Geology topics

Rachael Katelyn Paul-Wilson

Publications and source records attributed to Rachael Katelyn Paul-Wilson.

4 recordsLinked to original sources

USGS2025

Seasonal movements and demographics of the endangered White River Spinedace to inform restoration and translocation

Objective Translocation is a tool being explored to restart extirpated populations or facilitate new populations of endangered spring-dependent fish populations. Our objective was to provide information on habitat requirements for endangered White River Spinedace Lepidomeda albivallis during all seasons of the year and the population demographics that are necessary to plan conservation translocations of this species Methods We tagged and released White River Spinedace with passive integrated transponders during four twice-a-year events. Fish were subsequently recaptured or detected on six passive antennas placed throughout the Flag Springs Complex, Nevada. We evaluated movement data to understand seasonal habitat use patterns, used a Barker model to estimate monthly survival rates, adjusted counts to account for capture probability and estimate abundance, and applied reverse-time mark–recapture models to estimate recruitment to 70 mm total length. Results White River Spinedace were more active but used similar habitats during spawning seasons than during nonspawning seasons. Median life expectancy was about 5 months after tagging, and only 1% of adult White River Spinedace survived 3–4 years posttagging. The estimated population size in the Flag Springs Complex during our sampling period (November 2020 to June 2022) was fewer than a thousand White River Spinedace, and this estimate has been steady or slightly increasing. Conclusions Complex spring habitats with water temperatures ranging about 13°C to 21°C that are free from piscivorous fish are appropriate for White River Spinedace. The White River Spinedace population at Flag Springs is small but stable or increasing in size.

Transactions of the American Fisheries Society↗

USGS2025

Predation of Lost River and Shortnose suckers by piscivorous colonial waterbirds in the Upper Klamath Basin: An analysis of predation effects during 2021–2023

Previously published research indicated that predation by piscivorous colonial waterbirds in the Upper Klamath Basin was a source of mortality for Lost River suckers ( Deltistes luxatus ) and Shortnose suckers ( Chasmistes brevirostris ), including mortality of Sucker Assisted Rearing Program (SARP) fish. Avian predation on recently released Chinook Salmon ( Oncorhynchus tshawytscha ) in the Upper Klamath Basin has not been studied. To provide fisheries managers with the most up-to-date information, we estimated predation rates on passive integrated transponder tagged (PIT) suckers and Chinook Salmon by breeding colonies of American White Pelicans ( Pelecanus erythrorhynchos ), Double-crested Cormorants ( Nannopterum auritum ), Caspian Terns ( Hydroprogne caspia ), California Gulls ( Larus californicus ), Ring-billed Gulls ( L. delawarensis ), Great Blue Herons ( Ardea herodias ), and Great Egrets ( A. alba ) during 2021–2023. Predation rate estimates were variable depending on the fish species, age-class (juvenile, adult), waterbody (Upper Klamath Lake, Clear Lake Reservoir, Sheepy Lake), and year. Results indicated that avian predation rates were highest on juvenile suckers and on suckers in Clear Lake Reservoir. SARP fish released in the spring/summer were more likely to be consumed by breeding birds than those released in the fall/winter, although the number of fish released in the fall/winter that survived to the spring/summer was unknown and could bias predation estimates low. Predation rate estimates on Chinook Salmon varied by year, release timing (spring/summer, fall/winter), release location (Upper Klamath Lake, Klamath River), and age-class (subyearling, yearling). The location and size of colonies were also highly variable depending on the bird species, colony location, and year. Future research could focus on identifying biotic and abiotic factors associated with sucker susceptibility to piscivorous colonial waterbirds and determining to what degree avian predation limits the recovery of suckers in the Upper Klamath Basin.

