A Natural History of Conewago Falls—The Waters of Three Mile Island
Fishes
FISHES
of the Lower Susquehanna River Watershed
With (forthcoming) commentary on the species including notes from the historic writings of nineteenth-century geologist, naturalist, and philologist Professor Samuel Steman Haldeman, Linnaean Society of Lancaster City and County naturalist Jacob Stauffer, and ichthyologist Tarleton Hoffman Bean.
Samuel Steman Haldeman was born in 1812 at Locust Grove along the Susquehanna River just downstream of Conewago Falls near Bainbridge, Lancaster County, Pennsylvania. In 1842 and 1844, he was the first to describe the Chesapeake Logperch (Percina bimaculata), a fish which was long considered to be synonymous with the widespread Common Logperch (Percina caprodes) until recent mitochondrial DNA analysis proved it to be a valid species unique to the lower Susquehanna and other tributaries of the upper Chesapeake Bay. (Mathew Brady image-Library of Congress)Tarleton Hoffman Bean (back row left) with co-members of the Smithsonian Institution staff, circa 1878. Bean was born in Bainbridge, Lancaster County, Pennsylvania, in 1846 and spent his youth along the Susquehanna River there. He studied botany at the nearby Millersport State Normal School, present-day Millersville University. (Smithsonian National Museum of Natural History image www.si.edu)
SPECIES STATUS KEY
extinct-a native species no longer existing or living.
extirpated-a native species no longer occurring in the wild in the Lower Susquehanna River Watershed.
exotic-a free-ranging escaped or released non-native species or variety; most are unwanted pets, domesticated farm animals, or zoo specimens.
introduced-a non-native species released into the waters of the Susquehanna watershed, including fishes stocked to create temporary populations as well as those that establish self-sustaining breeding populations—often at the expense of one or more native species. Introduced fishes include “native transplants”, species native to North American waters, but not indigenous to the Susquehanna and its tributaries.
Federally Endangered-a native species listed by the United States government as imminently in danger of extinction.
PA Endangered-a native species listed by the Commonwealth of Pennsylvania as imminently in danger of extinction or of extirpation as a breeding species in the state.
MD Endangered-a native species listed by the State of Maryland as imminently in danger of extinction or of extirpation as a breeding species in the state.
Federally Threatened-a native species listed by the United States government as under threat to become an endangered species in the foreseeable future.
PA Threatened-a native species listed by the Commonwealth of Pennsylvania as under threat to become an endangered species in the state in the foreseeable future.
MD Threatened-a native species listed by the State of Maryland as under threat to become an endangered species in the state in the foreseeable future.
PA Candidate-an uncommon native species that could, in the future, become listed by the Commonwealth of Pennsylvania as endangered or threatened in the state.
A LIST OF THE FISHES
of the Lower Susquehanna River Watershed
Classified using traditional taxonomic ranks and selected cladistic groups.
Domain-Eukaryota
Kingdom-Animalia
Phylum-Chordata
Class-Hyperoartia?:
The lampreys, a group with disputed relationships to other chordates, are, in accordance with traditional listings of fishes, placed here.
Least Brook Lamprey (Lampetra aepyptera). (United States Fish and Wildlife Service image of specimen in NCTC Freshwater Fisheries Teaching Collection)Sea Lamprey (Petromyzon marinus). (NOAA Fisheries image by Paul Music)Sea Lamprey (Petromyzon marinus). (NOAA Fisheries image by Paul Music)
Subphylum-Vertebrata
Superclass-Osteichthyes/Clade-Euteleostomi:
The “bony vertebrates” including the Actinopterygians, the ray-finned fishes, and the Sarcopterygians, the lobe-finned fishes and tetrapods. All members of the clade Sarcopterygii presently occurring in the Susquehanna watershed (amphibians, reptiles, birds, and mammals including humans) are tetrapod descendants of extinct lobe-finned fishes.
Longnose Gar (Lepisosteus osseus). (United States Fish and Wildlife Service image by Ryan Hagerty)
Order-Amiiformes
Family-Amiidae
Amia calva (Bowfin)-introduced
Bowfin (Amia calva) are indigenous to the Great Lakes, the Mississippi and Ohio Rivers, and the Atlantic and Gulf Coastal Plains south of Virginia. They were introduced into the lower Susquehanna River as native transplants in the years prior to 1972’s Hurricane Agnes. Few were seen after the polluted floodwaters receded. (United States Fish and Wildlife Service image by Ryan Hagerty)
Order-Anguilliformes
Family-Anguillidae
Anguilla rostrata (American Eel)
American Eel (Anguilla rostrata). (Vintage 35 mm image)American Eel (Anguilla rostrata).
