382 U. S. BUEEAU OF FISHERIES 



live will be to supply a large amount of forage food to carry the bass 

 through the summer until October or November, in which case there 

 will be a smaller number of large bass. 



An allotment from the Public Works Administration has made pos- 

 sible the construction of a number of bass ponds at the Leetown 

 (W. Va.) experimental station, but these ponds were not completed in 

 time to be used during the season of 1934. 



TROUT CULTUEE 



Feeding experiments. — Owing to lack of sufficient funds the feeding 

 experiments which have been carried on at the Pittsford and Lee- 

 town stations for several years were discontinued. However, at the 

 Leetown station some preliminary studies were made on the growth 

 of yearling and 2-year-old trout. These fish were fed a diet composed 

 of 60 percent sheep liver, 20 percent salmon egg meal, and 20 percent 

 meat meal. Each experimental lot consisting of 325 fish was held in 

 a circular pool 22 feet in diameter. It was found that the rate of 

 growth of Ijotli yearling brook and rainbow trout as Avell as that of 

 2-year-old rainbow and brown trout was considerably smaller than in 

 the case of fingerlings. In feeding fingerlings the amount of food 

 consumed increases steadily throughout the summer; but with the 

 older fish on the diet used, the amount consumed remained unchanged 

 in some instances for 2 months or more, the fish continuing to grow 

 nevertheless. 



It was found that both yearling brook and rainbow trout con- 

 sumed a greater amount of food per day in proportion to their body 

 weight than the 2-year-old fish. The experiment also showed that 

 rainbow and brown trout could eat more of the diet fed without ill 

 effects than the brook trout. In other words, the brook trout, when 

 given an opportunity to eat all they could, suffered injurious effects 

 as indicated by high mortality and loss of appetite. This indicates 

 that brook trout are more easily overfed than brown or rainbow 

 trout. 



The nutrition studies have been continued at the Cortland, N. Y., 

 hatchery by Dr. C. M. McCay and A. V. Tunison. Two lines of 

 research were conducted during the past year: (1) Studies of the 

 interrelationship between various foodstuffs, rate of growth, and 

 mortality were continued; and (2) chemical-balance studies with 

 trout have been initiated. The chemical-balance studies depend 

 upon accurate chemical analyses of both the food ingested and the 

 excreta. 



The experiment to determine the relative ability of lake trout 

 {Cristivomer namaycush)^ brown trout {Salmo fario), rainbow 

 trout {SaJmo irideus), and brook trout {Salvelinus fontinalis) to 

 convert foodstuffs into body tissue were carried through the ninety- 

 second week. All four species were maintained under similar con- 

 ditions and fed the same diet, which consisted of 2 parts fresli beef 

 liver and 1 part dry skim milk. The number of individuals was 

 reduced from time to time so as to prevent overcrowding. The uni- 

 formity of the growth rates of the four species is surprizing. Over 

 long periods of time the growth tends to be strictly logarithmic. 

 However, the rate changed to a lower one after the thii-ty-second 



