Daily Invader

Chesapeake Bay Fishes

Rock Bass (Ambloplites rupestris)


Rock Bass (Ambloplites rupestris) was stocked in the Chesapeake drainage in the late 1800s.

Rock Bass is native to the North Atlantic (St. Lawrence, Great Lakes, Hudson Bay and Mississippi drainages, etc) but has been widely introduced throughout the US starting in the late 1800s with stocking by the United States Fish Commission, the predecessor to the National Marine Fisheries Service. Rock Bass are a small (max ~15 inches) freshwater fish that are important as sport fish. They are rare in the tidal sections of Chesapeake Bay but are common in the freshwater tributaries. They are competitors and predators of the Redbreast Sunfish (Lepomis auritus) and the young of Smallmouth Bass (Micropterus dolomieu), trout, and other sport fish. Complete Record  



Bowfin (Amia calva)


Bowfins (Amia calva) are native to the southern Bay and introduced to the northern tributaries.






Bowfin are native to much of the Chesapeake Bay watershed including the Atlantic Coastal Plain from the Potomac southward, but are included here because they have been stocked locally in the northern and upland parts of the Chesapeake Bay drainage. The native range of the Bowfin extends includes much of Eastern and Central North America from the St. Lawrence-Great Lakes South to the Gulf coast and west to the Mississippi River from Quebec to north Minnesota. Bowfins are as native to the southern part of the Chesapeake Basin, the Potomac, Rappahannock, York, and James River systems, and introduced through stocking into the Susquehanna River and Upper Bay tributaries. They were stocked as a sport fish, although this is limited, and as a predator to thin out stunted stocks of sunfish. They have been introduced in 16 states in the eastern and Midwestern U.S. They are generally rare in Chesapeake Bay and can be confused with the recently introduced Northern Snakehead (Channa argus). To find out how to distinguish the two here. Complete Record


Goldfish (Carassius auratus)


Goldfish (Carassius auratus) are both culturally important and widely introduced.



Goldfish are native to China, Korea, and Eurasia, but they have been widely introduced both deliberately and accidentally. They have been found in all states except Alaska, in at least 50 countries, and on all continents except Antarctica. US government agencies raised and distributed Goldfish to at least 37 states between 1878 and 1893 and populations are established in many urban rivers. The first record for Chesapeake Bay was in 1876, and individuals have been found in many tributaries throughout the Bay. The impact of Goldfish on the ecology of the Bay is probably minor, and they are an important prey for sport fishes in the Potomac where they are most abundant. Culturally, the Goldfish remain important and are sold for pets, bait, and as 'feeder' fish. In 1939 they were eaten by numerous college students throughout the US. Complete Record  


Fliers (Centrarchus macropterus)

Drawing by Duane Raver 

Fliers (Centrarchus macropterus) are an example of a fish that is both native and introduced to Chesapeake Bay.



Can a species be both native and introduced within one watershed? Fliers are small (to 7 inches) sunfish native to the Mississippi and Gulf of Mexico drainages and to drainages of the Atlantic Coastal Plain from Texas to Illinois and Indiana. In Chesapeake Bay they are native to the Rappahannock and James Rivers in Virginia. Their only known introduction is within the Chesapeake Bay watershed. In 1981 they were found in a small pond in St. Mary’s County, MD, on the north side of the Potomac. In 1998 they were found in Port Tobacco Creek and Zekiah Swamp Run, in Charles County, MD. They were likely introduced with live bait or with other stocked fishes. Its introduction appears to have had no economic impact, nor have any ecological impacts on native species been reported. Complete Record  


Northern Snakehead (Channa argus)


Northern Snakehead (Channa argus) caught in Rhode River by research team: SERC Scientists Eric Bah and Stacey Havard, interns Philip Choy and Diana Sisson and visiting student Alison Everett (pictured).






