The Chesapeake Bay has long been a vital resource for fishing, crabbing, and oyster harvesting by local watermen. But recent decades have seen considerable damage done to the Bay and its unique ecosystem. Populations of native species have declined, and invasive species, such as blue catfish and zebra mussels, have exploded. Read on to learn about the Bay's invasive animals and plants and steps being taken to control them. Be sure to check out your Library’s collection for books on the Chesapeake Bay, opens a new window and what it means to those living in its watershed:, opens a new window
Books about the Chesapeake and those who made their livelihood from it.
A Barrage of Fish
The Chesapeake Bay is exposed to heavily populated coastal areas, international shipping, and lucrative sport fishing. The Chesapeake was noted for its wealth of sealife by explorers as early as John Smith’s expeditions. He reported, opens a new window “fish lying so thick with their heads above the water as for want of nets (our barge driving amongst them) we attempted to catch them with a frying pan.” Smith’s journeys in the Chesapeake can be traced by modern travelers using the Captain John Smith Chesapeake National Historic Trail, opens a new window.
But the introductions of invasive animals and plants over the centuries mean today’s explorers will encounter a far different Chesapeake ecosystem than the one Smith experienced. Perhaps the most successful invasive fish in the Chesapeake is the blue catfish. They were first introduced as a sport fish, opens a new window in the 1970s, but they were too successful to be controlled by sport fishing alone. Over 100 million blue catfish are now estimated to live in the Chesapeake!
Several factors make blue catfish hard to control in the Bay. They are considered a freshwater fish, but can tolerate brackish water very well and rapidly expand their populations in the coastal Chesapeake Bay. As the largest estuary, opens a new window in the United States, salinity, opens a new window in the Bay varies greatly, based on location in the watershed, and blue catfish can tolerate high salinity much more readily than most freshwater fish.1 A study, opens a new window from spring 2025 revealed that only a relatively high salinity level of 14 Practical Salinity Units poses a barrier to the movement of blue catfish. In the Chesapeake, they have very few predators, opens a new window other than osprey, bald eagles, and humans.
This makes adult “blue cats” apex aquatic predators of the Chesapeake, and they will eat large numbers of valuable native animals, such as blue crabs, menhaden, and shad. Though small and often overlooked in favor of large game fish, menhaden are very important as food, opens a new window for many animals . The recent decline in osprey, opens a new window populations in the Chesapeake region is connected to the decline in the number of menhaden. Blue catfish can also produce a massive number of eggs with each spawning, and the amount increases with the size and weight of the catfish. A female that weighs 20 pounds can produce 40,000 eggs, opens a new window per spawning!
Fishing--and subsequent dining--are both needed to curb the growth rates of the blue catfish population. There is now a commercial fishing industry, opens a new window that specializes in Chesapeake blue catfish. The blue catfish is second only to menhaden in terms of total weight of caught fish per year. Virginia’s Department of Wildlife Resources has produced a video explaining, opens a new window the best ways sport fishermen can catch “blue cats,” so anyone with a rod, a fishing license,, opens a new window and a willingness to learn can help out. The current catch limits for blue catfish in Virginia can be found here, opens a new window; most areas have no limit for fish under 32 inches long. Virginia blue catfish can be prepared in a wide variety of recipes, opens a new window besides the traditional fried catfish. Some local restaurants, such as Bubba's Shrimp Shack, opens a new window at Cosner's Corner, Orleans Bistro, opens a new window at Southpoint, and Catfish Kelly's, opens a new window in Fredericksburg and King George, offer catfish on their menus, too.
