Table 5 . — Estimated returns of planted adult rainbow trout to the 

 fishermen from the Madison River in 1954 and from the Madison 

 and Gibbon in 1955. Number of fish caught includes those caught 

 in Madison, Gibbon 1, and Firehole I. 



Plantings 



Number of fish caught 



Stream Dates Number Total 1954 



length 

 in inches 



1955 



1956 All 

 and years 

 1957 



Madison 6-13 to 24,792 10-12 



and Gibbon 7-24, 1955 



12,828 12,828 



Percentage 

 recovery 



Madison 6-15 to 25,006 8-10 8,130 170 8,300 33.2 



7-17, 1954 



51.7 



Total 



49, 798 



8,130 12,998 21,128 



42.4 



Below Biscuit Basin in the Firehole River 

 both brown and rainbow trout were common at 

 all stations sampled, althou^ reliable estimates 

 of the total populations could not be made . A 

 total of 1,062 catchable-size brown trout and 103 

 catchable-size rainbow trout were collected per 

 mile of stream at all seven stations . Age Class 

 brown trout were also present in most stations 

 (table 8), but were most abundant above Nez 

 Perce Creek, where the best spawning gravel 

 was present. Rainbow trout young-of -the -year 

 were most abundant in the middle section of the 

 Firehole River around Midway Geyser. In 

 shallow sections of stream with fast riffles, 

 such as Station F, the number of Age Class 

 rainbow exceeded the number of Age Class 

 brown trout. Rainbow trout were not as abun - 

 dant as brown trout in stream sections with a 

 large inflow of warm water from geysers or hot 

 springs. Gradient, however, was greater in 

 sections where rainbows were abundant and 

 could have influenced the numbers of rainbow 

 trout as much as could thermal water inflow. 



Madison River 



Our fish population information in the 

 Madison River was limited to that collected by 

 the electric seine; this represented only a small 

 percentage of the total population . Brown trout 

 was the most abundant species in the Madison 

 River, although rainbows were more common in 

 the Madison than in the Firehole (table 6). Age 

 Class brown (ages determined from table 7) 



and small rainbow were collected at all stations 

 but were most abundant in shallow water riffles 

 of moderate gradient. The total number of 

 catchable-size trout and whitefish collected at 

 the seven stations per mile of stream was: 

 brown, 271; rainbow, 21; and whitefish, 72. 



The Madison River meanders in open 

 meadow areas of low gradient, and deep (6 to 10 

 feet) holes are washed out under the banks . 

 These areas often harbored catchable-size 

 browns and rainbows. Large whitefish were 

 collected most commonly in fast, deep (3-10 

 feet) water in the middle of the stream . Brown 

 trout were most numerous in sections of the 

 stream with abundant rooted aquatic plants . 

 Rainbows were most numerous on fast riffles 

 with a small amount of cover such as occasional 

 boulders or logs . Many large whitefish and 

 brown trout were collected or observed in deep 

 holes in the lower section of the river. Young- 

 of -the -year whitefish were collected downstream 

 from the highway bridge (Station M). Sculpins 

 and longnose dace were common on all sections 

 of the stream, but were most abundant on fast, 

 shallow riffles and were associated with Age 

 Class brown and rainbow trout. 



GROWTH RATES OF WILD FISH 



Firehole River 



Brown trout in the Firehole River were 

 growing rapidly during all years of the investiga- 



14 



