118 THE FISHING INDUSTRY 



The herrings are caught in September when they 

 assemble in shoals for the purpose of spawning. They 

 are thus most easily caught at the time when their food 

 value is at a maximum. 



The flesh of clupeoid fish herrings, sprats, pilchards, 

 sardines contains a quantity of oil disseminated 

 throughout the flesh in the form of fine globules. From 

 the above table it will be seen that the percentage of 

 oil in the flesh of the herring may be as low as 2-5 per 

 cent in May, and as much as 31-5 per cent in August. 

 In summer the adipose tissue forms two distinct layers, 

 one situated just below the skin, the other being parallel 

 to the first, but separated from it by a layer of muscular 

 tissue. In winter the oil content becomes so small 

 that these layers of adipose tissue disappear. A com- 

 paratively small amount of oil is contained in the liver 

 of the fish. 



In gadoid fishes, e.g. cod, as well as in skates 

 and rays, the oil is almost entirely confined to the 

 liver. During the summer the liver grows larger and 

 richer in oil, until sometimes the oil amounts to more 

 than half the total weight of the liver. (When cod are 

 caught the livers are removed and kept apart, to be 

 treated subsequently for their oil.) The percentage of 

 oil in the flesh of the cod varies from 0-1 per cent to 1-0 

 per cent. Unlike that of the herring, therefore, the food 

 value of the flesh of the cod does not fluctuate markedly 

 according to the season. 



When fish are dry-salted a certain proportion of the 

 proteins and mineral salts in the flesh is extracted by the 

 brine pickle that is formed. In Russia and Poland, 

 where the greater proportion of salted herrings are 

 consumed, the peasants eat them without further 

 cooking, and also consume the pickle. 



A great gain in food value per pound results from the 



