| Abstract/Description or Keywords |
The Nechako River population of white sturgeon (Acipenser transmontanus) is ranked as a critically imperilled species in British Columbia (BC Conservation Data Centre 2008), as well as a species listed as endangered under Schedule 1 of the Species at Risk Act (SARA). Genetic analysis indicates that the Nechako River population is distinct from that of the Fraser River, suggesting that there is no or limited inter-breeding between the populations (Smith et al. 2002). Research also suggests that the Nechako population is experiencing recruitment failure, with the population dominated by larger and older fish with few juveniles (Nechako White Sturgeon Recovery Initiative (NWSRI) 2008). At present the reasons for the recruitment failure are unknown, however, a recent report has suggested that alteration of critical spawning habitats may play a role (McAdam et al. 2005). Extensive radio tagging programs in recent years have allowed for the tracking of adult white sturgeon movements in the Nechako River. As of the spring of 2008, there were approximately 79 radio tagged adults in the system. Approximately 27 of these tags were implanted by Golder Associates in the fall of 2005 (Golder Associates, 2006) with the remainder implanted in the spring of 2006 through 2008 by the BC Ministry of Environment (MoE) in conjunction with the Carrier Sekani Tribal Council (CSTC). The MoE/CSTC tagging was initiated by the Nechako White Sturgeon Recovery Initiative- Technical Working Group (NWSRI-TWG), to capture brood stock, and subsequently incubate, hatch and raise juvenile sturgeon for release in order to meet the goals of the breeding plan (NWSRI 2005). These programs also provided an assessment of fish reproductive state, which helped focus telemetry effort and the interpretation of telemetry data for the study reported here. Radio tagging efforts (NWRSI), and work completed by Triton Environmental Consultants Ltd. (Triton) in 2004 through 2007 formed the basis for the monitoring and sampling plan for 2008. In particular, a previously identified spawning area in the vicinity of Vanderhoof (Triton 2004) was the focus for the work in 2008. In addition, the physical conditions in the river around the time of the congregation in 2004 to 2007 (i.e. water temperature and discharge) were examined to identify the critical monitoring period for 2008. In particular, the information on timing and location of the 2004 and 2006 congregations was used since those years had similar temperature and flow regimes as was expected to occur in 2008. The 2008 Nechako white sturgeon spawning assessment project was initiated in order to monitor Nechako River white sturgeon during the expected period of spawning activity (mid-May to mid-June), and to complete field surveys should a congregation of sturgeon be observed. This report outlines the methods used to monitor the timing and location of white sturgeon spawning in the Nechako River in 2008, presents the results of field activities undertaken in May and June of 2008, and details a preliminary model that assesses the ability of a suite of environmental cues to predict the timing of white sturgeon spawning in the Nechako River. |
