William R. Daigle

Effects of Body Size and River Environment on the Upstream Migration of Adult Pacific Lampreys

Abstract Dams in the Columbia River basin present significant obstacles to declining populations of anadromous Pacific lampreys Lampetra tridentata. Mitigation efforts have focused on fine-scale improvements in passage at individual dams, but there is an increasing need for basinwide estimates of survival and escapement. We developed a half-duplex passive integrated transponder (PIT) tag monitoring array at five Columbia and Snake River dams to evaluate adult lamprey migrations. We tagged 3,598 lampreys over 3 years and calculated the rates of main-stem escapement through 15 river reaches. From these data, we assessed the relative effects of lamprey size, river discharge, water temperature, and migration timing on upstream passage. The results indicated high attrition as lampreys progressed upstream. In each year, about one-half of the fish passed one dam, 28–33% passed two dams, 17–19% passed three dams, 4–5% passed four dams, and about 1% passed the first dam on the Snake River (five dams and >300 km up...

Testing Adult Pacific Lamprey Performance at Structural Challenges in Fishways

Abstract Adult Pacific lampreys Lampetra tridentata migrate through areas of difficult passage and high water velocity by attaching their oral discs to substrate and then releasing and bursting upstream. In fishways at dams, this burst-and-attach behavior can be ineffective, particularly where suitable attachment surfaces are unavailable. We used an experimental fishway to test performance of adult Pacific lampreys when confronted with a series of structural challenges. These included vertical steps near fishway weir orifices, squared versus rounded orifice entrances, and floor-mounted metal grates. All experimental challenges simulated common existing structures in weir-and-orifice fishways at Columbia and Snake River dams. Most experiments were paired with field evaluations of radio-tagged Pacific lampreys or video observations of untagged individuals in situ. Field and experimental results consistently indicated that the structural challenges reduced passage efficiency and lengthened passage times. Imp...

Variability in migration timing of adult Pacific lamprey (Lampetra tridentata) in the Columbia River, U.S.A.

We examined the effects of river environment on the timing of spawning migrations by anadromous Pacific lamprey, Lampetra tridentata, in the Columbia River (U.S.A.). In a 41-year time series of adult lamprey counts, migration timing was earliest in warm, low-discharge years and latest in cold, high-flow years. Threshold temperatures associated with run timing were similar throughout the dataset despite significant impoundment-related warming, suggesting that temperature-dependent migration cues have been temporally stable. Within each year, migration rates of PIT-tagged lampreys were positively correlated with temperature and negatively correlated with discharge through multiple river reaches, offering additional evidence for environmental control of upstream movement. Both visual count and PIT-tag data indicated that there may be population-based differences in migration timing within the aggregate Columbia River lamprey run. These life history and behavioral results have potentially far-reaching implications for management of lamprey species.

Development of a Multipurpose Telemetry and Habitat Survey Instrument Platform for Small Boats

Abstract We developed a telemetry and remote-sensing instrument platform for a small vessel (6.1-m inboard jetboat) to collect fish telemetry and environmental data in real time as well as to collect data during habitat surveys in the Columbia River estuary. The instrumentation consisted of two acoustic telemetry hydrophones, an acoustic telemetry receiver, a conductivity–temperature–depth probe, an acoustic Doppler current profiler, a differential Global Positioning System, and a side-scan sonar integrated with an onboard portable computer. The system can be used on other vessels, has the flexibility to adapt to a range of telemetry and small oceanographic instrument systems, and allows for deployment and data collection from all instruments simultaneously.