PEOGRESS IN BIOLOGICAL INQUIKIES, 1930 599 



sui>eriority of the insulated type of screen over the grounded type, 

 (2) the superiority of hirge diameter electrodes over the chain 

 electrodes as previously employed, (3) the effectiveness of ordinary 

 60-cycle alternating current without resort to interruption or other 

 modification, and (4) they indicated in general the electrode spacing 

 and screen voltages required for effective operation of the screen. 



In Oregon the experimental work was started in the sluiceway at 

 Gold Ray power plant and later the installation was moved to the 

 Fort Klamath hatchery where facilities were better as regards 

 visibility, control of w^ater, and the availability of fish for use in the 

 experiments. At the former location the fish used were steelhead 

 fingerlings and at Fort Klamath a total of about 2,000 brook trout 

 averaging about 2 inches long were employed. All of these were 

 fine healthy fish. 



The experiments show^ed the screen to be most effective when the 

 electrode spacing Avas 4 feet center to center in rows and 6 feet 

 between rows, and when the potential was maintained at about 55 

 Aolts. 



The experimental work of the 1930 season has resulted in the 

 specification of new and improved electric screens for use in 1931. 



Kvlchak electric sci^een. — Based upon success of the Gold Ray 

 tailrace screen in stopping upstream migrating salmon and diverting 

 them to the fish ladders at the dam, the bureau this season sought 

 to employ the electric screen in its salmon-counting operation on the 

 Kvichak River, Alaska. The structure consisted of the ordinary 

 lype of wooden rack of picket construction equipped with counting 

 gates and carried out from each shore through the shallower depths. 

 Piles Avere driven across the main channel to support the electric 

 screen, the alignment of Avhich was in the shape of a V Avith the 

 apex 200 feet doAvnstream, from the line of the racks. Total 

 length of the electric screen was 755 feet including a 40-foot boat 

 passage at midstream. Design of this electric screen was based on 

 the Gold Ray tailrace installation. It Avas of the grounded type, 

 consisting of a curtain of chain electrodes and a ground element of 

 pipe laid in contact Avith the bed of the stream. For energizing the 

 screen the Bureau of Fisheries installed a power unit on shore con- 

 sisting of a 9-kiloAvatt generator, supplying 60-cycle alternating 

 current, driAen by a 15-horsepower gasoline engine. Current Avas 

 supplied to the screen at a potential ranging from 60 to 80 volts. 



In general, the installation stopped the upstream migrating salmon 

 but failed in its purpose Avhich Avas to lead or divert these fish to the 

 counting gates located in the rack structures extending out from 

 each shore. Some salmon succeeded in fighting their way through 

 the electric screen Avhich extended over about three-quarters ()f the 

 river channel but several hundred thousand of them — constituting 

 the greater portion of the run — dropped back doAvnstream after 

 encountering the electrified Avater and remained there, milling 

 around, and making no further attempt to pass upstream. The 

 reason for the failure of this screen is not knoAvn. One unfavorable 

 factor Avas the absence of definite Avater currents to attract the salmon 

 to the counting gates. This Avas because the obstruction offered by 

 the rack structure caused the tendency of the floAV at the rack to be 

 offshore along the upstream line of the rack and toAvard the great 