Another formidable invasive fish in the Chesapeake is the snakehead. The snakehead that appears in the Chesapeake is the northern snakehead, opens a new window, although Maryland brands it the “Chesapeake channa” to make it more marketable. This is a large, air-breathing fish that originates from East Asia and has a long body with a mouth full of sharp teeth. Like blue catfish, snakeheads have few natural predators, can grow to large sizes, and produce vast quantities of eggs per spawning. In two years, a female can produce as many as 150,000 eggs, opens a new window! Snakeheads can grow up to 40 inches in length, weigh up to 15 pounds, and survive out of water for four days, making it easier for them to colonize the entire Chesapeake Bay.2
Snakeheads are considered a delicacy in much of their native range, but, in the United States, it is very rare to find restaurants that serve them. Most people will have to prepare snakeheads themselves if they want to try them. Video tutorials, opens a new window on catching, opens a new window snakeheads can easily be found on YouTube. Snakehead can be prepared in a wide variety of recipes. From tacos, opens a new window to traditional Vietnamese, opens a new window recipes to lettuce wraps, opens a new window, there are many delicious ways to prepare snakehead. Just be aware that snakeheads will require a specific technique, opens a new window to fillet properly!
Invasive Plants in Bloom
The Chesapeake has also become home to numerous invasive plants that have degraded its environment. A particularly damaging tree is the tree-of-heaven, opens a new window, sometimes called the ailanthus tree or stinking sumac. Tree-of-heaven is resilient in most environmental conditions, resistant to drought, and grows rapidly. As an allelopathic plant, opens a new window, tree-of-heaven produces chemicals that are toxic to the growth of plants around it. Merely by existing in a forest, tree-of-heaven makes it more difficult for native plants to grow!
Tree-of-heaven has become even more damaging following the introduction of the spotted lanternfly, opens a new window, an invasive insect that damages plants by feeding and often uses tree of heaven as a place to lay its eggs. Tree-of-heaven is difficult to kill, and herbicide, opens a new window is recommended by the Alliance for the Chesapeake Bay to ensure a successful eradication.
Another common invasive plant in the Chesapeake is the water chestnut. In Virginia, this name is used for trapa bispinosa, opens a new window, the species also known as the two-horned water chestnut. It occurs in shallow freshwater, opens a new window areas rather than the parts of the Bay more connected to the ocean. Two-horned trapa were first recorded in Virginia in Westmoreland and Stafford rivers in 1995, opens a new window and have spread aggressively since then. This plant degrades the quality of rivers and lakes it grows in by blocking the sun and the flow of water with its large “horned” seed pods. It can completely infest, opens a new window ponds and lakes if not removed, making early reporting, opens a new window of it a must. Removing water chestnut is a labor-intensive process that takes several years.
Phragmites australis, opens a new window has been present in the Bay longer than other invasives, but its effect on the environment can also be negative. Also known as the common reed, opens a new window, this type of phragmites originally appeared in the Northeast U.S. in the 19th century and spread south into the Chesapeake. Like the water chestnut, phragmites can form dense infestations, opens a new window that crowd out native plants. The task of eradicating the invasive phragmites is even more difficult because it resembles a native plant, phragmites americanus. Distinguishing between the two species will require careful monitoring and research, as well as evaluating which areas, opens a new window will actually benefit from the removal of phragmites australis. In some parts of the Bay, the common reed may be helpful as a counter to climate change, opens a new window, as it can absorb carbon from the atmosphere very effectively.
Other Chesapeake Invasives
Fish and plants are not the only invasive life in the Chesapeake. Some of the most damaging invasives are mollusks. The rapa whelk, opens a new window, a large species of sea snail, is a formidable threat to the Chesapeake’s oysters. They can open oysters through the gap in their shells and consume the animal within and can produce multiple egg cases containing hundreds, opens a new window of eggs. With no natural predators once they reach their adult size, their population can increase rapidly, and they live in the Virginia portion of Chesapeake waters.
Zebra mussels, opens a new window don’t live in the Virginia portion of the Chesapeake, but they do live in the Maryland portion (the Susquehanna River, opens a new window entrance). They are small mussels that attach, opens a new window themselves to the shells of native mussels and oysters, making it difficult for them to open and ultimately killing them. They are a threat to Virginia’s oysters, and only diligent monitoring will prevent their spread into our waters. One infestation already occurred in Prince William County's Millbrook Quarry, opens a new window and took several years to eradicate.
