Science response : refining candidate critical habitat for White Sturgeon, UCR population

In Canada, White Sturgeon (Acipenser transmontanus) is found in rivers and lakes within the Fraser, Nechako, Columbia, and Kootenay river systems in British Columbia (BC). White Sturgeon is the largest (max length 6.10 m) freshwater fish species in Canada, with a lifespan that can exceed 100 years (Scott and Crossman 1998; McPhail 2007). The Upper Columbia River population of White Sturgeon is a designatable unit (DU) recognized as at-risk by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Recovery of the White Sturgeon, Upper Columbia River population or DU, is impeded by recruitment failure due to habitat changes, predominantly related to dams and river regulation (DFO 2014, 2023a; McAdam 2015). Other threats include direct and indirect alterations to habitat (e.g., instream activities; development of riparian, foreshore, and floodplain areas), incidental mortality, and ecosystem changes (e.g., invasive species; Hatfield et al. 2013; DFO 2014, 2023a). Recovery efforts for White Sturgeon in the Upper Columbia River began in 2000 with the establishment of the Upper Columbia White Sturgeon Recovery Initiative (UCWSRI), a coordinated transboundary Technical Working Group (TWG) formed to provide scientific advice, to develop plans to guide recovery of the species, and to oversee implementation and monitoring of these plans in cooperation with the responsible agencies. Albeit not being official documents under the Species at Risk Act (SARA 2002) in Canada, the UCWSRI TWG developed the original recovery plan in 2002, updated in 2012 (Hildebrand and Parsley 2013), which provides broad recovery objectives covering both the Canadian and United States (US) portions of the recovery area. In Canada, White Sturgeon were assessed by COSEWIC as six nationally significant populations in 2003, with the Upper Columbia River DU of White Sturgeon assessed as Endangered. This COSEWIC (2003) assessment subsequently led to the White Sturgeon, Upper Columbia River population, being listed under Schedule 1 of SARA as Endangered in 2006. In 2012, the COSEWIC reassessment revised the population structure and identified four White Sturgeon DUs and again assessed the Upper Columbia River DU as Endangered (COSEWIC 2013). Following the SARA listing in 2006, a federal Recovery Strategy (DFO 2014, 2023a) was produced that identified White Sturgeon critical habitat. Critical habitat is defined in SARA as “…the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in a recovery strategy or in an action plan for the species” [s. 2(1)]. Under SARA S.41.1(c) a species’ critical habitat must be identified “…to the extent possible, based on the best available information, including the information provided by COSEWIC, and examples of activities that are likely to result in its destruction.” At the time of original critical habitat identification for White Sturgeon, spawning within the Kinnaird reach (downstream of the Kootenay-Columbia River confluence) had only recently been detected and therefore evidence was deemed insufficient to support its inclusion as critical habitat. Nevertheless, the White Sturgeon Recovery Strategy (DFO 2014, 2023a), Action Plan (DFO 2023b), and Hatfield et al. (2013), assessed the Kinnaird reach of the Columbia River as important habitat since spawning had been recently observed. In line with the recommended schedule of studies in the recovery strategy (DFO 2014, 2023a), research and monitoring efforts on White Sturgeon in the Kinnaird reach of the Columbia River have increased, and the area appears to support all life stages (BC Hydro 2023a, 2023b). Fisheries and Oceans Canada (DFO) Species at Risk Program has requested science advice to support the refinement of additional candidate critical habitat for White Sturgeon, Upper Columbia River population, using data from recent monitoring efforts in the Kinnaird reach. The assessment and advice arising from this Canadian Science Advisory Secretariat (CSAS) Science Response process will be used by the Species at Risk Program to ensure critical habitat is properly identified to the greatest extent possible and protected for White Sturgeon, Upper Columbia River population. Existing critical habitats for the DU are not being considered in this review. The specific objectives of this review are to: 1. Review information available from the Kinnaird reach on the habitat necessary for survival and recovery of White Sturgeon, Upper Columbia River population. 2. Update the functions, features, and attributes of the habitat across life stages. 3. Present updated candidate critical habitat spatial attributes for the Kinnaird reach. This Science Response Report results from the January 11, 2024 regional peer review on the Information for Refining Candidate Critical Habitat for White Sturgeon (Acipenser transmontanus), Upper Columbia River Population.

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