FISHERY INDUSTRIES OF THE UNITED STATES, 1933 13 



By raisinj? the iip])er limit for iodine n\im})er from 180 to 190, the 

 danger of haddock-hver oil not meeting United States J^hwrma- 

 copoeia requirements should be entirely eliminated. 



SALMON OIL INVESTIGATION 



In an effort to bring about increased utilization of fishery waste 

 materials by conversion into useful products, the Bureau began, in 

 1933, an investigation concerned with the manufacture of vitamin- 

 active oil and high quality meal from salmon waste. The possibihties 

 for this development may be appreciated when it is considered that 

 during 1932 the waste available from the salmon fishery was capable 

 of yielding approximately 12,000 to 15,000 tons of meal and from 

 1,500,000 to 2,000,000 gallons of oil, while actual utiHzation resulted 

 in the manufacture of only 2,435 tons of meal and 250,871 gallons of 

 oil. During the season of 1933 studies were carried on in canneries 

 located on the Columbia River and on Puget Sound. This work was 

 largely of a preliminary nature to determine tlie nature and amount of 

 oil in the difTerent portions of the waste and the quality of the oil from 

 the different species. Work was also begun on improved methods of 

 oil manufacture. 



The preliminary indications are that an oil can be produced com- 

 mercially that will be comparable wdth cod-liver oil in both vitamins 

 A and D. Also carefully prepared salmon meal should prove to be 

 one of the best protein concentrates available for animal feeding. 



The investigation is being continued and will be reported further 

 next year. 



SWORDFISH-LIVER OIL 



With the discovery and successful exploitation of halibut-liver 

 oil in the field of human nutrition, there has been an increasing inter- 

 est in new sources of natural concentrates of vitamins A and D. 

 Working on the premise that vitamin storage in fish may be a function 

 of age, the Bureau began an investigation of the oil obtainable from 

 the liver of the swordfish taken commercially on Georges Bank and 

 adjacent fishing banks off the coast of New England. 



Livers were procured and investigated from the standpoint of oil 

 content and the nature of the oil present. Analysis showed that the 

 moisture content of the hver varied between 60 and 68 percent; oil 

 content, between 13 and 22 percent; and flesh residue, between 15 and 

 24 percent. The oil was a dark viscous fluid which solidifies at 

 relatively high temperatures. 



Samples of oil, examined colorimetrically, indicate that swordfish- 

 liver oil is an extremely potent carrier of vitamins A and D. Several 

 experimental methods of preparing the oil were studied. The vitamin 

 tests of swordfish-liver oil, described later on in this report, indicated 

 that solvent extraction methods yielded an oil of higher vitamin 

 potency than oil extracted from the livers by mechancial processes. 



CONTROLLING THE OXIDATION OF FISH OILS 



Fish oils are composed of glycerides of saturated and unsaturated 

 fatty acids. The unsaturated fatty acids have the ability to take up 

 oxygen from the air and, when spread in a thin layer, form a relatively 

 tough, protective film. This is known as drying, and constitutes the 



