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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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Friends of Kootenay Lake Stewardship Societys Shore-Spawning Kokanee Habitat Restoration & Research Project is a multi-year initiative to address the concern of shore-spawning kokanee salmon (SSKS) (Oncorhynchus nerka) redds and fry dewatering with the annual spring drawdown of Kootenay Lake.
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Author: Friends of Kootenay Lake Stewardship Society
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Date Published: May 2023
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Report ID: 62593
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Audience: Government and Public
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Kokanee populations in Kootenay Lake have suffered extreme declines, with a more than 99% population decline of main-lake kokanee observed between 2012 and 2017 from 1.25 million to 12 thousand, respectively (Province of BC, 2021). Main-lake kokanee returns since 2015 are only about three percent of the long-term historic average and egg deposition is decreasing over time (McPhearson, 2018). West Arm kokanee have also declined, beginning in the 1970s (Redfish Consulting 2002 as cited in Schleppe and McPherson 2022).
Shore-spawning kokanee, a genetically distinct population of kokanee salmon in Kootenay Lake that spawn along shorelines in areas of upwelling groundwater, face additional severe habitat constraints. The annual dam-controlled drawdown of Kootenay Lake in preparation for spring freshet causes the dewatering of SSKS redds and fry that were deposited the previous fall when water levels were higher. An analysis of Kootenay Lakes hydrograph showed an average 12% SSKS redd dewatering in pre-dam conditions between 1928 and 1932, and an average of 70% dewatering in post-dam conditions between 2000 and 2010 (Poisson and Redfish 2012).
SSKS redd dewatering is being mitigated one in every three years by drawing down Kootenay Lake to 1742 feet between mid-September and mid-October during the spawning period (mitigated in 2012, 2015, 2018 and 2021). While there is evidence that these actions help mitigate redd dewatering, it is not enough to support egg-to-fry survival for all redds, or every year. Therein lied the opportunity to pilot a restoration and research project to 1) better understand SSKS and their habitats and 2) test whether habitat restoration can be an effective approach to mitigating SSKS redd dewatering.
In September 2020, 80 cubic metres of gravel was sifted, sorted, and deposited along the foreshore of McDonalds Landing Regional Park at a known SSKS spawning location in a 50x2 metre strip below the low water mark (LWM). This was done in an attempt to encourage SSKS to spawn below the LWM at an elevation that will not dewater. The restoration project involved gravel maintenance and ongoing monitoring, assessment, and research into SSKS spawning numbers, redd development, groundwater discharge, and egg-to-fry survival in the restored versus natural substrate, and in deeper versus shallower areas.
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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 - Kootenay |
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Fish and Fish Habitat - Habitat and Stream Assessment |
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