INTRODUCTION 



The Arctic grayling population of the upper Big Hole River 

 and its tributaries is probably the last riverine population of 

 this species in the lower 48 United States (a small remnant 

 population possibly inhabits the upper Madison River, Montana) . 

 Reasons for the current decline of Big Hole River grayling have 

 not yet been adequately determined. Liknes (1981) proposed 

 overharvest, dewatering, and competition with brook trout 

 ( Salvelinus fontinalis ) as probable factors contributing to the 

 decline. Severe drought conditions during the summers of 1988 

 and 1989 undoubtedly contributed to the decline as well. In 

 September of 1989, a linear density of 338 grayling (YOY and 

 adult) per mile occurred in the river (R. Oswald, pers. comm.). 



In 1988, the Montana Natural Heritage Program, the Montana 

 Department of Fish, Wildlife and Parks, the Bureau of Land 

 Management, the U.S. Forest Service, and the Montana Cooperative 

 Fisheries Research Unit initiated a study of the habitat 

 requirements and habits of the Arctic grayling in the upper Big 

 Hole River near Wisdom, Montana. Research has emphasized 

 distribution and habitat use of YOY grayling (Skaar 1988) and 

 interspecific competition for food between Arctic grayling and 

 introduced brook trout (McMichael 1989) . Specific objectives of 

 this summer's research included: 



