Geology topics

Caylen Kelsey

Publications and source records attributed to Caylen Kelsey.

3 recordsLinked to original sources

USGS2022

Avian predation on juvenile and adult Lost River and Shortnose Suckers: An updated multi-predator species evaluation

Previous research suggests that predation by piscivorous colonial waterbirds may negatively influence the survival of Lost River Suckers (LRS) Deltistes luxatus and Shortnose Suckers (SNS) Chasmistes brevirostris in the Upper Klamath Basin (UKB), USA. However, estimates of predation from past studies, which were based on suckers with PIT tags, represent minimum estimates of sucker mortality because analyses did not account for the proportion of tags that were consumed by birds and deposited beyond their breeding colony. To address this uncertainty, we fed PIT-tagged suckers to American white pelicans Pelecanus erythrorhynchos to estimate deposition probabilities. A hierarchical Bayesian model was then used to estimate predation rates (percentage of available tagged fish that were consumed) on juvenile suckers that were released as part of the Sucker Assisted Rearing Program (SARP) and on wild juvenile and adult LRS and SNS during 2009–2020. Pelican deposition probabilities were estimated to be 0.47 (95% credible interval = 0.36–0.60), indicating that for every 100 tags consumed, 47 tags on average were deposited on breeding colonies by birds. Deposition-corrected estimates of predation rates were approximately two times greater than those previously reported and ranged annually from 4.3% (95% credible interval = 2.9–6.7%) to 8.5% (6.3–12.7%) on SARP juvenile suckers, from 4.3% (0.9–13.2%) to 10.5% (3.8–24.5%) on wild juvenile suckers, and from 0.1% (<0.1–0.3%) to 7.2% (2.8–16.4%) on adult suckers, depending on species and location. Results suggest that predation by colonial waterbirds, although not the original cause of sucker declines, was a substantial source of sucker mortality in some years. Future studies should consider models that jointly estimate both predation and survival and models that include environmental factors that potentially influence sucker susceptibility to avian predators in the UKB.

California, Oregon↗

USGS2022

Distribution of bull trout (Salvelinus confluentus) in conjunction with habitat and trout assemblages in creeks within the Klamath Basin, Oregon 2010–16

Bull trout ( Salvelinus confluentus ) in the Klamath Basin are on the southernmost border of the range of the species, where threats are most severe and where bull trout are most imperiled. In their recovery plan the U.S. Fish and Wildlife Service (2015, https://ecos.fws.gov/ecp/report/species-with-recovery-plans ) suggested that Klamath Basin bull trout are at increased risk of extirpation due to habitat fragmentation, degradation of habitat complexity, and introduction of non-native trout species that often outcompete bull trout. The goals of this study were to determine if there was a lack of connectivity between habitat areas impeding migration, habitat differences, or interference by non-native species affecting bull trout distribution in the Klamath Basin. This study examined three populations of bull trout in conjunction with a concurrent native species (redband trout [ Oncorhynchus mykiss gairdnerii ]), and a concurrent non-native species (brown trout [ Salmo trutta ]) in tributaries of the upper Sprague River within the Klamath Basin. Culverts present at the beginning of the study may have impeded migration of bull trout, but culvert upgrades made during the study appeared to eliminate the impediments to migration. The presence of non-native brown trout appeared to cause bull trout to use a smaller portion of Leonard Creek, whereas the low numbers of brown trout in the studied portion of Brownsworth Creek did not appear to interfere with the local distribution of bull trout. Downstream migration of bull trout may have been impeded if there were increased numbers of brown trout or increased temperatures in the lower portions of the creeks outside of the study area. Although habitat complexity was not examined in detail during this study, there was an attempt to enhance the habitat for bull trout by introducing large woody debris into treatment sections of the creeks. We compared bull trout numbers between the treatment sections and nearby control sections prior to and after introduction of the large woody debris. The introduction of large woody debris did not appear to enhance the use of those areas by bull trout, but the large woody debris may not have been of suitable size to enhance the habitat for bull trout.

Oregon↗

USGS2021

Avian predation of juvenile Lost River and Shortnose Suckers in Upper Klamath Lake: An assessment of Sucker assisted rearing program releases during 2018–2020

To bolster recruitment in Endangered Species Act (ESA) listed Lost River Suckers (Deltistes luxatus) and Shortnose Suckers (Chasmistes brevirostris) in the Upper Klamath Basin (UKB), the U.S. Fish and Wildlife Service (USFWS) and its partners have implemented the Sucker Assisted Rearing Program (SARP). As part of this program, juvenile suckers were reared in captivity, implanted with passive integrated transponder (PIT) tags (n= 8,857), and released into the Upper Klamath Lake or its tributaries during 2018–2020. Previous research suggests that predation by American White Pelicans (Pelecanus erythrorhynchos), Double-crested Cormorants (Nannopterum auritum), and Caspian Terns (Hydroprogne caspia) may negatively influence sucker survival, particularly predation on juvenile suckers. Estimates of predation impacts from past studies, however, represented minimum estimates of sucker mortality because analyses did not account for the proportion of consumed tags that were deposited by birds on their breeding colony where PIT tag recovery efforts took place. To estimate and account for deposition probabilities, we conducted a field study in which we fed pelicans PIT-tagged juvenile suckers (n = 401). We accounted for deposition probabilities of cormorants and terns by using previously published estimates. Sucker PIT tags were recovered from pelican, cormorant, and tern nesting sites in the UKB following each breeding season and a hierarchical Bayesian model was used to estimate predation rates (percentage of available tagged fish consumed) on SARP releases as well as naturally-reared or wild juvenile suckers and adult suckers that were PIT-tagged in Upper Klamath Lake and Clear Lake Reservoir. Pelican deposition probabilities were estimated at 0.47 (95% credible interval = 0.36–0.60), indicating that for every 100 PIT tags consumed, on average, 47 were deposited by pelicans on breeding colonies. Estimates of predation rates that incorporate corrections for deposition on SARP releases ranged annually from 4.4% (95% credible interval = 2.9–6.8%) to 8.8% (6.2–13.3%) during 2018–2020. Results suggest that colonial waterbird predation impacts on SARP releases likely constituted a small, but unknown, component of total mortality for suckers released into the Upper Klamath Lake system. Predation impacts on SARP juvenile suckers and wild juvenile suckers, which were estimated annually at 4.7% (1.0–13.9%) to 14.9% (7.6–29.3%), were consistently higher than those observed on adult suckers, with predation on adult suckers typically less than 4.0% of available fish annually. Future predation studies may consider models that integrate both live and dead detections of PIT-tagged suckers to generate more accurate and precise estimates of survival following release, as well as models that consider environmental factors that influence sucker susceptibility to colonial waterbird predation. Such models would provide a more holistic understanding of the degree to which avian predation limits the survival of ESA-listed suckers in the UKB.

Oregon↗