FISH 

 f Beaver Creek 



Species Composition and Distribution 



A total of 30 species of fish were collected in Beaver Creek. Estimates 

 of the relative abundance of each species was based mostly on the actual 

 numbers counted, and to a lesser degree on the frequency of occurrence 

 in collections. Those species occurring in half or more of the samples 

 were considered abundant, in more than a third of the collections but 

 less than half, are comnon; in more than a tenth, but less than a third, 

 are unconmon; and in fewer than a tenth, rare. A list of the fish and their 

 distribution in Beaver Creek for 1977 and 1978 are shown in Figures 13 

 and 14. A kite diagram (Figure 15) shows the distribution and relative 

 abundance of major species in the creek. 



Three species of fish, fathead minnow IPimcphalu pnomclciii] , creek 

 chub {Se:mpt-iiLU> (it^omacu^attit,) and white sucker {Cato.stcmnA cormeAioni] 

 are widely distributed throughout the Beaver Creek system. Fathead minnows 

 and white suckers are cormionly distributed in other small eastern Montana 

 streams. Elser and Schrieber (1978) found white suckers throughout Rosebud 

 Creek and Clancey (1977) found white suckers and fathead minnows to be 

 the two dominant species in Sarpy Creek. 



The creek chub, while native to Montana, maintains a limited distribution; 

 being restricted to the Yellowstone and Little Missouri River systems in 

 the extreme east-central portion of the state. It is considered quite rare 

 in Montana (Brown 1971). In Wyoming, the creek chub is common throughout 

 many drainages, inhabiting small streams (Baxter and Simon 1970). The creek 

 chub is also comrtion in Missouri, preferring small streams which cease to 

 flow in dry weather (Pflieger 1975). Beaver Creek appears to meet habitat 

 requirements for the creek chub, which do not thrive in streams that maintain 

 strong flows. A length frequency distribution of 390 creek chubs collected 

 from Beaver Creek in 1978 is shown in Figure 16. Fish ranged in length 

 from 30 to 218 mm . Prior to this study, the largest specimen reported 

 in Montana was 147 mm (Brown 1971). The dominant size group was from 

 41 to 70 mm, making up 43.6 percent of the sample (170 of 390). 



Several other species found in Beaver Creek also have limited distributions 

 in Montana. The sand shiner [Motfiopli itiaminuiA) is described as a hardy 

 species (Scott and Crossman 1973) which is able to withstand highly variable 

 flows (Summerfelt and Minckley 1969). Erratic flows are comon in Beaver 

 Creek and the sand shinner is common throughout the drainage. 



The brook stickleback {Cuiaca incomtam) is native to Montana, but 

 is limited to the eastern part of the state, found primarily in tributaries 

 of the Missouri River. While the stickleback is considered tolerant of 

 high salinities comon in intermittent streams (Nelson 1968), its preferred 

 habitat is small, clear streams rich in aquatic vegetation. Distribution 

 of stickleback in Beaver Creek was limited to the upper reaches (above station 74) 

 which meets its habitat requirements. 



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