FOREWORD 



For many years biologists and engineers have been studying the problem 

 of safeguarding juvenile salmon, shad, and striped bass from destruction in rivers 

 that have hazardous hydroelectric or irrigation developments. As part of their 

 research, they have studied the possibility of deflecting fish from their normal 

 routes to alternate routes around the hazardous areas. Numerous methods of 

 deflecting fish have been examined, such as bands of rising bubbles, curtains of 

 hanging chains, electrical stimuli, lights, louvers, sound, and water jets. These 

 methods were efficient under certain circumstances but were never completely 

 reliable. 



Notwithstanding the extensive and imaginative research, all fish guiding 

 or deflection devices in use today are burdened with one or more of the following 

 disadvantages: (1) high cost, (2) insufficient guiding efficiency, (3) mechanical 

 limitations where the depth is great, the volume of water large, or the cross- 

 sectional area of the canal or stream of extreme size, (4) excessive loss of head, 

 (5) limitation in safely guiding or collecting not only fry but eggs (of striped bass 

 and shad), (6) need for frequent adjustments to compensate for changes in flow 

 volume, and (7) excessive maintenance. 



The traveling screens described here were developed to overcome these 

 disadvantages. A traveling screen may be generally described as a conveyor belt 

 placed on edge diagonally across the path of juvenile fish migrating downstream. 

 Young fish that approach the screen tend to avoid it as they continue downstream 

 and thus are guided into a bypass at the downstream end of the structure. 



Since 1965, biologists and engineers of BCF (Bureau of Commercial 

 Fisheries) have developed and tested a series of six experimental traveling 

 screens; another is in the design stage. The early models were not completely 

 reliable, and fish were killed or damaged. The designs had to be improved. 



The developments reported in this Special Scientific Report - Fisheries have 

 greatly encouraged those who have to contend with the fishery problems arising 

 from the multiple use of our great river systems. Perfection of fish protective 

 devices will help eliminate one of the serious obstacles to the maintenance of 

 stocks of fish. 



^^^ M ■ M.'-^'^iJsut ' 



Charles H. Meacham, Commissioner 

 U.S. Fish and Wildlife Service 



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