PROGRESS IN BIOLOGICAL INQUIRIES, 1936 25 
stand the causes of these large fluctuations in the ratios between 
escapement and return. Recent studies are suggestive of a positive 
correlation between the growth of migrants during their stay in the 
lake and the returns from escapements. In reviewing the returns 
from the escapements from 1921 to 1931, we find that those from the 
escapements of 1921, 1922, and 1923 were good, those from the 
next 3 years poor, and those from the following 4 years fair, with an 
upward trend in the ratio of return to escapement. The small re- 
turns from 2 of the 3 years which produced very poor returns were 
caused, at least in part, by overcrowding on the spawning grounds 
due to large numbers of fish and relatively dry weather. However, 
on examining the data of the average length of the seaward migrants 
resulting from eggs laid in the gravels during the years 1922 to 1938, 
inclusive, it is quite apparent that there was a downward trend to 
the average size of the migrants for the first 3 years, that the average 
size remained constant for the next 4 years, and that there has been 
an upward trend in the size of the migrants since that time. If such 
a correlation between growth rate of fingerlings and their survival 
does exist, we may expect an even larger run of adult reds to the 
Karluk River in 1937 than was experienced in 1936, when the run 
amounted to approximately 2,400,000 fish, the largest run to the 
Karluk River during the past decade. These fish were, for the most 
part, the progeny from the spawning of 1931 when the escapement 
amounted to 873,428. 
Conditions favorable to the growth of fingerlings while in the lake 
would be expected to act favorably on their survival and thus to 
result in an increase in the number of adult fish surviving. Such 
an expectation is supported by marking experiments which have 
shown the survival value of the larger seaward migrants to be 
greater than that of the smaller individuals. Numerous factors at- 
fect the growth of the fingerlings, as, for example, their abundance, 
for in years when the lake contains a large population of fingerlings 
there is undoubtedly competition for food. 
Chemical analyses of the lake and stream waters made during the 
season were in close agreement with those made during 1935. Phos- 
phorus and silica were the two main limiting factors in the growth 
of phytoplankton in the lake. The phosphorus and silica brought to 
the lake by its affluents were taken up during the summer months by 
the plants as rapidly as they became available. As most of the phos- 
phorus introduced into the lake comes from the bodies of spawning 
fish, the number of fish in the escapements must have a profound 
effect on the growth of plankton. Unfortunately, the opportunity 
for artificially fertilizing a red-salmon lake has never been realized. 
While at first glance the cost of adequately fertilzing a large lake 
might appear prohibitive, the resulting increase in its productivity 
might make such a venture worth while. 
Two marking experiments were initiated during the season; 26,700 
seaward migrants were marked by the excision of the right ventral 
and adipose fins and a like number were marked by the amputation 
of both ventrals and the adipose fin. These experiments, in addi- 
tion to furnishing information on the survival value of these fish 
during their stay in the ocean, will furnish data on the relative value 
of these two marks. In the past it has been considered that they were 
of equal value, although the assumption has never been tested. 
