26 U. S. BUREAU OF FISHERIES 
On sampling the run for the presence of fish marked in previous 
years, 268,000 fish were examined and 1,598 marked fish were found, 
or approximately 25 percent of the fingerlings marked. The con- 
sistently large returns from the marking of Karluk River migrants, 
which, incidentally, are far greater than have been experienced from 
other similar marking experiments, fulfill the prediction made by 
Gilbert and Rich in 1927: “They (the seaward migrants) can well 
be expected to give a good account of themselves during their life 
at sea and should escape their enemies in larger measure than do the 
smaller fingerlings of many other streams.” Though the Karluk fin- 
gerlings attain their larger size, for the most part, by staying an 
additional year in fresh water, where they are subject to the depreda- 
tions of enemies in the lake, they benefit by having a higher survival 
value during their stay in the ocean. 
It has been impossible to determine the mortality rate between 
the fry stage and the seaward migrant stage owing to the difficul- 
ties involved in collecting adequate samples of fingerlings. During 
this period of their life fingerlings are ordinarily subject to various 
diseases and parasites, and are preyed upon by their natural ene- 
mies, such as trout and birds. Samples of fingerlings collected at 
Karluk have always been composed of extremely healthy individuals. 
Birds do not prey to any great extent on the Karluk fingerlings and 
the stomachs of trout taken in the lake during the past season and 
previous seasons indicate that the trout feed very sparingly on them, 
possibly because other forms of food are more easily obtainable. 
Tt would appear, therefore, that the habit of spending an extra year 
in the lake has a salutary effect on the survival value. 
PINK SALMON 
The activities of the pink-salmon investigation in 1936 as in past 
years were confined mainly to studies of the pink salmon populations 
of southeastern Alaska, where the bulk of the pack of this species is 
made each season. Both the marine and fresh water environments in 
southeastern Alaska are so varied that they represent practically all 
the biological conditions that may be found in the habitats of pink 
salmon throughout the entire range of its distribution, hence it is 
believed that the fundamental facts secured from the study of the 
fishery in this section may be applied generally throughout Alaska. 
A field station is maintained at Little Port Walter on Baranof 
Island where the greater part of the biological studies are carried on 
by Dr. F. A. Davidson and S. J. Hutchinson. 
The collection of data for racial studies was continued for the 
purpose of determining the homogeneity or heterogeneity that exists 
in the various populations in any one season and the racial differences 
prevalent in the odd- and even-year groups. By operating a counting 
weir in the stream, a total count of each year’s population is made. 
The fish returning to the stream in 1936 from the 1934 spawning gave 
the first returns from a known spawning population in this stream. 
In 1934 the run into the stream consisted of 6,952 pinks, which 
resulted in the return. of 5,164 spawners to the stream in 1936. A 
study is being made to determine the factors responsible for the 
inability of the 1934 population to reproduce itself. Of the number 
passing through the weir, 52 percent were females and 48 percent were 
