PROGRESS IN BIOLOGICAL INQUIRIES, 19 3 4 333 



by a responsible and experienced fishery biolo<^ist, and are so dis- 

 tributed as to cover each of the major geographical sections of the 

 United States. 



The problems of the fresh-water fisheries throughout the country 

 at the present time are concerned chiefly with increasing hatchery 

 outi)ut and stocking interior waters. The chief hatchery problems 

 concerning output are proper diet and the control of disease. 

 Through 10 years of research the Division has found cures for several 

 bacterial diseases of hatchery fish, and has improved diets until 1 

 pound of trout can be produced from 3 pounds of food, with an 

 increase in efficiency in feeding of about one-third. 



The most outstanding problems in the stocking of interior waters 

 are concerned with the development of a stocking policy. More at- 

 tention must be given to placing the fish in suitable waters which 

 contain an adequate natural food supply, and to producing larger 

 fish better able to survive than heretofore in order to provide better 

 angling. In this field the Bureau is cooperating with the United 

 States Forest Service in devising better management of fishery re- 

 sources comparable with the improved game-management program. 



One of the most serious limitations on the maintenance of abundant 

 stocks of food and game fishes in interior waters and the chief hin- 

 drance in stocking these waters with additional supplies is pollution 

 from domestic and industrial sources. The destruction of fish life 

 b}'^ polluting substances, already acute in many localities, is growing 

 rapidl}^ throughout the more densely settled and industrialized sec- 

 tions of the country. A temporary staff, working on emergency 

 funds, has made great progress during the past year in determining 

 the effect of stream pollution on aquatic life. The classification of 

 polluting substances according to their biological effects and the de- 

 termination of their potencies will permit the formulation of stand- 

 ards of water purity favorable to the production of an abundant fish 

 supply and form the basis of an effective policy of stream purification 

 and protection. 



The second major activity of the Division is concerned with investi- 

 gations of the commercial fisheries. During the past 10 years prog- 

 ress has been made in determining the causes of great changes in 

 abundance of commercial fishes. During the period continued ob- 

 servation of the trend and condition of the fisheries has revealed 

 dangers of depletion and abuses in commercial practice that menace 

 the supply. It remains, however, to educate the public regarding 

 conservation measures to be followed voluntarily by the trade or to 

 be enforced by legislation. It also remains to keep continual check 

 by scientific means from year to year on the changing supply and the 

 effects of regulation. 



One of the most significant and promising new undertakings of the 

 Division during the past year is the inauguration of a comprehensive 

 study of the fisheries of the Columbia River Basin. Attacking the 

 problem of the fisheries of the basin as a whole, attention is being 

 given to such matters as regulation of the commercial fishing in the 

 lower estuary of the Columbia, which is believed to be depleting the 

 stock; the protection of upstream migrants from loss at power dams; 

 the reclamation or improvement of spawning areas to increase nat- 

 ural reproduction; improvement in the technique of artificial propa- 



