the need for information, exceeds this 

 figure. 



Most of the salmon tags are recovered 

 in the intense commercial fisheries in 

 bays and estuaries as schools of salmon 

 approach the mouths of their spawning 

 streams. However, in 1959 the important 

 Bristol Bay, Alaska, commercial red 

 salmon fishery was to be drastically 

 reduced to allow enough escapement to 

 provide adequate seeding of the spawning 

 grounds by the expected small rxin. Be- 

 cause of this reduction in the fishery, 

 other methods of tag recovery had to be 

 devised. One of these methods was the 

 use of electrical fish-shocking apparatus 

 described in this paper.* 



In the nnain tributary rivers of Bristol 

 Bay, schools of red salmon follow rather 

 restricted routes of migration, which are 

 not in the fast water in the main portion 

 of the river but are usually fairly close 

 (6 to 25 feet) to shore in 3 to 8 feet of 

 water, thus making them accessible to an 

 electrofishing installation. This habit of 

 the salmon has been utilized in the "tower 

 method" of salmon enumeration as they 

 ascend the trunk rivers.' 



MATERIALS AND METHODS 



The electrofishing experiment was con- 

 ducted at Igiugig Camp of the Fisheries 

 Research Institute (fig. 1), on the Kvichak 

 River about 1 mile below the outlet of 

 Lake ILiamna, where the river is about 

 300 to 500 feet across. The Institute ob- 

 servers in the counting towers, one on 

 each side of the river, counted the salmon 

 as they pass over light-colored panels 

 laid on the river bottom. 



The fish used in the tests of the elec- 

 trical method were members of the 

 naturally migrating schools of red salmon 

 as they passed the electrofishing installa- 

 tion. Certain individuals within the schools 

 were specifically identified by gill-net 

 marks, early development of spawning 



Ummediately prior to the opening of the fishing season in 

 Bristol Bay permission was granted the commercial fleets 

 for a more liberal and extensive fishing operation. Plans for 

 the electrofishing tag- recovery effort proceeded as an experi- 

 mental operation for possible future applications. 



2 Fisheries Research Institute. 1959. Report of Operations, 

 1958. College of Fisheries, University of Washington. March, 

 24 pp. 



coloration, or by isolation. During the 

 height of the run some fish were captured, 

 tagged, and released near the installation 

 area by the Institute personnel; these 

 tagged fish were occasionally utilized as 

 test fish as they continued their upstream 

 migration. Either white or red and white 

 tags were put on the salmon on the high 

 seas. Tags used within the Kvichak sys- 

 tem by the Institute were of solid colors 

 other than red and white, and were of 

 larger diameter than the high-seas tags. 

 Therefore, there was little chance of 

 confusion of the source of the tagged fish 

 seen. 



With the use of the direct-current 

 shocker, efforts could be made to recover 

 all tags passing the installation. Fish 

 bearing undesired tags could be released 

 unharmed to continue their migration up- 

 stream. In this operation efforts were 

 made to capture all tagged fish which 

 might bear a high-seas tag. 



During the test operations attempts 

 were made to capture individual fish 

 from all areas within the usual migration 

 path and from all positions within the 

 schools of fish. This was done as objec- 

 tively as possible. Tagged fish would be 



Figure 1. — Location map of Igiugig electrofishiiigsite. 