A team of researchers and student interns caught a Northern Snakehead fish in the Rhode River July 14, 2011. This, along with other recent reports, indicates a possible range expansion of the snakehead population. The Northern Snakehead, native to Asia, was first caught in a pond in Crofton, MD in 2002. They are a major concern here because they are voracious predators and could impact our native fish species. Their 2002 discovery prompted a rapid response and eradication effort that lead to the removal of over 1,000 juvenile fish. However, in 2004, an established population of Snakeheads was found in the Potomac River. Genetic analysis indicates that the fish have been introduced many times in North America. Because Snakeheads are imported for food and occasionally sold in the aquarium trade, their introductions are likely to be a combination of accidental and intentional (illegal) introductions. Snakeheads have not yet had a significant ecological or economic impact, but the Potomac River population has spread to brackish waters near the mouth of the river and, as of this spring, may be moving into other tributaries. In April-July of 2011, several catches of snakeheads were reported in the Bay outside the Potomac River, including St. Jeromes Creek, Nanticoke River, and up the bay to the Rhode and Northeast Rivers. Their spread may have resulted from heavy winter and early spring rains which resulted in unusually low salinities in Chesapeake Bay permitting wider dispersal. The most recent catch by researchers at the Smithsonian Environmental Research Center was a large (22.9 inch) egg-bearing female caught in a seine during a routine survey in the Rhode River. It remains to be seen whether the wide dispersal of this fish will result in established populations in other Chesapeake Bay tributaries. Complete Record


Cisco (Coregonus artedi)


Cisco or Lake Herring (Coregonus artedi) are declining in their native range and haven’t established in Chesapeake Bay.




Cisco, also called Lake Herring, are native to the St. Lawrence River, the Great Lakes, Arctic, and upper Mississippi Basins. In their native range they are an important food source for many larger fish such as Lake trout, Northern Pike, and Walleye, and in the 19th and 20th centuries they were fished commercially. Now, they are endangered in Lake Ontario and Lake Erie, and rare and possibly threatened in Lakes Michigan, Huron, and Superior. Although they were introduced and stocked in many areas outside of their native range, they rarely established. They were introduced into the Susquehanna watershed at Harvey's Lake, Luzerne County PA, in 1969-1972, and are listed on species lists for Maryland because one specimen was collected below Conowingo Dam in 1972. The current status of the population in Harvey's Lake is unknown, but the lower Susquehanna River where an individual was found appears to be outside the tolerance range of this cold-water fish, and thus the fish is considered a failed Maryland introduction. Complete Record 


Lake Whitefish (Coregonus clupeaformis)

Lake Whitefish (Coregonus clupeaformis) didn’t survive in the Bay in spite of efforts to introduce them.


In the 1800s United States Fish Commission and State Fish Commissioners set out to stock local waterways with fish that everyone liked to catch. Back then people weren’t thinking about preserving what was native, they were thinking about making improvements to local flora and fauna by adding species they liked from other places. As part of this effort Lake Whitefish from the North—including most of Canada south into New England, the Great Lakes Basin, and central Minnesota —were stocked into the Chesapeake Bay and many of its tributaries in the 1880s. Five thousand fish were stocked in Patuxent River near Laurel, MD and a million eggs were shipped to Baltimore and stocked in six locations in the upper Bay and Eastern Shore Tributaries in 1884. In 1886 and 1888 a million eggs were put into Delaware Bay. But in spite of these efforts, none of these fish survived because the climate and water conditions in the Chesapeake and Delaware Bays are outside the tolerance limits of this species. Complete Record  


Grass Carp (Ctenopharyngodon idella)


Grass Carp (Ctenopharyngodon idella) are illegal in Maryland, but legal (if sterile) in Virgina. But will they stop at state lines? 








