Summary The white sturgeon (Acipenser transmontanus) of the Kootenai River was listed as endangered on September 6, 1994 by the United States Fish and Wildlife Service. This transboundary population, residing in Kootenay Lake and Kootenay River in Canada, and the Kootenai River in the US, has been in general decline since the mid‐1960's. There has been very little recruitment to this population in the last 20 years. This population became isolated from other white sturgeon populations of the Columbia River basin during the last ice age of approximately 10,000 years ago. The population adapted to the pre‐development conditions of the Kootenai system, with a high spring freshet and extensive side channel and low‐lying delta marshlands. Modification of the Kootenai River by human activities, such as industrial developments, floodplain dyking, and dam construction has changed the hydrograph of the Kootenai River, altering sturgeon spawning, incubation and rearing habitats and reducing overall biological productivity. A Kootenai River white sturgeon draft recovery plan was prepared by the US Fish and Wildlife Service in cooperation with other agencies in the US and Canada. The plan was peer reviewed and there was a parallel public consultation process, where public commentary was invited from both sides of the international border. The short‐term recovery objectives of the recovery plan are to prevent extinction and re‐establish successful natural recruitment. The identified long‐term objectives are the re‐establishment of a self sustaining population and the restoration of productive habitat, in order to downlist to threatened status and subsequently delist this population when recovery is well established. Specific actions needed for recovery include spring flow augmentation during the reproduction period; a conservation aquaculture program to prevent near‐term extinction; habitat restoration, and research and monitoring programs to evaluate recovery progress.

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A simple, inexpensive apparatus (embryo incubation unit [EIU]) was developed and used to assess the relationship between sediment cover (Kootenai River sediments, 97% by weight in the 0.83-mm-to 1.0-mm-diameter range) and survival of white sturgeon Acipenser transmontanus embryos in the laboratory. An apparatus-testing trial assessed the effects of two sediment depths (5 and 20 mm), three EIU ventilation hole sizes (4.8, 6.8, and 9.5 mm) providing three levels of intrasediment flow, and EIU location (upstream or downstream in laboratory troughs) on embryo survival at two above-substrate flow velocities (0.05 and 0.15 m/s). A second trial assessed the effects of sediment cover duration (5-mm sediment cover for 4, 7, 9, 11, or 14 d, with a ventilation hole size of 9.5 mm and a flow velocity of 0.17 m/s) on mean embryo survival and larval length and weight. In the apparatus-testing trial, embryo survival was reduced (P , 0.0001) to 0-5% under sediment covers of either 5 or 20 mm in both the higher-flow and lower-flow troughs; survival in control EIUs without sediments exceeded 80%. Survival was not significantly affected by ventilation hole size but was weakly affected by EIU location. In the second trial, embryo survival was negatively correlated (P ¼ 0.001) with increasing duration of sediment cover and was significantly higher for embryos covered for 4 d (50% survival) or 7 d (30% survival) than for those covered for 9, 11, or 14 d (15-20% survival). Sediment cover also delayed hatch timing (P , 0.0001) and decreased mean larval length (P , 0.0001). Our results suggest that sediment cover may be an important early life stage mortality factor in rivers where white sturgeon spawn over fine-sediment substrates.

As there are few larval‐diet rearing methods for burbot Lota lota, it is important to develop these methods for ongoing conservation and future commercial aquaculture efforts. The performance and macronutrient composition of age‐0 burbot were compared after fish were fed four different diets for 8 weeks. Diets included three commercial larval‐rearing diets and Daphnia magna. Performance metrics involved mean length and weight, survival, and cannibalism. The macronutrient composition (dry matter) of fish and diets was measured as the percentages of moisture, lipid, protein, and ash, along with energy content. Significant differences in mean length and weight occurred, although survival and cannibalism were not different among treatments at the end of the experiment. Mean weight and length were significantly higher with diets 1 and 2. Fish fed diet 2 had the greatest mean survival (32%), followed by those fed the D. magna diet (30%), diet 3 (27%), and diet 1 (25%). Fish fed diet 1 experienced the greatest amount of cannibalism (48%), followed by those fed the D. magna diet (43%), diet 3 (43%), and diet 2 (26%). The macronutrient compositions of whole‐body burbot were 81.83–86.91% for moisture, 4.42–20.49% for lipid, 63.53–75.65% for protein, and 8.41–14.25% for ash, and energy content was 4,818–5,915 kcal/g. Diets 1 and 2 provided the best performance among the all diets and may be used in ongoing and future burbot aquaculture efforts. This study demonstrates that burbot can be reared with multiple commercial larval diets and provides the first reported macronutrient compositions and relative cannibalism of age‐0 burbot. This study will help advance the ongoing Kootenai Tribal burbot conservation aquaculture program and may have important applications in other conservation and future commercial production efforts.

