Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
of adults were detected in the lower Nechako and Willow rivers in mid-October. Many of these fish were
close to spawning. Five such fish were radio-tagged in the lower Nechako and eight fish near spawning
(males running milt) were radio-tagged in the mainstem Fraser. These radio-tagged fish were followed until
freeze-up (late November). Two of the Nechako fish made micro-movements (a few 100 m) but stayed in
the aggregation area. Three Nechako fish moved downstream in the Fraser where they stayed for several
days and then moved downstream in fits and starts (e.g., they would hold position for a few days and then
suddenly move 15 km, stop and hold position again, and then suddenly make another spurt of movement).
The maximum tracked downstream movement of these Nechako fish was 50 km. The radio-tagged Fraser
fish showed a similar pattern of movement: hold for a few days, then move 10 - 20 km downstream and hold
again. All of the radio-tagged fish that moved, moved downstream. It is not clear if this was a spawning
migration or if the tags were too large and the fish were slowly losing ground.
For adults, it was not clear how much mixing there was between the major tributaries and the main river.
There was a scale signature (a false annulus) that was only found in mainstem fish. However, not all fish
sampled in the mainstem showed this scale mark. So far, the data suggest some fish move from the
tributaries into the main river and some stay in the tributaries. We took tissue samples (adipose fin clips)
from all adult fish and are using single locus probes to ascertain if there are genetically different stocks in
this area.
Another problem with adults that is being examined is the presence of two “forms” of mountain whitefish in
the area: a long-nosed “pinocchio” form and a normal form. The pattern of head growth in the two forms
starts to diverge at about 80 mm and becomes more exaggerated with size. It looks like a foraging
polymorphism and we collected paired samples (collected at the same site and same time) of both types.
These are being examined for both trophic and genetic differences.
Other Species
During the course of collecting whitefish data, information was also collected on the movements of redside
shiners, squawfish, peamouth chub and suckers. The general pattern of movement that appeared in these
animals was a spawning movement into tributaries in the spring, use of the lower reaches of tributaries by yo-y,
movement into the main river in September, and then movement to a winter refuge (deeper water?) in
October.
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