Document Type

Thesis

Abstract

The Gulkana River supports the northernmost population of steelhead and rainbow trout Oncorhynchus mykiss in North America. The summer habitat of Gulkana River juvenile trout (i.e., steelhead and rainbow trout) was identified and described. Analysis of geomorphological features of stream reaches (stream entrenchment, bankfull width-to-depth ratio, sinuosity, channel material, and slope) in relation to differential use of habitat by juvenile trout indicated a strong preference for type C reaches (predominately riffle/run habitat) over type E reaches (predominately slow run habitat). A comparison of micro-habitats (riffle, run, pool, slow run) within those same reaches and distribution of juvenile trout indicated a preference for riffle and run habitat. Most type C reaches in the Mainstem were sparsely populated by juveniles throughout summer. The Middle Fork was devoid of juveniles in early summer. In mid- and late summer, coinciding with the arrival of spawning chinook O. tshawytscha and sockeye salmon O. nerka, most riffle/run reaches in the Middle Fork were occupied by juvenile trout. The steelhead spawning population has declined from an estimated 200-1,000 fish two decades ago to 20-50 fish during this study (1993-1995). Rainbow trout stocks are also apparently low. Monitoring of Copper River fisheries and Gulkana spawning populations and an investigation into other steelhead spawning populations in the Copper River basin are recommended

Publication Date

5-17-1999

Handle

http://hdl.handle.net/11122/15756

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