. The Canadian field-naturalist. 178 The Canadian Field-Naturalist Vol. 106 123''i 40' W. • sampling site 0 5 10 123°| 40' W Figure 3. Liard River study area. Mature males appear to continue to move upriver in small numbers through late September (Dillinger 1989), although the vast majority of fish have already proceeded well upriver and can be found in the region of the confluence of the Peel and Snake Rivers (D. Charley, personal communication 1985). These late-season smaller males probably do not contribute, to any appreciable extent, to the spavi'ning population. The presence of these fish
. The Canadian field-naturalist. 178 The Canadian Field-Naturalist Vol. 106 123''i 40' W. • sampling site 0 5 10 123°| 40' W Figure 3. Liard River study area. Mature males appear to continue to move upriver in small numbers through late September (Dillinger 1989), although the vast majority of fish have already proceeded well upriver and can be found in the region of the confluence of the Peel and Snake Rivers (D. Charley, personal communication 1985). These late-season smaller males probably do not contribute, to any appreciable extent, to the spavi'ning population. The presence of these fish does suggest a different life history picture than that seen in the Arctic Red River. Arctic Red River The Arctic Red River stock has more variable run timing. This river may contain a "split" spawning run, two or more distinct, large pulses of upstream migrants. Hatfield et al. (1972*) reported fish in the river in late June 1971. Fish were captured 40 miles upriver in July 1987 and six miles upriver in July 1988 (Dillinger 1989, Sekerak 1989*). Males and females in spawning condition have also been cap- tured at the mouth of the river in mid-September to early October (Nelson et al. 1987*; DiUinger 1989). Local residents who fish for "herring" look for them both at this time of the year, and in December when nets are set under the ice to catch them on their downstream migration (S. Lennie, personal commu- nication 1985). There are three possible explanations for these observations (1) the presence of two annual spawn- ing runs or two distinct stocks, (2) a run which varies greatly among years in its timing, and (3) a run which extends throughout the summer. The third possibility appears unlikely based on the data col- lected by Hatfield et al. (1972*), and on sampling conducted near the mouth of the Arctic Red River in 1987 by Memorial University. The periods of time which passed during which no fish were caught in both of these studies suggest that th
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