work are described briefly as follows: 



Type A. --Two parallel rows of hanging 

 electrodes suspended across the stream by 

 a catenary cable (fig. 2). 



Type B. --A single row of suspended 

 electrodes and a horizontal submerged elec- 

 trode parallel to the suspended electrodes 

 (fig. 3). 



Type C. --Two horizontal, submerged 

 electrodes lying parallel across the stream 

 bed (fig. 4). 



The kind of device used was determined 

 by the physical characteristics of each stream. 

 Type A was installed in deep, soft -bottomed 

 streams, where water velocities were low. 

 Type B structures were used in streams hav- 

 ing moderate depths, relatively firm bottoms, 

 and reasonably fast water velocities. Type C 

 barriers were installed in shallow, rapid- 

 flowing streams. All installations were en- 

 ergized by 110 -volt, 60-cycle, alternating 

 current, which was supplied from commercial 

 lines or by gasoline -powered generators. 



The streams were grouped by operational 

 zones, each of which contained as many 

 streams as a service crew could handle in a 

 day. The devices were visited by a two-man 

 crew at least once a day. The men removed 

 the live sea lampreys from the traps and the 

 dead or disabled lampreys from the electrical 

 field below and destroyed them. All fish in 

 the traps were counted and recorded by species 

 and were released upstream . Generators were 

 checked and refueled as needed. Only two 

 zones were operated on Lake Superior in 1953; 

 in 1954, the number was increased to seven 

 zones on Lake Superior, and one zone was es- 

 tablished on Lake Michigan. 



Sea lampreys and fish caught or killed 



Ten electrical control devices were 

 operated in 1953 along the south shore of 

 Lake Superior between Sault Ste . Marie 

 and Marquette, Mich . , during most of 

 the sea -lamprey migration period. Opera- 

 tions began April 4 and ended August 14. 

 Original plans called for 23 devices in 

 streams selected for the pilot project on 

 the basis of surveys of 1950-51 (Loeb and 

 Hall 1952), but considerable delay was 

 encountered in obtaining leases or ease- 

 ments on lands needed for the placement 

 of the structures. Consequently, only 10 

 of the proposed 23 were completed in time 

 for operation, Nine more units were in- 

 stalled by June 1, but owing to the lateness 

 of the season and the lack of manpower 

 occasioned by official recruitment restric- 

 tions they were not operated. 



In 1954, the 19 electrical control 

 structures that had been installed by the 

 end of the preceding season, plus 24 addi- 

 tional devices, were operated on the south 

 shore of Lake Superior, thus expanding 

 the area of control to Porcupine Mountain 

 State Park, Mich. In addition, a large 

 mechanical weir was constructed on the 

 Chocolay River near Marquette, Mich. 

 Seven more barriers were constructed and 

 operated in streams tributary to Big Bay de 

 Noc and Little Bay de Noc of northern Lake 

 Michigan . 



Sea lamprey. --Although the operation 

 of the pilot project in 1953 was incomplete, 

 it proved that sea lampreys could be 

 blocked effectively in their upstream migra- 

 tion. Lampreys were taken in 9 of the 10 

 streams under control in 1953. The elec- 

 trical barriers in these streams captured 



