FISH LADDER 



%-HATCHERY PONDS 



COLUMBIA RIVER 



Figure 1. — Map of Drano Lake and migration route of juvenile salmon from Little White Salmon National Fish Hatchery 



to the Columbia River. 



In an attempt to find a method of controlling 

 or eliminating the northern squawfish in such 

 areas as Drano Lake, we designed laboratory- 

 tests to determine the effectiveness of various 

 electrical fields in blocking the passage of 

 adult squawfish while permitting the passage 

 of salmon fingerlings. The tests were made 

 August 18-28, 1953, at the BCF (Bureau of 

 Commercial Fisheries) Biological Laboratory, 

 Seattle, Wash. The electrical fields produced 

 were based on electrical stimuli that had been 

 previously tested and found to direct the 

 movements of salmon fingerlings. 



tank's concrete floor and construction-block 

 walls were covered with an electrically in- 

 sulated lining of several coats of blue 

 Amercoat 3 paint. In inside dimensions, the 

 experimental area was 8.8 m. long, 3.2 m. 

 wide, and 25 cm. deep. The water depth was 

 about 18 cm. 



The problem was to create electrical con- 

 ditions that would be effective either in pre- 

 venting squawfish from entering the electrical 

 field or in blocking the progress of the fish 

 once they had entered the field, while per- 

 mitting the salmon fingerlings to pass through 

 unharmed. The factors for consideration were: 



MATERIALS AND METHODS 



The experimental area was a portion of a 

 large insulated tank, constructed for studies of 

 electrical guiding of salmon fingerlings. The 



2 Collins, G. B., CD. Volz, and R.H. Lander. 1953. The 

 effectiveness of pulsating direct current in controlling the 

 movement of salmon fingerlings. Bur. Comm. Fish. Biol. 

 Lab., Seattle, Wash. (Unpublished manuscript.) 



1. The spacing between electrodes in each 

 row. 



2. The arrangement of the electrodes in the 

 two rows. 



3. The distance between the two rows of 

 electrodes. 



3 Trade names referred to in this publication do not imply 

 endorsement of commercial products by the Bureau of 

 Commercial Fisheries. 



