Lower Columbia River Opportunistic Assessment of High Flow Events (CLBMON-30). Years 3-5 Data Report

Author: B.C. Hydro

The overall objective of this study is to determine the effect of high flow events on levels of natural recruitment through long term monitoring of adult and larval and juvenile White Sturgeon demographic variables in the lower Columbia River. Specific objectives during the early stages of the program were to: 1) tag sufficient numbers (>25) mature adult White Sturgeon with acoustic transmitters (10 year life span) to describe annual movement patterns, habitat use, and possible spawning site selection in relation to flows, 2) improve our understanding of how inflow forecast can be used to accurately predict high water years that could trigger a decision around opportunistic flow changes, as recommended by the CC, and 3) initiate consistent long term monitoring focused on early life stages (eggs, larvae, juveniles). The CRwater use plan Fish Technical Subcommittee (FTC) defined the scope of an opportunistic assessment of high flow events program to include the following elements: 1. detection of spawning events, 2. juvenile detection, 3. water quality sampling, and 4. monitoring of erosion and flood impacts associated with the high flow events. Specifically, objectives of this program are to: -Identify alternative lower Columbia River spawning site(s) identified through the telemetric monitoring of adult movements in both high flow years and low flow years (CLBMON 28). o Through addition of sufficient resources to the existing adult monitor program (CLBMON#28) to provide for monitoring of changes in adult movement during high flow events. -Compare habitat conditions of spawning and egg distribution locations during high flow years compared to reference years. o Through addition of sufficient resources to the existing adult monitor program (CLBMON#28) to provide for monitoring of changes in spawning events and egg distribution during high flow events. -Detection of wild origin juveniles and determining the year of birth for these individuals to examine environmental conditions in those years. The collection of wild juveniles represents the highest probability of detecting a positive effect on recruitment from physical conditions in the lower Columbia River. Additionally, comparisons of juvenile growth and survival among years evaluated in the program are warranted. o Through addition of sufficient resources to the existing juvenile survival program (CLBMON#29) to provide for monitoring of wild recruitment, juvenile abundance, growth and survival.

MQ: Are there unidentified spawning sites in the lower Columbia River that are used during higher flows?
Relating spawning site selection and flows is challenging due to challenges associated with sampling at higher flows (e.g. 2012 flow year) and a relatively small dataset on spawning locations outside of the primary site at Waneta. Spawning (documented through egg and larval captures) had only been identified to occur at the Waneta area prior to the monitoring studies under the Columbia River Water Use Plan being implemented. Results from recent work reveal that spawning occurs downstream of HLK and ALH in some years, though it is not known if this site is used annually for spawning and continues to be the focus of additional monitoring. Spawning also occurs on an annual basis in the Kinnaird area, as egg and larval captures have been collected from 2007-2013. However, the main geographical boundaries of the spawning location where eggs are deposited remain uncertain. Finally, there are multiple sites used for spawning south of the international border on an annual basis. Additional years of data are required to address this management question in further detail.
MQ: How does the interaction among presumed subpopulations of sturgeon in the lower Columbia River change during high flow events?
White Sturgeon have high fidelity to specific habitat or location for a large portion of the year. Movements for feeding or spawning are primarily made during the summer and fall months. Further, movements that are suspected to be spawning related are made primarily within 20 km of where the individual is residing year-round. There is a large sample size of male and female White Sturgeon (n>100) with 10 year acoustic transmitters that are being monitored under this program. It is expected that at the end of this program, there will be sufficient data to describe White Sturgeon movements in the lower Columbia River.
MQ: Are probabilities of survival higher at the egg stage in years of higher flows?
Insufficient data exist to address this management question and complexities with sampling methods in large rivers may not allow this management question to be addressed directly over the course of this program. This stems from insufficient knowledge pertaining to numbers of adults spawning, egg distributional data, and knowledge around capture efficiency of the sampling gear is required to address this question. Given the non-random sampling technique employed when setting egg mats and drift nets, it will be difficult to provide an annual estimate of egg survival. Genetic work under CLBMON28 found that 121.5 ± 34.7 adults (mean ± SD) were spawning within the Canadian section of the lower Columbia River within each of two years (2011 and 2012). Ultimately, assessment of egg survival across flow years will be limited to detection of wild juveniles surviving and recruiting to the juvenile sampling program (CLBMON29). Importantly, 2011 and 2012 were considered to be above normal flow years (sustained flows >200kcfs) and will serve as test years for this program.
MQ: What effects do higher flows have on recruitment to the larval stage?
Further data are required to address this question. There is no relationship between flows and numbers of larvae captured for the years monitoring has been completed (~8 years).
MQ: What is the effect (and associated mechanisms) of higher flows on juvenile survival in the lower Columbia River?
Survival of juveniles released from the conservation aquaculture program is high and has been estimated at approximately 25% in the first year and more than 80% thereafter. Capture data from the lower Columbia from 2009-2013 suggests that annual survival estimates may be underestimated but further data are required to examine age specific survival. Finally, several wild juveniles that have been captured in the lower Columbia and in Lake Roosevelt are of an age that is consistent with the 1997 year class. 1997 was an above normal water year and though the sample size is small, it is possible that more juveniles of this age class will be picked up in future sampling. The 1997 flow year discharge data are presented in this report as a comparison to high flow years that occurred in the lower Columbia River in 2011 and 2012.

