360 U. S. BUREAU OF FISHERIES 



the bureau has taken steps to cooperate with various fishing clubs and 

 other organizations in rearing both bass and trout to the larger 

 fingerling sizes before supplying them to applicants or liberating 

 them in public waters. 



ROCKY MOUNTAIN TROUT STATIONS 



Fish-cultural operations at this group of eight stations and sub- 

 stations are confined to the various species of trout found in the 

 mountain streams and lakes of the Rocky Mountain region. The 

 species to which special attention was given during the year were the 

 brook, rainbow, black-spotted, and Loch Leven trouts, while at one 

 of the stations grayling were handled in comparatively small 

 numbers. 



Bozeman (Mont.) Station and Substations 

 [W. T. THOMrsoN, Superintendent] 



The cooperative relations heretofore maintained with the Montana Fish 

 and Game Department were continued throughout the year. The exchange 

 of fish eggs on a large scale between the station and the State is proving 

 mutually beneficial and economical. Were each organization compelled to 

 maintain fields for the collection of the species exchanged, the expense of 

 conducting the work would be materially increased. 



Bozeman (Mont.) station. — During the excessively warm weather experienced 

 in July a severe outbreak of Octomitiasis occurred among the brook-trout finger- 

 lings carried over from the stock of the previous fiscal year, and about 165,000 

 perished before the disease could be checked. During December and January 

 1,569,500 eyed brook-trout eggs were acquired, of which 270,000 were donated 

 to the station by the Southside Sportmen's Club of Oakdale, N. Y. Part of 

 the fry hatched from this stock of eggs were distributed during the spring, 

 and about 620,000 were on hand in the fingerling stage at the end of June. 

 Large numbers of rainbow, black-spotted, and Loch Leven trout fingerlings 

 were being carried at the beginning of the year, together with a small number 

 of landlocked salmon. In advance of the distribution period these fish were 

 attacked by the same disease that occurred among the brook trout and heavy 

 losses resulted. In addition to a small number of eggs obtained from the 

 station brood stock of rainbow trout. 624.000 eyed eggs of that species were 

 transferred to the station from the Meadow Creek field. At the close of the 

 year the young fish produced from these eggs were being reared for later distri- 

 bution. 



During January and February 1.796,000 eyed Loch Leven trout eggs were 

 transferred to the Bozeman hatchery from the Meadow Creek auxiliary. 

 All of these, with the exception of 41,000 retained at the station, were imme- 

 diately repacked and shipped, some to applicants and some in exchange 

 for eggs of other species. The entire stock of 1,554,000 black-spotted trout 

 eggs handled was received from the Montana Fish and Game Department, 

 the eggs having been collected during May and June near Georgetown, Mont. 

 On reaching the eyed stage 500,000 were shipped to the New Mexico Fish and 

 Game Department and 325,000 were used for stocking mountain lakes in 

 Montana. The remainder were incubated in the hatchery. 



Meadow Creek (Mont.) substation. — Soon after the collection of the first 

 Loch Leven trout eggs of the season on October 13 unfavorable weather set 

 in, which delayed further operations until about the middle of November, 

 at which time a large run of fish appeared in the stream. Between November 

 15 and December 8, 12,220.000 eggs of this species were taken, establishing a 

 new record in the work of the substation. For some unknown reason the 

 losses of eggs were large during the incubation period, the percentage of hatch 

 being only 72%, as compared with 90% per cent hatched the preceding year. 

 The rainbow trout began spawning on April 12, somewhat later than usual 

 and between that date and May 19, 2,698,000 eggs were taken. Though consid- 

 erably smaller than the collection in 1925, the quality of the eggs was far 

 superior, the number brought to the eyed stage amounting to 92 per cent of 



