282 



SALMON OF THE KARLUK RIVER, ALASKA 



run or which are fall run seaward migrants. The percentage occurrence of marked 

 fish of each age group is fairly constant throughout the season, indicating that pro- 

 portionate numbers of the two runs are marked. 



EXPERIMENTS IN 1926 



A total of 47,691 seaward migrant red salmon were marked by the amputation 

 of two fins. Two combinations were used, the adipose and right ventral, and the 

 adipose and left ventral. Since approximately the same number of fish were marked 

 each day by each mark, the data can be grouped together and considered as one 

 experiment or divided according to the marks used and considered as duplicate 

 experiments. Although the experiments were carried on simultaneously, the one in 

 which the fish were marked by the amputation of the adipose and right ventral fins 

 will be referred to as the first experiment, and the one in which the fish were marked 

 by the amputation of the adipose and left ventral fins will be referred to as the second 

 experiment. 



Commercial fishing was limited in 1929 and the run of that year could not be 

 adequately sampled to detect the presence of marked fish. Consequently, no accu- 

 rate means of determining the number of three-ocean fish returning from these experi- 

 ments is available. The number of marked fish returning and the percentage return, 

 as presented, are lower than they would have been had information on the three- 

 ocean fish been available. 



In the first experiment (table 31), 25,000 seaward migrants were marked, 740 

 marked fish were recovered and a calculated total of 5,151 marked fish returned from 

 this experiment, not counting the marked fish returning during 1929. The return 

 from this experiment was at least 20.6 percent. 



Table 31. — Data for the first 1926 marking experiment 



i Based on incomplete data, see text. 



The incomplete returns from the marked 2-, 3-, 4-, and 5-year seaward migrants 

 were 7.6, 19.5, 24.3, and 40.8 percent, respectively. Very few 2- and 5-year seaward 

 migrants were marked, and the returns from those age groups are based on the re- 



