of the, Salmon in Fresh Watei'. 165 



16. ON THE CHANGES IN THE VALUE OF SALMON 

 AS A FOOD STUFF. 



BY JAMES C. DUNLOP, M.D., F.K.C.P.E. 



The measurements and analyses of salmon at the different seasons of 

 the year, described in the previous sections, enable us to consider the 

 value of the fish as a food stuff. Every salmon killed, whether early or 

 late in the year, causes the loss of one breeding unit. If the stock is 

 inexhaustible it matters not how many breeding units are destroyed. 

 But if, as is the case, the stock is a diminishing one, economy demands 

 that there must be a selection of fish, only those which give the best 

 return being killed, and those which, on account of their poor value 

 as a food stuff, do not compensate for that loss to the breeding stock, 

 being preserved. The subject of killing salmon for sport is outside the 

 scope of this section. 



Two methods of considering the value of salmon flesh as a food stuff 

 suggest themselves (1) The value per unit of weight of flesh, per 

 100 grms. may be taken ; or (2) the total value per fish killed may be 

 calculated. Both these will be considered. 



The value of a food stuff is measured by the amount of energy which 

 the combustion of its constituents produces, and is expressed as the 

 number of calories heat units produced by that combustion. Calories 

 are adopted as a convenient measurement of energy ; but when the 

 energy value of a food stuff is expressed as so many calories, it is not 

 implied that that food stuff is only capable of producing heat. One 

 form of energy is capable of conversion into other forms, and so the 

 measurement of the production of heat may be taken as a measurement 

 of the energy available for all purposes. The calories referred to in this 

 article are " great calories," each representing the amount of heat 

 required to raise the temperature of 1000 cc. of water 1 Centi- 

 grade. For practical purposes the food value of the flesh of fish may bo 

 considered to depend on two constituents, proteids and fats, carbo- 

 hydrates occurring in such a small amount that they may be dis- 

 regarded. In the calculations which follow, the measurements and 

 analyses of the fish are taken from the figures in the previous sections of 

 this work, while the calorie value of proteid and fat is taken from 

 Neumeister's Physiologische Chem., I., p. 282. 



Food Value per Hundred Grms. of Salmon Flesh at Different Seasons. 



In the following tables will be found a statement of the amount of 

 proteid and fat and calorie equivalent of the flesh of the salmon at the 

 different seasons, both from estuaries and upper waters. The calcula- 

 tions are based on the averages of the actual amounts found in each 

 group of female fish received in 1896 (vide pp. 95 and 122). 



