FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



253 



Table 19. — Cumulative totals of the runs of Karluh red salmon for each week from 1921 to 1936, and 

 percentage of the total run that had cumulated to the end of each week — Continued 



' The number of fish in the run from here to the end of the season was calculated as explained in the text. 



In discussing the time of appearance of the runs, Gilbert and Rich (1927, p. 63) 

 pointed out the apparent "uniformity in the development of the runs" from year to 

 year and stated that if supported by future data the size of the total run could be 

 predicted with some degree of accuracy at least by the end of June. Unfortunately, 

 additional data have shown that there is considerable variation in the cumulative 

 percentage occurrence of the runs from year to year. Up to the week ending July 5 

 the data indicate that from 25 to 60 percent of the run may have come in. Therefore 

 it is impossible to estimate, with any degree of accuracy, the size of the total run 

 early in the season. The main reason for the variation in tiie development of the runs 

 from year to year is that the run of any single year is composed of fish of several age 

 groups, and the various age groups do not appear uniformly during the season nor 

 is there a correlation as previously explained between the abundance or scarcity of 

 one age group appearing during one year with the abundance or scarcity of the other 

 age groups appearing during that same year. 



Figure 2 shows the average percentage of the run appearing during each 7-day 

 period of the season. There is a definite mode in June, a minimum during the week 

 ending July 12, followed by a second mode. The second mode itself is slightly bimodal; 

 however, the data for any single year clearly show that the minumum occurs during 

 the period of the week ending July 5 to the week ending July 19 and only one 

 mode is present during the fall run. It appears that there are two distinct red salmon 

 runs to the Karluk River each year, the spring run which reaches a maximum during 

 June and the fall run which reaches a maximum between the last week of July and the 

 first week of September. 



Overlapping of these two runs cannot be denied, but the bimodality of the runs 

 is evidenced not only in the appearance of the fish at the mouth of the river but also 

 in their appearance on the spawning grounds. The spring run first appears on the 



^1 



i i 



~j • r. - r 



