608 n. S. BUREAU OF FISHERIES 



In ])i'eparati()n for the experiments during; the snmmer of 1981, ti 

 hxrge stock of brood bass has been accumulated and is beintj held 

 over the winter in a sprin<j:-fed pond at Trempealeau, AVis. In the 

 spring these fish will be transferred to suitable ponds in wliich tliey 

 will be allowed to spawn, and the resultino; fry wnll be used for 

 stocking sloughs which have been put in readiness to receive them. 



TROUT CULTURE 



Investigations relating to trout culture were carried on at the 

 Pittsfoi'd (Vt.) station under the inmiediate supervision of Russell 

 F. Lord. As in previous years, these investigations included feed- 

 ing experiments with various rations and a systematic plan of selec- 

 tive breeding. Studies of the food and movements of trout in Ver- 

 mont streams w^ere also made, and it is planned to increase the scope 

 of these investigations in the near future. 



A number of additional rearing ponds were constructed during 

 the year which will considerably increase the capacity of the station. 

 The available supply of spring w^ater is now being utilized to its full 

 capacity, and, for this reason, no further increase in the number of 

 rearing ponds will be possible. 



Feeding experiments. — The feeding experiments during the sum- 

 mer of 1930 were conducted almost entirely with fingerling brook 

 trout. Owing to heavy losses among the yearling trout from furun- 

 culosis during the previous winter, only a few fish of this age were 

 available for experimental w^ork. As in previous years, each lot 

 containing 1,500 fingerlings occupied an entire hatchery trough 

 through the summer, llie fish were carried on experimental diets 

 from April 16 to September 3, inclusive. 



AVith very few exceptions the fish made a more rapid growth 

 than in previous years on comparable diets and the mortality was 

 relatively low. This was probablj^ largely due to the fact that the 

 fish used in the experiments were from eggs produced at the station 

 from selected stock. In previous experiments the fish were hatched 

 from eggs obtained from outside sources. 



The most striking feature of the experiments was the results 

 obtained with the use of dried salmon eggs. These when ground 

 into a fine meal make an excellent trout food, although, like all 

 dry foods, they should always be fed in combination with fresh 

 meat. In comparison with the controls fed straight beef liver the 

 fish on a ration composed of equal parts beef liver and dry salmon 

 eggs averaged one-third larger and the mortality was considerably 

 less. The fish fed salmon eggs were exceptionally lively and vigor- 

 ous and showed the brilliant coloration of wild trout of the same 

 age. This latter character is a very striking one, the pink fins and 

 iridescent sides appearing in marked contrast to the dull colors of 

 fish on other diets. 



As would naturally be expected, yearlings on a salmon-egg ration 

 developed even brighter colors than the fingerlings. After being 

 kept on such a diet for several weeks they could not be distinguished 

 from wild fish. 