One large rodent is also an invasive mammal in the Chesapeake. Sometimes called the “swamp beaver” or “coypu,” nutria, opens a new window are large caviomorph rodents that were introduced to the Chesapeake in the 1940s, opens a new window for the fur industry. Like other damaging invasive species, nutria breed quickly. They have no natural predators in the Chesapeake Bay, and their population increased rapidly once the market for their fur declined. Nutria damage the environment by creating burrows, opens a new window that erode marsh banks and soils, and by trying to eat plants down to their roots. Nutria were successfully eradicated from Maryland’s Delmarva Peninsula, opens a new window in 2018 following a campaign that began in 2002, but nutria remain in the Virginia portions of the Chesapeake. The danger of a nutria reinfestation will only be gone once nutria are eliminated from the entire Chesapeake.
History Spotlight: Virginia Watermen
Invasive species that threaten the Bay’s native fish, oysters, and crabs also pose a danger to the careers of Virginia’s watermen. Available in the hoopla Digital collection and also found in CRRL’s Virginiana Room, Warner's Beautiful Swimmers: Watermen, Crabs and the Chesapeake Bay, opens a new window is a history of Virginia’s crab industry and those who harvest them. Other recommended books in your Library’s collection on watermen and the history of the Chesapeake include Chesapeake Bay Blues, opens a new window, The Watermen of the Chesapeake Bay, opens a new window, and the Field Guide to Fishes of the Chesapeake Bay, opens a new window.
Learn more about the history of Virginia’s watermen by visiting museums across Virginia. Westmoreland County Museum, opens a new window will spotlight watermen of the Fredericksburg area with its temporary exhibit, “The Watermen of Westmoreland County,” which begins September 13, 2026. In an unincorporated port village in Westmoreland County, the Kinsale Museum, opens a new window details the history of how a community on the Chesapeake lived and worked on the Bay.
You may also enjoy the streaming video Watermen of Colonial Beach, opens a new window, part of the Library's CRRL Presents, opens a new window collection--and also available as a DVD., opens a new window
A little further afield from our service area in Yorktown, the Watermen’s Museum, opens a new window offers historical exhibits demonstrating how watermen have harvested the resources of the Chesapeake across the centuries. It includes resources on boat building, ship archaeology, and Yorktown’s time as a colonial settlement.
Saving the Bay
Learn more about the Bay's unique ecosystem and struggle to protect it by connecting with environmental organizations. The Chesapeake Bay Foundation is a nonprofit dedicated to restoring the Bay by eliminating pollution and invasive species. You can visit its website, opens a new window, complete with webinars, opens a new window on its current goals and blogs, opens a new window on the condition of the Bay. The Alliance for the Chesapeake Bay, opens a new window posts news,, opens a new window events,, opens a new window and other ways to get involved,, opens a new window as well as the Ask the Alliance, opens a new window webinar series.
Locally, the Friends of the Rappahannock's, opens a new window purpose is to be "the voice and active force for a healthy and scenic Rappahannock River," which is part of the Chesapeake Bay's watershed. They accomplish this mission through advocacy, restoration, and education.
1Fabrizio, Mary C., et al. “Tidal Habitats Support Large Numbers of Invasive Blue Catfish in a Chesapeake Bay Subestuary.” Estuaries and Coasts, vol. 41, no. 3, 2018, pp. 827–40. JSTOR,, opens a new window http://www.jstor.org.proxy.librarypoint.org/stable/44858073., opens a new window Accessed 20 May 2026.
2Mason, Marianne D. “The Saga of the Snakehead Fish.” Natural Resources & Environment, vol. 17, no. 4, 2003, pp. 242–44. JSTOR,, opens a new window http://www.jstor.org.proxy.librarypoint.org/stable/40924439., opens a new window Accessed 20 May 2026.
