EXECUTIVE SUMMARY The effects of ecological alterations in the Kootenay Lake watershed on abundance of the highly valuable Gerrard-origin rainbow trout have been monitored by a time series of daily spawner counts extending from 1961 to the present. Escapement estimates have been derived since 1978 by expanding the peak count at the spawning area at Gerrard by a factor of 3.08. Alternative analyses integrating all of the count data in a season, such as the area-under-the-curve (AUC) methodology or maximum likelihood-based run timing models, are attractive relative to the peak count methodology in that they account for variability in the shape and breadth of the spawner abundance curve, which can be substantial. In 2004 we initiated a telemetry study of Gerrard rainbow trout spawner movements, utilizing sonic and radio tags, with a particular focus on acquiring the spawner residence time estimates necessary for both the AUC and maximum likelihood analyses. Various fish capture methods were directed at the lower Duncan and Lardeau Rivers in 2004, with mixed success, but in 2005 and 2006 most tagged fish were captured using highly efficient tangle nets set in Kootenay Lake at the mouth of the lower Duncan River. A small number of captures using angling in the Lardeau River occurred during 2005-2007. We also monitored Gerrard rainbow trout tagged in Kootenay Lake as part of a separate study in 2008. Abundance of Gerrard rainbow trout milling at the mouth of the Duncan River, as indicated by capture rate in the tangle net during spring 2005 and spring 2006, appeared to be at its highest in late March and the beginning of April. Radio-tagged fish migrated past the Lardeau/Duncan confluence and into the Lardeau River over an extended period between the last week of March and the first week of May. Radio-tagged spawners that migrated as far as Gerrard took between 5 and 20 days to travel between the Lardeau/Duncan confluence and the outlet of Trout Lake. Several radio-tagged trout appeared to have spawned in locations other than Gerrard. Based on the total number of mature rainbow trout radio tagged at the mouth of the Duncan River in 2005 and 2006, and which went through the pattern of upstream migration followed by residence in a potential spawning stream and kelting past a fixed station (25 fish in total), 16% and 20% of radio-tagged trout spawned at other locations in the Lardeau River and at the Duncan Dam, respectively. Major, unexpected results of the study were the discovery of the population spawning below the tailrace of the Duncan Dam, and the discovery of potential methodologies for estimating their abundance including redd counts and nighttime boat surveys. Residence time at Gerrard did not differ greatly for tagged male and female rainbow trout spawners (6.18 1.33 days vs. 6.94 1.16 days, respectively), and the overall residence time estimate for the six years' pooled telemetry data (including 2008 Kootenay Lake-tagged fish without sex data) was 6.94 days (n = 33, SE = 0.852 days). Spawning timing for radio-and sonic-tagged females appeared to be representative of untagged fish. However, males from the early part of the run timing curve appeared to be under-represented in our telemetry sample. We recommend, therefore, that additional iii tagging and telemetry take place in future in order to increase representation of early-timed male rainbow trout spawners in the residence time estimate. Two population estimation methodologies, based on (1) trapezoidal AUC calculations and (2) a maximum likelihood run timing model, which incorporated the pooled residence time estimate, an estimate of the variability of observer efficiency based on replicate counts, and periodic count data from 1961-2009, showed relatively good agreement in their estimates and comparable confidence intervals. Expanded peak counts were in reasonable agreement with estimates generated using the trapezoidal AUC and maximum likelihood approaches, being on average 9.3% and 8.3% higher, respectively. Expanded peak counts were however highly variable relative to population estimates based on all the count data, ranging from 70% (1966) to 176% (2008) of the maximum likelihood estimates. The ability of the trapezoidal AUC and ML approaches to account for variability in the form of the spawner abundance curve, as well as provide estimates of uncertainty for the population estimates, suggest that these approaches are preferable for future monitoring and analyses of Gerrard rainbow trout spawner abundance.