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<p>Blue catfish <i>Ictalurus furcatus</i> (Valenciennes, 1840) has invaded all major rivers of the Chesapeake Bay watershed making it one of the most widespread invasive fishes in the mid-Atlantic region. The objectives of this study were to disclose key aspects of blue catfish movement and habitat use in a tidally influenced river, Patuxent River (Maryland), and to present management suggestions based on observed ecological data. Thirty-eight blue catfish adults (mean total length = 672&#xa0;mm, SE = 15; mean mass = 3855&#xa0;g, SE = 331) tagged with dual acoustic-radio DART tags in November 2020, and for 16 of them, we analyzed actively tracked geolocations between December 2, 2020, and February 26, 2021, to identify hot spots during winter using ArcGIS (Version 10.2, ESRI). Two hot spots occurred in the upstream portion of the survey area, in locations where in situ salinity averaged 0.19 (SE = 0.03) and water depth averaged 3.0&#xa0;m (0.3 to 7.6&#xa0;m). We compared these habitat conditions with those for 19 actively tracked geolocations for 11 fish in June 2021. We observed a more widespread distribution in June, but fish generally occurred in freshwater (average = 0.25, SE = 0.14) that was less than 4-m depth, similar to winter observations. Approximately two-thirds of all fish (or 67%) had moved less than 100&#xa0;m&#xa0;day<sup>−1</sup>. Three blue catfish with the greatest movement rates in the dataset had been tracked in June, when distance traveled per day averaged 797&#xa0;m&#xa0;day<sup>−1</sup> (SE = 479; range: 1&#xa0;m&#xa0;day<sup>−1</sup> and 2938&#xa0;m&#xa0;day<sup>−1</sup>). Movement downstream, closer to the river mouth and into the mesohaline habitat (salinity &gt; 5), had occurred by June but was not common. Our observations suggest river-wide actions for indiscriminate harvest of blue catfish in freshwater could overfish or reduce abundance of size class(es) of the core population, though immigration from adjacent riverine populations might cause rescue effects or lessen potential biomass reductions.</p>

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Movement and Habitat Use by Invasive Blue Catfish Ictalurus furcatus (Valenciennes 1840) in a Tidal Freshwater River (Maryland, USA)

  • 期刊论文

  • 发表日期：

    2025年5月31日

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  • Joseph W. Love,
  • Branson D. Williams,
  • Tim Groves,
  • Ross Williams,
  • Mary Groves

摘要

Blue catfish Ictalurus furcatus (Valenciennes, 1840) has invaded all major rivers of the Chesapeake Bay watershed making it one of the most widespread invasive fishes in the mid-Atlantic region. The objectives of this study were to disclose key aspects of blue catfish movement and habitat use in a tidally influenced river, Patuxent River (Maryland), and to present management suggestions based on observed ecological data. Thirty-eight blue catfish adults (mean total length = 672 mm, SE = 15; mean mass = 3855 g, SE = 331) tagged with dual acoustic-radio DART tags in November 2020, and for 16 of them, we analyzed actively tracked geolocations between December 2, 2020, and February 26, 2021, to identify hot spots during winter using ArcGIS (Version 10.2, ESRI). Two hot spots occurred in the upstream portion of the survey area, in locations where in situ salinity averaged 0.19 (SE = 0.03) and water depth averaged 3.0 m (0.3 to 7.6 m). We compared these habitat conditions with those for 19 actively tracked geolocations for 11 fish in June 2021. We observed a more widespread distribution in June, but fish generally occurred in freshwater (average = 0.25, SE = 0.14) that was less than 4-m depth, similar to winter observations. Approximately two-thirds of all fish (or 67%) had moved less than 100 m day−1. Three blue catfish with the greatest movement rates in the dataset had been tracked in June, when distance traveled per day averaged 797 m day−1 (SE = 479; range: 1 m day−1 and 2938 m day−1). Movement downstream, closer to the river mouth and into the mesohaline habitat (salinity > 5), had occurred by June but was not common. Our observations suggest river-wide actions for indiscriminate harvest of blue catfish in freshwater could overfish or reduce abundance of size class(es) of the core population, though immigration from adjacent riverine populations might cause rescue effects or lessen potential biomass reductions.