To date, more than 600,000 Sockeye have passed Bonneville in 2014, making this season the highest on record since fish counts began in 1938 at the dam’s construction. At Wells Dam, 490,840 sockeye were counted and at Rock Island 581,120.
Favorable ocean conditions, improved juvenile rearing habitat, and improved freshwater migration conditions have all benefited salmon in general this year; however, sockeye returning to the Canadian portion of the Okanagan subbasin have also had the added benefit of the Fish-Water Management Tool (FWMT). The FWMT is an innovative computer model created through a partnership between Douglas County Public Utility District, and the Canadian Okanagan Basin Technical Working Group (COBTWG) which is composed of three organizations; the Okanagan Nation Alliance, Department of Fisheries and Oceans Canada, and the British Columbia Ministry of Water, Land and Air Protection. Together these organizations identified three key limiting factors for Okanagan Sockeye: pre-spawn mortality, mortality from redd scouring, and habitat loss.
Before implementation of the FWMT, inconsistent flow from the Okanagan Lake Dam would often result in high-density mortality events such as redd desiccation/freezing, redd scouring during incubation, and dewatered reds. Additionally, inadequate flow also reduced spawning habitat and caused a high mortality of spawners in the spawning area immediately below McIntire Dam. The COBTWG recognized that better flow management could reduce the frequency and magnitude of these density-independent mortality events. The FWMT is an internet-accessible decision support system used by Canadian fish and water managers to inform water-release decisions incorporating real-time data such as lake levels, stream flows, snowpack, temperature, and dissolved oxygen, and near-real-time biological data. Development and collaborative use of the FWMT has optimized timing of water releases from Okanagan Lake Dam for sockeye production while balancing multiple human objectives and trade-offs. Implementation of FWMT in the Canadian Okanagan has eliminated or at least minimized density-independent mortality factors that had profoundly limited smolt production from the Okanagan Basin in the past. The FWMT has allowed managers to mitigate the oxygen-temperature “squeeze” that previously limited late-summer sockeye habitat availability in Osoyoos Lake. Since the adult sockeye from the first brood year to benefit from the FWMT returned over Wells Dam in 2008, the sockeye count at Wells has averaged 235,766, compared with the 1977-2007 average of 30,202.
Thanks to Tom Kahler for his contributions to this article