1959 SMOLT MIGRATION 

 1957 SMOLT MIGRATION 



Figure 31. --Comparative smolt migration on 

 the Ugashik River. 



average 16 fish per case. Preliminary 

 stream checks indicate that about 75 percent 

 of the spawners were female. Canneries 

 report that the quality of the pink salmon 

 was exceptionally good. 



Research activity in Bristol Bay was 

 carried out by both the Bureau of Commer- 

 cial Fisheries and the Fisheries Research 

 Institute. The Institute continued with 

 its industry-sponsored work on the Wood cuid 

 Nushagak Rivers. Principal emphasis in 

 these studies was placed on enumerating 

 upstream migrants, determining indices of 

 smolt abundance, and studying the eairly life 

 history of the red salmon in the lakes. 



Under support of a Bureau of Commer- 

 cial Fisheries contract, red salmon research 

 activities on the Kvichak River were con- 

 tinued by the Fisheries Research Institute 

 for the fourth consecutive year. Seaward 

 smolt migration was determined with the aid 

 of fyke nets, and adult escapement counts 

 were made with the use of towers. Biolo- 

 gists on the Kvichak noted an outmigration 

 far in excess of any recorded previously. 

 Special emphasis was placed on learning the 

 relationship between timing of the adult 

 salmon runs and the distribution of fish on 

 the spawning grounds. 



The Bureau continued its several 

 research programs in the Bristol Bay cirea. 

 Efforts were directed toward estimating the 

 extent of the night migration of salmon, 

 enumerating the smolts, and sampling to 

 determine the age composition of the catch. 



Knowledge of each of these factors would be 

 of material assistance in the management of 

 this fishery. 



Satisfactory night counts, obtained 

 by illuminating the migration paths directly 

 in front of the counting towers, produced 

 gratifying results. The lighting was done 

 with 6- or 24-volt spotlights arranged so 

 that the beam of light was angled downstream 

 from the bank. It had been assumed, from 

 experience on other waters, that red salmon 

 migrations at night were negligible, but in 

 these studies it was found the migration 

 peaked at night on the Igashik River. 



The smolt outmigrations in the Naknek, 

 Ugashik, and Kvichak systems were much 

 larger than any recorded for these rivers 

 over the past several years. In the Naknek 

 River there was an indication of an outmi- 

 gration of approximately 10 million smolts. 

 This compares with 6 million in 1956 and 

 3 million in 1957. On the Ugashik River, 

 evidence pointed to an outmigration some 

 20 times larger than that recorded in 1957 

 (figure 31). 



The Kvichak smolt index, which is 

 determined by the Fisheries Research Insti- 

 tute, is considerably higher for the 1958 

 outmigration than for the three previous 

 years. In 1955 the index was 203,000; in 

 1956, 50,000; in 1957, 23,000; and this 

 year (1958), 1,913,000. Most of the fish 

 were 2-year-olds. 



The Egegik outmigration work was 

 interrupted because of budgetary restric- 

 tions. Scale analysis showed that this 

 year's smolts were primarily the progeny 

 of the 1956 brood year — a year noted for 

 large escapements in some cf the major 

 tributaries of the Bay. 



The enumeration of red salmon finger- 

 lings was accomplished with the use of fyke 

 nets. Preliminary tests with electronic 

 counting devices utilized in the cod end cf 

 the net showed considerable promise, and if 

 such units can be satisfactorily developed 

 to the point where they can be used on a 

 wide scale, the enumeration of fingerlings 

 will be greatly facilitated. 



Development of methods and sampling 

 procedures to obtain age £Uid length data 

 of adult red salmon in the returning runs 

 was continued for the second consecutive 



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