, and the area upon which oysters were scattered was also ascertained approximately. The entire area in both sounds upon which oysters were found amounts to fifty-four square miles. The area covered by oysters, but only very thinly, they being scattered in small groups or singly, comprises in Tangier Sound fourteen square miles, and in Pocomoke Sound twenty-nine square miles. The area of the beds proper, or those grounds where the oysters are to a great extent uniformly spread and where the majority of the dredging-vessels work, amounts to six square miles in Tangier Sound and to four square miles in Pocomoke Sound.

The information obtained in 1878, so far as it related to the condition of the beds, may be summarized as follows: The number of oysters on the beds had been very much diminished since the commencement of the fishery, or during the last thirty years. The area of the beds had been greatly increased since the commencement of the fishery. There had been during the period alluded to no change of the usual natural conditions to which the animals are subjected.

Before attempting to draw any conclusions from the above, it will be well to see if the extension in area of the beds and diminution of the number of oysters can be accounted for by the action of natural, unassisted causes.

After the original formation and growth of the beds, they would at some time, the same conditions continuing to operate, cease their development, neither increasing in size nor in number of oysters, there being a natural limit to expansion in either direction. Suppose, then, a bed to have extended itself as far as the conditions of bottom and water or other natural limit would allow, all future expansion could be only in the number of oysters on the bed, and this is limited by the amount of food and room for development, the question of enemies not being considered, as, there being no increase, if they were not in sufficient numbers to prevent the growth of the bed and number of oysters, they would not be sufficient to cause its destruction or deterioration. The number of oysters on a limited bed would then steadily increase, as long as there were sufficient room and food supplied them, until they had reached their limit, a rather undefinable one, in that direction. Having reached that point, the number of oysters would to all intents remain the same as long as the conditions under which they had previously lived were not changed. To cause, then, either an increase or diminution of the number of oysters or the size of the