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Report: Snorkel Observations of Winter Steelhead Trout Escapement to the Englishman River, Vancouver Island, 2004

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Between February 4 and May 14, 2004, a series of six snorkel surveys were conducted to estimate steelhead escapement in the Englishman River watershed.

Author:  Silvestri, S.; BC Conservation Foundation

Date Published:  Dec 2004

Report ID:  5848

Audience:  Government and Public

The 2004 survey marks the third consecutive year of intensive steelhead enumeration by BCCF and MWLAP staff in the Englishman and South Englishman rivers. Estimates of adult escapement using snorkel techniques, smolt emigration using rotary screw traps, and fry standing stocks through closed-site electrofishing further develop the Englishman River as a key steelhead index stream on the east coast of Vancouver Island. Results from six snorkel surveys between February 4 and May 14 were evaluated using the AUC method to estimate a probable range of steelhead escapements. Observer efficiency and average residence time of Englishman steelhead were established based on radio-telemetry results from previous Vancouver Island studies, historical snorkel survey data from the Englishman watershed, and observations made during the 2002, 2003 and 2004 studies. The AUC estimate for 2004, assuming an average residence time of 60 days and an average observer efficiency of 60%, was 85 steelhead (most probable range: 58-136). This compares to estimates of 145 and 96 for 2002 and 2003, respectively, using the same observer efficiencies and residence times. Until these assumptions are tightened up if not eliminated, estimate confidence will not improve significantly. However, actions required to address these assumptions (mark-recapture component) may be too invasive given the extreme conservation concern associated with this stock. Given the importance of Englishman River steelhead, collection of abundance trend data should continue in 2005. Further development of the Englishman River as a key index stream for winter steelhead populations in the Georgia Basin is a high priority outlined in the Greater Georgia Basin Steelhead Recovery Action Plan (Lill 2002).

Report Type
  Fish and Aquatic Habitat Information
  Biogeoclimatic Zone - CDF Coastal Douglas-fir Zone
  Biogeoclimatic Zone - CWH Coastal Western Hemlock Zone
  Fish Species - Steelhead - Oncorhynchus mykiss
  Fish and Fish Habitat - Fish Inventory
  Fish and Fish Habitat - Management
  Fish and Fish Habitat - Stock Assessment
  Watershed Groups - 920 - Vancouver Island (East) Rivers

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