On account of the importations from Canada, Chesapeake Bay and the Great Lakes, the mackerel, cod and menhaden fisheries declined, especially after 1860, and the oyster and lobster fisheries are not as important as formerly.
They serve the trade of Lake Pontchartrain and the Florida parishes, the lumber, coal, fish, oyster and truck trade of New Orleans, and to some extent are the highway of a miscellaneous coasting trade.
The experiment by which Hoek conclusively proved the change of sex in the oyster was as follows.
The sponge and oyster fisheries are also important.
The Dutch had long claimed the whole coast from Delaware Bay to Cape Cod, but by the treaty of Hartford (1650), negotiated between himself and the commissioners of the United Colonies of New England, Stuyvesant agreed to a boundary which on the mainland roughly determined the existing boundary between New York and Connecticut and on Long Island extended southward from the west side of Oyster Bay to the Atlantic Ocean.
Starfishes devour large numbers; they are able to pull the valves of the shell apart and then to digest the body of the oyster by their everted stomach.
Oyster culture can evidently be carried on only by private enterprise, and the problem for legislation to solve is how to give such rights of property upon those shores which are favourable to oyster culture as may encourage competent persons to invest their money in that undertaking.
Huxley's conclusions as regards the future of the oyster industry in Great Britain are doubtless just as applicable to other countries - that the only hope for the oyster consumer lies in the encouragement of oyster-culture, and in the development of some means of breeding oysters under such conditions that the spat shall be safely deposited.
One of the oldest of Venezuelan industries, the Margarita pearl fisheries, was prohibited in 1909 for an indefinite time because of the threatened extinction of the oyster beds.
The middle series of the Lower Tertiaries, known as the Woolwich and Reading beds, rests either on the Thanet beds or on chalk, and consists chiefly of irregular alternations of clay and sand of very various colours, the former often containing estuarine and oyster shells and the latter flint pebbles.