Citation | Anderson, D. 2009. Salmon River adult fish passage assessment study. Prepared for BC Hydro. |
---|---|
Organization | BC Hydro |
URL | https://www.bchydro.com/bcrp/projects/docs/07.CBR.04.pdf |
Abstract/Description or Keywords | The Salmon River is amongst the largest watersheds on Vancouver Island with a drainage area in excess of 1200km2 . The 5.6m BCHydro diversion dam may interrupt access for upstream migrating adult salmonids to over 50km of mainstem and tributary habitat in 268km2 of watershed upstream. The upper Salmon River has valuable Coho spawning and rearing habitat (Craig et al. 1998, Wong, R. and V. Komori. 1999) that will become increasing important with the effects of global climate change. Utilization of the entire accessible watershed is important to the biodiversity of Coho populations; access to headwater habitats will be key to salmonid survivals through warming periods. These higher elevation habitats will warm the least and retain the most snow, as well as provide some protection against the increased intensity of winter storm discharges. This pilot study was initiated to determine if the returning Coho adults found the Fishway structure, if they successfully transited the diversion facility, under what flow conditions, and if possible understand the period of delay for upstream migrants. The results from the resistivity counter and the acoustic tagging program do provide some insight into the relationship of the migrating Coho to the changes in the Salmon River discharge; the configuration of the undersluice gate opening, mainstem flows and diversion flows are all important considerations in how the Coho behave. Mainstem discharges to 30m3 /sec, with the undersluice gate opening to nearly 1 meter, resulted in net upstream Coho migration, however with the undersluice gate decreased to 0.15m Coho were attracted to the fishway, but net upstream counts were negative during most flows. Only a few appeared to successfully move upstream through the fishway when the discharge to the lower river was 10-12 m3 /sec (adjusted by subtracting diversion canal flows from mainstem above the diversion). The acoustic tag information mirrors the resistivity counter finding. This appears to point to some obstruction, whether velocity or behavioural, within the fishway itself even at fairly low downstream discharges. Surface water level differences, from the canal to river downstream, and turbulence within the fishway will require further investigation. The 2008 study has established a foundation of information, communications, procedures and logistics that will be built on with the continuation of this study. Through understanding the limits or bottlenecks, if any, to upstream migration of both Coho and steelhead adults at the Salmon River diversion dam we can better formulate practical solutions to adult upstream fish passage. |
Information Type | report |
Regional Watershed | Vancouver Island North |
Sub-watershed if known | Salmon River |
Aquifer # | |
Comments | |
Project status | complete |
Contact Name | |
Contact Email |