Order-Clupeiformes
Family-Clupeidae
Alosa aestivalis (Blueback Herring)
Alosa mediocris (Hickory Shad)-PA Endangered
Alosa pseudoharengus (Alewife)-introduced
Alosa sapidissima (American Shad)
Dorosoma cepedianum (Gizzard Shad)
A Blueback Herring (Alosa aestivalison) on the top and, for comparison, an Alewife (Alosa pseudoharengus) on the bottom. (NOAA Fisheries image)Hickory Shad (Alosa mediocris).Alewife (Alosa pseudoharengus) during migration. (NOAA Fisheries image by Jerry Prezioso)A catch-and-release angler returning an American Shad (Alosa sapidissima) to the Susquehanna River. (Vintage 35 mm image)An American Shad (Alosa sapidissima) on the top and, for comparison, an Alewife (Alosa pseudoharengus) on the bottom. (NOAA Fisheries image by Jim Hawkes)Gizzard Shad (Dorosoma cepedianum) swimming by the counter’s window at the York Haven Dam Fish Passage just upstream from Conewago Falls.Schooling juvenile Gizzard Shad (Dorosoma cepedianum). (Vintage 35 mm image)
Order-Cypriniformes
Family-Cyprinidae
Campostoma anomalum (Central Stoneroller)
Carassius auratus (Goldfish)-introduced
Clinostomus elongatus (Redside Dace)-upper Susquehanna species
Central Stoneroller (Campostoma anomalum).Goldfish (Carassius auratus).Rosyside Dace (Clinostomus funduloides). (United States Fish and Wildlife Service image by Ryan Hagerty)Grass Carp (Ctenopharyngodon idella). (United States Fish and Wildlife Service image by Ryan Hagerty)Within the Lower Susquehanna River Watershed, there are two shiners in the genus Cyprinella: the Satinfin Shiner (C. analostanus) and the Spotfin Shiner (C. spiloptera). These very similar species are generally regarded as inseparable in the field. Male Cyprinella shiners in breeding condition (center) are known for their white-edged fins and vibrantly colored iridescent scales. (Vintage 35 mm image)A possible breeding male Satinfin Shiner (Cyprinella analostanus). Traditional field marks of the Satinfin Shiner include dark pigment in all margins between the rays of the dorsal fin and a total of nine rays in the anal fin. (Vintage 35 mm image)A possible breeding male Spotfin Shiner (Cyprinella spiloptera). Traditional field marks of the Spotfin Shiner include dark pigment in the margins between the rays at the anterior end of the dorsal fin and a total of eight rays in the anal fin.A probably Spotfin Shiner (Cyprinella spiloptera), based on a count of eight rays in the anal fin.Common Carp (Cyprinus carpio).Cutlip Minnow (Exoglossum maxillingua), also known as Cutlips Minnow.Cutlip Minnow (Exoglossum maxillingua), also known as Cutlips Minnow.Common Shiner (Luxilus cornutus).Common Shiner (Luxilus cornutus).A breeding male Common Shiner (Luxilus cornutus).A breeding male Common Shiner (Luxilus cornutus).A breeding male Common Shiner (Luxilus cornutus).Top view of a breeding male Common Shiner (Luxilus cornutus).Golden Shiner (Notemigonus crysoleucas).Golden Shiner (Notemigonus crysoleucas).Comely Shiner (Notropis amoenus). (Vintage 35 mm image)Emerald Shiner (Notropis atherinoides). (National Park Service image)Spottail Shiner (Notropis hudsonius).Spottail Shiner (Notropis hudsonius).Swallowtail Shiner (Notropis procne).Rosyface Shiner (Notropis rubellus). (Vintage 35 mm image)Rosyface Shiner (Notropis rubellus). (Vintage 35 mm image)Mimic Shiner (Notropis volucellus).A juvenile Mimic Shiner (Notropis volucellus).Fathead Minnow (Pimephales promelas).The “Rosy-red Minnow”, a xanthic (golden) morph of the Fathead Minnow (Pimephales promelas) first encountered among farm-raised baitfish populations, is commonly sold for home aquaria.Bluntnose Minnow (Pimephales notatus).A breeding male Bluntnose Minnow (Pimephales notatus).Eastern Blacknose Dace (Rhinichthys atratulus).A breeding male Eastern Blacknose Dace (Rhinichthys atratulus).A breeding male Eastern Blacknose Dace (Rhinichthys atratulus).Longnose Dace (Rhinichthys cataractae).On the bottom, a juvenile Longnose Dace (Rhinichthys cataractae). Above, two juvenile Blacknose Dace (Rhinichthys atratulus).Creek Chubs (Semotilus atromaculatus)Creek Chub (Semotilus atromaculatus) A breeding male Creek Chub (Semotilus atromaculatus).A breeding male Creek Chub (Semotilus atromaculatus).
