Geology topics

Lance A. Wyss

Publications and source records attributed to Lance A. Wyss.

5 recordsLinked to original sources

USGS2017

Conservation challenges and research needs for Pacific lamprey in the Columbia River Basin

The Pacific Lamprey Entosphenus tridentatus , an anadromous fish native to the northern Pacific Ocean and bordering freshwater habitats, has recently experienced steep declines in abundance and range contractions along the West Coast of North America. During the early 1990s, Native American tribes recognized the declining numbers of lamprey and championed their importance. In 2012, 26 entities signed a conservation agreement to coordinate and implement restoration and research for Pacific Lamprey. Regional plans have identified numerous threats, monitoring needs, and strategies to conserve and restore Pacific Lamprey during their freshwater life stages. Prime among these are needs to improve lamprey passage, restore freshwater habitats, educate stakeholders, and implement lamprey-specific research and management protocols. Key unknowns include range-wide trends in status, population dynamics, population delineation, limiting factors, and marine influences. We synthesize these key unknowns, with a focus on the freshwater life stages of lamprey in the Columbia River basin.

British Columbia, Idaho, Montana, Nevada, Oregon, ↗

USGS2017

Temporal genetic population structure and interannual variation in migration behavior of Pacific Lamprey Entosphenus tridentatus

Studies using neutral loci suggest that Pacific lamprey, Entosphenus tridentatus , lack strong spatial genetic population structure. However, it is unknown whether temporal genetic population structure exists. We tested whether adult Pacific lamprey: (1) show temporal genetic population structure; and (2) migrate different distances between years. We non-lethally sampled lamprey for DNA in 2009 and 2010 and used eight microsatellite loci to test for genetic population structure. We used telemetry to record the migration behaviors of these fish. Lamprey were assignable to three moderately differentiated genetic clusters ( F ST = 0.16–0.24 for all pairwise comparisons): one cluster was composed of individuals from 2009, and the other two contained individuals from 2010. The F ST value between years was 0.13 and between genetic clusters within 2010 was 0.20. A total of 372 (72.5%) fish were detected multiple times during their migrations. Most fish (69.9%) remained in the mainstem Willamette River; the remaining 30.1% migrated into tributaries. Eighty-two lamprey exhibited multiple back-and-forth movements among tributaries and the mainstem, which may indicate searching behaviors. All migration distances were significantly greater in 2010, when the amplitude of river discharge was greater. Our data suggest genetic structuring between and within years that may reflect different cohorts.

Oregon↗

USGS2014

Role of large- and fine-scale variables in predicting catch rates of larval Pacific lamprey in the Willamette Basin, Oregon

Pacific lamprey Entosphenus tridentatus is an anadromous fish native to the Pacific Northwest of the USA. That has declined substantially over the last 40 years. Effective conservation of this species will require an understanding of the habitat requirements for each life history stage. Because its life cycle contains extended freshwater rearing (3–8 years), the larval stage may be a critical factor limiting abundance of Pacific lamprey. The objective of our study was to estimate the influence of barriers and habitat characteristics on the catch-per-unit-effort (CPUE) of larval Pacific lamprey in the Willamette River Basin, Oregon, USA. We sampled lampreys at multiple locations in wadeable streams throughout the basin in 2011–13 and used an information theoretic approach to examine the relative influence of fine- and large-scale predictors of CPUE. Pacific lamprey was observed across the basin, but its relative abundance appeared to be limited by the presence of natural and artificial barriers in some sub-basins. Lower velocity habitats such as off-channel areas and pools contained higher densities of larval lamprey; mean Pacific lamprey CPUE in off-channel habitats was 4 and 32 times greater than in pools and riffles respectively. Restoration and conservation strategies that improve fish passage, enhance natural hydrologic and depositional processes and increase habitat heterogeneity will likely benefit larval Pacific lamprey.

Oregon↗

USGS2014

Spawning patterns of Pacific Lamprey in tributaries to the Willamette River, Oregon

Addressing the ongoing decline of Pacific Lamprey Entosphenus tridentatus across its range along the west coast of North America requires an understanding of all life history phases. Currently, spawning surveys (redd counts) are a common tool used to monitor returning adult salmonids, but the methods are in their infancy for Pacific Lamprey. To better understand the spawning phase, our objective was to assess temporal spawning trends, redd abundance, habitat use, and spatial patterns of spawning at multiple spatial scales for Pacific Lamprey in the Willamette River basin, Oregon. Although redd density varied considerably across surveyed reaches, the observed temporal patterns of spawning were related to physical habitat and hydrologic conditions. As has been documented in studies in other basins in the Pacific Northwest, we found that redds were often constructed in pool tailouts dominated by gravel, similar to habitat used by spawning salmonids. Across the entire Willamette Basin, Pacific Lampreys appeared to select reaches with alluvial geology, likely because this is where gravel suitable for spawning accumulated. At the tributary scale, spawning patterns were not as strong, and in reaches with nonalluvial geology redds were more spatially clumped than in reaches with alluvial geology. These results can be used to help identify and conserve Pacific Lamprey spawning habitat across the Pacific Northwest.

Oregon↗

USGS2014

Using spatial resampling to assess redd count survey length requirements for Pacific Lamprey

Pacific Lamprey Entosphenus tridentatus has declined across its range along the West Coast of North America, and an understanding of all life history phases is needed to address population recovery. Spawning surveys (redd counts) are common tools currently used to monitor returning adult salmonids, but such methodologies are in their infancy for Pacific Lamprey. Our objective was to assess the minimum spawning survey distance required to detect the presence of Pacific Lamprey redds and obtain precise redd density estimates from these data. To do this, we statistically resampled existing spawning locations of Pacific Lamprey collected during spawning surveys in four streams of the Willamette River Basin, Oregon, during spring of 2013. We found that the minimum survey distance for Pacific Lamprey redd detection was inversely related to the observed redd density and was always less than 1.2 km. Survey distance requirements to obtain precise redd counts (±20% of observed redd densities) were also inversely related to redd density and habitat availability, and varied between 1.3 km and 13.7 km. Our results suggest that spawning surveys are a potential tool for monitoring adult Pacific Lamprey abundance, but the specific objectives of the monitoring programs and acknowledgment of unknowns must be considered prior to implementation into recovery plans.

Oregon↗