INTRODUCTION 



Feeding trials are a necessary adjunct to other other forms of 

 nutritional research. Such trials are of particular importance in 

 investigations concerned with the nutritional requirements of salmon 

 and trout. Research in this field has not progressed to the point 

 where the dietary essentials are known and. therefore,, purified rations 

 cannot be fed. For this reason, feeding trials serve not only for 

 the determination of the comparative value o f various proteins as measured by 

 the growth response of the fish but serve also as a measure of the 

 nutritional adequacy of experimental rations as indicated by the pres- 

 ence or absence of recognizable deficiency symptoms. 



In view of the fact that more and more reliance is being placed 

 on artificial propagation to maintain the salmon runs of the Pacific 

 Northwest, it is essential that both an adequate and available diet 

 be developed to rear the fingerling to the time of liberation. The 

 purpose of the feeding trials conducted at the Leavenworth Laboratory 

 of the Fish and Wildlife Service during the years 19UU, 19^5, 19k7 , 

 and 19l*8 was to evaluate available food supplies and to develop ade- 

 quate diets for blueback salmon (O ncorhynchus nerka ) „ Experimentation 

 was limited to this species because proper facilities were not avail- 

 able to test diets on the other species of salmon native to the Upper 

 Columbia River watershed. 



Certain variables such as fish size, water temperature, and 

 slight alterations in the experimental techniques, exist between the 

 different years of experiment, but, because the design of the ex- 

 periments was such as to include two standard control diets in each 

 group, it is possible to compare the individual diets with the con- 

 trols of that group and thus determine whether they were inferior or 

 superior to these diets. Comparisons of different diets fed in dif- 

 erent years may be made by the determination of their relative po- 

 sitions with reference to the controls,, 



A detailed description of the experimental techniques used in 

 the diet studies has been included in this report because the pro- 

 cedures employed have a significant effect on the accuracy of re- 

 sults. The data for each group of experiments have been summarized 

 in a series of tables. The discussion of the results of the feeding 

 trials, however, has not been segregated according to the invividual 

 years but rather according to the type of diet tested and covers the 

 results of the experimentation for the four -year period. 



