Dietary analyses, health, and reproduction of blue catfish in tributaries of the Chesapeake Bay inform ecosystem impacts and mitigation strategies for this aquatic nuisance species.
The objectives of this study are to provide information related to blue catfish life history in Chesapeake Bay tributaries to inform resource managers as to (1) the potential ecosystem-level impacts of this aquatic nuisance species and (2) possible mitigation strategies to minimize these impacts. These objectives will be met through specific tasks that involve blue catfish dietary analyses and other life history indicators related to health and reproduction as well as range and movement studies by partner agencies.
Invasive species prevention and mitigation is a high priority for natural resource management in federal, state, and regional agencies and organizations. Aquatic nuisance species (ANS) are of particular concern to resource managers in selected aquatic habitats that support delicate ecosystems or important commercial and recreational fisheries. The Chesapeake Bay and its watershed provides one such example. One of the more prominent ANS recognized in Chesapeake Bay and some of its tributaries in Virginia, Maryland, and Delaware is the blue catfish, Ictalurus furcatus. Introduced to the region in the 1970s as a sport fish, the blue catfish is considered an important ANS due to its potentially large size and predatory nature, among other factors. Through consumption or competition, the blue catfish could displace indigenous catfish and other species, potentially even leading to population extirpations. With their potential large size (over 100 pounds) and longevity (over 20 year lifespan), blue catfish have few natural predators. With high tolerance for habitat variability and opportunistic feeding strategies, the blue catfish is an able aquatic invader.
As an ANS in Chesapeake Bay and its tributaries in Maryland, Delaware, and Virginia, the blue catfish is a high priority species for management. Maryland has identified blue catfish as a "high" level of concern priority for management in the 2016 Maryland Aquatic Nuisance Species Management Plan. Collaborative efforts between regional state resource management agencies, academic institutions, and USGS EESC are underway to identify and address science-based needs to help inform management in keeping with the priorities outlined by the Invasive Catfish Workgroup of the Chesapeake Bay Program in 2020. Through this coordinated effort, dietary analysis tools and information have been identified as both important to blue catfish management and readily and immediately investigable through coordinated efforts of these agencies. In addition, health and pathogen assessments of blue catfish and reproductive status evaluations in regional tributaries are also being undertaken to ascertain further information about life history that would be of use for management of this species. Dietary analyses and health assessments are being conducted in collaboration with partners across three tributaries of Chesapeake Bay in Maryland (Patuxent River and Nanticoke River), Delaware (Nanticoke River), and Virginia (James River). Additional reproductive assessments evaluating the presence of reproductive hormones coupled with gonadal staging are also ongoing in the Nanticoke River with the potential to expand to other tributaries as warranted. Partner agencies are using gross identifications of prey items, and molecular-based identification of gastric contents using amplicon sequencing methodology by EESC scientists supplements these gross dietary analyses. This technology allows for detectability and quantification of diet components at levels not achieved through gross observation or microscopy and expands our ability to assess diet related impacts of blue catfish on other aquatic animal resources. Health assessments through gross and histological examinations as well as microbial culture for pathogen identification as warranted are being applied across three tributaries as well. Diet, health, and reproductive parameters will also be assessed and correlated with fish age and morphometric data collected from specimens among these tributaries. Further investigations related to range, movement and dispersion of blue catfish along the Patuxent River, MD led by Maryland Department of Natural Resources have also been supported by USGS EESC.
- Overview
Dietary analyses, health, and reproduction of blue catfish in tributaries of the Chesapeake Bay inform ecosystem impacts and mitigation strategies for this aquatic nuisance species.
Sources/Usage: Public Domain.Blue catfish (Ictalurus furcatus) are an important aquatic invasive species throughout many Chesapeake Bay tributaries. Scientists from the EESC are working with federal, state, and regional partners to assess the potential impacts of blue catfish on native fauna and important fisheries resources throughout the region. Credit: Christine Densmore The objectives of this study are to provide information related to blue catfish life history in Chesapeake Bay tributaries to inform resource managers as to (1) the potential ecosystem-level impacts of this aquatic nuisance species and (2) possible mitigation strategies to minimize these impacts. These objectives will be met through specific tasks that involve blue catfish dietary analyses and other life history indicators related to health and reproduction as well as range and movement studies by partner agencies.
Invasive species prevention and mitigation is a high priority for natural resource management in federal, state, and regional agencies and organizations. Aquatic nuisance species (ANS) are of particular concern to resource managers in selected aquatic habitats that support delicate ecosystems or important commercial and recreational fisheries. The Chesapeake Bay and its watershed provides one such example. One of the more prominent ANS recognized in Chesapeake Bay and some of its tributaries in Virginia, Maryland, and Delaware is the blue catfish, Ictalurus furcatus. Introduced to the region in the 1970s as a sport fish, the blue catfish is considered an important ANS due to its potentially large size and predatory nature, among other factors. Through consumption or competition, the blue catfish could displace indigenous catfish and other species, potentially even leading to population extirpations. With their potential large size (over 100 pounds) and longevity (over 20 year lifespan), blue catfish have few natural predators. With high tolerance for habitat variability and opportunistic feeding strategies, the blue catfish is an able aquatic invader.
As an ANS in Chesapeake Bay and its tributaries in Maryland, Delaware, and Virginia, the blue catfish is a high priority species for management. Maryland has identified blue catfish as a "high" level of concern priority for management in the 2016 Maryland Aquatic Nuisance Species Management Plan. Collaborative efforts between regional state resource management agencies, academic institutions, and USGS EESC are underway to identify and address science-based needs to help inform management in keeping with the priorities outlined by the Invasive Catfish Workgroup of the Chesapeake Bay Program in 2020. Through this coordinated effort, dietary analysis tools and information have been identified as both important to blue catfish management and readily and immediately investigable through coordinated efforts of these agencies. In addition, health and pathogen assessments of blue catfish and reproductive status evaluations in regional tributaries are also being undertaken to ascertain further information about life history that would be of use for management of this species. Dietary analyses and health assessments are being conducted in collaboration with partners across three tributaries of Chesapeake Bay in Maryland (Patuxent River and Nanticoke River), Delaware (Nanticoke River), and Virginia (James River). Additional reproductive assessments evaluating the presence of reproductive hormones coupled with gonadal staging are also ongoing in the Nanticoke River with the potential to expand to other tributaries as warranted. Partner agencies are using gross identifications of prey items, and molecular-based identification of gastric contents using amplicon sequencing methodology by EESC scientists supplements these gross dietary analyses. This technology allows for detectability and quantification of diet components at levels not achieved through gross observation or microscopy and expands our ability to assess diet related impacts of blue catfish on other aquatic animal resources. Health assessments through gross and histological examinations as well as microbial culture for pathogen identification as warranted are being applied across three tributaries as well. Diet, health, and reproductive parameters will also be assessed and correlated with fish age and morphometric data collected from specimens among these tributaries. Further investigations related to range, movement and dispersion of blue catfish along the Patuxent River, MD led by Maryland Department of Natural Resources have also been supported by USGS EESC.
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