Having now attempted to define the field of modern fish culture, and to show what it has already accomplished, it remains to be said what appear to be its legitimate aims and limitations. Its aims, as I understand them, are:
1. To arrive at a thorough knowledge of the life history from beginning to end, of every species of economic value; the histories of the animals and plants upon which they feed or upon which their food is nourished; the histories of their enemies and friends, and the friends and foes of their enemies and friends, as well as the currents, temperature and other physical phenomena of the waters in relation to migration, reproduction and growth.
2. To apply this knowledge in such a practical manner that every form of fish shall be at least as thoroughly under control as are now the salmon, the shad, the alewives, the carp, and the whitefish.
Its limitations are precisely those of scientific agriculture and animal rearing, since, although certain physical conditions may constantly intervene to thwart man’s efforts in any given direction, it is quite within the bounds of reasonable expectation to be able to understand what these are and how their effects are produced.
An important consideration concerning the limitations of fish culture must always be kept in mind in weighing the arguments for and against its success. It is simply this: _that effort toward the acclimation of fishes in new waters is not fish culture, but is simply one of the necessary experiments upon which fish culture may be based_. The introduction of carp from Germany was not fish culture, it was an experiment: the experiment has succeeded, and fish culture is now one of its results. The introduction of California salmon to the Atlantic slope was an experiment. It has not succeeded. Its failure has nothing to do with the success of fish culture. If any one wants to see successful fish culture in connection with this fish, let him go to the Sacramento River. The introduction of shad to the Pacific coast was an experiment. It succeeded. Shad culture can now be carried on without fear of failure by the fish commissions of the Pacific states.
Shad culture is an established success, so is whitefish culture in the Great Lakes. The experiments with cod and Spanish mackerel were not fish culture, though there is reason to hope that they may yet lead up to it.