FISHERY INDUSTRIES OF THE UNITED STATES, 1929 713 

 WASTE FISH AND SHARKS 



Many fishermen in isolated localities catch, along with the marketa- 

 ble fish, small amounts of fish considered undesirable for human con- 

 sumption. In most cases the supply is too small to warrant the 

 installation of reduction machinery and is not utilized. Recently 

 one of the bureau's technologists conducted a series of tests on the 

 acidulation of raw shark flesh and flesh from waste fish taken by 

 Florida trap-net fishermen. It was found that by mixing the material, 

 finely chopped, with as little as 5 per cent by weight of commercial 

 sulphuric acid, decomposition would be arrested and the material 

 could be dried in the sun in the course of two or three days. This 

 product would make a very desirable fertilizer material. Best results 

 were obtained by spreading the acidulated material in a thin layer on 

 flakes constructed of acid-resisting material and so setting them above 

 the ground that the air had access to the lower surface of the layer as 

 well as the top. By this simple procedure many fishermen, without 

 any considerable effort or expense, can realize a profit from material 

 that is now nothing more than a nuisance. 



NUTRITIVE VALUE OF FISHERY PRODUCTS 



The bureau has undertaken an extensive program of cooperative 

 research in which the nutritive value of marine products is being 

 studied. There are two incentives back of this work: One is that 

 certain nutritional research is necessary for the furtherance of certain 

 phases of technological investigations of the bureau, and the other 

 incentive is the ever-increasing scientific knowledge that marine prod- 

 ucts are unexcelled in nutritive value. 



The bureau's investigator at Johns Hopkins University has com- 

 pleted a series of studies of the general feeding value of fish meals and 

 shellfish meals and the results will soon be published. These experi- 

 ments have covered a period of approximately two years and they 

 have had the following purposes in mind or have been studied from 

 the following viewpoints: (1) As sources of protein, (2) comparison 

 on an equal weight basis of different meals made by different methods 

 of manufacture, (3) comparison with packing-house products, (4) 

 preliminary investigations of the effect of free fatty acids in the diet. 

 It was found that differences in nutritive value of the various meals 

 lie not only in the variety of meal used, but also in the various methods 

 of manufacture of the same material. In general, it was demonstrated 

 that vacuum and steam dried products were superior to flame-dried 

 products. Steam and vacuum dried menhaden meals were superior 

 to flame-dried menhaden meal and vacuum-dried whitefish meal was 

 superior to flame-dried whitefish meal. 



According to data obtained in these experiments, meals rated as 

 follows in nutritive value: (1) Vacuum-dried whitefish meal and 

 steam-dried menhaden meal of about equal feeding value, (2) flame- 

 dried pilchard (California sardine), (3) flame-dried whitefish meal, 

 (4) flame-dried menhaden meal, (5) shrimp meal. 



In comparing packing-house products with fish meals, a high-grade 

 specially desiccated meat meal prepared from condemned carcasses 

 and obtained from the United States Department of Agriculture was 

 found to be about equal to the flame-dried fish meals. Commercial 

 meat meal was decidedly inferior to any of the fish meals and commer- 



