Phillip A. Groves

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...

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...

Two Carriers Used to Suspend an Underwater Video Camera from a Boat

Abstract Two underwater video camera carriers were designed by modifying hydraulic sounding weights and suspension equipment normally used for stream gaging. Both carriers were suspended from the bow of a boat and were used in a river up to 13 m deep with velocities to 3 m/s. One carrier consisted of an aluminum casing mounted on a single hydraulic sounding weight. This carrier provided a moderate degree of camera protection and created little drag, but it wobbled at water velocities greater than 1 m/s. The other carrier consisted of an aluminum frame attached between two hydraulic sounding weights. This carrier provided greater camera protection and wobbled less, but it was subjected to considerable drag in deep (>3 m), high velocity (>1 m/s) waters. Both carriers have been used successfully to search for spawning grounds and redds of chinook salmon Oncorhynchus tshawytscha in a large river and to collect video images for surficial substrate classification.

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...