James A. Chandler

Spawning Habitat Used by Fall Chinook Salmon in the Snake River

Abstract Literature describing spawning habitat used by fall-run chinook salmon Oncorhynchus tshawytscha is lacking for populations using large, main-stem rivers. A stable spawning flow regime in the Snake River below Hells Canyon Dam and enhanced survey capabilities using remote underwater videography allowed us to accurately describe spawning habitat used by fall chinook salmon within this large river. Water depth measured at 205 fall chinook salmon redds ranged from 0.2 to 6.5 m. Mean water column velocity at 145 redds ranged from 0.4 to 2.1 m/s, and substrate- level water velocity at 164 redds ranged from 0.1 to 2.0 m/s. Substrate size classifications from 112 redds indicated that areas having particle sizes that are relatively homogenous with diameters of 2.5–15.0 cm are used for spawning. During our study, spawning generally began as water temperatures dropped below 16.0°C, and concluded as temperatures approached 5.0°C. Our results corroborate earlier observations of fall chinook salmon spawning in...

Movement, Swimming Speed, and Oxygen Consumption of Juvenile White Sturgeon in Response to Changing Flow, Water Temperature, and Light Level in the Snake River, Idaho

Abstract The flow of the Snake River downstream of Hells Canyon Dam, Idaho, frequently fluctuates as dam operators alter the amount of electrical load generated in response to moment-to-moment power needs (termed load-following). Flow fluctuations due to load-following have the potential to increase the energy used by juvenile white sturgeon Acipenser transmontanus that move to avoid unfavorable habitat or that alter swimming speed to maintain position over a range of velocities. Following laboratory respirometry experiments, a field study using electromyogram (EMG) and sonic telemetry was conducted to determine whether movement (area and distance), swimming speed, or oxygen consumption of juvenile white sturgeon responded to the operation of Hells Canyon Dam during three study periods when flows were artificially fluctuated to resemble extreme load-following operation (192–836 m3/s), held high and stable (442–629 m3/s), or held low and stable (275–284 m3/s). Respirometry results confirmed that the oxygen...

Survival, Development, and Growth of Fall Chinook Salmon Embryos, Alevins, and Fry Exposed to Variable Thermal and Dissolved Oxygen Regimes

Abstract Some fall Chinook salmon Oncorhynchus tshawytscha initiate spawning in the Snake River downstream of Hells Canyon Dam at temperatures that exceed 13°C and at intergravel dissolved oxygen concentrations that are less than 8 mg O2/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 13°C to 17°C and dissolved oxygen levels from 4 to more than 8 mg O2/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 0.2°C/d and oxygen was increased in increments of 2 mg O2/L to mimic the thermal and oxygen regim...

Survival and Growth of Juvenile Snake River Fall Chinook Salmon Exposed to Constant and Fluctuating Temperatures

Abstract The incipient lethal temperature (ILT) and critical thermal maximum (CTM) methods are used to set temperature limits for fish. However, the standard application of these methods does not always match the temperature regimes that fish experience in the wild. We used alternative methods to determine the thermal tolerance thresholds of juvenile fall-run Chinook salmon Oncorhynchus tshawytscha exposed to the temperature regimes that are common in the entrapment pools that form along the shoreline of the Snake River when flows are altered to meet electric power demand. A modified CTM test with a steady temperature rise (1.5°C/h) showed that one-half the fish died when temperatures reached 27.4–27.9°C and that survival at 25°C was highly variable; the average time to the first death was 9.1 h, varying from 1.7 to 22.5 h. Over 30 d, 99.8% of the fish in the constant temperature regimes (14–22°C) survived. In the fluctuating temperature regimes (which varied from 10–14°C to 22–27.5°C), overall survival w...

Water-Level Fluctuation Effects on Centrarchid Reproductive Success in Reservoirs: A Modeling Analysis

Abstract An individual-based model of nesting smallmouth bass Micropterus dolomieu and white crappie Pomoxis annularis is used to compare reproductive success in a deep reservoir and a shallow reservoir under different amplitudes and periods of water-level fluctuations. The model simulates nest site selection, egg deposition, and the subsequent development and survival of young from eggs through dispersal in a two-dimensional spatial grid of habitat cells representing the reservoir bottom. All simulations are for May through September using a daily time step. Nest site (cell) selection is determined from species-specific habitat suitability indices based on substrate, slope, depth, and structure. The development of the young is temperature dependent. Mortality occurs via attrition, abandonment, and whole-nest catastrophe. Model corroboration was performed with observations of nesting white crappies and smallmouth bass in Brownlee Reservoir, Idaho–Oregon. The predicted egg-to-dispersal survival declined wi...