Family-Catostomidae
Carpiodes cyprinus (Quillback)
Catostomus commersoni (White Sucker)
Erimyzon oblongus (Creek Chubsucker)
Hypentelium nigricans (Northern Hogsucker)
Moxostoma anisurum (Silver Redhorse)-?
Moxostoma macrolepidotum (Shorthead Redhorse)
Quillback (Carpiodes cyprinus). (United States Fish and Wildlife Service image by Brett Billings)A juvenile Quillback (Carpiodes cyprinus).White Sucker (Catostomus commersoni). (United States Fish and Wildlife Service image by Brett Billings)Creek Chubsucker (Erimyzon oblongus). (Vintage 35 mm image)Northern Hog Sucker (Hypentelium nigricans). (Vintage 35 mm image)Northern Hog Sucker (Hypentelium nigricans).Shorthead Redhorse (Moxostoma macrolepidotum).
White Catfish (Ameirus catus). (Smithsonian Environmental Research Center image by Robert Aguilar)An adult Yellow Bullhead (Ameirus natalis). Juvenile Yellow Bullheads (Ameirus natalis). (Vintage 35mm image)Brown Bullheads (Ameirus nebulosus).Hundreds of juvenile Brown Bullheads (Ameirus nebulosus) in a densely packed school formation. To discourage predators, this behavior gives a mass group of dark-colored small fry the collective appearance of a large fish.Juvenile Brown Bullheads (Ameirus nebulosus) less than one inch in length in constant motion vying for positions toward the center of the protective school. The constant motion of so many targets can confuse the visual and lateral line sensory capabilities of a predatory fish and render it unable to focus on a single target. Blue Catfish (Ictalurus furcatus). (United States Fish and Wildlife Service image by Brett Billings)Channel Catfish (Ictalurus punctatus). (United States Fish and Wildlife Service image by Brett Billings)A juvenile Channel Catfish (Ictalurus punctatus).Tadpole Madtom (Noturus gyrinus). (United States Geological Survey image)Margined Madtom (Noturus insignis).A juvenile Flathead Catfish (Pylodictis olivaris) among the Pothole Rocks at Conewago Falls.
Order-Characiformes
Family-Sarasalmidae
Colossoma orPiaractus species (Pacu species)-exotic
As juveniles, these Red-bellied Pacu (Piaractus brachypomus) could be mistaken for Red-bellied Piranha (Pygocentrus nattereri). Both are tropical natives of South America’s Amazon River system. The former is sometimes sold in the aquarium and food trade using the name of the latter. Pacu are often called vegetarian piranhas. They possess teeth resembling human molars while piranhas have sharp-pointed teeth. As they age, Red-bellied Pacu soon lose their red color and attain lengths of two feet or more, quickly outgrowing most home aquaria. When no longer wanted as pets, pacu are oft times released into the ponds, lakes, and streams of the lower Susquehanna watershed. In 2009, an angler caught a Red-bellied Pacu while fishing in the Conestoga River in Manheim Township, Lancaster County, Pennsylvania. They’ve been found in Lake Placida on the campus of Elizabethtown College, also in Lancaster County. In autumn, pacu released into the waters of the Susquehanna basin are killed by falling temperatures. (United States Geological Survey image)
Order-Esociformes
Family-Esocidae
Esox americanus (Redfin Pickerel)-introduced
Esox niger (Chain Pickerel)
Esox reicherti (Amur Pike)-introduced
Esox lucius (Northern Pike)-introduced
Esox lucius x Esox reicherti (“Hybrid Pike”)-introduced-upper west branch species-186 fish stocked in Glendale Lake northwest of Altoona—last documented in 1976
Esox masquinongy (Muskellunge)-introduced
Esox lucius x Esox masquinongy (“Tiger Muskellunge”)-introduced
Redfin Pickerel (Esox americanus). (Maryland Biodiversity Project image by Emilio Concari under license: CC BY-NC)Northern Pike (Esox lucius). (National Park Service image)Muskellunge (Esox masquinongy). (United States Fish and Wildlife Service image by Eric Engbretson)The “Tiger Muskellunge” (Esox lucius x Esox masquinongy) is the sterile cross of a male Northern Pike and a female Muskellunge. These hybrids grow more vigorously under captive rearing conditions than their pure-bred parents. (United States Fish and Wildlife Service NCTC Freshwater Fishes Teaching Collection image by Matthew Patterson)
