Vancouver Island fisheries biologists are in the second year of a study investigating the kokanee salmon population in Comox Lake.
Kokanee form an important part of the Comox Lake ecosystem, providing food for cutthroat trout and dolly varden. Kokanee are zooplankton feeders, and are approximately 20-25 centimetres when mature. They are sometimes called “landlocked sockeye” as they spend their entire lives in fresh water.
In the first year of the study in 2016, biologists Esther Guimond and Caroline Heim identified key spawning habitat areas, based on suitable gravel sizes and habitat characteristics such as inputs from smaller streams and rivers. Specific spawning sites were monitored through the incubation period, and key spawning areas around Comox Lake and smaller upstream lakes were identified. Local knowledge was invaluable in the first year of the study, as many resident cabin owners on Comox Lake have watched and fished the lake for decades.
In the fall of 2018, the study ramped up with intensified sampling using a combination of gill net setting, remotely-operated towed video cameras, and scuba divers to verify camera footage. Preliminary results show that kokanee not only spawn in nearshore beach areas, but also at depths up to 17 metres (56 feet). While kokanee and sockeye are known to spawn in deep water in mainland lakes, Guimond and Heim were pleased to find the same may be true in Comox Lake.
“Eggs incubating in shallow locations are more vulnerable to changes in water levels,” said Heim. “Verifying that kokanee are using deeper water gravels to spawn in is exciting information.”
The biologists are currently assessing why a particular region of the lake at the south end is so attractive to the kokanee spawners. An estimated 500 kokanee were observed spawning in one specific beach area. Upwelling of groundwater may be one factor, and inter-gravel temperature monitoring is taking place over the winter months.
Guimond and Heim have partnered with the Courtenay and District Fish and Game Club for the study, and are grateful for the support from the Fish &Wildlife Compensation Program (FWCP). The FWCP is a partnership between BC Hydro, the Province of B.C., Fisheries and Oceans Canada, First Nations and public stakeholders to conserve and enhance fish and wildlife in watersheds impacted by BC Hydro dams.