PKOGRESS IN BIOLOGIOAX, INQUIRIES, 19 3 2 131 



fish which were wintered in the pond for 8 months. The pond was 

 stocked June 14 with snialhnouth fry at the rate of 22,130 per acre. 

 When drained September 13, 5,480 fingerlings were removed with an 

 average weight of 9,130 grams. This gives a return of 41 percent or 

 9,130 per acre. The total cost was entirely for labor at the rate of 

 $50 per acre, or $5.47 per thousand fingerlings. Although the num- 

 ber of fish produced was somewhat smaller by this method the bass 

 were larger and the cost of production much less. 



In another experiment the daphnia were cultured in a separate 

 pond, then flowed or netted over into the main pond. The total 

 area including the daphnia pond was 0.69 acre. A total of 8,760 

 pounds of fresh horse and cow manure was used in addition to about 

 2 inches of trout excrement. The pond was stocked June 9 wdth 

 smallmouth fry at the rate of 25,000 per acre. It was drained 

 September 9 and yielded 8,609 fingerlings with an average weight of 

 3.23 grams. This gives a return of 49.8 percent at the rate of 12,475 

 fingerlings per acre. It should be noted, however, that these fish 

 w^ere only one half the size of those in the other ponds. The total 

 cost of labor and manure was $12.40 per thousand fingerlings. 



It is evident from these experiments that smallmouth bass finger- 

 lings 3 to 4 inches long can be economically produced in heavily 

 fertilized ponds without the use of forage minnows. They also indi- 

 cate that the construction of separate ponds for the production of 

 daphnia are not necessary. As a matter of fact the pond supplied 

 with daphnia from another pond gave the poorest results of the 

 three, but of course no general conclusion can be drawn from such a 

 small number of experimental ponds. 



TROUT CULTURE 



Feeding experiments. — During the summer of 1932 feeding experi- 

 ments were conducted at the Pittsford (Vt.) station under the direc- 

 tion of R. F. Lord as in previous years. Fish were also carried on 

 experimental diets at the new hatchery at Leetown, W.Va., under 

 the direction of E. W. Surber. Unlike the experiments at Pittsford 

 those at Leetown will be continued through the winter. At Pitts- 

 ford brook trout were used in most of the experiments with finger- 

 lings, while at Leetown the majority of the experimental lots contained 

 rainbow and brown trout. Experiments with yearling rainbow trout 

 in out-door raceways were also carried on at Pittsford. 



As in previous experiments, dry salmon-egg meal proved to be 

 superior to any dry product now available for fish food. All diets 

 containing this product gave a very rapid grow^th and the fish w^ere 

 exceptionally vigorous and well proportioned. As emphasized in 

 previous reports they also exhibit the brilliant coloration character- 

 istic of w41d fish. These experiments show conclusively that the use 

 of the better dry products in the diet of trout will give better results, 

 both as regards growth and vigor, than can be obtained with any of 

 the straight meat diets. Furthermore, they are in general more eco- 

 nomical, since it requires a considerably smaller amount of food to 

 produce the same growth when animal meals are included in the diet. 



The results of the experiments with yearling rainbow trout agree 

 closely with those obtained with fingerling brook trout. In most 



