HARRISBURG, Pa. — The Pennsylvania Fish and Boat Commission on Wednesday asked anglers who fish in the Delaware River basin to be on the lookout for a pair of invasive fish species that have been spotted in increasing numbers recently.
The Freshwater Drum and the Blue Catfish are both non-native to the lower Delaware River basin, and their increasing numbers in waters outside their native range could pose ecological impacts, the PFBC said in a press release.
Freshwater Drum are the only member of a mainly saltwater family of fish that inhabits freshwater in North America, the PFBC said. Adults typically weigh between five and 15 pounds. Captures have been documented by PFBC biologists in the tidal Delaware River, as well as the non-tidal portion upstream to the vicinity of Upper Back Eddy, Bucks County.
Additionally, agency partners have collected Freshwater Drum in the lower Schuylkill River in Philadelphia, the PFBC said.
Blue Catfish have been collected by partner agencies in the vicinity of the Commodore Barry Bridge in the lower Delaware River, the PFBC said. Blue Catfish are the largest members of the catfish family in North America and are capable of attaining weights of over 100 pounds, although most larger adults are in the 30-pound range, experts said.
“Documentation of expansion of both non-native Freshwater Drum and Blue Catfish is of potential major concern for fisheries and natural resources in the Delaware River and its tributaries as these are considered invasive species with potential major ecological impacts,” said Sean Hartzell, PFBC Aquatic Invasive Species Coordinator. “Where introduced elsewhere, such as the Chesapeake Bay, invasive Blue Catfish have impacted economically important commercial and sport fisheries.
"The potential impacts of introduced Freshwater Drum are less well-known, but this species is considered a threat to native freshwater mussels in the Delaware River basin due to its feeding preferences on hard-bodied invertebrates.”
While not native to the Delaware River Basin, both Blue Catfish and Freshwater Drum are native to parts of the Ohio River basin in western Pennsylvania, the PFBC said. However, both species are considered invasive if introduced outside of their native range.
Introduction of Blue Catfish, Freshwater Drum and other fish species into Commonwealth waters where they do not naturally occur, or without written permission from the PFBC, is considered an unlawful act, the agency said.
In Pennsylvania, Freshwater Drum and all catfish species have no size limit or closed season, and up to 50 (combined with other species) may be taken per day by rod and reel.
In their native range, Freshwater Drum are frequently captured as bycatch by catfish anglers baiting bottom rigs with worms or shrimp, and thus anglers fishing for catfish in the Delaware River basin are most likely to encounter both Freshwater Drum and Blue Catfish, the PFBC said.
Anglers with suspected captures of Freshwater Drum or Blue Catfish in the Delaware River or its tributaries are encouraged to harvest these fish, take photos and report their captures to the PFBC’s online aquatic invasive species reporting form on the PFBC website.
While Blue Catfish are well-known as desirable table fare, Freshwater Drum are less frequently taken for consumption, but some anglers enjoy cutting fillets into strips and boiling to produce a flavor and texture similar to shrimp or lobster, the PFBC said. Freshwater Drum may also be harvested to use as chum bait for saltwater fishing, according to the PFBC.
Further information on the biology, potential impacts and identification of both species can be found at the United States Geological Survey’s Nonindigenous Aquatic Species webpages for Freshwater Drum and Blue Catfish.
