Non-indigenous Range Expansion of the Blue Catfish (Ictalurus furcatus) in the Satilla River, Georgia Timothy F. Bonvechio1,*, Bryant R. Bowen1, Jason S. Mitchell1, and Justin Bythwood1 Abstract - Here we present evidence of the first field observation of the nonnative Ictalurus furcatus (Blue Catfish) occurring on the Satilla River, GA, in May 2011, and additional collections since then. This is the second large, non-native riverine catfish to be found in the Satilla River basin. Pylodictis olivaris (Flathead catfish) was first collected from the Satilla River in May 1996. The ecological effects of Blue Catfish on native mussel and fish species in the Satilla River are currently unknown, but competition with native catfishes is likely. Ictalurus furcatus Lesueur (Blue Catfish) inhabit large rivers and major tributaries associated with swift chutes and flowing waters around deep pools, as well as oxbow lakes and reservoirs (Boschung and Mayden 2004, Jenkins and Burkhead 1994, Ross 2001). Although Blue Catfish are considered a freshwater species, they inhabit brackish waters (Greenlee and Lim 2011, Schloesser et al. 2011) and can tolerate salinities up to 15 ppt (Christmas and Waller 1973, Dennison et al. 1993, Perry 1968, Ross 2001). Blue Catfish are members of the North American bullhead catfish family, Ictaluridae, which is the largest family of freshwater fishes endemic to North America (Nelson 1976, Page and Burr 1991). I. furcatus and I. balsanus Jordan and Snyder (Balsas Catfish) comprise the I. furcatus species group, which is the sister group to the I. punctatus Rafinesque (Channel Catfish) clade (Lundberg 1992, Ross 2001). Distinguishing characteristics of the Blue Catfish include the unique two-vessel swim bladder and a straight anal fin-ray margin, with an anal fin-ray count ranging from 30 to 36 (Boschung and Mayden 2004, Etnier and Starnes 1993, Jenkins and Burkhead 1994, Page and Burr 1991, Smith 1979). The native range of the Blue Catfish in the United States includes the Mississippi, Missouri, and Ohio river basins along coastal drainages of the Gulf of Mexico from the Alabama River to the Rio Grande (Ross 2001). As a result of the Blue Catfish growing to exceptionally large sizes, they have been widely introduced as a food and sport fish and now occur in twenty-nine states throughout the Mississippi basin as well as the Atlantic, Pacific, and Gulf coastal slopes (Fuller et al. 1999, Graham 1999). Other reasons for nonindigenous occurrences include intentional stocking or unintentional flooding of private waterbodies (Guier et al. 1984, Metee et al. 1996). In Georgia, Blue Catfish are native to the Coosa River, but have been widely translocated to other river drainages (see http:// fishesofgeorgia.uga.edu/index.php?page=speciespages/species_page&key=ictafurc), including the Altamaha, Chattahoochee, Flint, and Savannah (Bonvechio et al. 2011a, Dahlberg and Scott 1971, Glodeck 1980, Homer and Jennings 2011, Straight et al. 2009). Currently, the only river drainages in Georgia where the Blue Catfish has not been documented include the Ochlockonee, St. Mary’s, and Suwannee. A Blue Catfish (368 mm total length, 448 g) was captured on the Satilla River in southeast Georgia, on 25 May 2011 (Fig. 1). The male Blue Catfish was captured as part of the current Pylodictis olivaris Rafinesque (Flathead Catfish) removal program by the Georgia Department of Natural Resources (GADNR; Bonvechio et al. 2011b). The capture location (30°53.290'N, 81°50.696'W) was 22.5 km upstream of the US Highway 1Georgia Department of Natural Resources, PO Box 2089, Waycross, GA 31502-2089. *Corresponding author - Tim.Bonvechio@dnr.state.ga.us. Notes of the Southeastern Nat u ral ist, Issue 11/2, 2012 355 356 Southeastern Naturalist Vol. 11, No. 2 17 bridge near the town of Bullhead Bluff, GA. This is the first documented report of a Blue Catfish existing in the Satilla River. Unlike the Flathead, for which illegal angler introduction is highly likely (Bonvechio et al. 2011b), it is believed that Blue Catfish migrated to the Satilla River down the intercoastal waterway, roughly 35 km from the Altamaha River sound, during the most recent high water period occurring in April 2009. Salinity measurements taken in the lower Satilla River in 2009 ranged between 0.1–8.6 ppt, within tolerance limits (T. Bonvechio, unpubl. data). The parental source of the Blue Catfish in the Altamaha River migrated downstream through hydrological releases from Lakes Oconee and Sinclair (Homer and Jennings 2011). The source of these original populations is unknown, but illegal stockings by the public are suspected (Bonvechio et al. 2011a). Additionally, a total of seven Blue Catfish were recovered from the Satilla River from May to October 2011, ranging between 360–492 mm total length and 337–1044 g. Two anecdotal sightings of Blue Catfish by GADNR staff were noted while electrofishing in June and August 2010, but no samples were collected at that time. Potential impacts by Blue Catfish on native fish and mussel species are unknown. Omnivorous feeding habits have been described in the introduced Blue Catfish population of the Altamaha River (Bonvechio et al. 2011a). Large Blue Catfish can be piscivorous, similar to large Flathead Catfish; thus, there is some concern over potential effects of Blue Catfish foraging on native fish species in the Satilla River (Bonvechio et al. 2009, 2011a). Nonnative taxa may affect native taxa through direct and indirect biotic interactions, including competition, predation, habitat alteration, and hybridization (Fuller et al. 1999, Sakai et al. 2001, US Fish and Wildlife Service 1994). Homer and Jennings (2011) found shifts in the gillnet catch of Ameiurus catus (L.) (White Catfish) to Blue Catfish in Lake Oconee, GA, and suggested that competition by introduced Blue Catfish and Flathead Catfish could drive declines in the abundance of native White Catfish. Similarly, White Catfish declines have also been noted in Virginia tidal rivers after Blue Catfish introduction (Schloesser et al. Figure 1. Picture of the first Ictalurus furcatus (Blue Catfish) (368 mm TL, 448 g) captured on the Satilla River, GA. It was caught on 25 May 2011. 2012 Southeastern Naturalist Notes 357 2011). White catfish are found in high numbers in the tidal areas of the Satilla River. Similar to other recently introduced Blue Catfish populations (Bonvechio et al. 2011a), increased detections suggest establishment in the Satilla River. While Blue Catfish numbers remain low, impacts would be difficult to detect or minimal. However, previous works suggest that displacement and or declines of native species, particularly other native catfishes such as the White Catfish, may be expected. Acknowledgments. This project was funded by the Georgia Department of Natural Resources Wildlife Resources Division and State Wildlife Grant T-49-R. Literature Cited Bonvechio, T.F., D. Harrison, and B. Deener. 2009. Populations changes of sportfish following Flathead Catfish introduction in the Satilla River, Georgia. Proceedings of the Annual Conference of the Southeastern Association of Fish and Wildlife Agencies 63:133–139. 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