GRAYLING SPAWNING REPORT 



INTRODUCTION 



The last riverine (fluvial) native population cf Montana 

 Arctic grayling ( Thymallus arcticus montanus QMilner]) in the 

 contiguous 48 United States exists in the upper Big Hole River of 

 southv'jestern Montana (Liknes and Gould 1987). The historic range 

 of the fluvial grayling in the lower 48 states included most of 

 the upper Missouri River basin above Great Falls and northern 

 Michigan. The Michigan populations were extirpated around 1936 

 (Hoi ton 1971; Scott and Grossman 1973). The distribution of 

 fluvial grayling in Montana has progressively been reduced 

 (Henshall 1906; Vincent 1962) until now the Big Hole River 

 supports the only true fluvial population in the state. A 

 population inhabiting a canal system (Sunnyslope Canal within the 

 Sun River drainage) and a remnant population in the Madison River 

 above Ennis Lake exist, however, the status of these populations 

 are likely dependent upon reservoirs within their systems (Bill 

 Hill, MDFWP, Choteau and Dick Vincent, MDFWP, Bozeman, personal 

 communication). This dramatic reduction in range has led to the 

 designation of the fluvial grayling as a "species of special 

 concern" by the Endangered Species Committee of the American 

 Fisheries Society (Johnson 1987), the Natural Heritage Program, 

 and the (Montana Department of Fish, Wildlife and Parks ( t-IDFWF ) , 

 as a "sensitive species" by the U.S. Forest Service, Northern 

 Region (files, USDA Forest Service, Northern Region, Missoula, 

 Montana), and a Category 2 species under consideration for ESA 

 listing by the Fish and Wildlife Service (Federal Register). 



Electrophoretic analyses conducted on seven Montana grayling 

 populations (Grebe Lake, Lake Agnes, Rodqers Lake, Elizabeth 

 Lake, Fuse Lake, Sunnyslope Canal, and the Big Hole River) and 

 one Alaska population (Chena River) found that the lake popula- 

 tions were not greatly divergent from each other (Everett and 

 Allendorf 1985). These authors found the Big Hole River, Chena 

 River and Sunnyslope Canal populations were more different from 

 the lake populations than from each other. Both the Big Hole and 

 Chena populations are fluvial populations. The origin of the 

 Sunnyslope Canal population is unknown, however, the most 

 reasonable theory about their genetic make-up is that these fish 

 undergo intense selective pressures because they live in a canal 

 where ail movement must be down stream and the canal is dewatered 

 every fall. The above authors implied that the Big Hole River 

 population has maintained its native fluvial genotypes even 

 though adfluvial (]a!:e) stocks may have been planted :;.n the iiig 

 Hole River during the rriid-1900' s. 



The MDFWP has attempted to fr.onitor the abundance of the Big 

 Hole River grayling population since the mid-1970's. Resulting 

 data indicated a relative decline in abundance which prompted 



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