CHAPTER XI 



FISH PRODUCTS 



THE industrial value and importance of fishes is by no 

 means limited to their use as food. They yield large 

 quantities of valuable oil. The fish waste, or offal, 

 chiefly heads, skins, bones and viscera that is discarded 

 by the fish curer, is worked up to yield fish glue, fer- 

 tilizers and cattle food. The skins of certain large 

 fishes, for example the shark, are tanned and 

 manufactured into a valuable leather. 



The story of the fishing industry would not be complete 

 without a brief description of the methods by which 

 these products are manufactured. 



Fish Oils. The various kinds of oil that are obtained 

 from different species of fish and other marine animals, 

 such as whales and seals, may be divided into three 

 classes, according to the part of the fish from which 

 they are extracted. 



(1) Fish oils proper are disseminated throughout the 

 flesh of the fish in the form of fine globules. They are 

 extracted from the entire fish, e.g. herring, sardine, 

 sprat, menhaden. 



(2) Liver oils are located in the fish liver, e.g. cod, 

 shark. 



(3) Blubber oils constituted thick layer of adipose 

 tissue just under the skin of the marine mammalia, 

 e.g. whale, seal, dolphin, porpoise. 



In oily fish, such as herrings and sprats, each minute 

 globule of oil is enclosed within a thin skin. It is prac- 

 tically impossible to rupture this skin and liberate the 

 oil simply by the application of pressure. When, 



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