BUREAU OF FISHERIES XXVII 
and studies on the environment of the fishes in Lake Erie. ‘The State 
of Ohio will provide investigators to carry on a series of biological 
studies on the conditions of fish life in the lake. The bureau’s staff, 
working in cooperation, will study the biological aspects of commer- 
cial fishing. In addition to these studies, the economic aspects of the 
regulation of fishing gear and the type of legislation required to 
restrict abuses in the fishery will be considered. The State depart- 
ment of agriculture, division of fish and game, will furnish and 
operate a vessel for the conduct of this work. 
PATHOLOGY AND EXPERIMENTAL FISH CULTURE 
Three important lines of investigation are being followed in the 
field of aquiculture—(1) pond culture of warm-water fishes, (2) ex- 
perimental trout culture, and (3) pathology of fishes. Experiments 
in the production of basses and other food fishes of the Mississippi 
River region have been carried out in the ponds at the Fairport 
biological station in an attempt to increase the food supply through 
fertilization of the waters and to increase the production of fish 
through proper handling of the fish themselves. Detailed chemical 
and biological examinations of the ponds are carried on throughout 
the growing season to determine the conditions most favorable to fish 
growth; and an attempt is being made to develop a measure of pro- 
ductiveness by which natural pond and swamp areas throughout the 
country may be determined, so that those suited for the production of 
fish may be stocked and conditions in others improved. Experiments 
in producing forage fish, such as the black-head minnow, have been 
markedly successful, and the advisability of using forage fish as food 
for bass was clearly evidenced by a considerably increased yield of 
healthy fish. Through cooperation by the division of fish culture, 
arrangements were made to begin the pond-cultural experiments on a 
jarger scale at the Neosho (Mo.) fish-cultural station; and in addi- 
tion to cultivating largemouth bass, experiments in the rearing of 
smallmouth bass and trout were undertaken here in the spring of 
1927. 
The work at the Holden (Vt.) experimental fish hatchery has been 
devoted to the solution of problems arising in the culture of several 
species of trout. Feeding experiments have been conducted for sev- 
eral years, in which the value of various diets for trout fry has been 
determined. In an attempt to develop a superior brood stock, selec- 
tive breeding experiments have been undertaken. <A stock of select 
brood trout has been secured from various places and tagged for 
future identification. The eggs from the various types of fish were 
segregated and the young reared in separate pools. It is believed 
that such qualities as rapidity of growth, strength and vitality of 
young, resistance to disease, and fecundity can be improved materially 
in hatchery-reared trout. The capacity of the experimental hatchery 
at Holden has been increased by additional ponds and raceways, and 
the whole station has been brought up to a high level of efficiency. 
Closely related to the work on pond culture and experimental trout 
culture is the study of fish diseases. Heavy annual mortality at the 
Holden station has been overcome through treatment of diseases and 
parasites, and a study of the cestodarian parasites of bass has been 
undertaken at the Fairport station and at the Neosho (Mo.) hatchery. 
