XVIII REPORT TO THE SECRETARY OF COMMERCE 
Work to date has been confined largely to four major lines of re- 
search—utilization of by-products, nutritive value of fish and shell- 
fish, preservation of nets, and improvements in merchandising fresh 
fish. 
A method was worked out for decreasing losses of the protein and 
oil contained in press liquors now discarded in the manufacture of 
fish meal and oil. The method produces a better oil and should help 
materially in diminishing pollution from these liquors in our coastal 
waters. In this connection a careful study of the menhaden industry 
was made, which revealed that certain steps should be taken to lessen 
production costs and improve the products, the results of which have 
been given to the industry. 
With the increasing demand for fillets, the quantity of waste that 
is collecting in certain fish markets has become considerable—suffi- 
cient to enable profitable by-products industries to be prosecuted with 
the development of suitable methods for handling the gluey waste 
from such fishes as cod and haddock. Such a method has been 
worked out, and the results of this work are being made available to 
those in the industry unable to overcome the present difficulty. 
The bureau has issued a document on the nutritive value of fish 
and shellfish, with chapters by experts on the chemical composition, 
mineral: constituents, vitamins, oils, and fats, and protein value of 
aquatic foods. This has been very helpful in creating a better reali- 
zation of the place of fish and shellfish in the diet. To add to our 
knowledge of the value of the proteins in fish, the bureau is conduct- 
ing an investigation at Johns Hopkins University under the direc- 
tion of Dr. E. V. McCollum, which indicates that the proteins in 
herring and haddock have high nutritive value, comparable with 
meat. Extensive tests are now in progress regarding the nutritive 
and corrective values of selected grades of fish meals, as demonstrated 
by rat-feeding experiments. 
Large-scale practical tests with copper oleate and copper paint mix- 
ture net preservatives have been conducted at points on the coast of 
North Carolina, Virginia, and New Jersey, in which trap nets and 
purse seines were used. In addition, experiments with a large number 
of new preservatives are in progress at the Beaufort (N. C.) station. 
Perhaps the most fertile field for experimentation hes in improve- 
ments in the methods of handling fresh fish from the place of capture 
until the product reaches the consumer. Holding or ripening meat 
improves its quality; the opposite is true of fish. The bureau has 
made a most important contribution to this branch of industry 
through the issuance of a handbook on the refrigeration of fish. 
This includes a history of the industry and important scientific prin- 
ciples involved; changes that take place in the fish in the fresh state 
and during freezing and holding; design, construction, and equip- 
ment of fish freezers; practical freezing methods; methods of brine 
freezing ; transportation of frozen fish; and many other points essen- 
tial to the proper understanding of the industry, its problems, and 
the product as a food. 
Experiments are now in progress to improve the quality of fish 
as landed by the fishing vessels and to reduce overhead expense 
through the adoption of labor-saving devices. 
_ The bureau also is arranging to provide research associate facili- 
ties, whereby firms or groups having special technological problems 
