294 REPORT OF THE SEORETARY OF THE INTERIOR 
Investigations necessary for the fulfillment of the purposes of the 
treaty were continued by the scientific staff of the Commission. 
These included the collection and analysis of current statistical and 
biological data which serve as a measure of the changes occurring in 
the stocks of halibut as a result of regulation and which are a neces- 
sary basis for the continued rational control of the fishery. The 
biological investigations made necessary the operation of two vessels. 
Tagging operations were carried on from a chartered halibut ves- 
sel during the winter spawning season in area 2. A total of 1,308 
halibut. were marked in northern British Columbia and southeastern 
Alaska. From the recovery of these marked fish it is anticipated 
that valuable information will be obtained concerning the relation- 
ship of the spawning populations to the other stocks within area 2 
and regarding the rate at which these spawning populations are 
being removed by the fishery. Materials for the study of age, 
growth, sex, and state of maturity were also collected during the 
operations. 
Measurements of halibut landed by the fleet were continued to 
determine the changes occurring in the size composition of the mar- 
ketable fish as a result of regulation. Material for the age studies 
was collected at the same time. Preliminary analysis of the meas- 
urements of area 2 fish has failed for the second successive year to 
show any increase in the average size or in the proportion of larger, 
and therefore mature fish. 
The abundance of halibut as shown by the catch per unit of gear 
fished did not show the improvement that has characterized the catch 
of the previous eight years. The abundance in area 2, between Cape 
Spencer in Alaska and Willapa Bay in Washington, was 12 percent 
lower in 1939 than in 1938, which brought it back to the 1937 level. 
No change in abundance from that of the previous year was indi- 
cated in area 3, where the stocks are in good condition. Although 
the abundance in area 2 is still 71 percent greater than in 1930, the 
last year of unrestricted fishing, the marked decrease in abundance in 
that area must be regarded with concern in view of the unsatisfac- 
tory condition of the spawning stocks there. 
The effects of regulation upon the production of spawn in area 2 
were again observed by means of net hauls taken at sea during the 
winter spawning season. Analysis of these observations shows that 
the decline in abundance of eggs from the peak of 1936-37 was con- 
tinued for the third consecutive year. While some fluctuations may 
be expected, due to variations in spawning conditions and spawning 
stocks, the occurrence of such a continuous decline must be regarded 
as serious. In view of the decreased catch per skate and the un- 
