WLR Monitoring Study

Author: W.G. Warnock, K.A. Caley

- Describe some of the basic biological characteristics of Rainbow Trout in Kinbasket Reservoir - Identify Rainbow Trout spawning habitat in Kinbasket Reservoir. - Assess whether the operation of Kinbasket Reservoir results in blockage or reduced success of upstream migration of Rainbow Trout spawners in tributary streams. - Assess whether the operation of Kinbasket Reservoir floods Rainbow Trout spawning habitat within the drawdown zone and lower sections of tributaries, causing adverse effects on egg and fry survival.] - Asses whether if modifications be made to the operation of Kinbasket Reservoir to protect or enhance these Rainbow Trout populations?

1) Radio telemetry
Fish tagged with biotelemetry tags were observed to have individual differences in home range size and location, with the most frequent occupation of home ranges between the Confluence of the Columbia and Canoe Reaches, and the inlet into Kinbasket Lake. Small sample sizes limited the power of the study.

– Rainbow Trout likely have great variety in home range size in Kinbasket Reservoir, with individuals ranging from relatively resident to their capture location to highly mobile.
– Pre-spawn movements generally occurred between late March and late April, and post-spawn return movement generally occurred between late May and mid-June
– Location of spawning is not possible to determine from this study, but it appears that all four fish made directed movements to the upstream portions of the Columbia Reach and Upper Columbia areas of the Reservoir in the pre-spawn period

2) Tributary access, stream habitat and thermal suitability
Two tributaries surveyed in 2017 may have at least partial fish migration barriers. An impassable fish migration barrier occurs on Tsar Creek, at an elevation of 735 m and would be exposed during periods of low pool in most years of operation. Additional suspected fish migration barriers may be present lower in the drawdown zone of Tsar Creek and Windfall Creek. Windfall Creek in particular has five potential fish migration barriers, scattered throughout the drawdown zone, and thus tributary access may be an issue if adfluvial fish use this stream for spawning during periods of low reservoir elevations. However, it is unknown if either of these streams contain runs of adfluvial Rainbow Trout and would thus be impacted.

Most tributaries surveyed in 2016 were on the border of or exceeded the 3% steepness threshold on average, with plane-bed, step-pool and cascade channel morphology. Based on gradient and channel morphology, these tributaries are likely to have marginal suitability for spawning except through limited reaches where gradient becomes shallower. Of the tributaries sampled, only Succour Creek and the Beaver River contain significant reaches of low gradient habitat.

Succour Creek was thermally suitable for Rainbow Trout spawning and incubation in the spring of 2015, and 2016 during the periods of lowest reservoir elevation, and continuing through the spring period of reservoir refilling. The inundation of potentially suitable spawning substrate was severe in 2015, but less severe in 2016, based on calculation of theoretical timing for initiation and cessation of spawning and fry emergence. These models indicated that reservoir refilling would inundate habitats suitable for spawning throughout the spawning and fry emergence periods, but in neither year were impacts so severe that all potentially suitable substrates were inundated.

3) Snorkel surveys
In contrast to all other tributaries surveyed in this study thus far, Succour Creek contains extensive patches of suitable spawning substrate, shallow slopes, and a thermal regime predicted to be suitable for spawning throughout the drawdown zone. Snorkel surveys and detailed redd surveys did not reveal any spawning activity of Rainbow Trout in the drawdown zone of Succour Creek in 2017 despite the apparent physical suitability of the habitat. Results of this study suggest that currently unoccupied habitat that may be suitable could be impacted by reservoir operations, but the severity of impact varies depending on the reservoir operation and thermal regime of the stream. It is possible that reservoir operations or some other factor limit the establishment of a local spawning population in this habitat by interrupting the processes that support embryo and fry development or early growth.

1) Radio telemetry
Fish tagged with biotelemetry tags were observed to have individual differences in home range size and location, with the most frequent occupation of home ranges between the Confluence of the Columbia and Canoe Reaches, and the inlet into Kinbasket Lake. Small sample sizes limited the power of the study.

– Rainbow Trout likely have great variety in home range size in Kinbasket Reservoir, with individuals ranging from relatively resident to their capture location to highly mobile.
– Pre-spawn movements generally occurred between late March and late April, and post-spawn return movement generally occurred between late May and mid-June
– Location of spawning is not possible to determine from this study, but it appears that all four fish made directed movements to the upstream portions of the Columbia Reach and Upper Columbia areas of the Reservoir in the pre-spawn period

2) Tributary access, stream habitat and thermal suitability
Two tributaries surveyed in 2017 may have at least partial fish migration barriers. An impassable fish migration barrier occurs on Tsar Creek, at an elevation of 735 m and would be exposed during periods of low pool in most years of operation. Additional suspected fish migration barriers may be present lower in the drawdown zone of Tsar Creek and Windfall Creek. Windfall Creek in particular has five potential fish migration barriers, scattered throughout the drawdown zone, and thus tributary access may be an issue if adfluvial fish use this stream for spawning during periods of low reservoir elevations. However, it is unknown if either of these streams contain runs of adfluvial Rainbow Trout and would thus be impacted.

Most tributaries surveyed in 2016 were on the border of or exceeded the 3% steepness threshold on average, with plane-bed, step-pool and cascade channel morphology. Based on gradient and channel morphology, these tributaries are likely to have marginal suitability for spawning except through limited reaches where gradient becomes shallower. Of the tributaries sampled, only Succour Creek and the Beaver River contain significant reaches of low gradient habitat.

Succour Creek was thermally suitable for Rainbow Trout spawning and incubation in the spring of 2015, and 2016 during the periods of lowest reservoir elevation, and continuing through the spring period of reservoir refilling. The inundation of potentially suitable spawning substrate was severe in 2015, but less severe in 2016, based on calculation of theoretical timing for initiation and cessation of spawning and fry emergence. These models indicated that reservoir refilling would inundate habitats suitable for spawning throughout the spawning and fry emergence periods, but in neither year were impacts so severe that all potentially suitable substrates were inundated.

3) Snorkel surveys
In contrast to all other tributaries surveyed in this study thus far, Succour Creek contains extensive patches of suitable spawning substrate, shallow slopes, and a thermal regime predicted to be suitable for spawning throughout the drawdown zone. Snorkel surveys and detailed redd surveys did not reveal any spawning activity of Rainbow Trout in the drawdown zone of Succour Creek in 2017 despite the apparent physical suitability of the habitat. Results of this study suggest that currently unoccupied habitat that may be suitable could be impacted by reservoir operations, but the severity of impact varies depending on the reservoir operation and thermal regime of the stream. It is possible that reservoir operations or some other factor limit the establishment of a local spawning population in this habitat by interrupting the processes that support embryo and fry development or early growth.