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If you have any questions on the information presented, or require additional report data or attachments, please contact the Report Contact
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A kokanee spawning assessment was conducted on Comox Lake to collect baseline information on the timing, spawning distribution, habitat selection, and spawning behavior of Comox Lake kokanee, as well as to determine potential limiting factors to kokanee production.
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Author: E. Guimond, C. Heim
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Old Reference Number: COA-F17-F-1210
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Old Reference System: FWCP Fish Wildlife Compensation Program - Coastal
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Date Published: Apr 2017
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Report ID: 52762
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Audience: Government and Public
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A kokanee spawning assessment was conducted on Comox Lake to collect baseline information on the timing, spawning distribution, habitat selection, and spawning behavior of Comox Lake kokanee, as well as to determine potential limiting factors to kokanee production. Kokanee are recognized as being an important fish both in the recreational sport fishery and as a key forage species fish for piscivores such as cutthroat trout, yet little information is available on their life history and spawning habitat preferences in Comox Lake.
Reconnaissance surveys were conducted that identified 16 potential shoreline spawning sites in Comox Lake. Criteria for suitable kokanee nearshore spawning sites included abundant, uniformly small (<30mm), non-compacted, clean gravel substrate, and water depth of less than 3m. Interviews with local cabin owners and fishermen that frequent Comox Lake were conducted that provided additional information that informed spawner survey planning and key areas to focus effort. Weekly spawning assessments were conducted on Comox Lake between October 7 and November 18, 2016 using a combination of boat and foot surveys. Willemar and Forbush Lakes in the Upper Puntledge River were surveyed by boat. Local knowledge was valuable in pinpointing the peak of the kokanee spawning period and specific locations of spawning activity.
Evidence of kokanee spawning in nearshore habitat at the south east end of Comox Lake (Site 10) was recorded on October 31, 2016. Over 50 kokanee were observed spawning and guarding redds at a depth of ~ 2.5 m. Confirmation of spawning activity allowed an opportunity to assess incubation success using eyed coho eggs buried in incubators at the site. Overall, eyed egg-to-fry survival was 85.5%. Average intergravel temperature data collected between December 2016 and March 2017 at the incubation site was 2 degrees warmer than surface water temperature, suggesting possible groundwater sources that may be attracting kokanee spawning to this location.
An analysis of historical reservoir elevations between 1993 and 2015 indicates that in two of every three years, reservoir drawdown may adversely impact kokanee reproductive success in Comox Lake.
Further assessments are recommended to gain more information about kokanee biology, spawn timing, spawning habitat selection and distribution within Comox Lake. This may include a combination of methodologies in addition to boat and foot surveys, such as aerial (UAV), underwater video (ROV), hydroacoustic and gillnetting , as well as an analysis of temperature characteristics at potential spawning sites for groundwater or other hydraulic processes. This information will be essential for understanding the potential effects of reservoir draw down and other limiting factors on kokanee spawning recruitment and incubation survival, and identifying future conservation and enhancement opportunities for kokanee in Comox Lake.
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Report Type
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Fish and Aquatic Habitat Information |
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Subject
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Fish Species - Kokanee - Oncorhynchus nerka |
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Region - Vancouver Island |
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Fish and Fish Habitat - Lake |
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Fish and Fish Habitat - Stock Assessment |
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