Order-Osmeriformes
Family-Osmeridae
Osmerus mordax (Rainbow Smelt)-introduced-upper Susquehanna/upper Juniata species
Rainbow Smelt (Osmerus mordax) were stocked as a forage and angling species in Harvey’s Lake in Lackawanna County (circa 1952) and Raystown Lake in Huntingdon County (pre-1988). (NOAA Fisheries image by Katrina Mueller)
Order-Salmoniformes
Family-Salmonidae
Oncorhynchus kisutch (Coho Salmon)-introduced-upper Susquehanna species
Oncorhynchus mykiss (Rainbow Trout)-introduced
Oncorhynchus nerka (Sockeye Salmon)-introduced-upper Susquehanna species
Oncorhynchus tshawytscha (Chinook Salmon)-introduced-upper Susquehanna species
Salmo salar (Atlantic Salmon)-introduced
Salmo trutta (Brown Trout)-introduced
Salvelinus fontinalis (Brook Trout)
Salmo trutta x Salvelinus fontinalis (“Tiger Trout” hybrid)-introduced
Salvelinus namaycush (Lake Trout)-introduced-upper Susquehanna species
Salvelinus namaycush x Salvelinus fontinalis (“Splake” hybrid)-introduced
Coho Salmon (Oncorhynchus kisutch) were stocked (circa 1967) in Harvey’s Lake in Lackawanna County, PA. (United States Department of the Interior Bureau of Land Management image)Rainbow Trout (Oncorhynchus mykiss). (United States Fish and Wildlife Service image by Ryan Hagerty)Sockeye Salmon (Oncorhynchus nerka) were stocked in Lake Winola west of Scranton (circa 1923), then in Harvey’s Lake near Wilkes-Barre in Lackawanna County, PA (circa 1967). (United States Fish and Wildlife Service image)Introductions of Chinook Salmon (Oncorhynchus tshawytscha) in the upper Susquehanna watershed near Scranton failed during the late nineteenth century and again circa 1940. (United States Fish and Wildlife Service image)Atlantic Salmon (Salmo salar) were stocked (circa 1975) in Laurel Lake (Reservoir) in the Juniata River watershed in Mifflin County, PA. (NOAA Fisheries image by Betty Holmes)Brown Trout (Salmo trutta). (United States Fish and Wildlife Service image by Robert Pos)Brook Trout (Salvelinus fontinalis). (United States Fish and Wildlife Service image)The “Tiger Trout” (Salmo trutta x Salvelinus fontinalis) is a hybrid occurring as a cross between two not-so-closely-related salmonids, a female Brown Trout (with 80 chromosomes) and a male Brook Trout (84 chromosomes). These hybrids are a rarity in locations where the former has been introduced among native populations of the latter. The hatching success for these wild crosses seldom exceeds 5% and all offspring are sterile. In the nursery, quick heat treatment of fertilized eggs alters DNA replication and improves hatching success to 85%. The farm-raised trout often show “hybrid vigor” and grow rapidly. But, like those occuring by chance in nature, they are unable to reproduce. On several occasions, these hybrids have been recovered on the lower Susquehanna River in the fish lift facilities at Conowingo Dam, Maryland. (Public Domain image by Mathew Tyree)One of several “Tiger Trout” (Salmo trutta x Salvelinus fontinalis) caught by anglers during 2019 and 2020 in the Gunpowder River watershed in Baltimore County, Maryland. During the spring shad runs of both 2019 and 2021, two of these hybrids were encountered on the nearby lower Susquehanna River in the fish lift facilities at Conowingo Dam, Maryland. (Image by baltimorefishing1 via iNaturalist under license CC BY-NC)Lake Trout (Salvelinus namaycush) have been stocked repeatedly in Harvey’s Lake in Lackawanna County, PA. A population introduced into glacial Ostego Lake, the source of the Susquehanna at Cooperstown, NY, reproduce successfully but face increasing numbers of invasive Zebra Mussels (Dreissena polymorpha) on their spawning areas. (United States Geological Survey image)The “Splake” (Salvelinus namaycush x Salvelinus fontinalis) is a hybrid created in a fish hatchery by crossing a female Lake Trout and a male Brook Trout. To the disappointment of avid anglers, a “trophy-size” Brook Trout can instead turn out to be a “Splake”. These hybrids have been observed as they transit the fish lifts at the hydroelectric dams on the lower Susquehanna. (United States Fish and Wildlife Service image by Lindsey Adams)
