and brown trout fingerlings and rainbow adults 

 and the regulation of fishing dates and catch 

 limits . 



The Firehole, Madison, and Gibbon 

 Rivers are described generally from physical, 

 chemical and biological standpoints . Hot springs 

 and geysers entering the Firehole River do not 

 appear to restrict the number of brown and rain- 

 bow trout. 



Stocking experiments were designed to 

 test the value of fingerling and adult trout stock- 

 ing. Of the 48,216 rainbow fingerlings planted, 

 only 78 (0.16 percent) were caught; none of the 

 29,249 brown trout fingerlings planted were 

 found in the catch . In adult stocking experiments 

 about 40 percent of planted fLsh, 25,006 in 1954 

 and 24,792 in 1955, were marked by fin clipping. 

 From the 1954 plants 8,300 were caught; from 

 the 1955 plants 12,128 were caught. It was 

 originally assumed that the ratio of marked to 

 unmarked fish in the plantings would persist in 

 the catch, but a different ratio was found. Ex- 

 amination of scales showed that hatchery fish 

 could be easily distinguished from wild fish. 



The number of fishing trips on the 

 Madison River system was: 1953, 19,504; 1954, 

 27,233; 1955, 23,477; 1956, 24,293; and 1957, 

 25,599 (not including Gibbon). Fishing pressure 

 increased when adult rainbows were planted in 

 the Madison and Gibbon Rivers . 



trout were eight inches long by June of their 

 second year . Whitefish were also growing 

 rapidly. No differences in growth rates of wild 

 fish could be discerned among different calendar 

 years when stocking rates were changed. The 

 catch of brown trout in both the Firehole and 

 Madison was composed principally of fish in 

 their third and fourth years, while rainbow 

 trout were most commonly caught in their 

 second and third years. The whitefish catch 

 represented older age classes. 



There was no evidence of heavy exploita- 

 tion of brown trout, but there was some evidence 

 of high exploitation of rainbow trout . 



Neither wild brown nor rainbow trout 

 populations appeared to be adversely influenced 

 by heavy planting of fingerling brown and rain- 

 bow trout or by adult rainbows . 



Faulty conclusions may result from mark- 

 ing experiments when only about 40 percent of 

 the adults are marked by fin clipping. In such 

 studies it would be most desirable either to mark 

 all planted fish or use the scale method to cal- 

 culate returns. 



Future management in these streams 

 should emphasize the use of wild brown and 

 rainbow trout. 



LITERATURE CITED 



Wild rainbow catches in the Madison and 

 Firehole Rivers have remained relatively stable 

 in spite of the large number of fingerlings and 

 adults planted. Wild brown trout catches in- 

 creased with heavier fishing pressure due to 

 adult rainbow stocking on the Madison, but not 

 on the Firehole . 



Fish population studies were conducted 

 in September, 1957, with an electric shocker 

 in the Firehole and Madison Rivers. Age Class 

 and catchable-size brown trout were very 

 abundant; Age Class and catchable-size rain- 

 bows were common in both streams. White- 

 fish were common in the Madison River. 



Wild adult brown and rainbow trout in 

 both the Madison and Firehole Rivers were 

 growing rapidly at about the same rate . Brown 



Allen, K. Radway 



1951. The Horokiwi stream, a study of a 

 trout population . New Zealand 

 Marine Dept., Fish Bull. No. 10, 

 231 pp. 



Armitage, Kenneth Barclay 



1954. The comparative ecology of the 



riffle insect fauna of the Firehole 

 River, Yellowstone National Park, 

 Wyoming. Ph.D. Dissertation, 

 University of Wisconsin, 54 pp. 



Brown, C.J.D. and Gertrude C. Kamp 



1942 . Gonad measurements and egg counts 

 of brown trout ( Salmo trutta ) from 

 the Madison River, Montana. Trans. 

 Amer. Fish. Soc, 71:195-200. 



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