10 American Fisheries Society 



this, while the total mass of the muscle is greater, as 

 was shown of the total body weight, yet the total mass 

 of the dry substance has remained almost constant. In 

 fact, the percentage of dry has dropped slightly, from 

 25.9% to 23.1%. This, along with the water determina- 

 tions, shows that the apparent increase in weight of the 

 Black Diamond fish over the sea forms at Monterey is 

 not due to an increase by actual growth, but rather is 

 due to a taking on of water. The substance of the dry 

 muscle figured in per cent, of the total weight of the fish 

 falls under that of the standard Monterey salmon by 

 2.8% as just shown. In the Baird salmon, the dry muscle 

 is only 9.1% of the total fish. Furthermore, if these 

 figures be converted into percentages of the standard 

 weight for the particular lengths selected then they 

 read: Monterey fish 25.9% of the standard, 25.6% for 

 the Black Diamond fish, and only 6.8% for the spawners 

 at Baird. 



I have computed the percentage of dry substance of 

 muscle without making any distinction as to the com- 

 position of the material. Of course, the actual nutritive 

 value of the salmon flesh is found in the dry substance. 

 This has been shown to decrease remarkably in the in- 

 dividual specimens during the migratory run. But when 

 the chemical composition is taken into consideration it 

 is obvious that the actual food value represented by the 

 dry substance is found primarily in the fats. The fact 

 is, the fat runs from 15% to 20% in the down river 

 forms, but only 1% to 2% in the spawning ground 

 salmon. 



These three sea salmon of the table have an average 

 of 15.6% of protein and 18% of fat in the muscle. At 

 the head of brackish water the fat has already decreased 

 somewhat both in percentage composition and in abso- 

 lute amount. On the spawning grounds, in contrast with 

 feeding sea salmon, the protein has dropped to 14.4% 

 while the fat is almost entirely gone, 1.6%. See Table III. 



One gram of fat represents a fuel value of over twice 

 that of one gram of protein, i. e., 9,300 Calories for fat 



