508 



ir. S. BUREAU OF F1S»ERI«S 



Another tendency, however, is plain in the case of the shad, which 

 run in the spring and spawn at that time of the year. Three female 

 shad analyzed April 13, May 22, and June 19 show percentages of 

 fat running from 13.93 to 5.87 and down to 2.95. This is a case 

 where the fat of the tissue of the fish was being rapidly ti^ansf erred 

 from the flesh into the roe (eggs), the variation being due not so 

 much to seasonal factors as to the approaching maturity of the fish. 

 In all of these cases, whether bluefish, butterfish, or shad, changes in 

 the percentage of fat are reflected by great changes in the fuel value 

 per pound. In other words, a person who bought a fem^ale shad on 

 June 19 got considerably less tlian one-half the same number of 

 calories as the person who bought one two months earlier. 



It does not seem worth while to present any more general tables 

 giving the food value of fish flesh in this connection, but under the 

 section entitled "Variation in composition" some very interesting 

 and important tables are shown to illustrate the different kinds of 

 variation already mentioned. However, it may be of interest to 

 many people who enjoy eating the roe of shad and other fishes to 

 know that the food value is usually quite high, particularly from 

 the standpoint of the percentage of protein, which is the most essen- 

 tial and valuable constituent in fish and shellfish. Table 4 gives an 

 idea of the food value of the roe of some typical food fishes. 



Table 5. — Composition of va/rious canned fish 



ilucludes salt. 



PRESERVED FISH 



As canning is the most important, economically, of all the methods 

 of preserving fish, we give Table 5, which shows the composition 

 and food value of the more important types of canned fish. As the 



