Excess energy expenditure during the upstream migration of adult fall chinook salmon Oncorhynchus tshawytscha may reduce spawning success or lead to increased prespawning mortality. Recent advances in biotelemetry make it possible to assess the energetic costs of upstream migration. Our objectives were to evaluate the use of physiological telemetry to estimate the energy expended by adult fall chinook salmon at different swimming velocities and to compare these data to those associated with other species of salmonids. An electromyogram (EMG) telemetry system was used to obtain, transmit, and record an integrated EMG pulse signal that represented the time between muscle contractions. The EMG telemetry system provides a means to evaluate the effects of structural or operational changes in the hydropower system on energy expenditure and reproductive success of upstream migrant adult salmon. Seven adult salmon (71.5 to 106 cm fork length [FL]) were tagged and exercised in a respirometer at 15 and 20°C. The EMG pulse rates were similar between temperatures tested, but small fish (≤90 cm FL) had a greater pulse rate than did large fish (>90 cm FL). Oxygen consumption was related to swimming velocity, and approximately 76% of the variance in oxygen consumption could be explained by a model that included EMG pulse rate and fish size‐class designation. The results of our study showed that adult fall chinook salmon had similar swimming performances when compared with other salmonids, and EMG transmitters could be used to assess activity rates (and oxygen consumption) in wild migrating fall chinook salmon.
Published seed storage data for 92 species derived frotn 13 localities were subjected to probit analysis to determine the half-viability period (P.^o) for each satnple. Estitnates of half-viability petiod for each species averaged over all 13 localities were calculated using a least square tneans procedute applied to known values for the half-viability period for each species at each of its storage stations. The results reported hete represent an itiitial step in the objective organization of seed longevity data.
Some fall Chinook salmon Oncorhynchus tshawytscha initiate spawning in the Snake River downstream of Hells Canyon Dam at temperatures that exceed 138C and at intergravel dissolved oxygen concentrations that are less than 8 mg O 2 /L. Although water temperature declines and dissolved oxygen increases soon after spawning, the initial temperature and dissolved oxygen levels do not meet the water quality standards established by the states of Oregon and Idaho for salmonid spawning. Our objective was to determine whether temperatures from 138C to 178C and dissolved oxygen levels from 4 to more than 8 mg O 2 / L during the first 40 d of incubation followed by declining temperature and rising dissolved oxygen affected survival, development, and growth of Snake River fall Chinook salmon embryos, alevins, and fry. During the first 40 d of incubation, temperatures were experimentally adjusted downward approximately 0.28C/d and oxygen was increased in increments of 2 mg O 2 /L to mimic the thermal and oxygen regime of the Snake River where these fish spawn. At 40 d postfertilization, embryos were moved to a common exposure regime that followed the thermal and dissolved oxygen profile of the Snake River through emergence. Mortality of fall Chinook salmon embryos increased markedly at initial incubation temperatures of 178C or more, and a rapid decline in survival occurred between 16.58C and 178C; there were no significant differences in survival at temperatures up to 16.58C. Initial dissolved oxygen levels as low as 4 mg O 2 /L over a range of initial temperatures from 158C to 16.58C did not affect embryo survival to emergence. There were no significant differences in alevin and fry size at hatch and emergence across the range of initial temperature exposures. The number of days from fertilization to eyed egg, hatch, and emergence was highly related to temperature and dissolved oxygen; fish required from 6 to 10 d longer to reach hatch at 4 mg O 2 /L than at saturation and up to 24 d longer to reach emergence. In contrast, within each dissolved oxygen treatment, fish required about 20 d longer to reach hatch at 138C than at 16.58C (no data were available for 178C) and up to 41 d longer to reach emergence. Overall, this study indicates that exposure to water temperatures up to 16.58C will not have deleterious effects on survival or growth from egg to emergence if temperatures decline at a rate of 0.28C/d or more after spawning. Although fall Chinook salmon survived low initial dissolved oxygen levels, the delay in emergence could have significant long-term effects on their survival. Thus, an exemption to the state water quality standards for temperature-but not oxygen-may be warranted for the portions of the Snake River where fall Chinook salmon spawn.
The research presented in this report is part of the regional habitat restoration program in the lower Columbia River and estuary (LCRE). As part of this program, we have established a suite of reference sites to help meet the goal of understanding and restoring wetland habitat. The data collected at these reference sites from 2005 through the present were analyzed in this study to meet two primary objectives: 1) to inform restoration planning and design by quantifying the ecological and hydrological conditions necessary for development of wetland plant communities and tidal channel networks and 2) to evaluate the effectiveness of wetland restoration actions in the LCRE by comparing restoration and reference site monitoring data. In this report, we present the results of the analysis of 51 reference wetland sites, focusing on the elevation, sediment, and inundation ranges required by native tidal wetland vegetation. We describe critical factors influencing existing wetland patterns in the LCRE, including the vegetation assemblages present, the elevation ranges at which they occur, and the inundation dynamics that result in their current distribution. Finally, we present how these data can be used to evaluate restoration action effectiveness. v Executive Summary vi Hydro-Vegetation Zones Shallow-water vegetation assemblages show distinct differences along the gradient between the mouth of the river and the upstream end of the estuary at Bonneville Lock and Dam. There are three zones based on species richness; the central region (rkm 50 to rkm 150) has the greatest number of species, and the upper and lower ends of the estuary have lower numbers of species. These three species richness zones can be characterized hydrodynamically as tidal-dominated, mixed tidal and riverdominated, and river-dominated, moving from the mouth of the Columbia River to Bonneville Dam. We hypothesize that fewer vegetation species are physiologically adapted to the extreme inundation in the upper end of the estuary, and, likewise, few are adapted to the tidal variability and salinity in the lower estuary. The fact that the mixed zone contains the greatest number of species suggests that the natural ecological disturbance regime may be lower there, and there may be a larger species pool adapted for these conditions in this zone. This intermediate disturbance hypothesis has been used in many ecosystems to describe the conditions that result in higher species diversity. Further examination of the hydrologic gradient revealed that the estuary can be divided further into five zones, driven primarily by salinity intrusion at the lower end and stronger fluvial flooding influence at the upper end. The breaks for these zones occur at approximately rkm 40, 104, 136, and 181. These breaks are preliminary and should be refined with additional data in areas of sparse sites and with other hydrologic analyses currently under way. The five hydro-vegetation zones developed from this analysis provide a means of determining the ranges of controlling factors ...
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