PROGRESS IN BIOLOGICAL INQUIRIES, 1935 441 



thus appears that only a small percentage of the fish planted reached 

 legal size, the results are much better than in the previous year, when 

 only nine marked fish were recaptured. 



COOPERATIVE WORK IN NATIONAL FORESTS 



Under the terms of a cooperative agreement recently completed 

 with the United States Forest Service the Bureau of Fisheries as- 

 sumes responsibility for conducting research necessary for the devel- 

 opment of a comprehensive program of fish management for waters 

 of the national forests. 



Owing to lack of funds the Bureau was unable to continue stream 

 surveys in the national forests during the summer of 1935, and its 

 activities in connection wdth stream improvement were confined to 

 exercising technical supervision over the AAork carried on in this 

 field by the Forest Service. 



During the latter part of May a sliort field course for training 

 men to plan and direct stream-improvement work was conducted by 

 the Bureau and the Forest Service in the Pisgah National Forest, 

 N. C. Early in June a similar training school was conducted in the 

 Cache National Forest, Utah. At the close of these training courses 

 the men were employed by the Forest Service to take charge of 

 stream-improvement work in national forests throughout the country. 



The stream-improvement work carried on during the last 2 years 

 has been largely experimental, the idtimate aim being to determine 

 to what extent this work can be relied upon to improve angling con- 

 ditions. The results indicate that in streams notably lacking in pools 

 and shelter much can be clone to provide better living conditions for 

 fish. In some cases it has been possible to provide additional s])awn- 

 ing beds and to improve those already })resent, thus permitt^ing a 

 considerable increase in natural propagation. 



In the average mountain stream dams in one foi'm or another have 

 been found to be more valuable on the whole than any other type of 

 structure. Since such streams are often deficient in pools and are 

 subject to the scouring action of frequent floods, structures are needed 

 that will tend to retard erosion rather than accelerate it. Deflectors 

 have also been used to advantage, but usually have proved most valu- 

 able when used in connection with dams to improve circulation in 

 pools and to prevent deposits of silt and sand. 



A considerable part of the stream-improvement woi-k has consisted 

 of tlie removal of obstructions of various kinds that interfered with 

 the movements of fish. Other work has been the planting of trees, 

 shrubs, and other vegetation to furnish shade and beautify the banks. 

 It is evident that in many instances reforestation will do more to 

 improve stream conditions than all other methods combined. 



In view of the urgent need for further information on the value 

 of stream improvements and on other means of improving fishing 

 conditions in the national forests, arrangements were made for a 

 number of ex])erimental projects in this field. These projects, wliieh 

 are being carried on in cooperation with the Forest Service, and in 

 some cases with State conservation agencies, are designed to throw 

 more light on the more important factors concerned in fish manage- 

 ment. 



