Skykomish Draft Final Report - Wild Fish Conservancy

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flow system also contained significantly more fish (i.e. higher average count of all fish species within pools) during the summer than either the spring brook or mainstem (t-tests: d.f.=23, 32; P
and overall was comprised of three fewer species of salmonids than the summer population (Tables 5, 6). Chum salmon succeeded Chinook as the most prevalent adult anadromous fish (Fig. 11A,B). In addition, the ratio of juvenile-to-adult trout and salmon observed in pools fell from approximately 10 to 0.01 over this period, reflecting a pronounced change in life historystage usage of the mainstem during the day. Snorkel survey data collected during summer and winter 2004 in side channel network SCC highlights additional seasonal variation in fish relative abundance, diversity, and age class structure. Mean daytime fish counts in surface-flow and spring-brook side channel pools showed a significant decrease between the two survey seasons, a pattern also observed in mainstem pools between summer and fall (Fig. 22A). The daytime winter population in side channel network SCC lacked five species observed in the summer (rainbow and cutthroat trout, sculpin, largescale sucker and mountain whitefish) but contained adult chum salmon (Table 10). As in the mainstem, a seasonal reduction in the relative abundance of juvenile salmonids was measured in side channel network SCC. Between summer and winter, the ratio of juvenile-toadult trout and salmon observed in pools during daylight hours fell roughly 2000-fold in the surface-flow side channel system, and 20-fold in the spring brook channels. Associated with these patterns of seasonal variation in fish use was an 8–13 °C average decline in daytime water temperature in mainstem and side channel pools (Fig. 22B). Paired day–night snorkel surveys were performed in side channel network SCC in December 2004 to test the hypothesis that fish are in fact present within side channel pools during the winter, but take cover during daylight hours. These surveys revealed that both juvenile and adult trout and salmon, presumably seeking refuge during the day, indeed emerge during the night. Both surface-flow and spring-brook side channel pools showed a trend toward increasing overall relative fish abundance (i.e. juveniles and adults of all species) at night; this pattern was statistically significant for pools fed by surface flow (t-test: d.f.=14; P
Page 1 and 2: Skykomish River Braided Reach Resto
Page 3 and 4: Trout in August and September 2004.
Page 5 and 6: foot; polarized sunglasses were wor
Page 7: Oncorhynchus mykiss; and mountain w
Page 11 and 12: Burnett, 2001). Accordingly, the Sk
Page 13 and 14: Patterns of Salmon Spawning Activit
Page 15 and 16: Summary, continued Salmon spawning
Page 17 and 18: Jackson, C. (2005a). Email to E. Dr
Page 19 and 20: Figure Legends for maps on pages 19
Page 21 and 22: Figure 9 Representative Skykomish R
Page 23 and 24: Figure 10. Relationship between sno
Page 25 and 26: Figure 12 (legend on p. 33) 31
Page 27 and 28: Figure 12. Relative densities of al
Page 29 and 30: Figure 15. Comparison of adjusted r
Page 31 and 32: Figure 17. Relative fish densities
Page 33 and 34: Figure 19 (legend on p. 40) 39
Page 35 and 36: Figure 21. Seasonal variation in Sk
Page 37 and 38: Figure 23. Diel variation in winter
Page 39: Figure 25. Salmon redd counts by ha

Skykomish Draft Final Report - Wild Fish Conservancy

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