anemic condition in the fish. It is obvious from thesr experiments 

 that condemned canned salmon does not compare favorably with salmon 

 viscera when included at levels of hS per cent or over in the diet 

 of blueback salmon. 



Tuna Viscera 



Tuna viscera wouli be available in sufficient supply on the Pacific 

 Coast to form a reliable source of fish food should it prove of value. 

 Evaluations of this product were made during the 19U£ feeding trials. 

 Three separate combinations of tuna viscera were included in the ex- 

 periments (Table 3, Diets 3, 5> and 13). In every instance the growth 

 rate was poor and an anemia developed before the conclusion of the lLi- 

 x-jeek experimental period. Tuna viscera should not be included in the 

 diets of blueback salmon because of its poor growth potential and ap- 

 parent deficiency in essential vitamins. 



Hake 



Hake (Merluccius p roductus ) occur in large numbers in the trawl 

 fishery of the Pacific Coast „ There is so little commercial demand 

 for this species that it is regarded as a scrap fish in this area. 

 For this reason, the cost per pound is low, and a cheap, adequate 

 source of fish food is available. The preliminary feeding trial con- 

 ducted in 19U7 (Table U, Diet llj), in which hake was fed at the 100 

 per cent level, indicated that this product had an excellent growth 

 potential but was deficient in the anti-anemic factor. Although an 

 acute anemia developed in the stock after eight weeks of feeding, the 

 growth rate was such as to exceed that of the beef liver control at 

 the conclusion of the experimental period (see Table h) . Wales (19W-0 

 used hake in combination with 50 per cent beef liver and produced an 

 adequate diet for trout. This high level of liver was considered im- 

 practicable in irLew of the difficulties encountered in the procurement 

 of this product. 



Two composite diets including hake were tested in I9I48 to determine 

 if an adequate diet could be produced with hake which still retained 

 a growth rate comparable to that of diets in which salmon viscera was 

 fed. In one test, hake was substituted for salmon viscera in the stand- 

 ard meat-viscera-meal combination and compared with the diet in which 

 salmon viscera was included (Table 5>, Diets 2 and 3). The substi- 

 tution of hake resulted in a significant reduction in the growth rate 

 of the fish although the gains were greater than the bj-ef liver con- 

 trol. In the second trial, salmon viscera, hake and salmon viscera 

 meal were fed in combination (Table 5, Diet 6). While the t,ain in 

 weight was below that of the first combination it was still superior 

 to the gains made by the beef liver control and comparable to those 

 made on the best Cortland diet. The fish, however, were acutely 



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