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The chart above comes from a Six Rivers National Forest Excel spreadsheet and shows the number of Chinook juvenile downstream migrants captured at the Willow Creek downstream migrant trap from April to July 1996. The migration pattern exhibited by Chinook in Willow Creek is very similar to that of nearby Horse Linto Creek (see Topic Fish: Horse Linto Cr Downstream Trap Results 1996). Downstream migration extended into July with the peak of migration extending into June. Extended peak migration may be in response to very high flows in 1996. Chart taken as image from Six Rivers National Forest Excel spreadsheet.


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The graph above shows the number of older age steelhead (1+ and 2+) by week at the Willow Creek downstream migrant trap in 1996. Older age steelhead (>80 mm) showed an extended migration peak in this year of very high flows. This contrast with results from nearby Horse Linto Creek in a very dry year (see Topic Fish: Horse Linto Cr Downstream Trap Results 1994), which showed almost no migration of older age steelhead after May. Chart taken as image from Six Rivers National Forest Excel spreadsheet.


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The chart above was taken from a Six Rivers National Forest Excel spreadsheet and shows young of the year juvenile steelhead caught in the Willow Creek downstream migrant trap by week in 1996. The pattern of immigration is similar to that shown in nearby Horse Linto Creek with high numbers of young steelhead captured late in the season. The difference is in the a peak of out-migration with Horse Linto samples peaking in the second week in June and those in Willow Creek in the second week in July. High flows and cold water temperatures in 1996 could have delayed hatching and slowed growth, which could then be linked to later out-migration. See Info Links for more information.


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The length frequency of Chinook salmon by week in 1996 at the Willow Creek trap is shown above. The average length of Chinook fry was less than 40 mm in May and the length increased in June 1996 to an average of 60-70 mm. Horse Linto Creek juvenile Chinook in June 1996 showed an average length of 50-60 mm. Horse Linto is colder because its headwaters are at higher elevation in the Trinity Alps. The largest migrant Chinook captured in Willow Creek in 1996 was over 110 mm while the largest on Horse Linto was less than 90 mm. (see Topic Fish: Horse Linto Cr Downstream Trap Results 1996). The Lower Trinity Ranger District, Six Rivers National Forest, provided the graph above in an Excel spreadsheet. See Info Links for more information.


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The graph above shows the size of juvenile steelhead by month at the Willow Creek downstream migrant trap in 1998. Older age steelhead (>80 mm) showed an extended migration peak in this year of very high flows. Young of the year steelhead do not show in April samples and very small when they appear in May (<40 mm). The high flows of 1998 were likely associated with cold stream temperatures, which in turn would make emergence of young of the year steelhead later, and their growth after emergence slower. This would be consistent with very small size of young of the year steelhead into June and July. Chart taken as image from Six Rivers National Forest Excel spreadsheet.


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This diagram shows the relative location of the Willow Creek USFS downstream migrant trap. It is 260 meters upstream of the convergence with the Trinity River.