Page:Popular Science Monthly Volume 20.djvu/41

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31
DETERIORATION OF AMERICAN OYSTER-BEDS.

in danger of soon becoming so. It rests with us, then, to determine that question with as much accuracy as possible, and, should we find the evil an existing one, to show the best means of removing it.

First, are the beds of Maryland and Virginia deteriorating?

It is only possible to speak with entire accuracy of a limited portion of the entire area covered by oysters in these States, but, as the influences affecting the beds are very similar, it may be assumed with safety that the condition of the beds of one district will be, approximately, that of all; at least, it is certain that beds or localities presenting like peculiarities will be in a similar condition as regards reproduction. The only locality in this country which has been thoroughly studied lies on. the eastern shore of Chesapeake Bay, opposite the mouth of the Potomac River. The investigation was carried on by the Coast and Geodetic Survey during the summers of 1878 and 1879, and included the survey of the beds of Tangier and Pocomoke Sounds, the measurement of the depth of water over the beds, and direction and force of currents; the ascertainment of the character of the bottom, the constituents and specific gravity of the water on both flood and ebb tides; the temperature during the summer months or spawning-season; the effect of gales, ice, and freshets; and of the fishery either with dredges or tongs. In general terms, as elaborate a study of the beds of the locality was made as was possible.

Tangier and Pocomoke Sounds were selected on account of the immense extent of their oyster-beds, and because they permitted the study of all the varying conditions affecting the oysters.

The two sounds are arms of Chesapeake Bay, and lie opposite the mouth of the Potomac River, on the eastern side of the bay. Tangier Sound extends north from Watt's Island, at its entrance, about thirty-six miles, and is separated from the bay by a chain of low, marshy islands; it receives from the eastern peninsula the waters of several creeks and rivers, all of considerable importance. The shoals on each side of the channel are covered with oyster-beds, and, where the beds do not exist, the oysters are scattered either in groups or singly. They are also found as continuations of the beds, or scattered in the straits separating the different islands and joining the waters of the sound to those of the bay. On each side of the channels of the tributaries of the sound oyster-beds are also found, and, generally speaking, it may be said that throughout Tangier, in depths between one and six fathoms, oysters may be taken in varying numbers. The entrance to Tangier Sound is also the entrance to Pocomoke Sound, Watt's Island lying between the two at their confluence. Pocomoke stretches to the northward and eastward, extending into the peninsula, while Tangier lies along its western boundary.

Pocomoke Sound is twelve and a half miles long and about nine miles broad near the middle, decreasing in breadth near the head and entrance. The channel is narrow and tortuous, and the main body