MQ: Are there unidentified spawning sites in the lower Columbia River that are used during higher flows?
Relating spawning site selection and flows is challenging due to challenges associated with sampling at higher flows (e.g. 2012 flow year) and a relatively small dataset on spawning locations outside of the primary site at Waneta. Spawning (documented through egg and larval captures) had only been identified to occur at the Waneta area prior to the monitoring studies under the Columbia River Water Use Plan being implemented. Results from recent work reveal that spawning occurs downstream of HLK and ALH in some years, though it is not known if this site is used annually for spawning and continues to be the focus of additional monitoring. Spawning also occurs on an annual basis in the Kinnaird area, as egg and larval captures have been collected from 2007-2013. However, the main geographical boundaries of the spawning location where eggs are deposited remain uncertain. Finally, there are multiple sites used for spawning south of the international border on an annual basis. Additional years of data are required to address this management question in further detail.
MQ: How does the interaction among presumed subpopulations of sturgeon in the lower Columbia River change during high flow events?
White Sturgeon have high fidelity to specific habitat or location for a large portion of the year. Movements for feeding or spawning are primarily made during the summer and fall months. Further, movements that are suspected to be spawning related are made primarily within 20 km of where the individual is residing year-round. There is a large sample size of male and female White Sturgeon (n>100) with 10 year acoustic transmitters that are being monitored under this program. It is expected that at the end of this program, there will be sufficient data to describe White Sturgeon movements in the lower Columbia River.
MQ: Are probabilities of survival higher at the egg stage in years of higher flows?
Insufficient data exist to address this management question and complexities with sampling methods in large rivers may not allow this management question to be addressed directly over the course of this program. This stems from insufficient knowledge pertaining to numbers of adults spawning, egg distributional data, and knowledge around capture efficiency of the sampling gear is required to address this question. Given the non-random sampling technique employed when setting egg mats and drift nets, it will be difficult to provide an annual estimate of egg survival. Genetic work under CLBMON28 found that 121.5 ± 34.7 adults (mean ± SD) were spawning within the Canadian section of the lower Columbia River within each of two years (2011 and 2012). Ultimately, assessment of egg survival across flow years will be limited to detection of wild juveniles surviving and recruiting to the juvenile sampling program (CLBMON29). Importantly, 2011 and 2012 were considered to be above normal flow years (sustained flows >200kcfs) and will serve as test years for this program.
MQ: What effects do higher flows have on recruitment to the larval stage?
Further data are required to address this question. There is no relationship between flows and numbers of larvae captured for the years monitoring has been completed (~8 years).
MQ: What is the effect (and associated mechanisms) of higher flows on juvenile survival in the lower Columbia River?
Survival of juveniles released from the conservation aquaculture program is high and has been estimated at approximately 25% in the first year and more than 80% thereafter. Capture data from the lower Columbia from 2009-2013 suggests that annual survival estimates may be underestimated but further data are required to examine age specific survival. Finally, several wild juveniles that have been captured in the lower Columbia and in Lake Roosevelt are of an age that is consistent with the 1997 year class. 1997 was an above normal water year and though the sample size is small, it is possible that more juveniles of this age class will be picked up in future sampling. The 1997 flow year discharge data are presented in this report as a comparison to high flow years that occurred in the lower Columbia River in 2011 and 2012.