340 U. S. BUREAU OF FISHERIES 
This work was carried on in close cooperation with the division of 
scientific inquiry, and many biological data also were secured. In- 
complete analysis of the data, both statistical and biological, indicates 
that the unusually large runs of mackerel in 1925 and 1926 were due 
almost entirely to one successful spawning season, provisionally 
determined to be that of 1923. Very few mackerel belonging to other 
age groups were present in the catch. 
By continuing the collection of these data in future years, it will 
be possible to determine how many years a successful crop of mackerel, 
like that of 1923, will continue to furnish good catches. It will also 
enable us to detect another good spawning season as soon as its 
progeny first appear in the catch. These two lines of evidence will 
be of predictive value; and by so foreseeing the coming years’ 
catches the fishermen may outfit intelligently for the mackerel 
season and the industry may be guarded from loss in buying, freezing, 
and selling this species. It may be possible thus to stabilize the 
market and save outfitting costs at ill-advised times. 
TECHNOLOGICAL INVESTIGATIONS 
Tn its technological work the Bureau of Fisheries is endeavoring to 
improve present practices and to develop new equipment, methods, 
and products within the fisheries industries and to bring about proper 
utilization of wastes and by-products. To accomplish these ends, 
investigations are made and science, in many forms, is applied to the 
problems at hand. Information thus gained is made available to 
the industry, and its application is directed until it becomes an 
integral part of the same. There are but few more fruitful fields for 
scientific work than the fisheries industries, and much must be done 
before they can be placed on the same plane of efficiency with other 
food-producing industries. Properly carried out, work along these 
lines can be expected to, and actually does, yield large returns. 
The bureau’s policy is to select broad, fundamental studies on 
urgent problems which promise to be of the greatest value to the 
largest number and which are possible with the funds and personnel 
available for the purpose. In such work the direct results obtained 
are not the only results. A successful investigation gives general 
confidence in what science can do for the fisheries industries and leads 
to independent initiative. Moreover, the principles developed in 
one investigation frequently are applicable to the solution of other 
problems. 
Utilization of by-products—The annual production of fish meal in 
the United States approximates 100,000 tons, valued in excess of 
$3,250,000. It is estimated that in the production of this fish meal 
about 23,000 tons of nitrogenous material, with a value of about 
$1,000,000, are wasted. The bureau has been working upon this 
problem and has developed a method for decreasing losses of protein 
and oil in press liquors now discarded in the menhaden industry. 
Moreover, this method gives better oil and should help materially 
in diminishing pollution from these liquors in certain coastal waters. 
In connection with this work the bureau made a careful study of 
the menhaden industry. This showed that certain steps should be 
taken to lessen production costs and improve the products obtained, 
and the nature of these improvements has been pointed out to the 
industry. As an example of this work, it has been found that the 
