SALMON EGGS AS FOOD FOR SALMON FRY ' 



By Martin Nokgobe 

 Seattle, Washington 



It is exceedingly important to the fish culturist to obtain efficient 

 and cheap food. In fact, to one who operates a hatchery on a com- 

 mercial basis, success or failure depends largely on the cost of food. 

 For a long time it has been known that fresh food is necessary at 

 certain intervals to prevent undue, if not complete, mortality. But as 

 long as food was valued on a calorie basis only, the reason for this 

 requirement in hatcheries was not known. In the light of what is 

 now known concerning the role of vitamines in the diet, however, 

 many curious phenomena occurring in hatcheries may be explained. 

 It is now well established that protein, carbohydrates, fats, and min- 

 eral salts are not sufficient to keep an animal in healthy condition and 

 make it grow. There are certain properties called accessory food sub- 

 stances, or vitamines, which the food must possess. At least three 

 of these have been recognized on the basis of their solubilities, namely, 

 (a) fat soluble, or growth promoting; (b) water soluble, or anti- 

 neurotic, and (c) water soluble, or antiscorbutic. 



It need hardly be mentioned that as yet little is known concerning 

 vitamines. But it seems that certain of them are destroyed by heat- 

 ing, salting, or drying at high temperatures. The fat soluble is the 

 most stable, while the water solubles are more easily destroyed. Little 

 is known about the effect of low temperature on the accessory food 

 substances, but it seems that cold storage foods retain the vitamines 

 if kept properly and not too long. 



Since the early days of fish culture, liver, melts, and Tcidneys have 

 been used to supply the fresh food requirements of the fish. But it 

 happens that at present these meats are expensive and often difficult 

 to obtain. Consequently, if a substitute could be found which is 

 cheaper and contains all the necessary vitamines, fish could be pro- 

 duced at a lower cost. Successful efforts have been made to sub- 

 stitute, in part, other products for liver or melts. Dr. G. C. Embody 

 has found that trout will keep well and grow on a diet of meat, fish, 

 or shrimp meals for six days, and liver on the seventh. In some 

 hatcheries canned salmon and liver have been used with good results. 

 But no successful attempt has been made, so far as the author is 

 aware, to dispense with meats altogether. 



* Results of some experiments carried on in the experimental hatchery at the College 

 of Fisheries, University of Washington, Seattle, Wash., and published with the permission 

 of Mr. John N. Cobb, Director of the College. 



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