Klickitat River - Juvenile O. mykiss Survival and Transit Time

The objective of this project was to estimate migration survival for juvenile O. mykiss through the 1.3 mile reach (Klickitat River Delta; KRD) of the Klickitat River that is influenced hydrologically by the Columbia River. Survival was also estimated through reaches located upstream and downstream of the KRD which provides context to the KRD estimates.

Juvenile O. mykiss were collected at the floating rotary screw trap located at Klickitat RM 2.8 and tagged with an acoustic transmitter and Passive Integrated Transponder (PIT). Both of these tags were surgically implanted in the fish (Liedtke et al. 2012). 612 Steelhead and 200 Coho were tagged during the project, a substantially greater number than originally estimated, which increased the precision of survival estimates. Historic screw trap data was evaluated and cross referenced with data from on-going tributary PIT tag studies to generate a distribution of out-migrant timing. The distribution of out-migrant timing will be utilized to design a tag-release strategy that distributes tags proportionally to outmigration timing to mimic the normal outmigration pattern over a range of Klickitat and Columbia River flows.

Fish were released at a location upstream of the screw trap, and telemetry arrays were situated to measure survival 1) from release to head of the KRD, 2) from the head of the KRD to the Columbia River, and at selected sites in the Columbia River upstream of Bonneville Dam. Arrays detected fish moving downstream and provided information about migration timing and survival. The presence of the PIT-tag provided additional detection capabilities for study fish as they passed Bonneville Dam and also contributed life cycle information if PIT-tagged fish were detected when returning as adults. Mark-recapture models were then used to estimate detection and survival probabilities.

Worksite #1 Actual Work:
Juvenile natural-origin steelhead (O. mykiss) and hatchery-origin Coho (O. kisutch) were collected at a floating rotary screw trap located at Klickitat RM 2.8 during spring migration in 2018 and 2019. Trapped fish wiere tagged with an acoustic transmitter and Passive Integrated Transponder (PIT). Both of these tags were surgically implanted in the fish. Fish were released at a location upstream of the screw trap, and telemetry arrays were situated to measure survival 1) from release to head of the KRD, 2) from the head of the KRD to the Columbia River, and at selected sites in the Columbia River upstream of Bonneville Dam.

Salmon and steelhead native to the Klicktiat subbasin were impacted by the construction of Bonneville Dam in 1935 which inundated the lower 1.2 miles of the Klickitat River. Due to the confluence of the Klickitat River being backwatered by the Bonneville Pool shallow, multi-thread river channels, and riparian cottonwood galleries were lost. These changes resulted in reductions in riparian vegetation, spawning substrate, and rearing habitat and an increase in the presence of non-native piscivorous fish.

Anthropogenic alterations to the habitat conditions in the lower Klickitat River and their impact on adult and juvenile fish are further exacerbated by changes in river flow, channel modifications, water quality (temperature, contaminants, etc.), and predation in the mainstem Columbia River. Hydro operations in the mainstem Columbia effect fish migration conditions from river mile 1.2 of the Klickitat River downstream to the Columbia River estuary. Historical flow records at The Dalles and Bonneville Dam demonstrate that annual peak flows have been reduced by about 50 percent, as water is stored for power generation and irrigation, and winter flows have increased about 30 percent.

The lack of historical data (pre-Bonneville Dam) limits quantitative evaluation of the impacts of Bonneville pool inundation on native fish, plant, and wildlife species. The Yakima Nation Fisheries Program initiated a physical habitat assessment of the Klickitat River delta in 2009 in order to assist identification of factors limiting salmonid production. This assessment included collection of water surface elevation and temperature data at several locations within the confluence. The water level information will be utilized to evaluate inundation frequency of landforms and coarsely describe water temperature distributions in the vicinity of the Klickitat River delta (KRD). This project to evaluate juvenile O. mykiss migration survival through the KRD complements the ongoing physical habitat assessment. The KRD currently has slower velocities and greater depths than historically were present. These changes in physical conditions potentially result in longer transit times and increased avian and non-native fish predation.

The results of this study, presented in the USGS open file report, will be utilized to determine additional predation and geomorphic assessments to address losses in salmonid production in the KRD and Bonneville Pool