The primary goals of the Chilko River Chinook Salmon Mark-Recapture Project are to develop and estimate the spawning abundance that meets or exceeds the Chinook Technical Committee data standard for escapement indicator stocks. Specifically to determine:
1) estimates of spawning escapement by age and sex that will, on average, attain a coefficient of variation (CV) of 15% or less on the spawner estimates; and
2) consistent estimates that are asymptotically unbiased.
Additional objectives include bias testing of application and recovery data, and improving the efficiency of the study in-season and annually.
SSP14-01 Chilko River Chinook Salmon Mark-Recapture (Fraser River Summer-run Age 1.3 Stock Group). Year 5
SSP13-04 Chilko River Chinook Salmon Mark-Recapture (Fraser River Summer-run Age 1.3 Stock Group). Year 4
SSP12-02 Chilko River Chinook Salmon Mark-Recapture (Fraser River Summer-run Age 1.3 Stock Group). Year 3
SSP11-05 Chilko River Chinook Salmon Mark-Recapture (Fraser River Summer-run Age 1.3 Stock Group). Year 2
SSP10-06 Chilko River Chinook Salmon Mark-Recapture (Fraser River Summer-run Age 1.3 Stock Group). Year 1
Feasibility of stream flow improvement projects continued in collaboration with fisheries agencies, First Nations, regional district and municipal governments, landowners, area streamkeepers and other ENGOs. Select east coast Vancouver Island (ECVI) watersheds were first prioritized in 2006 and have been reviewed annually by Fisheries and Oceans Canada (DFO) and Ministry of Environment (MoE; now Ministry of Forests, Lands and Natural Resource Operations, MoFLNRO). Evaluation involved a multifaceted process involving biological, hydrological and engineering assessments required for landowner consent, public support and regulatory approval. The work was then further focused on five high priority watersheds/sites Craigflower (Thetis Lake), Millstone (Brannen Lake), Englishman (Shelton Lake), Courtenay (Wolf Lake), and Quatse (Quatse Lake) where new storage could be developed or where existing storage could be improved or increased.
S12-H01 Water Storage Feasibility on East Coast Vancouver Island - Year 5 of 5
S11-H01 Water Storage Feasibility on East Coast Vancouver Island - Year 4 of 5
Stoltz Bluff is a deposit of glacial sediment that extends for approximately 600 m at the outside of a natural meander bend on the Cowichan River, 27 km upstream of Cowichan Bay. Stoltz Bluff was previously identified as the largest point source of fine sediment on the river, representing on average 35-45% of the river’s annual total suspended sediment (TSS) load (KWL Assoc. Ltd. 2005). This is significant in that effective sediment management was identified as the second highest fish habitat restoration priority in the Cowichan Recovery Plan, prepared for Cowichan Tribes’ Treaty Office (LGL Ltd. 2005).
The primary objective of a potential Stoltz Bluff remediation project evolved over 25 years to become “the effective control of massive sediment transport from the bluff (i.e., 10,000-28,000 m3/year since 1993) (KWL Associates Ltd. 2005)), that had been negatively affecting Cowichan River fish habitats and stocks for many kilometres downstream (Burt and Ellis 2006).” The recent Cowichan River Watershed Health and Chinook Initiative (Ayers 2017) reemphasized the value of improved year-round water quality and salmonid spawning habitat as an ongoing strategic management objective.
Beginning in July 2006, the BC Conservation Foundation (BCCF) coordinated a major sediment remediation project at Stoltz Bluff. Work included construction of an engineered 600 m rip-rap berm and terrace, complete with a series of weirs, channel gradient controls and bioengineering treatments designed to move river flows away from the base of the bluff and prevent further bank erosion and major slope failures.
The initial phase of the project took 10 weeks to build, and was supported by a group of seven partners who contributed $830K in funds and in-kind construction materials (including $250K from PSC). For 10 years following the project’s inception, there was a significant improvement in the river’s water quality (i.e., TSS and turbidity) and downstream fish habitats (Gaboury et al. 2012), which is thought to have contributed to incremental gains in annual returns of the river’s fall Chinook and chum salmon stocks, as well as winter steelhead.
However, since 2014, there has been a notable (and even dramatic) change in slope stability at Stoltz Bluff, apparently prompted by the cyclical return of wetter winter weather conditions (McQuarrie 2017). Mass wasting events in the Bluff’s gullies and numerous smaller slope failures have collectively overwhelmed existing sediment retention infrastructure, resulting in higher sediment loads entering the Cowichan River. If this is not effectively mitigated in subsequent annual maintenance activities, a decade of improved spawning conditions will likely become incrementally reversed.
S11-H03 Cowichan River – Stoltz Bluff Remediation Monitoring (Year 4 of 4)
S10-H04 Cowichan River – Stoltz Bluff Remediation Monitoring. Year 3
S07-H05 Cowichan River – Stoltz Bluff Remediation (Year 2)