Order-Beloniformes
Family-Belonidae
Strongylura marina (Atlantic Needlefish)
Tylosurus acus (Agujon)
Atlantic Needlefish (Strongylura marina) wander from the brackish waters of Chesapeake Bay into the fresh waters of its tributaries. They were probably a regular visitor to the lower Susquehanna prior to the construction of man-made dams. Since their installation during the late twentieth century, Atlantic Needlefish have occasionally been recorded using the fish lifts at the hydroelectric dams to ascend the river. (NOAA Southeast Fisheries Science Center image from the collection of Brandi Noble)
Order-Gadiformes
Family-Lotidae
Lota lota (Burbot)-introduced
Order-Cyprinodontiformes
Family-Cyprinodontidae
Fundulus diaphanus (Banded Killifish)
Fundulus heteroclitus (Mummichog)
Banded Killifish (Fundulus diaphanus). (Vintage 35 mm image)Mummichogs (Fundulus heteroclitus). (Vintage 35 mm image)
Mosquitofish (Gambusia species), female (left) and male (right).Gravid female Mosquitofish (Gambusia species) gather in 2 to 3 inches of vegetated water to give birth.
Fourspine Stickleback (Apeltes quadracus). (Smithsonian Environmental Research Center image by Robert Aguilar)
Order-Scorpaeniformes
Family-Cottidae
Cottus bairdi (Mottled Sculpin) ?
Cottus caeruleomentum (Blue Ridge Sculpin)
Cottus cognatus (Slimy Sculpin)
Cottus girardi (Potomac Sculpin)
Slimy Sculpin (Cottus cognatus). (United States Fish and Wildlife Service image by Ryan Hagerty)Potomac Sculpin (Cottus girardi). (United States Fish and Wildlife Service image by Ryan Hagerty)
Order-Perciformes
Family-Percichthydae
Morone americana (White Perch)
Morone chrysops (White Bass)-introduced
Morone saxatilis (Striped Bass)
Morone saxatilis x Morone chrysops (“Hybrid Striped Bass”)-introduced
White Bass (Morone chrysops). (United States Fish and Wildlife Service image)Striped Bass (Morone saxatilis). (United States Fish and Wildlife Service image by Ryan Hagerty)A “Hybrid Striped Bass” (Morone saxatilis x Morone chrysops) is a hatchery-produced cross of a male Striped Bass and a female White Bass, or of a female Striped Bass and a male White Bass. The former is sometimes called a “Sunshine Bass”, the latter a “Palmetto Bass”. These hybrids are able to withstand higher water temperatures and lower dissolved oxygen levels than pure-bred Stripers, hence they are better suited for aquaculture and nursery rearing. Because female Striped Bass produce far more eggs than can female White Bass, the cross yielding the “Palmetto Bass” is favored by hatchery operators. In the lower Susquehanna valley, “Hybrid Striped Bass” are raised commercially at a fish farm just downriver from Conewago Falls on Brunner Island in York County. (United States Fish and Wildlife Service image by Ryan Hagerty)
Rock Bass (Ambloplites rupestris). (United States Fish and Wildlife Service image)A juvenile Rock Bass (Ambloplites rupestris).Blue-spotted Sunfish (Enneacanthus gloriosus). (Maryland Biodiversity Project image by Emilio Concari, under license: CC BY-NC)Redbreast Sunfish (Lepomis auritus). (United States Fish and Wildlife Service image by Ryan Hagerty)Juvenile Redbreast Sunfish (Lepomis auritus). (United States Fish and Wildlife Service image by Ryan Hagerty)Bluegill (Lepomis macrochirus).A juvenile Bluegill (Lepomis macrochirus).“Hybrid Sunfish” (Lepomis macrochirus x Lepomis cyanellus) are produced in fish hatcheries by crossing a male Bluegill with a female Green Sunfish. The offspring, of which ninety percent or more are male, grow quickly to an attractive size for anglers. Other Lepomis hybrids are possible in the wild, especially where non-native sunfish have been introduced among native species. (United States Fish and Wildlife Service image by Sam Stukel)Green Sunfish (Lepomis cyanellus).A juvenile Green Sunfish (Lepomis cyanellus). (Vintage 35 mm image)A Pumpkinseed (Lepomis gibbosus) defends its nest to the lower left while a Green Sunfish (Lepomis cyanellus) protects its scrape to the upper right.Pumpkinseed (Lepomis gibbosus).Redear Sunfish (Lepomis microlophus). (United States Fish and Wildlife Service image by Ryan Hagerty)Smallmouth Bass (Micropterus dolomieu). (Vintage 35 mm image)Largemouth Bass (Micropterus salmoides).A juvenile Largemouth Bass (Micropterus salmoides).Black Crappie (Pomoxis nigromaculatus). (United States Fish and Wildlife Service image by Eric Engbretson)
