Download PDF Download Document

An Investigation Into the Migratory Behavior of Bull Trout (Salvelinus confluentus) in the Touchet River Basin

Category: Fish/Shellfish Research and Management - Fish/Shellfish Research

Date Published: January 2003

Number of Pages: 27

Author(s): Glen Mendel, Chris Fulton, and Rey Weldert

INTRODUCTION:

The Touchet River originates in a network of deeply incised streams on the northwestern slopes of the Blue Mountains and from seasonal streams draining the Palouse hillsides to the north (Mendel et. al. 2001). Fish habitat has been severely degraded by urban and agricultural development, grazing, tilling, logging, recreational activities and flood control (Mendel et. al. 2001). Historically bull trout were thought to be widely distributed in the Touchet River watershed. Factors which have elevated the water temperatures such as damaged riparian vegetation, increased sedimentation and decreased water flows have also decreased the range of this cold water species (Mongillo 1993).

The Washington Department of Fish and Wildlife (WDFW) has captured and enumerated bull trout at the adult steelhead trap in Dayton, in southeast Washington, each spring for the past several years while trapping steelhead as part of the Lower Snake River Compensation Program (LSRCP). Captured subadult and adult bull trout apparently over winter downstream of Dayton and return to headwater areas within several of the Touchet River tributaries during late spring and early summer to hold over until spawning. Similar movements have been documented in the Tucannon River, which is the adjacent watershed to the east of the Touchet River (Martin et al. 1992 and Underwood et al. 1995). The spatial and temporal distribution of bull trout in the Touchet River during winter and spring is currently unknown.

In the spring of 2000, WDFW proposed a cooperative bull trout radio telemetry project that was implemented in 2001 and 2002. This project was initiated to provide a better understanding of the spatial and temporal distribution of migratory bull trout in the Touchet River. It was anticipated that the study would also assist the Confederated Tribes of the Umatilla Indian Reservation (CTUIR) with a steelhead telemetry study in the Walla Walla River basin, and help identify migratory barriers or passage problems in the Touchet River watershed. Bull trout migration information is critical for identification, prioritization, and selection of habitat protection and restoration efforts in the Touchet River. The project was also intended to help determine whether bull trout populations in the upper Touchet River tributaries are genetically isolated from one another, as well as from Walla Walla Basin populations. This information would be valuable for determining the level of risk of extinction for these populations. This projected 3-4 year radio telemetry study was intended to provide information necessary for determining the river reaches and habitat used by subadult and adult bull trout and adult steelhead, and to identify critical habitat areas for maintaining these populations. By providing information about connectivity and potential genetic exchange among bull trout populations in the Touchet River, and other Walla Walla Basin populations, managers and the public could examine potential risks of population extinction and determine the importance of protecting or expanding small, isolated spawning habitats.

In 2001, WDFW secured a small amount of funding from the USFWS Section 6 funds for bull trout work, and from the Columbia County Conservation District. These funds enabled WDFW to initiate this telemetry project by purchasing surgical supplies, 20 radio tags, a telemetry receiver and yagi antenna in early 2001. Radio tagging and tracking began in spring 2001.

This project complements several other salmon recovery efforts in the Touchet Watershed and the Walla Walla Basin. It is expected to provide critical data for bull trout and steelhead that would fill data gaps identified in the yet-unpublished Walla Walla Watershed Assessment Report (WSU and CTUIR) and in .Chapter 11: Umatilla . Walla Walla Recovery Unit. of the Bull Trout (Salvelinus confluentus) Draft Recovery Plan (USFWS, 2002). These data gaps have also been identified in the recently completed publication Salmonid Habitat Limiting Factors Water Resource Inventory Area 32 – Walla Walla Watershed (Kuttel 2001). This project also complements the BPA funded project Assessment of Salmonids and Their Habitat Conditions in the Walla Walla River Basin of Washington: 2001 Annual Report that examines adult bull trout spawning, and juvenile bull trout rearing distribution and relative abundance (Mendel et. al., 1999, 2000, and 2001). The Walla Walla telemetry coordination group that designed and is currently implementing the Walla Walla river basin bull trout and steelhead telemetry projects supports this project. The intent of this study is to fulfill the need for bull trout migratory behavior and over-wintering information in the Touchet River.

This project includes many partnerships, and is partially funded from several sources. The Columbia County Conservation District, the US Fish and Wildlife Service (USFWS) Section 6 monies, the US Forest Service (Pomeroy District), and the Tristate steelheaders provided funding, equipment or materials for this project. WDFW contributed labor to administer the project, to assist with tagging and tracking, and to provide technical oversight. The Touchet bull trout project also contributed to a much larger radio telemetry study in the Walla Walla Basin that includes partnerships with several Irrigation Districts, the Walla Walla Watershed Council in Oregon, the Oregon Dept. of Fish and Wildlife and the CTUIR. Their contributions included funding and donated labor or materials for the bull trout and steelhead radio telemetry study in the mainstem Walla Walla and Mill Creek. They were to supply us with bull trout telemetry data in areas they radio track (including the lower Touchet River, Mill Creek and the Walla Walla River) and we were to provide them with bull trout and steelhead radio telemetry data for the Touchet River upstream of Plucker Road (river mile 14.9). The CTUIR was responsible for radio tagging steelhead in the lower Walla Walla River, Mill Creek, and the lower Touchet River, and summarizing the data obtained. The WDFW was also a member of the technical oversight committee for the larger telemetry effort for steelhead and bull trout in the Walla Walla Basin. WDFW involvement in all projects helped ensure that the proposed Touchet River bull trout project and the other Walla Walla Basin efforts were well coordinated and that resources and data were shared.

This radio telemetry project was an assessment of the movements of migratory bull trout in the Touchet River. The project was proposed to address the following objectives:

1) Determine spatial and temporal distribution of migratory bull trout in the Touchet River. 1a) Determine migration timing, distribution, and possibly habitat use downstream of spawning and juvenile rearing areas in the Touchet River,

1b) Determine migration timing and distribution in spawning and rearing areas upstream of Dayton,

1c) Determine whether Touchet River bull trout migrate far enough downstream to enter the Walla Walla or Columbia rivers during winter or spring.

2) Determine the level of interaction or isolation among bull trout populations within the Touchet River system, and contribute to a larger study of bull trout movements and interactions for the entire Walla Walla Basin.

3) Identify passage problems or delays and movements at fish passage facilities or other obstructions in the Touchet River system.

4) Assist CTUIR and their cooperators by collecting supplementary steelhead telemetry data in the Touchet River to contribute to a larger multi-agency and private effort to examine steelhead and bull trout spatial and temporal distribution, movements, and passage in the Walla Walla Basin.

The study design was to capture and radio tag up to 30 bull trout annually from the Touchet River for 2-3 years. Fish were to be captured in an existing trap at a small dam in Dayton, by hook and line, or with electrofishing, if necessary. Selected fish were radio tagged by surgical implantation of digitally encoded transmitters in the abdominal cavity. The tags emit unique codes per fish with an expected tag life of one to two years. Fish were to be tracked with mobile receivers and by several fixed-site receivers deployed at selected sites in the Touchet River basin. Mobile fish tracking was to occur throughout the year at a frequency of approximately 1-3 times per week during periods of intensive tracking, and approximately once every two weeks when fish were not moving extensively. Fixed-site receivers were to be downloaded approximately once every two or three weeks.

Radio telemetry appeared to be the most feasible way to obtain the desired information on migration movements and timing, and to determine interaction or isolation of bull trout populations within the Touchet River drainage and the Walla Walla River basin.