Lower Columbia River Adult White Sturgeon Monitoring Program (CLBMON-28). Year 11 Data Report

Author: B.C. Hydro

The objectives of CLBMON-28 when first developed were to 1) collect data to describe abundance trends, population structure and reproductive status of adult White Sturgeon, 2) collect mature adult White Sturgeon to serve as broodstock for the annual Conservation Aquaculture Program as needed, 3) determine White Sturgeon spawning locations, habitat use, and movements using both direct (capture) and indirect (telemetry) methods, and 4) determine the timing and frequency of spawning events.

What are the abundance trends, population structure and reproductive status of adult White Sturgeon in the lower Columbia River?

– A systematic stock assessment encompassing the entire Transboundary Reach of the lower Columbia River in Canada and the US was initiated in 2013 and has been completed annually. The goals of the stock assessment were to estimate population abundance and survival that can be used to track recovery for this population. At the conclusion of 2018, twelve sessions have been completed in Canada and preliminary data analyses have estimated a wild population abundance of 1,071 (629-1,512) individuals. This is similar to the estimate of 1,100 developed by Irvine et al. (2007) prior to the Columbia water use plan program being implemented.

– The wild population remains dominated by adult age classes, with limited wild juveniles captured during sampling programs (<1%). Juveniles released from the Conservation Aquaculture Program are surviving and are represented in a large proportion of the adult captures. There are an estimated 5,725 (5,022-6,428) hatchery-origin individuals in Canada from analyses conducted using the stock assessment data. These juveniles have extended the estimated extirpation of this population by several decades and are now reaching a size and stage of maturity where they will start entering the adult population. - An aquaculture program that centers on using wild collected embryos and larvae was developed in 2014 based on results from previous years genetic analyses. As of 2015, this is currently the sole source of offspring collected for stocking purposes in order to meet long term genetic goals for the population. It has resulted in suspending the traditional broodstock program going forward, which was an original objective of this monitoring program. How much spawning occurs annually at known spawning locations, and are there other spawning locations unidentified in the lower Columbia River? - Wild spawning has been detected annually at up to 5 locations in the transboundary section of the Columbia River, with the mean number of spawning events ranging from 1.6 at the Arrow Lakes Generating Station (ALH) site to 11.1 at the Waneta site from 20112018. Embryos survive to hatch at all locations. - Using genetic methods, it was 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). - Spawning occurs annually at the Waneta area, with the number of estimating spawning days varying by year. - Spawning has been identified through embryo and larval captures downstream of Hugh L. Keenleyside Dam and ALH. ALH represents the second known location of egg deposition in the Canadian section of the lower Columbia River and has been incorporated into annual monitoring programs to further describe spawning frequency and duration. - An additional spawning location is used annually (2007-2018) in the vicinity of Kinnaird but the exact location(s) of egg deposition remains unknown. - Additional spawning sites are used annually south of the international border (e.g., Northport WA). What is the degree of interaction among subpopulations of White Sturgeon in the lower Columbia River? - Though fidelity to specific habitats or locations has been identified as high, individuals have been identified to move throughout the river during the spring and summer months based on subsequent captures or telemetry tracking. We know through direct capture and telemetry methods that some individuals move between Canada and the United States, though this exchange is higher for hatchery origin individuals soon after release. Analyses using the stock assessment data found that there was less than a 1% chance of movement between countries for wild adults captured more than once during the 5 year monitoring period. An analysis of longterm movements is underway in 2019 to determine the interaction (i.e., spawning) of individuals from different sections of the transboundary reach. How do existing river operations affect adult movements, habitat preference, spawning site selection, or spawning activity? -Adults select deep, slow moving sections of the river, which are currently not limited by the existing operating regime of the river. Site fidelity is extremely high to very specific habitats and individuals spend >60% of their time at a single location and >90% of their time within a specific river reach (10 km of river habitat). When movements do occur, they tend to occur during periods of warmer water and increasing flows and are assumed to be for either feeding or spawning.

– Spawning related movements have been identified for a select number of mature males and females. Individuals tend to move to spawning locations within the reach of river where they spend the majority of their time.

What are the abundance trends, population structure and reproductive status of adult White Sturgeon in the lower Columbia River?

– A systematic stock assessment encompassing the entire Transboundary Reach of the lower Columbia River in Canada and the US was initiated in 2013 and has been completed annually. The goals of the stock assessment were to estimate population abundance and survival that can be used to track recovery for this population. At the conclusion of 2018, twelve sessions have been completed in Canada and preliminary data analyses have estimated a wild population abundance of 1,071 (629-1,512) individuals. This is similar to the estimate of 1,100 developed by Irvine et al. (2007) prior to the Columbia water use plan program being implemented.

– The wild population remains dominated by adult age classes, with limited wild juveniles captured during sampling programs (<1%). Juveniles released from the Conservation Aquaculture Program are surviving and are represented in a large proportion of the adult captures. There are an estimated 5,725 (5,022-6,428) hatchery-origin individuals in Canada from analyses conducted using the stock assessment data. These juveniles have extended the estimated extirpation of this population by several decades and are now reaching a size and stage of maturity where they will start entering the adult population. - An aquaculture program that centers on using wild collected embryos and larvae was developed in 2014 based on results from previous years genetic analyses. As of 2015, this is currently the sole source of offspring collected for stocking purposes in order to meet long term genetic goals for the population. It has resulted in suspending the traditional broodstock program going forward, which was an original objective of this monitoring program. How much spawning occurs annually at known spawning locations, and are there other spawning locations unidentified in the lower Columbia River? - Wild spawning has been detected annually at up to 5 locations in the transboundary section of the Columbia River, with the mean number of spawning events ranging from 1.6 at the Arrow Lakes Generating Station (ALH) site to 11.1 at the Waneta site from 20112018. Embryos survive to hatch at all locations. - Using genetic methods, it was 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). - Spawning occurs annually at the Waneta area, with the number of estimating spawning days varying by year. - Spawning has been identified through embryo and larval captures downstream of Hugh L. Keenleyside Dam and ALH. ALH represents the second known location of egg deposition in the Canadian section of the lower Columbia River and has been incorporated into annual monitoring programs to further describe spawning frequency and duration. - An additional spawning location is used annually (2007-2018) in the vicinity of Kinnaird but the exact location(s) of egg deposition remains unknown. - Additional spawning sites are used annually south of the international border (e.g., Northport WA). What is the degree of interaction among subpopulations of White Sturgeon in the lower Columbia River? - Though fidelity to specific habitats or locations has been identified as high, individuals have been identified to move throughout the river during the spring and summer months based on subsequent captures or telemetry tracking. We know through direct capture and telemetry methods that some individuals move between Canada and the United States, though this exchange is higher for hatchery origin individuals soon after release. Analyses using the stock assessment data found that there was less than a 1% chance of movement between countries for wild adults captured more than once during the 5 year monitoring period. An analysis of longterm movements is underway in 2019 to determine the interaction (i.e., spawning) of individuals from different sections of the transboundary reach. How do existing river operations affect adult movements, habitat preference, spawning site selection, or spawning activity? -Adults select deep, slow moving sections of the river, which are currently not limited by the existing operating regime of the river. Site fidelity is extremely high to very specific habitats and individuals spend >60% of their time at a single location and >90% of their time within a specific river reach (10 km of river habitat). When movements do occur, they tend to occur during periods of warmer water and increasing flows and are assumed to be for either feeding or spawning.

– Spawning related movements have been identified for a select number of mature males and females. Individuals tend to move to spawning locations within the reach of river where they spend the majority of their time.