Grass Carp are freshwater herbivores. They eat aquatic plants and were imported to the United States, Europe, Africa, Japan, Mexico, and other areas to control unwanted aquatic plants. They are native to China and the Amur basin of Russia and are cultivated in China for food. They were first brought to the United States in 1963 from Malaysia by researchers at the United States Fish and Wildlife Service Fish Farming Experimental station. At the time people thought that if the fish were only used in lakes and other slow moving water bodies they would not become established because they need large swift-flowing rivers to reproduce. But very soon they were released into the lower Mississippi drainage were they established breeding populations. By 1978 they had been introduced to 35 states and are now in 45 states. The fact that Grass Carp eat aquatic vegetation is useful in areas with high densities of introduced aquatic weeds. But Grass Carp don’t discriminate between aquatic weeds and valuable native submerged vegetation, they eat them all. Trying to balance the desire to control aquatic weeds and introducing a nonnative fish that eats native plants led to efforts to develop nonreproductive fish for weed control. These sterile triploids are stocked in some states, such as Virginia and banned in others, including Maryland. So far there is no evidence of reproduction in the Chesapeake Bay watershed. Complete Record


Common Carp (Cyprinus carpio)


Common Carp (Cyprinus carpio) another fish whose import seemed like a good idea, but didn’t turn out to be. 




Common Carp are native to Eastern Asia, but have been widely introduced, domesticated, and hybridized in the US and elsewhere. They were first introduced to North America about 1831 and are now found in the lower 48 states and Hawaii. Common Carp were imported to the United States from Germany in 1877 by the United States Fish Commission (USFC) and stocked in many areas starting in the Chesapeake Bay near Baltimore (1878) and Washington DC soon after. The Virginia Fish Commission started stocking carp in Virginia waters in 1880-81 through the distribution of the ~260,000 carp to private individuals across the US who wanted to culture them for food. This distribution ended in 1896, but by then, the fish were becoming established through most of the United States. Carp were an attractive import at the time because they eat aquatic vegetation and thrive in conditions not suitable for other fish. Managers at the time did not expect them to impact native species, unfortunately, they have lead to the decline of many native fish populations. Complete Record  


Threadfin Shad (Dorosoma petenense)


Threadfin Shad (Dorosoma petenense), an introduced fish stocked to feed other introduced fish.


Threadfin Shad are native to the Mississippi and Gulf of Mexico drainages from Indiana and Illinois south to Guatemala but has been introduced in 24 states as a forage fish in reservoirs in 1950's when sport fish were being stocked, but in many reservoirs the stocked populations have died out due to cold weather. Threadfin Shad were introduced in the Chesapeake starting in the 1950’s. Populations were stocked in Currituck Sound and the James, York, and Potomac Rivers, and have been found in several areas in the upper bay and eastern shore drainages. Today the populations of shad in Chesapeake Bay are limited and not abundant due mainly to mortality at low temperatures. The presence of shad has both positive and negative impacts; they do provide food for sport fish but could also compete with native fish. Complete Record


Muskellunge (Esox masquinongy)


Muskellunge (Esox masquinongy) populations are reliant on continued stocking efforts.  


Muskellunge, "muskie" for short, is a long and thin fish that looks like a Northern Pike (Esox lucius). They are native to the St. Lawrence River, Great Lakes, Hudson Bay (Red River) and the Mississippi River basin. As a sport fish they were frequently introduced and have established populations in 31 states. Stocking in the Chesapeake Watershed began in the 1950s. Most were introduced the reservoirs but juveniles have been seen in the upper James River in Virginia and the Susquehanna River in Pennsylvania. So far Muskellunge haven’t invaded beyond these rivers and the reservoirs around the Coastal Plain where they’ve been stocked. Reproduction within these populations is rare and is dependent on stocking. Stocking has ended in Pennsylvania but continues in Virginia. Significant impacts on native fishes haven’t been reported. Complete Record


Greenside Darters (Etheostoma blennioides)


Greenside Darters (Etheostoma blennioides) were used for bait then discarded.





