mortality. When 20 percent of predicested raeal vras used, the mortality- 

 was tremendously increased. The amino acid supplemented meal produced 

 a mortality comparable to that of the c^oup fed the vacuum-dried salmon 

 viscera meal. From the results of these experiments, it appears that 

 inhibition of amino acid absorption was not the factor causing the 

 mortality in these diets. More complete experimental data are needed 

 to determine the actual cause of the mortality. 



The second hypothesis was based on the assumption that the addition 

 of meal to an otherwise adequate diet inhibited the absorption of or 

 increased the requirement for the vitamins of the B-coraplex during the 

 cold-water period. In Diet 17 the vacuum-dried salmon viscera meal 

 was fortified with certain vitamins of the B-complex in the following 

 amounts ; 



Vitamins Daily Supplement 



Milligrams per kilogram of body vifeight 



Thiamin hydrochloride O.I96 mgs . 



Riboflavin O.68O mgs . 



Nicotinic acid Il.lOO mgs. 



Pyridoxine hydrochloride 0.^90 mgs. 



Calcium pantothenate 1.2^0 mgs. 



Biotin 0.077 mgs. 



Folic acid 0.29^ mgs. 



The amount of each vitamin was derived from established maximum require- 

 ments for trout as reported by Phillips (19U6) and McLaren et al. (I9U7). 

 Although the resulting mortality was significantly lower than those fed 

 the unfortified diet (Diet 13), it was still significantly higher than 

 the meat-viscera mixture without raeal (Diet 8). It is possible that a 

 more complete vitamin supplement m.ight correct the mortality resulting 

 from feeding meals but the results of this experiment are inconclusive. 



In Diet I6 the meal content was reduced from 10 to 5 percent. The 

 mortality vras significantly reduced below that of the fish fed 10 percent 

 meal (Diet 13) and v;as comparable to the loss in the meat-viscera control 

 (Diet 8). The total gain in weight of the fish fed 5 percent meal was 

 not significantly'- different from those fed the 10 percent meal supplements 

 (Diets 13 and lU). All of these diets showed significantly higher gains 

 than the meat-viscera control. The addition of 5 percent raeal to the 

 meat-viscera mixture was accompanied by a marked increase in growth rate 

 without a resultant increase in mortality. It is apparent that blueback 

 salmon will both tolerate and utilize a 5 percent addition of vacuum- 

 dried salmon viscera meal to the meat-viscera mixture during the periods 

 of cold water. 



During this experiment the mortalities due to the addition of salmon 

 viscera meal at the 10 percent level approximated 2 percent for the 

 12-week period. These mortalities while significantly different from the 



