Page:Popular Science Monthly Volume 87.djvu/100

96 to fishery problems. Under some conditions a degree of stream pollution may prove distinctly favorable to the abundance of fish: in other cases it is unequivocally injurious. If the matter is one of significance to the fisheries, it is certainly true, on the other hand, that the problem of stream pollution, in its phases of ordinary interest, can not be studied to a definite conclusion except through analyses of the effects of the pollution upon the living aquatic organisms. This is to say, that the study of the sanitation of our streams involves the investigation of the effects upon fish or upon the organisms constituting the food of fish.

The dredging of channels and the construction of wing-dams as aids to navigation exert an unmistakable influence upon the distribution of fish and affect the fortunes of their existence in more or less obvious ways.

The conservation of water upon the farm remains for our consideration; but, if we may be permitted to draw a conclusion at this stage, it is this:—Whether we deal with head-water reservoirs for the regulation of stream flow, with water-power development and the incident pools, with reclamation or irrigation projects, with the dredging and damming for navigation purposes, or with stream pollution by any means, we find a vital relation to fishery problems and to fish-cultural operations. We find also a real necessity for the accumulation of a sufficient store of knowledge regarding the habits of fish, their requirements for feeding and breathing and breeding, and how these requirements are affected by the conditions that may prevail in our streams, lakes and ponds. We need, in short, an effective fishery science.

We have already expressed the belief that the relation of fishery development to water conservation is not one of dependence only, but one of reciprocal benefits as well. It must be clear that we are speaking of development, not by protection, but by conservation of fish, with all that the term may imply. The word itself is unavoidably repeated frequently in such a discussion, because "conservation" alone seems to embody the whole thought of increase in supply along with development in utilization, as opposed to hoarding or restriction in use.

Could we think of an agriculture based upon protective measures? Could we imagine a modern nation dependent upon corn and cattle and poultry growing wild? Suppose a series of limitations for the perpetuation of crops and stock-yield, similar to the familiar measures for the preservation of fish or game; no scythe to have a blade more than 3 feet long, no individual to take more than 500 ears of corn per day, or to kill more than 10 pigs or 5 sheep or 2 cows per year. The very suggestion has a touch of absurdity: and yet such is the present