30 U. S. BUREAU OF FISHERIES 
recovery of only a few of these tags from the Icy Strait fishery dem- 
onstrated that there is some intermingling between the Juneau 
spawners and an unknown population which supports this fishery. 
The failure to recover any of the Juneau tags im the lower Chatham 
Straits-Iphigenia Bay area confirms the former findings that estab- 
lished the independence of these populations. The failure to recover 
more than a few tags from the Rose Inlet tagging demonstrated 
that this population, although it intermingles to a shght extent with 
that of Craig, contributes no appreciable part to the commercial 
catch in the areas at present being fished. 
A consideration of major importance is the fact that certain fac- 
tors, in addition to the inroads made on the stocks by man’s fishing, 
influence the abundance of each of the populations whose existence 
has been demonstrated. Of these factors, the most important ap- 
pears to be the survival rate of the offspring from a given spawning. 
The result of particularly propitious spawning conditions is the ap- 
pearance of a “dominant” year class; that of particularly adverse 
conditions is a virtual failure of that brood to appear in the catch. 
All degrees between these two extremes appear. ‘The dominant year 
classes which result from a successful spawning have been demon- 
strated to be one of the major causes for the fluctuations in abun- 
dance which are observed to occur. The system of bi-weekly sam- 
ples to show the size and age composition of the catch from the more 
important fishing areas is therefore maintained to determine the 
status of the various brood years which make up the stocks of her- 
ring. This analysis has disclosed that the Cape Ommaney fishery has 
been maintained for the past 3 years by the offspring from the 1931 
spawning, which entered the catch for the first time as 3-vear-olds 
in 1934, continued to dominate as 4-year-olds in 1935 and as 5-year- 
olds in 1936. There was evidently a virtual failure of the 1932 and 
1933 spawnings. This has led to a relatively low abundance as re- 
flected in a low catch per unit of gear in this area, despite a reduc- 
tion in the amount of fishing effort. A 6-week closed season was 
imposed on this area during the year to afford this population the 
necessary protection. 
GREAT LAKES FISHERY INVESTIGATIONS 
Dr. JOHN VAN OOSTEN, in charge 
No field work was conducted on the Great Lakes during the calendar 
year 1936. This enabled the staff, under the direction of Dr. John 
Van Oosten, to make excellent progress in the compilation of data 
collected during earlier investigations in the field. During the year 
18 papers dealing with the Great Lakes were written for publication 
by members of the Great Lakes staff and cooperating associates. The 
manuscript on the deep-water trap net in relation to the whitefish 
of Lake Huron and Lake Michigan was completely revised for pub- 
lication, as was the manuscript entitled, “A Limnological Survey of 
Western Lake Erie with Special Reference to Pollution.” 
The Great Lakes staff continued its cordial relations and active 
cooperation with the various States fronting the Great Lakes, as well 
as with the fishing industry of these lakes. A large number of 
memoranda to be used as a basis for uniform fisheries legislation 