California, Oregon↗

USGS2025

Predation of Lost River and Shortnose Suckers by piscivorous colonial waterbirds in the Upper Klamath Basin: An analysis of predation effects in 2024

The recovery of endangered fish requires an understanding of the sources of mortality that regulate population dynamics. We estimated avian predation rates on passive integrated transponder tagged (PIT) adult and juvenile Lost River Suckers ( Deltistes luxatus ), Shortnose Suckers ( Chasmistes brevirostris ), Klamath Largescale Suckers ( C. snyderi ), and juvenile Chinook Salmon ( Oncorhynchus tshawytscha ) by breeding colonies of American White Pelicans ( Pelecanus erythrorhynchos ), Doublecrested Cormorants ( Nannopterum auritum ), Caspian Terns ( Hydroprogne caspia ), California Gulls ( Larus californicus ), Ring-billed Gulls ( L. delawarensis ), Great Blue Herons ( Ardea herodias ), Great Egrets ( A. alba ), and Black-crowned Night Herons ( Nycticorax nycticorax ) in the Upper Klamath Basin (UKB) in 2024. Results from 2024 contribute to a long-term (2009–2023) avian predation dataset in the UKB. The largest numbers of pelicans (1,422 breeding adults), terns (610 adults), and gulls (3,872) were nesting on islands in Clear Lake Reservoir. The largest number of cormorants (787 adults) were on an island in Sheepy Lake, and the largest numbers of herons (450 adults) were at arboreal sites adjacent to Upper Klamath Lake. Predation rate estimates in 2024 were highly variable depending on the fish species, ageclass (juvenile, adult), waterbody (Upper Klamath Lake, Clear Lake Reservoir, Sheepy Lake, Tule Lake), and release or reencounter date for juveniles (spring/summer or fall/winter). Results indicated that avian predation rates were the highest on wild and hatchery juvenile suckers. An estimated 19.4% (95% credible interval = 15.7–24.0) of Sucker Assisted Rearing Program (SARP) hatchery fish, released or reencountered during the spring and summer, were consumed by the colonies included in the study. Predation was also appreciable on wild juvenile suckers in Clear Lake Reservoir (13.4% [9.9–17.7]) and SARP juvenile suckers released or reencountered in Upper Klamath Lake in the fall/winter (11.2% [9.6 13.2]). Predation rate estimates on adult suckers were significantly lower than those of juvenile suckers, with predation ranging from 0.3% (0.2–0.7) to 2.6% (1.9–3.5) in adult Lost River Suckers in Upper Klamath Lake and adult Shortnose Suckers-Klamath Largescale Suckers in Clear Lake Reservoir, respectively. Predation rate estimates on juvenile Chinook Salmon, which were released in fall/winter, were 2.9% (2.2–3.6). Pelican (312 adults) and cormorant (301 adults) colonies in Upper Klamath Lake, however, were not scanned for fish PIT tags following breeding season, resulting in minimum estimates of predation on UKB fishes (both suckers and Chinook Salmon) in 2024. Future research could examine what biotic and abiotic factors best explain variation in predation and to what degree predation limits sucker survival using the long-term dataset that has been complied to date.

California, Oregon↗

USGS2023

Validating a non-lethal method of aging endangered juvenile Lost River and Shortnose Suckers

Populations of imperiled Lost River Deltistes luxatus and Shortnose Chasmistes brevirostris suckers in Upper Klamath Lake, Oregon, are experiencing long-term decreases in abundance due to limited recruitment of juvenile suckers into the adult populations. Researchers use estimated ages based on fin rays to study environmental factors affecting year-class formation, generate annual juvenile sucker survival indices, and study variations in early life history. Biased or imprecise age estimates can lead to erroneous conclusions and have implications for age-based survival estimates, indications of recruitment, and growth estimators. We examined fin rays collected from individual suckers captured on multiple occasions and determined that juvenile suckers deposit a translucent increment on fin rays annually. Size-at-age data for suckers first captured as young as age 0 corroborated our finding of annual increment formation and indicate that the first increments are formed at age 1. We used edge and marginal increment analysis conducted on fin rays to determine the timing of annual increment formation. Our results indicate that increment formation occurs on fin rays of juvenile suckers from October to May and peaks between February and April.

Oregon↗