BUREAU OF FISHERIES XXV 



industries and domestic sewage combined with silt eroded from the 

 farms and deforested hinds. Studies have been directed to testing 

 tlie feasibilit}^ of growing mussels commercially in artificial channels 

 with controlled water supply at the Fort Worth (Tex.) station, 

 where a large supply of brood mussels has been collected and grown 

 for many months. 



The atlverse etfects of river pollution have been so greatly aggra- 

 vated by the construction of dams as a part of the War Department's 

 program of canalization of important rivers in the Middle West that 

 the bureau's investigators have given that phase of the pollution 

 problem special attention and have cooperated with the United States 

 Engineer Corps in making special studies of conditions at Keokuk 

 and Wilson Dams and at Hastings (Minn.) pool with a view to 

 mitigating the disadvantages to wild life in future construction proj- 

 ects. It is evident that while in itself the construction of dams in 

 the Mississippi River or its tributaries will not adversely aifect 

 aquatic organisms but may indeed increase fish production, it will 

 result in increasingly bad conditions until soil erosion is reduced and 

 excessive sewage pollution is eliminated. 



LAW-ENFORCEMENT DIVISION 



The limited appropriation for the enforcement of the law regulat- 

 ing interstate transportation of black bass permitted the Bureau of 

 Fisheries to organize in nearly all the States east of the one hundred 

 and fifth merid'an, and to obtain a reasonable enforcement of the law 

 with 1 law enforcement officer, 2 black bass law inspectors, and 1 

 office assistant. At least two more inspectors are needed before satis- 

 factory enforcement can be had. This is exclusive of the Rocky 

 Mountain and Pacific Coast States, which can not be cared for under 

 existing appropriations. 



During the year the Secretary appointed 68 State wardens located 

 in 25 States as deputy black bass law inspectors to assist the Federal 

 officers in enforcing the law. These receive no salary from the Fed- 

 eral Government but have been of material assistance and have in- 

 creased the cooperation already existing between the State fish and 

 game authorities and the Federal officers. 



Every effort has been made during the year to broadcast the pro- 

 visions of the law and to obtain the cooperation of the fishing public, 

 both commercial and sport. Conservation magazines, the daily press, 

 and other publications have heartily cooperated and have published 

 numerous articles relative to furthering the protection for and thus 

 increasing the black bass. 



As the Federal law is predicated on an infraction of an existing 

 State law and an interstate transportation, it is essential that persons 

 interested should know the various laws protecting the black bass, for 

 which purpose Fishery Circular No. 9, containing a summary of the 

 black bass laws for 1932, the Federal black bass law in full, and other 

 valuable information pertaining to the protection and increase of 

 game fish was published. 



A large number of reports of infractions have been received and 

 all investigated. Some failed to reveal any violation or it w\as found 

 impossible to prove a violation of a State law. In several instances 

 evidence of violation of State law was obtained which, at the request 



