. Biology; the story of living things. Shellfish What has been said with regard to the great destruction of fish is equally true of shellfish. The oysters in Chesapeake Bay were thought to be inexhaustible until they were almost exterminated, when the state of Maryland found that in order to preserve this great natural asset, oyster culture was necessary. Oysters are now con- served here and in other states by cultivation. In certain areas of shallow water old oyster shells, broken stone, or bunches of fagots are placed on which the young, free-swimming larvae may attach themselves. After thes
. Biology; the story of living things. Shellfish What has been said with regard to the great destruction of fish is equally true of shellfish. The oysters in Chesapeake Bay were thought to be inexhaustible until they were almost exterminated, when the state of Maryland found that in order to preserve this great natural asset, oyster culture was necessary. Oysters are now con- served here and in other states by cultivation. In certain areas of shallow water old oyster shells, broken stone, or bunches of fagots are placed on which the young, free-swimming larvae may attach themselves. After these "seed oysters" have grown to a sufficient size, they are removed and placed in beds in shallow water, where they are later harvested. There are two general aspects of the question dealing with the shellfish industry, namely, as it affects marine or fresh-water forms. Among the problems of fresh-water biology those relating to the life history of the fresh- water mussel should be noted. It is known that the propagation of fresh-water mussels, the shells of which are used in the pearl button industry, depends upon whether the larval stage, or glochidium, finds the proper temporary fish host. This tiny larval mussel attaches itself to the fins or gills of certain species of fish. The host builds a protecting cyst wall about it, when it undergoes fur- ther development. After reaching a sufficiently advanced stage, it drops from its host, which by this time may have reached quite a different locality, and continues its own battle for life. The rivers of the mid-west, especially the Mississippi and Ohio systems, are the great producers of fresh-water mussels. The con- struction of dams and the addition of pollution to these streams have killed off a large percentage of these mussels. Here the United States Bureau of Fisheries came to the rescue and used the fish they were salvaging from the back waters of the Mississippi system as hosts for the glochidia of the mussels. W
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Keywords: ., bookauthorwalterherberteugeneb1867, bookcentury1900, bookpublish