The objective of this study was to determine the effect of temperature on growth and survival of larval and juvenile burbot, Lota lota maculosa. Burbot aquaculture is developing primarily in response to declining wild stocks and a need to restore such populations. Beyond conservation efforts, there is also potential to culture this species commercially. However, many important aspects of burbot culture remain unaddressed. In this study larval and juvenile burbot were reared at three constant water temperatures (10, 15, and 20°C) in an intensive culture setting. Two 30 day trials were conducted during the larval life stage and one 60 day trial during the juvenile life stage. In Trial 1, larval burbot (mean total length ± SD, 6.9 ± 1.0 mm, approximately 65 days post hatch) reared at 20°C grew the fastest, while growth was lowest in the 10°C treatment. Survival was inversely related to temperature, with the lowest average of 6.6% observed in larvae reared at 20°C. The percentage cannibalized was quantified and found to be positively correlated with water temperature, and reached 58.0% in larvae reared at 20°C. In Trial 2, as larvae approached metamorphosis (12.9 ± 1.9 mm, approximately 100 days post hatch), growth was also highest in fish at 20°C and lowest in those at 10°C. At this stage survival was higher in fish at lower temperatures, but the percentage cannibalized appeared independent of temperature, averaging over 50% in fish at all temperatures. In Trial 3, growth of juveniles (59.9 ± 12.4 mm, approximately 205 days post hatch) reared at 15 and 20°C was not significantly different, yet both displayed significantly increased growth relative to juveniles reared at 10°C. Juveniles were fully transitioned to a dry diet, and survival averaged > 93% in all culture temperatures. The percentage cannibalized during this life stage averaged b 5%, and was not affected by temperature. This study demonstrated the importance of water temperature, as it clearly affects culture performance of larval and juvenile burbot. Results from this study have implications for maximizing growth during larval and juvenile life stages of this species, and provide a comparative, empirical framework for establishing conservation, or commercial aquaculture programs for burbot.

A key challenge in watershed restoration is identifying the appropriate assessments, data, and analyses needed to identify disrupted natural processes, lost and degraded habitats, and limiting factors to ultimately identify and design successful restoration projects. This has proven particularly challenging for large restoration programs focused on recovery of threatened and endangered salmon and trout where numerous tools, models, and other assessments have been developed to assist with habitat restoration at the watershed, reach, and project scale. Unfortunately, it is often unclear which step in the restoration process these various assessment tools will actually address. To assist with identifying the appropriate assessment tool (e.g., model, data collection, analysis, and survey), we reviewed major categories of watershed restoration assessment tools to determine their goals, inputs, outputs, and their utility in helping plan, prioritize, and implement restoration actions. The major categories of assessment tools reviewed were: (1) life cycle and fish–habitat models, (2) watershed assessment methods and techniques, (3) reach assessments, (4) prioritization tools, and (5) common monitoring methods to identify, prioritize, and plan river and watershed restoration projects. We specifically indicated whether these assessment tools directly or indirectly assisted with the key steps in the restoration process that are required to develop successful restoration plans and projects. These steps involve assessing watershed conditions, identifying limiting habitats and life stages, identifying problems and restoration actions, selecting restoration techniques, prioritizing restoration actions, or designing actual restoration projects. It is important to recognize that no single assessment tool will address all the steps in the restoration process. Selecting appropriate assessment tools requires a clear understanding of the goals of the restoration program and which step in the restoration process will be addressed by a particular tool. We provide recommendations for how restoration practitioners and managers can use our review to help select the appropriate assessment tools needed for their watershed.

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