PROGRESS IN BIOLOGICAL INQUIRIES, 19 31 499 



the remainder being made up mostly of midge larvae and sowbugs. 

 The fish in both ponds made a rapid and remarkable uniform growth, 

 the average increase in weight being about 1 gram a week. The 

 maximum variation in length between the largest and smallest speci- 

 mens was only 19 millimeters, while in other ponds variations in 

 length as great as 111 millimeters were recorded. 



These results are of great interest for comparison with those ob- 

 tained at Fairport, since the methods employed were very different. 

 The production of approximately 15,500 fingerlings per acre was no 

 greater than has been obtained at Fairport, but the growth was more 

 rapid, due, no doubt, to the heavy fertilization, which greatly ex- 

 ceeded anything which has been attempted in the ponds at that 

 station. 



The results also show that when sufficient numbers of Daphnia 

 and insects are available bass can be reared successfully to a length 

 of 3 inches or more without the use of forage fish. It is doubtful, 

 however, if under ordinary conditions these animals can be raised 

 in sufficient abundance through the summer to supply the needs of 

 fingerling bass when the ponds are heavily stocked. 



During the season of 1932 it is planned to carry on a series of 

 experiments at Hackettstown to determine the relative value of 

 Daphnia as the principal item of food throughout the summer as 

 compared with forage minnows. 



TROUT CULTURE 

 PITTSFORD STATION 



As previously stated, the investigations relating to trout culture 

 have been conducted at the experimental hatchery at Pittsford, Vt., 

 which is operated under the direction of Russell F. Lord. These 

 investigations include feeding experiments with both fingerling and 

 yearling trout, selective breeding for the purpose of developing a 

 superior strain of brook trout, and studies on trout diseases. Some 

 field work is also being carried on, which includes a study of the 

 natural food of trout throughout the year and the tagging of trout 

 liberated in certain streams. 



Construction work during the past year was confined to extensive 

 repairs to the hatchery, which was in very bad condition, and minor 

 repairs to several other buildings. 



Feeding experiments. — As in previous years, fingerling brook trout 

 from the same general stock of eggs were divided into lots each 

 containing 1,500 fish. Each lot occupied a standard hatchery trough 

 and was carried on an experimental diet from May 5 to September 3, 

 Throughout the summer samples of fish were counted out and 

 weighed at 2-week intervals. 



Emphasis was laid on the further testing of dry products, which 

 appear to offer the best possibilities as trout foods. A record was 

 kept of the amount of food fed each lot of fish and its cost. In 

 every case the fish were fed all they would eat without waste. No 

 tests were made of straight meat diets, since sufficient data on these 

 foods have already been secured. Beef liver was in most instances 

 used in combination with the dry products, but with salmon eggs it 

 was thought desirable to use other meats as well. Since beef liver 



