PROGRESS IN BIOLOGICAL INQUIRIES, 1939 1D 
agement. While there is a limit to the production of fish in any body 
of water, it is probable that, in many cases at least, the yield of game 
fish can be materially increased. Investigations have shown that 
present methods of stocking and other practices often fail to produce 
the results expected, and it is evident that much remains to be done 
before fish management can be established on a sound basis. 
These problems are being attacked along three principal lines. 
One deals primarily with the artificial propagation and rearing of 
game fishes; a second with the parasites and diseases of fish, es- 
pecially those prevalent at hatcheries and which frequently seriously 
curtail the output; and a third line of investigation is concerned with 
field problems relating to fish management, such as comparative 
survival and growth of hatchery and wild fish under natural condi- 
tions, the ecological requirements of different species of game and 
food fishes, and the possibility of increasing fish production in natural 
waters. 
In the interest of greater efficiency, the headquarters of the Aqui- 
cultural Investigations was moved to the experimental hatchery at 
Leetown (P. O. Kearneysville), W. Va., in the spring of 1939. This 
station, operated primarily for experimental work with both trout 
and warm-water fishes, also has adequate laboratory facilities, and 
hence affords an excellent opportunity for studies related to hatchery 
operations. 
TROUT 
Investigations on trout have been concerned chiefly with field 
studies of the results of artificial stocking and other problems re- 
lated to fish management, with the development of cheaper and better 
diets for hatchery fish, and with selective breeding for the purpose 
of developing strains that are superior to those ordinarily found 
at hatcheries. 
Feeding experiments—Feeding experiments were continued at the 
Leetown Station by Dr. J. S. Gutsell. These experiments were de- 
signed primarily to develop better methods of feeding animal meals, 
since previous work had shown that these products, ‘when combined 
with fresh meat, make an excellent and economical diet for trout. 
It was found that under ordinary conditions it is not advisable to 
use more than 50 percent dry meal in the diet. While trout can sub- 
sist on diets containing considerably larger amounts of meals, the 
meals are utilized less efficiently and there is considerably more waste 
in feeding. The rate of growth of trout on those diets is materially 
increa ased by the addition of small amounts of either cod-liver oil 
or kelp meal and is increased still further if both are included in 
the diet. 
Experiments designed to show the effect of food on the quality 
of trout eggs have confirmed the belief of many fish-culturists that 
overfeeding is distinctly detrimental, since a larger percentage of 
the eggs fail to hatch. To produce eggs with the greatest hatcha- 
bility, at the lowest cost, the fish should be fed a well-balanced diet 
in moderate amounts. 
Experiments at Leetown, and at Hackettstown, N. J., in coopera- 
tion with the New Jersey Fish and Game Commission, have shown 
conclusively that frozen fish, when fed continuously in considerable 
