GRAYLING SPAWNING REPORT 



Other authors have noted thxs type of annual rnxgraticn 

 pattern in other riverine grayling populations. The following 

 discussion of grayling movements in Alaska systems is taken from 

 Armstrong (1986). He summarized the reasons for these "complex 

 migrations to overwintering, spavNining, and feeding sites" to be 

 "adaptions to different systems or differemc parts of the same 

 system" which "enables the young [which "emerge early and develop 

 rapidly"] to leave systems before they become frozen and 

 uninhabitable in winter." He further states that "entire 

 populations of grayling migrate downstream and out of certain 

 tributaries and enter" main stem rivers for the winter. These 

 populations leave streams which dry up or freeze solid, but also 

 leave spring— fed streams. In conversations with Steve Tack 

 (Fairbanks, Alaska) Armstrong and Tack speculated that the reason 

 grayling leave these spring-fed streams is that these streams 

 often have extensive frazil ice in winter. Armstrong also states 

 that in larger unsilted rivers in Alaska (the iSig Hole would most 

 closely resemble these systems) most grayling inhabit the upper 

 reaches during the summer and migrate down stream to overwinter 

 in the deeper water of the main stem. 



The majority of these Alaska populations begin this down 

 stream movement in September, similar to the time Big Hole 

 grayling population moved down river from the upper basin in 

 previous normal flow years. Grayling in Alaska were found to 

 migrate from a tew miles up to iOO miles to reach overwintering 

 habitat. In these unsilted Alaska rivers grayling use different 

 portions of the system during the summer depending upon their age 

 and maturity. Young— of —the— year tended to remain near areas 

 where they emerged, usually m the upper reaches of the system. 

 Juveniles (ages I, II, and III) used the lower portions oT the 

 rivers and their tributaries. Adults either moved upstream to 

 feed in the upper reaches of the rivers, or if they spawned in 

 the upper reaches, remained there throughout the summer. The 

 grayling in Alaska were found to return annually to feeding areas 

 and it was suggested that they probably show similar fidelity to 

 spawning sites. 



Hubert et al.'s (1985) review documented the same types of 

 migration patterns and clarified the following. Downstream 

 migration to wintering areas was found to occur when water 

 temperatures approached 32 F (Yoshihara 1972). All ages of 

 grayling moved downstream to overwintering areas in large streams 

 and rivers during late summer and fall (Yoshihara 1972; Kratt and 

 Smith 1977; Tack 1980). Wintering areas included pools of 

 intermittent and flowing streams, as well as spring-fed tog 

 streams (Craig and Poulin 1975) which did not freeze to the 

 bottom during winter months ( Krueger 1981). 



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