FISH CULTURE or Pisciculture. Propagation of the principal food fishes is con ducted on a steadily expanding scale in the United States and the results long ago demonstrated the immense national profit derived. The salmon, the shad and many other important fishes would in all probability be practically extinct to-day if the hatcheries had not supplied billions of young fish to help take the place of those har vested from the waters for human consumption. Such assistance is especially neces sary in the case of all fresh-water fish and such salt-water fish as the salmon and shad, which leave the ocean to deposit their spawn in river beds and thus make total extermination possible.
The greater part of the work is now performed under the jurisdiction of the U. S. Fisheries Commission, supplemented by that of the State Fisheries Commissions and various sportsmen's associations and clubs. The U. S. Fisheries Commission maintains a number of hatcheries along the coast, in the chief shad and salmon rivers, at various points along the Great Lakes, etc. Their product is variously utilized— part of it is distributed in the natural spawning grounds of the immediate vicinity; great quantities are shipped, principally as "fry" and "fingerlings," to all parts of the country for the stocking and replenishing of ponds, rivers, lakes, etc., and a small percentage are brought to maturity for breeding purposes.
The fish most extensively cultivated are the various varieties of salmon, shad, cod. flounder, whitefish, trout, perch, Pollack, smelt, bass, lobster, oyster, clam and terrapin.
In addition to helping replenish the natural supply, fish culture has resulted in creating new sources of food by introducing valuable varieties into waters in which they were previously unknown. Shad, for example, was formerly unknown on the Pacific coast, but it is now nearly as plentiful there as on the Atlantic.
The eggs are obtained from many sources—purchased from fishermen, taken from fish caught for the purpose, obtained from fish specially bred, etc. They are first fertilized and then placed in the hatchery. With some varieties, the hatching appara tus consists of wire trays held in troughs of varying size—a single tray of the kind generally used for salmon, about 1 foot wide and 2 feet long, will hold two gallons, or 30,000, of salmon eggs. Others, as for whitefish, shad, lobsters, etc., generally consist of glass jars, similar to those shown in the accompanying illustration, from which the "fry" as hatched are discharged into glass tanks.
The "fry" may be distributed as such or, according to circumstances, held in troughs or artificial ponds or enclosures until six or seven months old. A seven months trough-raised "fingerling" salmon averages from to 3 inches in length.
During the year ending June 30, 1909, the U. S. Fisheries Commission distributed 724,558,703 eggs, 2,370,975,068 "fry" and 11,598,140 fingerlings, yearlings and adults.