2 U. S. BUREAU OF FISHERIES 



True conservation of such resources as the fisheries means not only 

 guarding; them against depletion but making use of them to tlie great- 

 est possible extent compatible with their perpetuation. Experience 

 with domestic animals has taught us that the normal production of 

 individuals is in excess of the number required to maintain the species, 

 and that man may spend this excess without exhausting the capital 

 stock. Our experience with domestic animals shows further, how- 

 ever, that the amount of this excess stock varies from year to year. 

 In some years production is especially good, and then. a greater 

 number of animals may be utilized; but in other years the excess 

 production is negligible or the stock may drop even below the level 

 of maintenance, due entirely to causes outside the control of man. 

 Although not so clearly apparent, the same thing is true of stocks of 

 wild animals, including fish. 



The difficulty is to determine from year to year what the excess 

 production is and how much of the stock may be taken by man 

 without endangering the future supply. This is especially difficult 

 in the case of fish, which are, for most of their lives, out of reach 

 of direct observation. In the case of stocks of domestic animals, or 

 even of wild land animals and birds, it is possible to determine with 

 considerable accuracy their population and the increases in their num- 

 bers from year to year, but in the case of fish this is practically im- 

 possible. Yet information of this kind is just as essential for the 

 proper care of our fishery resources as it is for the care of land ani- 

 mals, whether domestic or wild. It will take more effort and more 

 time to determine the yield of our aquatic resources from year to 

 year and the causes of the fluctuations in the yield, but this expend- 

 iture will be amply justified by the more intelligent care we will be 

 able to give them. 



A new branch of applied science, aquiculture, is being devel- 

 oped and may be expected eventually to include the care of our 

 aquatic resources in much the same way that agriculture takes care 

 of our land resources. The problems of aquiculture are the more diffi- 

 cult ones, perhaps, but it is certain, nevertheless, that this science 

 must be developed as agriculture has been — on a firm foundation of 

 scientific facts. We must know the causes of fluctuations in the 

 yield from year to year and how these fluctuation may be controlled, 

 if that be possible, if we are to increase the productivity of our water 

 areas and maintain it at the highest level. 



Cooperation with the bureau by the States in conducting investi- 

 gations was continued with very satisfactory results. During the past 

 year work was conducted in cooperation with the States of North Caro- 

 lina, South Carolina, Florida, Texas, Michigan, Wisconsin, Washing- 

 ton, Oregon, and California, and additional work is planned for the 

 immediate future. The States provided men, laboratories, boats, and 

 other equipment, and by this means the division was able to extend 

 its activities far beyond the limits set by its own appropriations. 



Perhaps the greatest difficulty in the way of the proper develop- 

 ment of the work of the division lies in securing properly trained 

 men interested in fishery investigations. More investigators are 

 needed on our own staff, and frequently we have requests from State 

 organizations for trained men, yet the greatest difficulty is experienced 

 in finding really qualified investigators. It is hoped that some 



