A Synthesis of Kootenai River Burbot Stock History and Future Management Goals

Abstract

AbstractIn Idaho, Burbot Lota lota are endemic only to the Kootenai River, where they once provided an important winter fishery to the indigenous people and European settlers. This fishery and that of Kootenay Lake in British Columbia may have been the most robust Burbot fisheries in North America. However, the fishery in Idaho rapidly declined after the construction of Libby Dam by the U.S. Army Corps of Engineers in 1972, and it closed in 1992. Concomitant to the collapse in Idaho was the collapse of the Burbot fishery in Kootenay Lake and the Kootenay River. The operation of Libby Dam for hydroelectric power generation and flood control created major changes in the river's nutrient concentration, temperature, and seasonal discharge, particularly during the winter when Burbot spawn. Libby Dam operations were implicated as the major limiting factor to Burbot recruitment, giving rise to higher winter temperatures and widely fluctuating flows. Because the Burbot in the Kootenai River are at risk of demographic extinction, a conservation strategy was prepared to outline the measures necessary to rehabilitate the Burbot population to a self‐sustaining level. The strategy indicated that operational discharge changes at Libby Dam are required during winter to provide suitable temperature and discharge conditions for Burbot migration and spawning. Studies recommend that the discharge at Bonners Ferry average 176 m3/s for a minimum of 90 d (mid‐November through mid‐February). Furthermore, preferred Burbot water temperatures of about 6°C are necessary for migration and cooler temperatures of 1–4°C for spawning. With each passing year, Burbot stock limitations increasingly constrain rehabilitation. Thus, coordination of intensive culture, extensive rearing, and pen rearing among the Kootenai Tribe of Idaho, the British Columbia Ministry of Environment, the University of Idaho's Aquatic Research Institute, and the Idaho Department of Fish and Game is important for restoration.