28 REPORT OF THE COMMISSIONER OF FISHERIES. 



The practical application of methods evolved in the investijiationi 

 of the principles of proservinof 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. 

 908). The repoH is based on the lesidts 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 tlie 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 thennometer,. 

 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 Avell as facilities. In 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-l'KODUCTS 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 declined 

 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. 



