28 REPORT OF THE COMMISSIONER OF FISHERIES. 
The practical application of methods evolved in the investigation 
of the principles of preserving fish with salt has been embodied in a 
report entitled “ Improvements in Process of Salting River Herring, 
Especially Adapted to Warm Climates” (issued as Document No. 
903). The report is based on the results of actual field tests in 
Florida designed to overcome the failures heretofore experienced by 
fishermen, and the fundamentals of the method, which should be fol- 
lowed wherever fish are to be preserved by salting in a warm tem- 
perature, are: Careful handling of the fish before “salting, thorough 
cleaning and removal of all blood, use of salt of a high degree of 
purity, and application of the salt in a dry state. 
A report on the preservtion of fish nets has been prepared and 
published (as Document No. 898). This important means of econo- 
mizing in the expense of nets has been largely neglected in this. 
country. In view of the fact that our fishermen employ gear to a 
value exceeding $15, 000,000, a large part of which is in twine, and in 
view of the increasing cost of “such netting such information is 
greatly needed and has been appreciated. The document sets forth 
the fundamental principles governing net preservation and gives for 
use those recipes which seem best calculated to serve the purpose of 
the fishermen. The Bureau has initiated some additional studies in. 
net preservation which it plans to continue as opportunity affords in. 
order that the industry may benefit to the fullest possible extent 
through the application of desirable methods. 
For investigations in the refrigeration of fish the Bureau has a 
modern air-freezing plant with a sharp freezer capable of produc- 
ing a temperature of —40° and automatic carbon-dioxide compressor 
and controls; a plant for freezing fish in brine; a precision tempera- 
ture-measuring apparatus consisting of precision thermometer, 
Wheatstone’s ‘bridge, precision double potentiometer, conductivity 
apparatus, etc.; and a commercial apparatus for the experimental 
utilization of frozen fish. This equipment has been assembled and 
prepared for use in the conduct of investigations for which the trade 
lacks information as well as facilities. Tn view of the widespread 
interest in the industry in the freezing of fish in brine, this subject 
is to be investigated in detail, and considerable preliminary work 
has been completed. 
INCREASING THE USE OF BY-PRODUCTS OF THE FISHERIES. 
The Bureau has continued to aid in increasing the saving and use 
of the by-products of the fisheries with most gratifying results. It 
is inevitable that the year 1921 will show a heavy curtailment in 
production owing to unsettled market conditions. Fish oils now 
command about a fourth and fish scrap less than half war-time 
prices, while costs of operation and transportation have deciined 
but little. 
It is estimated that in 1920 the production of scrap and meal from 
all fishery products in the United States including Alaska was in 
excess of 125,000 tons. Of this amount the Pacific coast is to be 
credited with nearly 17,000 tons. As a result of the Bureau’s work 
on the Atlantic seaboard there was a large increase in the produc- 
tion of fish meal for stock-feeding purposes, and menhaden and 
