Perry, Stephen

Environmental DNA Sampling Informs Fish Eradication Efforts: Case Studies and Lessons Learned: Worldwide, freshwater ecosystems are threatened by invasive species, resulting in adverse effects on infrastructure, economy, recreation, and native aquatic communities. In stream settings, chemical piscicides can be an effective tool for eradicating invasive fishes. However, chemical treatments are expensive and time consuming, and they do not discriminate between invasive and native species in a system. Therefore, managers would ideally limit treatment to only the area occupied by the invasive species. Because traditional survey methods may not accurately detect individuals in low abundance (e.g., at the edge of their distribution, or following an eradication effort), chemical treatments may be applied more broadly and more often than is necessary to ensure complete coverage. Furthermore, inadequate post-treatment sampling can fail to detect survivors of a treatment. As a result, managers may erroneously conclude that eradication was successful, leaving the ecosystem vulnerable to reestablishment by the invader. More sensitive sampling tools should allow for more precise definition of the treatment area and more accurate evaluation of project success. This would reduce project costs and overall effects on native species. Here, we illustrate how environmental DNA (eDNA) sampling addressed these challenges through three case studies, each of which used eDNA sampling to inform the removal of Brook Trout Salvelinus fontinalis in small streams. We found that eDNA methods can be informative throughout all stages of eradication projects in stream settings. It can assist with delimiting the population prior to treatment, provide detailed location data on surviving target individuals, and serve as an efficient and relatively inexpensive monitoring tool to assess long-term treatment efficacy. When combined with traditional survey tools, such as electrofishing, eDNA sampling may help reduce the size and number of treatments that are necessary to reach project goals. This translates directly to increased efficacy of treatments, reduced labor and cost, and reduced adverse effects on the native community.
Located in Science and Data / Brook Trout Related Publications
An updated geographic distribution of Myxobolus cerebralis (Hofer, 1903) (Bivalvulida: Myxobolidae) and the first diagnosed case of whirling disease in wild-caught trout in the south-eastern United States: Myxobolus cerebralis (Bivalvulida: Myxobolidae), the aetiological agent of salmonid whirling disease, was detected in 2 river basins of North Carolina during 2015, which initiated the largest spatial–temporal monitoring project for the disease ever conducted within the south-eastern United States (focused mainly in eastern Tennessee and western North Carolina). A total of 2072 rainbow trout Oncorhynchus mykiss, 1,004 brown trout Salmo trutta and 468 brook trout Salvelinus fontinalis were screened from 113 localities within 7 river basins during June 2017 through October 2019. Infections were detected by pepsin–trypsin digest, microscopy and the species-specific nested polymerase chain reaction (PCR) in 19 localities across 6 river basins. Myxospore morphology was indistinguishable from the published literature. In 2019, five rainbow trout that symptomatic for whirling disease (sloping neurocranium and lordosis) were captured and processed for histopathology. Myxospores were detected in the calvarial cartilage of two deformed trout with associated erosion of the cartilage consistent with reported whirling disease lesions. This is the first report of M. cerebralis in Tennessee and the first histologically confirmed cases of whirling disease in southern Appalachian (south-eastern United States) rivers and streams and expands the distribution of M. cerebralis throughout western North Carolina and eastern Tennessee.
Located in Science and Data / Brook Trout Related Publications
A new species of Myxobolus (Myxozoa: Bivalvulida) infecting the medulla oblongata and nerve cord of brook trout Salvelinus fontinalis in southern Appalachia (New River, NC, USA): Myxobolus neurofontinalis n. sp. infects the brain and medulla oblongata of brook trout (Salvelinus fontinalis [Mitchill, 1814]) in the New River, western NC. It is the first species of Myxobolus described from the brook trout and resembles another congener (Myxobolus arcticus Pugachev and Khokhlov, 1979) that infects nerve tissue of chars (Salvelinus spp.). The new species differs from M. arcticus and all congeners bymyxospore dimensions and by having a mucous envelope and distinctive suturalmarkings. A phylogenetic analysis of the small subunit rDNA (18S) suggests that the new species shares a recent common ancestor with some isolates identified as M. arcticus and that the new species and its close relatives (except Myxobolus insidiosus Wyatt and Pratt, 1973) comprise a clade of salmonid nerve-infecting myxobolids. The phylogenetic analysis indicates that several isolates of “M. arcticus” (sensu lato) in GenBank are misidentified and distantly related to other isolates taken from the type host (Oncorhynchus nerka [Walbaum, 1792]) and from nearby the type locality (Kamchatka Peninsula, Russia). Serial histological sections of infected brook trout confirmed that myxospores of the new species are intercellular and infect nerve cord and medulla oblongata only. A single infected brook trout showed an inflammatory response characterized by focal lymphocytic infiltrates and eosinophilic granulocytes; however, the remaining 4 brook trout lacked evidence of a histopathological change or demonstrable host response. These results do not support the notion that this infection is pathogenic among brook trout.
Located in Science and Data / Brook Trout Related Publications
EBTJV Key Conservation Actions: This documents contains the EBTJV's current key conservation actions.
Located in Projects / … / 2023 Project Application Information / EBTJV Range-wide Habitat Goals, Objectives, and Key Conservation Actions
EBTJV Range-wide Habitat Goals and Objectives: This document contains the EBTJV's current range-wide habitat goals and objectives.
Located in Projects / … / 2023 Project Application Information / EBTJV Range-wide Habitat Goals, Objectives, and Key Conservation Actions
EBTJV Range-wide Habitat Goals, Objectives, and Key Conservation Actions: This folder contains documents that describe the EBTJV's current range-wide habitat goals and objectives, as well as its key conservation actions.
Located in Projects / EBTJV Funding Opportunities / 2023 Project Application Information
Cantrell Creek Habitat Improvement: Pisgah Trout Unlimited and The Pisgah Conservancy partnered to complete a project on Cantrell Creek, a tributary of the South Mills River. This video produced by Real Digital Productions shows how this project came to be conceived, funded, and implemented.
Located in The Story of Wild Brook Trout / Brook Trout Video and Webinar Gallery
SEACAP: Southeast Aquatic Connectivity Assessment Project: Assessing the ecological impact of dams on Southeastern rivers.: This report provides details about the data, methods, results, and tools developed for SEACAP.
Located in Science and Data / Aquatic Organism Passage I&A and state design guidelines
Northeast Aquatic Connectivity: An Assessment of Dams on Northeastern Rivers.: A report that describes an approach to strategically reconnect fragmented river, stream, coastal, reservoir, lake and estuarine habitat by removing or bypassing key barriers to fish passage.
Located in Science and Data / Aquatic Organism Passage I&A and state design guidelines
Chesapeake Fish Passage Prioritization: An Assessment of Dams in the Chesapeake Bay Watershed.: Prioritizing fish passage barriers.
Located in Science and Data / Aquatic Organism Passage I&A and state design guidelines

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