would, because of manpower availability 

 and expense, have to be incorporated with 

 the counting tower operations. In such 

 an arrangement, it would be possible to 

 have the equipment installed and in a 

 constant state of readiness, so that the 

 person making counts and observations 

 from the tower could operate the shocker 

 and capture the tagged fish. One generator 

 and one pulser could be used for electrode 

 operations on both sides of the river. A 

 battery-powered starter would provide 

 for repaid remote starting of the generator 

 by observers on either tower. A switch 

 could connect the power source with the 

 desired set of electrodes. With the gen- 

 erator operating and the proper set of 

 electrodes connected, a switch could be 

 thrown to energize the electrodes when 

 the selected tagged fish was in the right 

 location. When the operator saw that the 

 fish had been pulled into the anode and 

 electronarcotized, he would descend the 

 tower and make the final capture of the 

 fish with a long-handled dip net. The 

 remainder of the fish in the area would 

 be allowed to escape; no harm would be 

 caused to them by the direct current. 



Some minor disruption of the rate of 

 migration of the schools of fish was 

 caused by the use of the shocker. During 

 testing operations the shocker was op- 

 erated extensively, at times for 30 seconds 

 every 5 minutes. The violent attempted- 

 evasion antics of the fish in the electrical 

 field (fig. 4) would cause fish further 

 downstream to slow down, and some to 

 turn around and go downstream. From 2 

 to 5 minutes would elapse before the 

 migration would assume its normal rate. 

 Reactions of fish to the current and 

 alarm movements of fish attemping to 

 evade the electrical field varied with 

 density of the migration. When small 

 schools of fish were separated by 

 distances of 30 yards or more, the effect 

 of the disturbance was greater and a 

 longer time passed before the normal 

 movement of fish resumed. When there 

 was a steady stream of migrating fish 

 the disruption was less, and a shorter 

 time elapsed before they resumed their 

 normal rate of movement. Same dis- 

 ruptions of migration were observed 

 when boats passed over the path of migra- 

 tion, and the time before resurription was 

 the same with either the boat or electri- 

 cal shocker disturbance. 



Once the equipment has been installed 

 and testing operations completed, the 

 use of the electrofishing apparatus 

 probably would be limited to tag re- 

 coveries; thus, the effect of the machine 

 on the rate of migration would be negli- 

 gible. The high value of a recovered tag 

 would make the possibly slight loss of 

 accuracy of fish counts from the towers 

 during tag-recovery efforts insignifi- 

 cant. 



The visibility of the fish would have 

 some effect on the efficiency of the 

 shocker, as poor visibility would effect 

 any operation with fish where they must 

 be observed. Usually, when surface light 

 is low or ripples distort subsurface visi- 

 bility, the tag is seen before the fish 

 itself is visible. At any time when visi- 

 bility is adequate for fish counting from 

 the towers, it is sufficient for electrical 

 collection of fish. When the electrodes 

 are energized and the fish in the area 

 are disturbed, causing further water- 

 surface distortion, it may be difficult 

 to keep the tagged fish in sight. How- 

 ever, with a proper electro-system lying 

 astride the migration path, the electrical 

 control of the fish should be good and 

 they should be forced to swim towards 

 the anode. There, in shallower water, 

 the fish would be easily visible. 



As mentioned earlier, a tagging pro- 

 gram was being conducted at Igiugig by 

 the Fisheries Research Institute. Red 

 salmon were captured in the river, tagged, 

 and released with the intent to deter- 

 mine the distribution of the fish on the 

 spawning grounds of Kvichak River. Most 

 fish tagged were captured by beach- 

 seining in the river near the counting 

 towers. However, at times the fish would 

 not be available at these seining grounds. 

 Attempts to capture fish for tagging pur- 

 poses were made with the electrofishing 

 apparatus. At Site No. 2 these attempts 

 proved quite successful. The one man 

 operating the shocker apparatus was 

 able to provide fish to keep a two-man 

 tagging crew continuously supplied. After 

 tagging, the fish were released at the 

 shocker site and allowed to proceed on 

 their way to the spawning grounds. 



Subsequent recovery on the spawning 

 grounds indicated that equal percentages 



