Steelhead trout production characteristics of the Chilliwack-Vedder system were investigated through a joint project carried out by the Fisheries Improvement Unit and regional Fisheries Branch staff from 1983-86. The principal objective was to provide sound biological direction for management of steelhead harvest on this extremely important river system. Steelhead habitat capability was defined on the basis of current production models, primarily the weighted usable area (WUA) approach.
A significant positive linear correlation between steelhead fry abundance and WUA (based on depth and velocity measurements) explained 86-99% of the variability in annual fry density. Mean adjusted density (@ WUA=1.00) ranged from 136-231 fry/100 m2 and 232-296 g/100 m2. Best growth slope (Iwama and Tautz, 1981) calculated was 11.1 at 136 fry/100 m2, compared to an estimated mean water temperature of 13.5 deg C for the same time period.
Total mainstem area was ca. 226 ha above the Vedder Canal. Usable width for fry was estimated at 25% based on whole stream transects and field observations. Using the fry density-WUA model, 11,000 wild adults could be produced at full rearing capacity. In addition, hatchery adult returns of approximately 5,000 should be expected from recent annual releases of 120,000 smolts.
It is recommended that mainstem fry stocking be discontinued provided spawning escapements exceed the number required to saturate fry rearing habitat. A larger harvest of marked hatchery steelhead should be encouraged to reduce potential impact on the wild gene pool. Angler density reduction and greater access to the resource might be achieved by opening the mainstem above Slesse Creek to angling. To confirm the reliability of adult escapement and juvenile standing stock relationships, annual juvenile population monitoring should continue until the summer of 1989 (completion of one life-cycle).
Russell, J. R. L.. 1987. Steelhead Production Characteristics of the Chilliwack-Vedder River System. BC Ministry of Environment. Fisheries Improvement Unit. FIU-07
Topic: Fish and Fish Habitats
Keywords: British Columbia, Abbotsford, Vedder, Fraser Valley, Cultus, steelhead, anadromous, Fisheries Improvement Unit, spawning, fry, hatchery, angling, sportfishing
Scientific Name: Oncorhynchus mykiss
English Name: Rainbow Trout
Other Identifier: FIU-07
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