BUREAU OF FISHERIES 10] 
between the growth of seaward migrants during their stay in Karluk 
Lake and the returns from the escapements. ‘Such a correlation, if 
established beyond question, will throw light on observed fluctuations 
in abundance and will prove useful in predicting the relative size of 
the runs to be expected 1n any season. Chemical analyses of lake and 
stream waters to determine factors influencing the growth and sur- 
vival of fingerlings have been continued. Returns from marking 
experiments of previous years were consistently large, indicating that 
Karluk fingerlings, most of which migrate seaward during the spring 
of their third or fourth year, have a higher survival value in the sea 
than those which migrate at an earlier age. 
Similar studies are being made of pink salmon, the most valuable 
species in southeastern Alaska. Studies of the migratory routes of 
pink salmon in Clarence Strait may be expected to aid the fishery in 
the establishment of boundaries for future protective measures to 
allow adequate escapement. Cooperative work with the National 
Canners Association of Seattle on the physical and chemical changes 
that take place within pink salmon during their period of spawning 
migration was continued. The native and exotic distribution of the 
Pacific salmons has been investigated during the past year and a report 
has been prepared for publication. 
The collection of statistics of the Alaska salmon fisheries was con- 
tinued. These data provide a permanent source of information of the 
daily catch records of the various forms of gear from each of the geo- 
graphical divisions of the Territory, and are indispensable to the 
important regulation of the fishery. 
The investigation of Alaska herring, which has been prosecuted 
since 1925, has established the fact that these fish are not a homoge- 
neous population, but are composed of separate races, each of which 
inhabits a restricted area. During the past year the tagging program 
has been extended to include areas for which data had not previously 
been available, and has demonstrated that certain races support the 
fisheries of two separate areas during different parts of the season, and 
are therefore especially susceptible to overfishing. Studies have also | 
been carried on to evaluate the effect of dominant “year classes” in pro- 
ducing the fluctuations in abundance which have been cbserved to 
occur. 
Great Lakes fisheries investigations —The program of investigations 
on the Great Lakes has continued during the fiscal year 1937 to empha- 
size the practical phases of scientific research, that is, the conservation 
of the fisheries. This has been made an urgent necessity by the fact 
that the more important species, such as the whitefish, yellow perch, 
and the several species of chubs are definitely on their way to com- 
mercial extinction, a fate that has already overtaken the Lake Erie 
cisco. Although no field work was conducted during the fiscal year 
1937, the staff made excellent progress in the compilation of data col- 
lected during earlier investigations. Active cooperation with the 
fishery authorities of the various States fronting on the Great Lakes 
included the furnishing of a large amount of data to be used as a basis 
for uniform fisheries legislation. The detailed analysis of commercial 
fishery statistics of the “Great Lakes waters under the jurisdiction of 
the State of Michigan was continued. One of the important findings 
resulting from the application of statistical methods was the demon- 
stration that fluctuations in the abundance and production of yellow 
