The completion of Mica Dam in 1973 and Revelstoke Dam in 1984 created about 530 km2 of reservoirs on the Columbia River system in British Columbia. Kinbasket Reservoir was stocked with kokanee during 1982-85 by the Ministry of Environment. This led to the establishment of a resident population, which subsequently colonized Revelstoke Reservoir further downstream. A stock assessment program was initiated in 1991 to determine the status of the introduced kokanee. Hydroacoustic surveys and supporting trawl- and gill-net studies were conducted during the following three year period. This report summarizes the results of the kokanee stock assessment for each reservoir.
In 1993, when the most extensive survey was conducted, kokanee populations in the Kinbasket and Revelstoke reservoirs were estimated at 3.8 million and 0.3 million, respectively. Almost all of the pelagic fish caught with trawl- and gill-nets were kokanee. The kokanee abundance increased by a factor of about six from 1991 to 1993 in Revelstoke Reservoir, although a longer time series is required to determine whether these increases indicate an upward trend or reflect variation in year class strength due to entrainment or environmental effects. Increased abundance was also apparent in Kinbasket Reservoir, but this was most likely attributed in part to changes in survey coverage. The mean fork lengths of ages 1+ and 2+ kokanee in Kinbasket Reservoir were 18 and 21 cm respectively. Kokanee exhibited high growth rates despite oligotrophic conditions. Further monitoring is required to determine habitat carrying capacity, changes in community structure and future angling opportunities for kokanee in these reservoirs. Information provided by stock monitoring is also potentially important for assessing the impacts of reservoir operations on fish production.
Sebastian, Dale, Scholten, George; Addison, Dean; Labelle, Marc; Green, David. 1995. Results of the 1991-93 Hydroacoustic Surveys at Kinbasket and Revelstoke Reservoirs. BC Ministry of Environment, Lands and Parks. Stock Management Unit (ENV). Report No. 1