Greenside Darters are small freshwater fish native to Midwestern United States and the Great Lakes. Male and female darters have different color patters, similar to birds, male darters are the colorful ones. Breeding males have 4-7 dark green bands along their bodies and a red band along the base of their first dorsal fin and their fins and head can be bright green. Green Darters were first discovered in the Potomac River in 1954 and soon after at the mouth of the Shenandoah River at Harper's Ferry, WV and every tributary westward into West Virginia and Maryland. By the 1960s they were in Sinnemahoning Creek, a tributary to the Susquehanna River in Potter County, PA. By 1999, they were being found throughout much of the Susquehanna watershed from New York to the Maryland border. They have not yet been found in tidal waters of Chesapeake Bay, but have been collected just upstream of Conowingo Dam, and from Cabin John Run, only a few miles from the head of tide of the Susquehanna and Potomac, respectively. Greenside Darters may have been introduced by fisherman using them as bait. Complete Record


Blue Catfish (Ictalurus furcatus)


Blue Catfish (Ictalurus furcatus) is one of the largest catfish in North America.


Blue Catfish is one the largest catfish in North America and as such is a very popular sport fish. Blue Catfish are native to Mississippi River and the Gulf of Mexico, a range that extends from the Gulf north to Pennsylvania and South Dakota. Due to their size and popularity as a sport fish, they have been introduced in several states including Maryland, Virginia, and many Western states like California and Arizona. They may have boon introduced into the Potomac River with the Channel Catfish (Ictalurus punctatus) by the United States Fish Commission at the turn of the century, but we know for sure they were stocked in the James and Rappahannock Rivers in 1975 by the Virginia Division of Inland Fish and Game. The Potomac River was stocked with Blue Catfish in the 1980s, and now the fish are widespread and increasing in abundance. Very large fish are being caught in both Maryland and Virginia; the Maryland state record is a 67lb fish caught in the Potomac River in 2008, and the Virginia state record is a 102lb fish caught in the James River in 2009. They are one of the largest predators in these rivers and feed on many species of native fishes, including migratory fish such as American Shad (Alosa sapidissima). The Blue Catfish is regarded as a major threat to American Shad restoration efforts. Complete Record


Longear Sunfish (Lepomis megalotis)


Longear Sunfish (Lepomis megalotis) is one of the prettiest of the sunfish and has been sporadically  introduced.



Longear Sunfish are small (~8 inches) freshwater fish that are native to much of the Northern and Central United States including the St. Lawrence-Great Lakes, Mississippi basins, and the Gulf slope from Florida to the Rio Grande. These sunfish is not a game fish, so its introduction outside its native range was likely incidental to the introduction of larger fishes or as a released aquarium fish. It was first collected in the Chesapeake Region in a tributary to the Potomac River 1953, since then it has become widespread in upper Potomac drainage and the Gunpowder River system starting in 1996. This species is fairly rare and so its impacts are not well understood, but it probably competes for food with other Sunfish such as Redbreast Sunfish (Lepomis auritus) and has also been known to hybridize with the native Pumpkinseed (L. gibbosus). Complete Record


Burbot (Lota lota)


Burbot (Lota lota) are cold water fish; the Bay is much too hot for them.


Burbot is the only freshwater Codfish (family Gadidae). They are cold water fish, preferring the deep, cold water lakes of northern North America and Eurasia. They are common in Lake Erie and the other Great Lakes where they are occasionally caught by anglers, but are apparently not highly regarded as a sport fish. They have, however, been stocked in a few locations in the Midwest and Atlantic Coast, but few of these have been successful. Records from Chesapeake Bay date back to 1884 when they were collected in the upper Susquehanna River in Pennsylvania, it isn’t know whether these populations are native or introduced. However, introduced fish have been caught in the upper Chesapeake Bay on Susquehanna Flats southeast of Perry Point Veterans Hospital. This occurrence was probably a result of unauthorized stocking. The water temperatures in the Bay are much too warm for this species to establish. Complete Record


Bull Chub (Nocomis raneyi)


Bull Chub (Nocomis raneyi) spread with the introduction of the Asian clam.





