produce good grovrth are essential in the diet of salmon fingerling. Ex- 

 perimental data indicate that higher survival rates to the adult stage 

 may be anticipated from large fingerling than from smaller fingerling of 

 a compai^ble age when liberated. Analyses of protein content are not 

 necessarily indicative bf the growth potential of that particular pro- 

 duct when used as fish food. Apparently salmon and trout are capable of 

 utilizing certain proteins more readily than otha's. Heat is one factor 

 responsible for an alteration in the structure of a protein and, reports 

 indicate, those alterations due to intense heat are responsible for a re- 

 duction in growth rate when fish meals of this type are fed to salmonoid 

 fishes. On this basis, an acetone-extracted meal might have a higher growth 

 potential than a tunnel-dried meal if a portion of the protein were altered 

 and made unavailable by the latter process. 



Another fish meal, designated as flame-dried salmon offal meal, was 

 available for experimental evaluation. This meal was a commercially pre- 

 pared product derived from the whole cannery waste and dried by intense 

 heat. Although derived from a different source and therefore not strictly 

 comparable to the other meals tested, its value as a protein supplement 

 in the ration of fingerling salmon had not been determined. Its inclusion 

 in the diet studies would be a marked contribution to the evaluation of 

 the potential utilization of Alaska salmon cannery waste for hatchery feed- 

 ing purposes. 



The freezing of the raw products offers another solution to the trans- 

 portation of salmon waste without spoilage. The cost of transportation for 

 the frozen material undoubtedly would be increased over that for fish meal. 

 If, on the other hand, growth rates were increased and nutritionally ade- 

 quate products found, these advantageous features might adequately compensate 

 for the higher transportation cost. Because of the short term of the ex- 

 perimental period it was impossible to determine nutritional adequacy except 

 in markedly deficient diets. 



As stated previously, the number of products to be tested was limited 

 at the time of initiation of the experiment. Unfortunately only two frozen 

 products, salmon viscera and salmon trimmings, were procurable at the time. 

 Both were secured from Columbia River canneries. 



Salmon viscera had been tested previously and found to have a growth 

 potential superior to any meat product customarily used in the diets of 

 salmon fingerling. On short-term experiments (18 weeks) it contained ade- 

 quate amounts of the anti-anemia factors to support fish life. The salmon 

 viscera was included in these studies both to confirm these earlier results 

 and to compare it with the fish meals being tested. 



The salmon trimmings consisted of the scrap from hand-butchering 

 operations. It did not include the viscera, testes or eggs, but was com- 

 posed of heads, collars, fins, etc. It, together with salmon viscera, 

 would represent the total waste material available from the salmon canneries. 

 1'he salmon trimmings were included in these evaluations primarily to deter- 

 mine if this segment of the total cannery waste would be comparable to the 

 visceral portion as a growth producing ration. 



52 



