above £0 degrees . At water temperatures approximating US degrees, 

 both the recommended Cortland diets had a deleterious effect on 

 the survival rate of blueback salmon. The Cortland NOo 6 meal mixture 

 should not be included in the ration of blueback salmon during periods 

 of low water temperatures. 



The Effect of Storage on Prepared Diets 



20. The experiments indicate that prepared diets, ground, mixed, 

 packaged, and retained in frozen storage, lose a portion of their 

 vitamin content during storage period. If the original diet contains 

 more than a minimal vitamin content and the food intake is high the 

 fish may receive sufficient vitamins for adequate maintenance but 

 when the food intake is reduced vitamin deficiencies may develop. 



Acknowledgments 



Acknowledgment is made to the Branch of Game Fish and Hatcheries, 

 particularly to Dr. 0. Lloyd Meehean, rt illiam Hagen, Jr., and E M. 

 Tuttle, for use of facilities at the Leavenworth Fish-Cultural Station 

 and the procurement of the major items of fish food used in these 

 experiments. Appreciation is expressed to the Branch of Commercial 

 Fisheries, Seattle Technological Laboratory, particularly M„ E. Stansby, 

 G„ Ivor Jones, and Neva Karri ck for the procurement and preparation 

 of special diet ingredients and the analysis of the diet components. 



37 



