714 U. S. BUREAU OF FISHERIES 
to the point where it is largely self-sufficient for its supply of rainbow, 
Loch Leven, steelhead, and lake trout, and landlocked saimon, 
but the satisfaction of the requirements for brook trout still remains 
a problem. The commercial hatcheries supply this demand, but 
the States are filling their needs from the same source, and the 
supply of good eggs is often inadequate and always expensive. Once 
the eggs are secured and hatched, the question of space for rearing 
arises. This is in process of solution through the system of cooper- 
ative rearing heretofore referred to and through physical expansion 
of the stations. 
In one sense, the culture of pondfishes is not artificial propagation; 
it is merely the provision of optimum conditions for the natural 
reproduction of the species. It is subject, therefore, to the same 
checks and limitations, such as unfavorable weather conditions, 
etc., that apply in a state of nature. The chief limiting factor is the 
lack of pond space and the difficulty of obtaining a satisfactory brood 
stock. The various stations are creating new ponds and enlarging 
present ones as fast as possible, and provision has been made for the 
establishment of four new pond stations. Until these are placed 
on a productive basis there probably will be a considerable “carry 
over” of unfilled applications annually. 
ROCKY MOUNTAIN TROUT STATIONS 
These stations, in addition to propagating brook, rainbow, Loch 
Leven, and black-spotted trout for stocking the waters of the region, 
constitute a source of supply for eggs of these species to be trans- 
ferred to eastern stations. While there are eight main stations, the 
operation of a number of subsidiary egg-collecting fields influences a 
wide territory. The maintenance of good fishing in the national 
parks and national forests is an important function of these stations. 
BozEMAN (Monvt.) STATION AND SUBSTATIONS 
[W. T. THompson, Superintendent] 
This station reports the greatest output since its establishment. A grand 
total of 32,190,960 fish and eggs handled sets a very high mark for game-fish 
production. 
Bozeman (Mont.) station—Continuation of cooperative relations with the 
State of Montana has been an important factor in making 1927 a banner year 
at this station. In return for furnishing 2,370,200 Loch Leven and 150,000 
rainbow eggs, the bureau received 3,221,050 grayling eggs for cooperative planting 
in waters in which both agencies were interested. In addition, the State fur- 
nished 3,941,780 black-spotted trout eggs, 2,000,000 of which were to be repaid 
from later Yellowstone Park collections; the remainder were for planting on @ 
general cooperative basis. The early receipt of black-spotted trout eggs to be 
replaced by later park collections is of great assistance to the bureau, as it per- 
mits distribution before the cars are needed on the Mississippi River and permits 
a shorter season in Glacier National Park. 
Brook-trout eggs were received by transfer from the Leadville station and from 
outside sources. While losses in incubating and rearing some of these lots were 
unduly high, there was less evidence of an outbreak of Octomitiasis, which usually 
accounts for a heavy mortality in the spring. A cold, late season and the pro- 
vision of plenty of space delayed any evidence of the trouble until near the close 
of the fiscal year. It is hoped that plans for early distribution will minimize 
any further losses from this cause during the present summer. One-half the 
fingerlings on hand at the opening of the year were lost during the summer and 
fall of 1926. The matter will require detailed study before a remedy can be 
prescribed. Some 430,000 brook-trout fingerlings and between 1,100 and 1,200 
yearlings and adults were on hand at the close of the fiscal year 1927. 

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