Invasion

Invasion Description

1st Record: Hog Island Wildlife Refuge (1965, Burkhead et al. 1980; Jenkins and Burkhead 1993).

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1st Record: Philadelphia/PA/Schuyllkill River (USGS Nonindigenous Aquatic Species Program 2014)

Geographic Extent

Susquehanna River- In July, 2002, several juvenile P. olivaris were caught downriver of Safe Harbor Dam in PA, about 50 km above tidal waters. This species is apparently now established in the river, and can be expected to colonize upper Chesapeake Bay. Fishermen have been asked not to release any fish that they catch. The source of these fish is not known (Pennsylvania Fish and Boat Commission 2002). In 2004, 7 P. olivaris were captured in the West Fishlift of Conowingo Dam, just above the tidal portion of the Susquehanna (Brown et al. 2005). They are now regularly caught in the tidal Susquehanna and in upper Eastern Shore Tributaries (Garman et al. 2010).

Potomac River- Flathead Catfish were introduced to the Qccoquan Reservoir before 1993, and found in the tidal river by 1995.  It is apparently still uncommon in the River, and mostly above the tideline (Jenkins and Burkhead 1993; Starnes et al. 2011).


York River system- Flathead Catfish were first reported from the Pamunkey River in 2008, and have established a population there. One fish was caught in the other branch, the Mattaponi River (Schmitt et al. 2019).

James River- Pylodictis olivaris was accidentally released 1965 at Hog Island Wildlife Refuge (~ 50 fish); a population was established. Catches in the upper James in the Blue Ridge-Allegheny region (starting in 1983) were probably due to a separate, undocumented introduction (Burkhead et al. 1980; Jenkins and Burkhead 1993). Catches of large P. olivaris in the James River were mentioned in occasionally in fishing columns of the Washington Post in the summers of 1995-2000, though much less frequently than those of Ictalurus furcatus (Blue Catfish). Websites indicate that this is a popular gamefish in the James River.

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Delaware River- Pylodictis olivaris (Flathead Catfish) was first collected in the Blue Marsh reservoir, on the Schuyllkill River, 120 km upstream of Philadelphia PA. This catfish is now established in the Delaware River system (USGS Nonindigenous Aquatic Species Database 2002). Currently, this catfish has been collected from the mouth of Delaware & Raritan Canal at Lambertville NJ, above the head of tide at Trenton, to Philadelphia (Brown et al. 2005). The fish could have been introduced as a contaminant in a shipment of Ictalurus punctatus; (Channel Catfish), but illegal releases by fishermen are much more likely (Brown et al. 2005); Wilmington/DE/Brandywine Creek (9/3/2018, (USGS Nonindigenous Aquatic Species Database 2019)