272 



SALMON OF THE KARLUK RIVER, ALASKA 



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PERCENTAGE OF FOUR - FRESH-WATER FISH IN ESCAPEMENT 

 Figure 9. — Percentage of four-fresh-water fish in return plotted against percentage of four-fresh-water fish in escapement for the 

 years 1922 and 1924 to 1929, inclusive. The straight line represents a ratio of 1 to 1. 



SEAWARD MIGRATIONS 



The seaward migration of Karluk River red salmon takes place during the last 

 week of May and the first 2 weeks of June each year. A few fish migrate sometimes 

 a day or two earlier or later than this period but the major part of the migration, and 

 frequently the entire migration, takes place during these 3 weeks. During the migra- 

 tion period the seaward migrants can be observed in front of the counting weir where 

 they congregate in schools of a few hundred to tens of thousands. Only occasionally 

 can they be seen going through the weir during the daytime, but just at dusk the 

 schools above the weir drop downstream and begin to pass through the spaces between 

 the pickets. Where there is any appreciable current, the fish always head upstream 

 even when migrating downstream. Seaward migrants are present in the river above 

 the weir for only 10 to 16 days each year, although the migration period may extend 

 over a period of 3 weeks. They may be quite abundant one day, entirely absent the 

 next, and present again the following day. 



The percentage occurrence of the various age groups in the random samples of 

 seaward migrants collected at the weir site is presented in table 26. Samples were not 

 collected every day that migrants were present in the river, but since 1930 samples 

 have been taken every day that fish were abundant. 



