1990 Grayling Spawning Report 



history patterns followed by Big Hole River grayling. One segment 

 of the population may move seasonally between the lower and upper 

 river and one segment may remain in the upper and/or lower river 

 year round. 



Tag return evidence from one tagged fish also suggests that 

 Big Hole River grayling use the lower portion of Swamp Creek for 

 spawning. We infer from movement exhibited by this fish that it is 

 likely that grayling populations in the lower portions of Steel, 

 Swamp, Big, and Rock creeks are probably very similar, if not a 

 direct subset, of the Big Hole River population. We believe it is 

 likely that grayling populations within the lower portions of Big 

 Hole River tributaries receive enough genetic transfer with Big 

 Hole River grayling that grayling in these tributaries should be 

 considered as members of the Big Hole River grayling population. 



We are unsure of the status of isolated grayling populations 

 inhabiting the upper portions of tributaries such as Mussigbrod 

 Creek, upper Wise River, and Wyman and Bobcat creeks. We believe 



that these populations originated with outmigranta from lake 



populations, but are unsure how long they have been genetically 

 isolated and the result of potential genetic isolation and 

 adaption. 



SPAWNING HABITAT CHARACTERISTICS 



We found ripe Big Hole grayling over gravel that was very 

 clean on the surface located in riffle areas in close proximity to 

 pool or deep run habitats. This observation made in 1988 was 

 further substantiated in 1989 by classifying substrate composition. 

 Ripe grayling also appeared to seek areas where water velocities 

 were faster and water was deeper than was generally available 

 (Figures 6 and 7). 



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