GRAYLING SPAWNING REPORT 



SPAWNING SITE CHARACTERISTICS 



We found Big Hole grayling spawning over gravel that was 

 very clean on its surface. Spawning occurred in riffle areas in 

 close proximity to pool or deep run habitats. Most previous 

 investigators have found that grayling spanned in riffles or in 

 transition zones between riffles and pools (hlershall 1907; Rawson 

 1950; Nelson 1954; Bishop 1971). Eggs and spawning have 

 generally been found on gravel and not on mud, silt, sand, or 

 clay substrates (Henshail 1907; Rawson 1950; Nelson 1954; Warner 

 1955; Bishop 1971; Tack 1971; Tack 1973; Kratt and Smith 1977), 

 however, Bi^ovMn (1938) found the Agnes Lake, Montana spawners 

 spawning over silt and sand at a ratio of 3:1 in the inlet, 

 Curtis (1977) found grayling from Wyoming lakes in inlet and 

 outlet streams spawning over a sand/ fine gravel substrate, 

 Bendock (1979) found a lake population of grayling spawning over 

 a wide variety of material from large rubble to vegetated silt 

 within the lake. Reed (1964) found grayling spawning over mud in 

 a side slough, and Tack (1980) found grayling spawning on sedges 

 m a stagnant pond. To summarize, it appears that lake popula- 

 tions of grayling may have adapted to spawning over fine 

 material, while river and stream populations generally spawn over 

 gravel in riffle areas. There has been little work done to 

 evaluate spawning success in different substrate conditions. 

 This question should be addressed in future research. 



STATUS OF POPULATION AND ENHANCEMENT FEASIBILITY 



We will give a brief assessment of our opinion on the 

 present status of the riverine grayling population in the Big 

 Hole River system and briefly explain recent attempts directed at 

 enhancement of this population. We will also briefly discuss the 

 problems which will likely be associated with attempting to re- 

 establish riverine populations of grayling into other waters m 

 the state. The following is speculation based on observation and 

 a review of the literature. 



The riverine population which exists in the upper Big Hole 

 River system above Divide, Montana appears to be a single 

 population and at least a portion of this population uses the 

 entire upper river system on a seasonal basis. This population 

 is presently at a low level and the recent trend (from 1983 to 

 the present) has been a declina (Oswald m prep.). Year class 

 strengths and weaknesses appear to be linked to river flows with 

 below average flows producing weak year classes and normal a^-^d 

 slightly above average flows producing strong year classes. 

 Ironically, it appears that flows which B.re way above average 

 may also produce weak year classes. Grayling £ire notoriously 



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