MANX SUMMER HERRINGS, 1916 COMPOSITION OF THE FLESH OF THE FISH: MONTHLY MEANS ------+----------+------+-------+--------+------+------+------- Date.|Condition.|Water.|Oil and|Proteid.| Ash. |Total.| Food | | | Fat. | | | | Value. ------+----------+------+-------+--------+------+------+------- May |Empty | 75·0 | 2·5 | 21·1 | 2·3 |100·9 | 1,100 June |Filling | 66·1 | 11·4 | 18·6 | 2·0 | 98·1 | 1,806 July |Filling | 55·8 | 21·6 | 18·4 | 2·3 | 98·1 | 2,762 August|Half full | 48·4 | 31·5 | 16·5 | 2·3 | 98·7 | 3,608 Sept. |Full | 51·9 | 25·2 | 17·3 | 2·6 | 97·0 | 3,050 ------+----------+------+-------+--------+------+------+------- 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 comparatively 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 removal of so much water from the flesh of the fish. Freshly caught cod flesh contains about 80 per cent water and 17 per cent protein; after being dry-salted for export it contains about 25 per cent of water and 55 per cent protein. Thus, 1 lb. of dry cod is equal in food value to about 3 lbs. of fresh cod. The increased food value of salted fish will be seen from the following analyses— THE EFFECT OF CURING AND DRYING UPON THE FOOD VALUE OF DIFFERENT FISHES