Fantail Darter (Etheostoma flabellare). (United States Fish and Wildlife Service image by Ryan Hagerty)Fantail Darter (Etheostoma flabellare). (Maryland Biodiversity Project image by Emilio Concari: under license CC BY-NC)Tessellated Darter (Etheostoma olmstedi).Tessellated Darter (Etheostoma olmstedi).A juvenile Tessellated Darter (Etheostoma olmstedi).Maryland Darter (Etheostoma sellare), a specimen collected in October, 1985. This Federally Endangered Species was last seen in 1988 in Deer Creek, a Susquehanna River tributary in Harford County, Maryland. (Smithsonian Environmental Research Center image by Robert Aguilar: under license CC BY-NC)Banded Darter (Etheostoma zonale). (Vintage 35 mm image)Banded Darter (Etheostoma zonale).A Banded Darter (Etheostoma zonale) on top and, for comparison, a Tessellated Darter (Etheostoma olmstedi) on the bottom.Chesapeake Logperch (Percina bimaculata), a species first described by Samuel Steman Haldeman in 1842 and 1844. Long considered to be synonymous with the widespread Common Logperch (Percina caprodes), recent mitochondrial DNA analysis proved it to be a valid species unique to the lower Susquehanna and other tributaries of the upper Chesapeake Bay. (United States Fish and Wildlife Service Image by Kayt Jonsson)Shield Darter (Percina peltata). (United States Fish and Wildlife Service Image by Kayt Jonsson)Yellow Perch (Perca flavescens). (United States Fish and Wildlife Service image by Brett Billings)Walleye (Sander vitreus) swimming by the counter’s window at the York Haven Dam Fish Passage located just upstream from Conewago Falls.
Order-Cichliformes
Family-Cichlidae
Tilapia aurea (Blue Tilapia)-exotic
During the early 1980s, Blue Tilapia (Tilapia aurea) were raised at a fish farm on Brunner Island just downstream of Conewago Falls. During the colder months, the facility used warm water from the coal-fired steam-electric generator there to increase the temperature in the grow-out channels. Anglers enjoyed an occasional catch of a colorful Blue Tilapia that had escaped into the Susquehanna. During the winter, cold water was fatal to both tilapia in the river and, if the power plant experienced a shutdown, those in the fish culture facility. As a result, efforts to raise tilapia were abandoned in favor of growing cold-tolerant species including Channel Catfish, Hybrid Striped Bass, and ornamental Goldfish. (United States Geological Survey image by Howard Jelks)
Order-Anabantiformes
Family-Channidae
Channa argus (Northern Snakehead)-introduced
The Northern Snakehead (Channa argus), an introduced species from eastern Asia, was first reported in the Susquehanna watershed near the river’s mouth and in the nearby Octararo Creek in Cecil County, Maryland in 2016. During 2018, it was found upstream in the river to Conowingo Dam and had advanced on the Octararo Creek into Pennsylvania. During 2019, the Northern Snakehead was found in Deer Creek in Harford County, Maryland, the last known habitat of the endangered Maryland Darter. (United States Fish and Wildlife Service image)The mouth of a Northern Snakehead (Channa argus), a potentially invasive species that could catastrophically impact native aquatic animals including fish, amphibians, reptiles, and even freshwater mussels. They had, by 2019, already infiltrated the range of the Least Brook Lamprey, Hickory Shad, Tadpole Madtom, Maryland Darter, and Chesapeake Logperch, each a species of conservation concern in the lower Susquehanna watershed. (United States Geological Survey image)Northern Snakehead (Channa argus) being examined after removal from the wild. (United States Fish and Wildlife Service image by Brett Billings)
SOURCES
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