Assessment of Kokanee Spawning in Comox Lake
This project will assess the Kokanee spawning population in Comox Lake, including the timing, spawning distribution and habitat selection, as well as determine potential limiting factors to Kokanee production. Since there is very limited information on the life history, habitat requirements and population size of Comox Lake Kokanee, results from this project will begin to provide a greater understanding of the Kokanee population, and will help build a database on longer-term population trends and potential future enhancement opportunities.
This project will provide insight into the spawning population of Kokanee in Comox Lake, including spawning distribution, habitat selection, and potential limiting factors, as well as verify whether spawning success, incubation survival, and adult recruitment are limiting factors to the low Kokanee production in Comox Lake that was observed in 2013. A greater understanding of the Kokanee population is essential to making informed decisions regarding future enhancement and restoration opportunities for Kokanee and other resident salmonids in Comox Lake.
Final Report: Executive Summary
A kokanee spawning assessment was conducted on Comox Lake to collect baseline information on the timing, spawning distribution, habitat selection, and spawning behaviour 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.
Click the provincial database link below to read the full final report for this project.