2 BULLETIN 635, U. S. DEPARTMENT OF AGRICULTURE. 



The commercial supply of fish depends on weather conditions and 

 on the brief periods during which certain fish appear at banks or in 

 rivers to feed or to spawn. Much of the fish crop, therefore, is as 

 strictly seasonal as are the harvests of most of the perishable land 

 crops. During certain seasons fish are landed in quantities far in 

 excess of immediate needs, and, without effective conservation, these 

 vast temporary surpluses would go to waste. The importance ot 

 saving the surplus of spring, summer, and fall catches for later use 

 was appreciated long before conservation by freezing became known. 

 Each fishing season large quantities were saved, as they still are, by 

 canning, smoking, salting, and pickling. Freezing and storage, how- 

 ever, has the advantage over these other methods, in that it does not 

 alter the flavor or appearance of fish, and therefore makes available 

 months later, in almost the natural condition, the spring or summer 

 catches of seine or hook. 



The fish-freezing plants (PL I, fig. 1) located at many points on 

 our coasts and the Great Lakes, and constituting an important indus- 

 try, are becoming increasingly useful as sources of nitrogenous food 

 to make up the deficiencies in the meat supply. Their work is true 

 food conservation. Harvests of fish, unlike land crops, add to rather 

 than take from the fertility of our soils. Meat represents the con- 

 version by animals of grain or other foodstuffs into another form of 

 food. Fish, however, represent the conversion of valueless aquatic 

 vegetation or animal material into human food, and, had merely for 

 the labor of harvesting, they are a net gain in the food supply. 



PREPARATION OF FISH. 



To produce frozen fish which after several months of storage will 

 be practically equal in food value and flavor to freshly caught fish, 

 it is essential that they be placed in the freezing rooms as soon as 

 possible after they leave the water. The fish should be handled as 

 little as possible, for any bruising, breaking of the skins, or damage 

 to fins either lessens their keeping quality or lowers the attractiveness 

 of the fish at market. Under no circumstances should fish be allowed 

 to become warm from the time they are caught until they are frozen. 

 Very slight exposure to warmth causes changes in their flesh which 

 no amount of freezing will remove. 



The ideal method of freezing fish is that employed in winter In 

 Canada and other very cold sections (PL I, fig. 2), where fish caught 

 through the ice or on the edge of the ocean are allowed to freeze natu- 

 rally as they leave the water. Such fish from our northern lakes, 

 and others, like the smelt from Nova Scotia and New Brunswick, 

 begin to freeze while they are still flopping on the ice or in the snow. 

 These frozen fish, which commonly have twisted bodies, due to being 

 frozen almost instantaneously while still alive, are known on the 



