in the diet. It produced poor gro*rth in the fish and its anti-anemic 

 properties were law. At least 25 percent of beef lirer Huist be 

 included to combat the anemia of the fish when cajined salmon is fed 

 at 45-percent level or more in the diet. 



Miscellaneous raw fish products 



Numerous species of fish taken in the ccnmercial fishery have no 

 ready market for human consumption. In addition, certain methods of 

 prejiaring fishery products for the retail trade produce large amounts of 

 waste material. Both the scrap fish and waste materials offer a source 

 of cheap available fish food. Of these products, hake, cod, halibut 

 sawdust, rockfish, tuna viscera, and tuna liver have been evaluated to 

 determine their possibilities as food for salmon and trout. 



Hake 



Hake ( Marluccius productus ) were used in a series of extensive tests 

 with various coaiposite diets. The results indicated that hake, although 

 deficient in the ainti-anemic factor, produced a growth rate about compar- 

 able to diets contadning hog spleen but inferior to those containing 

 salmon viscera. Hake appears to be particularly adapted to cold water 

 feeding in that the growth response of the fish to adequately fortified 

 diets containing 20 percent hake is proportionately greater at tempera- 

 tures of 50° or lower. Hake offers a cheap source of protein in diets 

 for salmon. 



Cod 



Cod (Gadus macrocephalus ) produced a growth response comparable to 

 hake when fed in similar diets. The indications are that cod and hake may 

 be used interchangeably. 



Halibut Sawiust 



Halibut ( Hypoglossus stenolepis) sawdust, the handsaw waste result- 

 ing from the preparation of halibut steaks for the retail market, permitted 

 a growth rate superior to either hake or cod when fed at the 20 -percent 

 xevel in comparable diets at water temperatures above 50*^. Although this 

 product is not in abundant supply, it is a cheap soxirce of excellent 

 protein when available. 



Rockfish 



Rockfish, a term used to define several species of the genus 

 Sebastodes, when fed either whole or as the fillet waste produced a rate 

 of growth definitely inferior to hake. These products offer lit tie possi- 

 bility in diets for salmon. 



48 



