WLR Monitoring Study No. CLBMON-46 (Year 10) Lower Columbia River Rainbow Trout Spawning Assessment
Author: R.L. Irvine, J.T.A. Baxter, J.L. Thorley
This monitoring program was initiated in 2008 and all field work was completed in spring 2018. The current Rainbow Trout (RBT) spawning assessment monitoring program, which commenced in 2008, was implemented to better understand the linkages between the spring flow regime and the abundance of the Rainbow Trout population and to assess population trends in this ecologically and recreationally important species. 2017 is the final year of the current WLR monitoring program assessing the population of Rainbow Trout in the LCR and LKR. As such this report presents an overview of approaches and results to date including the final years surveys and analyses. It also provides recommendations for addressing the remaining unknowns about the Rainbow trout in the LCR and LKR.
1. Does the implementation of RTSPF over the course of the monitoring period lead to an increase in the relative abundance of Rainbow Trout spawning in the LCR downstream of HLK?
The number of Rainbow Trout spawners has roughly doubled since 2008. RTSPF may be responsible for this increase but no flow changes have occurred over the period of study to allow causal mechanisms to be tested.
2. Does the implementation of RTSPF over the course of the monitoring period lead to an increase in the spatial distribution of locations (and associated habitat area) that Rainbow Trout use for spawning in the LCR downstream of HLK?
The spatial distribution of Rainbow Trout spawning was significantly higher in 2008-2017 than in 1999-2007. RTSPF may be responsible for this increase but no flow changes have occurred over the period of study to allow causal mechanisms to be tested.
3. Does the implementation of RTSPF over the course of the monitoring period protect the majority of Rainbow Trout redds (as estimated from spawning timing) from being dewatered in the LCR downstream of HLK?
Yes. RTSPF (in conjunction with exclusion fencing at Genelle Channel E) have protected on average over 99% of the redds from dewatering. The dewatering rate was estimated to be 50-75% in shallow water habitat on Norns Fan in 1990 and 1991 prior to implementation of RTSPF.
1. Does the implementation of RTSPF over the course of the monitoring period lead to an increase in the relative abundance of Rainbow Trout spawning in the LCR downstream of HLK?
The number of Rainbow Trout spawners has roughly doubled since 2008. RTSPF may be responsible for this increase but no flow changes have occurred over the period of study to allow causal mechanisms to be tested.
2. Does the implementation of RTSPF over the course of the monitoring period lead to an increase in the spatial distribution of locations (and associated habitat area) that Rainbow Trout use for spawning in the LCR downstream of HLK?
The spatial distribution of Rainbow Trout spawning was significantly higher in 2008-2017 than in 1999-2007. RTSPF may be responsible for this increase but no flow changes have occurred over the period of study to allow causal mechanisms to be tested.
3. Does the implementation of RTSPF over the course of the monitoring period protect the majority of Rainbow Trout redds (as estimated from spawning timing) from being dewatered in the LCR downstream of HLK?
Yes. RTSPF (in conjunction with exclusion fencing at Genelle Channel E) have protected on average over 99% of the redds from dewatering. The dewatering rate was estimated to be 50-75% in shallow water habitat on Norns Fan in 1990 and 1991 prior to implementation of RTSPF.
Resources Data:
Name: CLBMON-46 YR10 2018-04-29
Format: PDF
URL: https://www.bchydro.com/content/dam/BCHydro/customer-portal/documents/corporate/environment-sustainability/water-use-planning/southern-interior/clbmon-46%20Yr10%202018-04-29.pdf
Additional Info
Study Years: 2017, 2016, 2015, 2014, 2013, 2012, 2011, 2010, 2009, 2008
Published: 2018
WLR Monitoring Study No. CLBMON-46 (Year 10) Lower Columbia River Rainbow Trout Spawning Assessment
Author: R.L. Irvine, J.T.A. Baxter, J.L. Thorley
Tags: Abundance, Brilliant Dam, CLBMON46, Flow, Flow Regime, Hugh L Keenleyside Dam, Kootenay River, Lower Columbia River, Monitoring Recommendations, Norn Creek, Oncorhynchus Mykiss, Population, Rainbow Trout, Redds, WLR
This monitoring program was initiated in 2008 and all field work was completed in spring 2018. The current Rainbow Trout (RBT) spawning assessment monitoring program, which commenced in 2008, was implemented to better understand the linkages between
the spring flow regime and the abundance of the Rainbow Trout population and to assess population trends in this ecologically and recreationally important species. 2017 is the final year of the current WLR monitoring program assessing the population of Rainbow Trout in the LCR and LKR. As such this report presents an overview of approaches and results to date including the final years surveys and analyses. It also provides recommendations for addressing the remaining unknowns about the Rainbow trout in the LCR and LKR.
Summary
1. Does the implementation of RTSPF over the course of the monitoring period lead to an increase in the relative abundance of Rainbow Trout spawning in the LCR downstream of HLK?
The number of Rainbow Trout spawners has roughly doubled since 2008. RTSPF may be responsible for this increase but no flow changes have occurred over the period of study to allow causal mechanisms to be tested.
2. Does the implementation of RTSPF over the course of the monitoring period lead to an increase in the spatial distribution of locations (and associated habitat area) that Rainbow Trout use for spawning in the LCR downstream of HLK?
The spatial distribution of Rainbow Trout spawning was significantly higher in 2008-2017 than in 1999-2007. RTSPF may be responsible for this increase but no flow changes have occurred over the period of study to allow causal mechanisms to be tested.
3. Does the implementation of RTSPF over the course of the monitoring period protect the majority of Rainbow Trout redds (as estimated from spawning timing) from being dewatered in the LCR downstream of HLK?
Yes. RTSPF (in conjunction with exclusion fencing at Genelle Channel E) have protected on average over 99% of the redds from dewatering. The dewatering rate was estimated to be 50-75% in shallow water habitat on Norns Fan in 1990 and 1991 prior to implementation of RTSPF.