PROGRESS IN BIOLOGICAL INQUIRIES, H>:;4 363 



The colu) saliuou aro less abundant at present than at any lime 

 since the. bo«rinnin<r of tlie fishery. It appears that tiiey are in need 

 of more strinizent protective rcfrulations. 



The pink sahnon. althoujrh niain(ainin<; a fair level of abundance 

 since 1J)15 are in no wise as abundant as in 1911 and 1913, before the 

 slide of 191;^ in ITell's (iate Canyon com])letely wiped out the popula- 

 tion spawning in the Thom])son and Nicola Rivers and the tributaries 

 of Seton and Anderson Lakes. 



KARLFK RIVER RED SALMON INVESTIGATION 



The Bureau of Fisheries early realized the necessity of obtaining 

 information on the number of red salmon that shouhl be permitted 

 to spawn in the streams in order to produce returns that would pro- 

 vide the maxinunn suri)lus for the fishery. Since this involved a 

 study of the com]dete returns from known spawning escapements, a 

 stream had to be selected wdiere both the portion of the run taken 

 for commercial purposes and the portion escaping to the spawning 

 grounds could be determined. The Karluk River on Kodiak Island 

 was the first stream selected for this study since it supports a large 

 red salmon poj^dation which is subject to commercial capture only in 

 the vicinity of its mouth. Furthermore, the Karluk River is cen- 

 trally located in a large red-salmon-producing area, and it was hoped 

 that the fundamental facts secured from the study of its fishery 

 could be applied generally to the fisheries of the other red-salmon- 

 producing areas in Alaska. This investigation has been carried on 

 continuously each year since its inception in 1921, and at the present 

 time is being conducted by J. T. Barnaby, assisted b}'' L. D. Town- 

 send. 



The information available to date on the returns from known 

 spawning escapements in the Karluk River indicates that wide fluc- 

 tuations may be expected in the rate of reproduction of its spawn- 

 ing populations. During the past year a complete analysis was 

 made of the returns from the known escapements of 1921 to 1928. 

 The escapements for these years are as follows: 1921, 1,500,000; 

 1922, 400,000; 1923, 694,579; 1924, 1,000,000; 1925, 1,620,927; 1926, 

 2,533,402: 1927. 872,538; and 1928, 1.093,817. The ratio of return 

 to escapement for these years is as follows: 3.0 to 1, 5.6 to 1, 2.9 to 

 1, 0.8 to 1, 1.0 to 1, 0.6 to 1, 1.8 to 1, and 2.1 to 1, respectively. 

 The smallest escapement, 400,000 fish, produced the greatest return 

 per spawning fish, 5.6 to 1, whereas the largest escapement, 2,533,402 

 fish, produced the smallest return per fish, 0.6 to 1. In other words, 

 there seems to be little opportunity of selecting a spawning escape- 

 ment that will consistently produce a large population. 



In 1926 a series of marking experiments were established for the 

 purpose of determining the mortality of the red salmon during their 

 life in the sea. These experiments have consisted of the marking 

 of 50,000 seaward migrants each spring. The proportion of the 

 adult salmon bearing the marks that have returned from each experi- 

 ment indicates that although the mortality in the sea is consider- 

 able it seems to remain fairly constant from year to year. However, 

 the rate of groA\i:h of the salmon in the ocean varies considerably 

 and is responsible for the length of time the fish from different 