Population viability analysis of white sturgeon and other riverine fishes

Abstract Many utilities face conflicts between two goals: generating cost-efficient hydropower and protecting riverine fishes. Research to develop ecological simulation tools that can evaluate alternative mitigation strategies in terms of their benefits to fish populations is vital to informed decision-making. In this paper, we describe our approach to population viability analysis of riverine fishes in general and Snake River white sturgeon in particular. We are finding that the individual-based modeling approach used in previous in-stream flow applications is well suited to addressing questions about the viability of species of concern for several reasons. Chief among these are: (1) the ability to represent the effects of individual variation in life history characteristics on predicted population viability; (2) the flexibility needed to quantify the ecological benefits of alternative flow management options by representing spatial and temporal variation in flow and temperature; and (3) the flexibility needed to quantify the ecological benefits of non-flow related manipulations (i.e., passage, screening, and hatchery supplementation).

Evaluating Salmon Spawning Habitat Capacity Using Redd Survey Data

Abstract Management and recovery goals for fish populations often rely on estimating the number of fish that can be supported by finite habitats. In the absence of direct measures of carrying capacity, management decisions are commonly informed by results of habitat models. However, the shortcomings and spatially explicit nature of most habitat models result in making assumptions, often preclude inclusion of important variables, and are rarely validated at the reach level. We analyze long-term, redd-count data for a population of Chinook Salmon Oncorhynchus tshawytscha to evaluate spawning habitat capacity of a major river. Adult escapement generally increased during the years 1994–2012; consequently site use and total redd counts also increased. Together, the annual use of spawning sites and the redd counts (as functions of adult escapement) provided evidence for density-dependent changes in the availability and capacity of spawning sites. Redd counts exceeded one recovery criterion specific to one spawn...

Comparison of Temperature Data Collected from Artificial Chinook Salmon Redds and Surface Water in the Snake River

Abstract During three incubation periods, we collected temperature data from within artificial redds constructed in known spawning locations of Chinook salmon Oncorhynchus tshawytscha and from the surface water of the Snake River. Our objectives were to compare the data to determine (1) whether estimates of fry emergence timing differed between the two environments and (2) whether surface water data could be used to predict thermal conditions within redds. Statistical tests indicated that no differences could be detected between accumulated thermal units calculated from intraredd and surface water data (all P ≥ 0.06). We observed very little diel thermal fluctuation or daily difference within and between environments. Regression of intraredd temperature on surface water temperature was significant (r2 ≥ 0.98; all P < 0.01), indicating that surface water temperature data can be used to predict intraredd temperature. We conclude that it is feasible to use surface water temperature as a surrogate for intrare...

The Effect of Fluctuating Temperatures and Ration Levels on the Growth of Juvenile Snake River Fall Chinook Salmon

Abstract Determining the fate of juvenile fish that are exposed to elevated temperatures is complicated by the fact that the optimum temperature for the growth and survival of salmonids decreases as the amount of food becomes restricted. In this study, naturally produced juvenile Snake River fall Chinook salmon Oncorhynchus tshawytscha were fed daily ration levels of 1, 4, or 8% of their body weight and exposed to either constant temperatures (10–14°C) or fluctuating temperatures that mimicked the heating rate (1.5°C/h) and maximum daily temperatures (19–23°C) of entrapment pools that form along the shoreline downstream of Hells Canyon Dam when river flows are altered to meet electric power demand. The survival rate for all groups was 99.9%, and there was no evidence that juvenile fall Chinook salmon fed reduced rations and exposed to constant temperatures grew to a greater extent than juvenile fall Chinook salmon exposed to fluctuating temperatures. The only exception was with the 1% ration level in whic...

Upstream migration and spawning success of Chinook salmon in a highly developed, seasonally warm river system

ABSTRACT This review summarizes what is known about the influence of water temperature and velocity on the migration and spawning success of an inland population of Chinook salmon Oncorhynchus tshawytscha. Models are then developed and used to illustrate how migration and spawning success might change if temperatures and velocities increase under a future climate. The illustration shows the potential for moderate increases in temperature and velocity to reduce homing and increase energy expenditure. Those two outcomes would reduce the abundance, productivity, and diversity of the population studied. Under the future scenario illustrated, it would become difficult for fish management actions alone to recover conservation-reliant populations of inland Chinook salmon.