Invasion
Invasion Description
1st Record: VA/James River estuary (1974, Jenkins and Burkhead 1993, 64, 100 fish stocked); VA/Rappahannock River estuary (1975, Jenkins and Burkhead 1993, 97,800 fish stocked)
Ictalurus furcatus was reported to have been introduced to the Potomac at the turn of the century by the United States Fish Commission (Smith 1907), as an accidental contaminant of stocks of I. punctatus (Channel Catfish). However, preserved voucher specimens, labelled as I. furctatus were actually I. punctatus (Burkhead et al. 1980), so these early reports are unverified.
Geographic Extent
Conowingo Dam/MD/Susquehanna River (8/3/2011, USGS Nonindigenous Aquatic Species Program 2011); Elk; Sassafras, and Susquehanna River (Maryland Department of Natural Resources 2010; Schloesser et al. 2011; Nepal and Fab\irizio 2019); MD/upper Patuxent River (2008, Schloesser et al. 2011); MD/Nanticoke River (Nepal and Fabirizio 2019); VA/Burke and Brittle Lakes, Potomac watershed (1981-1985, Jenkins and Burkhead 1993); Haines Point/DC/Anacostia River (1987, Nammick and Fulton 1987, 1 fish); MD/DC/VA/Potomac River estuary ((Starnes 2002; Maryland Department of Natural Resources 2010; Starnes et al. 2011; epal and Fabirizio 2019); Greenlee and Lim 2011; Schloesser et al. 2011, current distribution River Km 54 -181, Schloesser et al. 2011); VA/Rappahannock River estuary (1975, Jenkins and Burkhead 1993, 97,800 fish stocked; current distribution River Km 23.1-146.7 Schloesser et al. 2011; Nepal and Fabirizio 2019); VA/Piankatank River (2000, Schloesser et al. 2011, River Km 28.5-34.2); VA/York-Pamunkey-Mattaponi Rivers (1985, Greenlee and Lim 2011; Schloesser et al. 2011, current distribution River Km 37-182; Nepal and Fabi\rizio 2019); VA/James River estuary (1974, Jenkins and Burkhead 1993, 64,100 fish stocked; Greenlee and Lim 2011; current distribution River Km 9.4 -138.7, Schloesser et al. 2011; Nepal and Fabriizio 2019); Seaford/DE/Nanticoke River (2010, USGS Nonindigenous Aquatic Species Program 2018). Multiple record-size fish had been caught, by August 1917 (http://www.wmdt.com/news/delaware/state-record-catfish-caught-from-the-nanticoke-river-in-seaford/601447789); off Smith Point VA to Gunpowder Neck/MD/Chesapeakes Bay (2018-2019, Nepal and Fabrizio 2019, 0-21 PSU, 98.6 < 10 PSU)
Vectors
| Level | Vector |
|---|---|
| Probable | Fisheries Intentional |
Regional Impacts
| Economic Impact | Fisheries | |
Blue Catfish (Ictalurus furcatus) are popular sportfish and commercial species, and one of the Chesapeake's largest fishes (Jenkins and Burkhead 1993; Murdy et al. 1997). In the spring and summer of 1995, and 1996, catches of large fish in the James and Rappahannock were frequently mentioned in the Washington Post. As populations increased in the Potomac, record fish captured attention among local fishermen and there was uncertainty in the Maryland Department of Natural Resources as to whether recognizing record catch would encourage illegal introductions of this invasive fish (Thomsen 2010). As a new top predator, they may be reducing abundance of other fishes, particularly shads, migratory herrings (Alosa spp.), and menhaden (MacAvoy et al. 2000; Schloesser et al. 2011). Potentially, Blue Catfish and the other introduced giant catfish, Pylodictis olivaris (Flathead Catfish), may be interfering with attempts to restore American Shad (Alosa sapidissima) (Garman et al. 2010; Groves and Love 2010). Management of Blue Catfish is complicated by need to balance the recreational fishery with the need to protect native fish stocks. Some Chesapeake watermen have switched from Blue Crabs to Blue Catfish, and this invasive fish is advertised by local restaurants (NOAA Chesapeake Bay Office 2018). However, large Blue Catfish have high levels of chemical contamination making them unsafe to eat (Schloesser et al. 2011).Fish under 760 mm (30 in.) are considered safe to eat. | ||
| Ecological Impact | Predation | |
| Predation- Blue Catfish (Ictalurus furcatus) are likely to be important predators, given their size and piscivorous food habits (Carlander 1969; Jenkins and Burkhead 1993). Statistical analyses indicate that Blue Catfish have adversely affected clupeid (herring- family fishes) populations in the James and Rappahannock Rivers (Austin 1998, personal communication). Gut and isotope analyses indicate that anadromous Alosa spp. (Shad, Alewives, Blueback Herring) form a substantial fraction of the Blue Catfish’s diet, resulting in a strong marine signature in the isotope composition of the freshwater predator (MacAvoy et al. 2000). Feeding studies indicate that younger fish in the James, York, and Rappahannock Rivers (smaller than 300 mm) feed mostly on benthic invertebrates, but that larger fishes (300-600mm) feed mostly on fishes. Menhaden (Brevoortia tyrannus) was the most frequent prey species (Schloesser et al. 2011). DNA studies show that Blue Catfish feed on at least 20 species of fishes (Aguilar et al. 2017). | ||