125 DEPARTMENT OF THE NAVAL SERVICE 



2. THE FLESH OF SELACHIANS WITH PARTICULAR REFERENCE 

 TO ITS USE AS FOOD. 



(a) THE STRUCTURE OF THE FLESH. 



The fleshy part or muscle tissue of Selachians is light in colour and of a texture not 

 very different from that af the halibut. As in all fishes the muscular part of the 

 body is distributed on either side of the "backbone" or vertebral column. Owing, 

 however, to the fact that Selachians are without true bones and the cartilagninous ribs 

 are only short rods, the flesh of sharks and dogfish can be easily taken off in two large 

 fillets, corresponding to either side of the body and entirely free from bpne. This is an 

 advantage in preparing the fish both for the table and for canning. 



The shape and size of dogfish is such that they can be handled and prepared for 

 shipping fresh or for salting in exactly the same way as cod or haddock. The flesh 

 is as firm or firmer than that of the cod or haddock and stands handling weU.'^' The 

 shape of a fillet of dogfish, which is long, narrow and of nearly uniform thickness for 

 the greater part of its length, is convenient for canning, it being possible to roll the 

 fillet into an ordinary cylindrical can. 



In the case of skates and rays the usable part of the flesh is found in the " wings " 

 or pectoral fins. The practice is to cut the wings from either side of the body including 

 in them the large cartilaginous fin-rays. These wings are convenient for cooking. The 

 writer is not aware of «ny attempts made to prepare skates and rays for canning, 

 although he sees no reason why they should not be canned as successfully as dogfish. 



The skin of most sharks and dog-fishes is leathery. There are no true scales like 

 those of the bony fishes but in their place are small polygonal plates each bearing a 

 spine which projects above the surface, giving to the skin a rough and rasping quality. 



The toughness of the skin of the dogfish and shark makes them more difficult to 

 skin than most fishes, and hence tends to make the handling of them unpopular with 

 the fisherman, to whose lot usually falls this part of the preparation. This difficulty 

 is a serious one from the point of view of some of the firms''*^ which handle dogfish 

 and can it under the name of '' grayfish."*^* The labour involved may, however, be 

 partly reduced by the development of improved methods of skinning and more practice 

 in handling this kind of fish by fishermen and f actoi^y hands ; also the greater labour 

 may be partly compensated for by the utilization of the skin. 



(&) THE CHEMICAL COMPOSITJOX OF SELACHIAX MUSCLE. 



(1) As to Nutrient Value. 



The chemical composition of fish in general resembles that of meat in the nature 

 of its constituents but differs in the proportions in which those constitiients occur. 

 " Comparing the nitrogenous components of each, we find in fish more of the gelatine- 

 yielding matter (collagen) and less of the extractives than in meat."*^' The mineral 

 content of fish, as a rule, exceeds that of meat and contains more phosphates."^ 



Hutchison classifies fish as follows with reference to their content of fat®: — ■ 



Lean : Fish having less than 2 per cent fat, such as cod and haddock. 

 Medium: Fish having 2 to 5 per cent fat, such as halibut and anackerel. 

 Fat: Fish having more than 5 per cent fat, such as eel, salmon and herring. 



3 For the keeping qualities of dogfish see section on chemical composition. 



4 The writer was told in an interview with Mr. McDonald, manager of one of the Gordon- 

 Pew factories in Boston, that the skinning was one of the most* troublesome parts of the 

 process. 



5 The term "grayflsh" has been adopted in Canada and the United States as the trade name 

 of the dogfish. 



6 The writer here quotes from Leach, 1909, p. 254. 