Bull Chubs are strange looking minnows with a thick body and large whitish speckles on their foreheads that eat mollusks (clams and mussels). They were described in 1971, and shown to be distinct from the River Chub and Bluehead Chub, also found in the Chesapeake watershed. They are believed to be native to the Chowan, Roanoke tar, and Neuse drainages in North Carolina but possibly introduced in the James River. Based on preserved specimens from 1951, the fish were thought to be found in only a single location in the James River, Craig Creek in Virginia. It was thought that their rapid spread from Craig Creek, VA to the lower James following the introduction of the Asian Freshwater Clam (Corbicula fluminea), suggested a recent introduction in the James River system, but with very little data between 1951 and their classification as a separate species in 1971, this may simply be a case of a native species expanding its range due to the presence of a introduced prey species. Without further information, we consider this fish cryptogenic. Complete Record


Mimic Shiner (Notropis volucellus)


Bull Chub (Nocomis raneyi) spread with the introduction of the Asian clam. 





Mimic Shiners are small thin fish (max size 66mm) native to much of North America including the Great-Lakes and St. Lawrence, Hudson Bay, and Mississippi River basins from Quebec and Vermont west to Manitoba and south to the Gulf Slope from Mobile Bay basin to the Nueces River in Texas. On the Atlantic coast there are native populations in the Mountain and Piedmont regions of Virginia and North Carolina including the James River in the Chesapeake Bay watershed. With such a large native range it’s no surprise that these fish were introduced to adjacent waterways. In the 1977 they were discovered in the Susquehanna River in Pennsylvania PA and the headwaters of the Potomac in West Virginia in the 1995. We would not be surprised to see Mimic Shiners in the tidal tributaries of the Chesapeake Bay and could be present now in the tidal Susquehanna River and uppermost Bay, but overlooked due to their small size. If you collect this species in the upper Bay please let us know. Complete Record


Flathead Catfish (Pylodictis olivaris)


Flathead Catfish (Pylodictis olivaris) have been described as mouths with fish attached.




Flathead Catfish are giant fish (up to 60 inches, 130 lbs), and very popular among anglers because of their size and tastiness. They are native to Mississippi and Gulf drainages. These catfish have been stocked or otherwise released into drainages in 18 states. The first Chesapeake release in 1965 was accidental; the Virginia Division of Fish and Game was keeping them in ponds on Hog Island Game Refuge for research when about 50 fish escaped into the James River during a flood. Although only a few fish were released at that time they established sustaining populations. Similarly, only 12 fish were stocked in the Occoquan Reservoir, but that was enough to establish a population. Populations of flathead catfish have been found in many other areas of the Chesapeake watershed, including the Susquehanna River, and it is suspected that small numbers of fish were released by anglers due to their popularity as a sport fish. This species’ ability to colonize river systems, as well as its role as a top predator with an enormous appetite, means that unauthorized stockings by fisherman are a serious problem. Complete Record


Brown Trout (Salmo trutta)


Brown Trout (Salmo trutta) is a popular sport fish imported from Europe.


Brown Trout are native to Iceland, Ireland, Great Britain, North Africa and Eurasia. A popular fish in their native range, they were brought to the United States starting in 1883 and stocked by the United States Fish Commission. Brown Trout have been stocked in 47 states and annual stocking still occurs in many areas. Some populations on the coast are anadromous; meaning they live in the ocean most of the time and come into fresh water to breed. Inland populations remain in fresh water throughout their lives. Stocking of Brown Trout began in the Chesapeake Bay region in the late 1880s. Brown Trout reproduce sporadically in the Bay region, and are maintained by stocking in upland streams, for sport-fishing. Due to their wide temperature and oxygen tolerances they survive in some areas better than the native Brook Trout (Salvelinus fontinalis), and are planted in the last stockings of trout season in 'put and take' fisheries. Nonetheless, they also compete with and eat native fish such as Brook Trout. Complete Record


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