286 



SALMON OF THE KARLUK RIVER, ALASKA 



EXPERIMENTS IN 1931 



Two marking experiments were conducted in 1931 (tables 37 and 38). For easy 

 reference they have been designated first and second although they were simultaneous. 



In the first experiment, 50,000 seaward migrants were marked by amputating the 

 adipose and both ventral fins, 1,549 of these fish were recovered, and a calculated total 

 of 11,790 fish returned (23.6 percent of the number marked). The return from the 

 2-, 3-, 4-, and 5-year marked fish was 54.8, 21.2, 34.5, and 40.8 percent, respectively. 



In the second experiment, 5,000 seaward migrants were marked by amputating 

 the adipose and dorsal fin, 124 were recovered, and a calculated total of 1,016 fish 

 returned (20.3 percent). The return from this experiment, although slightly lower, 

 agrees closely with results of the first experiment. Amputation of the entire dorsal 

 fin close to the base results in a large wound that may have a deleterious effect on the 

 fish. The results of the first experiment are believed to be more reliable than those 

 of the second. 



Table 37. — Data for the first 1931 marking experiment 



