Invasive species, or plants and animals that have been introduced to an area, can cause harm when they establish themselves at the expense of native wildlife. These invaders pose a threat to native species by outcompeting them for resources like food and habitat that are necessary for survival. Often, these species expand their range and population numbers at such a rapid pace that landowners and wildlife managers struggle to contain their spread.
Brian Knox is President of Sustainable Resource Management, Inc., a natural resource consulting firm based out of Davidsonville, Md., that deals primarily with managing forest vegetation. Knox has seen success in combating invasive plants by implementing outside-the-box tactics. “A lot of people these days are getting more conscious about their herbicide usage,” said Knox. “As a very small company, we’re not afraid to try anything.”
In 2007, Knox began unleashing a herd of goats—referred to as Eco-Goats—on areas overrun by invasive vegetation. The goats have proven to be a viable option for these problem areas, because they can go many places that people and machinery cannot reach, like steep slopes and hillsides. Additionally, because of the goats’ mouth shape and digestive system structure, they are able to grind up seeds in a way that ensures seeds are not returned to the soil to resprout at the end of the digestive process.
A herd of about 30 goats can work through about a half-acre of dense vegetation in 3 to 4 days. “Goats are very good at biomass reduction,” explained Knox. “Typically, a goat can eat about 25 percent of its bodyweight a day in green material. If you figure an average of 100 pounds, that’s 25 pounds of vegetation going into every goat that’s out there.”
Although the goats are fond of invasive species like kudzu, porcelain berry, wine berry and mile-a-minute and are undeterred by thorns, they do not discriminate against native species. So before committing his goats to an area, Knox surveys each site to make sure the vegetation is appropriate. “A misapplied goat is every bit as bad as a chemical spill,” said Knox. “You can do damage with a goat... I look for native species and ask, ‘Is there more here to save than there is to get rid of?’ If so, that’s a terrible place for a goat.”
Spending your day with a herd of goats may sound like fun, but managing the goats is hard work. “A lot of people think it’s just sitting around and watching the goats, and boy, that would be a great job. And then you talk to them about how it took me two days to get the fence up and I’m soaked through to my socks by eight in the morning,” said Knox. “But clearly there’s something that I really love about this. And it’s the educational aspect of it, seeing people’s eyes light up while watching the goats.”
To view more photos, visit the Chesapeake Bay Program’s Flickr page.
Images and video by Keith Rutowski
Text by Jenna Valente
An economic analysis from the U.S. Fish and Wildlife Service (USFWS) shows that federal investments in on-the-ground restoration can stimulate local economies, creating jobs and supporting small businesses.
With a focus on two of its habitat restoration programs—the Partners for Fish and Wildlife Program and the Coastal Program—the USFWS determined that for every federal dollar spent, $7 to $9 of restoration work happens on the ground and almost $2 of economic activity is gained by the state in which the work takes place.
Both of these nation-wide programs use federal and private funding to implement on-the-ground habitat restoration projects on public and privately owned land. According to the USFWS, the programs' impacts cut across two dimensions: first, their understood expertise and stable funding pulls in additional funding from other partners; second, the programs’ spending creates work, generates tax revenues and stimulates local economies through paid wages and subsequent spending.
Image courtesy Margrit/Flickr
In Maryland, for instance, the Coastal Program has directed $1.4 million toward the eradication of nutria from marshes and wetlands. Introduced to the region in the mid-1940s, the invasive nutria has destructive feeding habits, pulling up plant roots that would otherwise hold valuable marshland in place. The Maryland Nutria Project, which is administered by the USFWS and brings federal, state and private partners together to trap and manage nutria, has created more than 55 jobs and generated $2.5 million in spending on Maryland’s Eastern Shore.
“The Partners for Fish and Wildlife and Coastal programs are important drivers for creating employment,” said USFWS Director Dan Ashe in a media release. “The benefits reach far beyond the local communities where these projects take place to provide national economic stimulus. At the same time, this restoration work provides benefits to all Americans by creating healthy natural areas, including shorelines, streams, wetlands and forests on privately owned lands.”
I enjoy eating fish. I also enjoy catching them. And after learning about the impact that a couple of recent invaders have had on the Chesapeake Bay, I’ve added two new fish species to my catch list.
About a year ago, I sat in a meeting (which I do a lot) and listened to a presentation on yet another threat to the Chesapeake Bay’s aquatic environment. This threat came in the form of the blue and flathead catfish, the finfish equivalent to the invasive zebra mussel that has upset the aquatic ecosystem of the Great Lakes.
Blue catfish are considered “apex predators”; they sit at the top of the food chain. They consume not only other finfish, but shellfish as well. They have no predators. Introduced to Virginia’s James, Rappahannock and York rivers as a sport fish in the 1960s, ‘70s and ‘80s, they have multiplied and extended their reach into other parts the Bay. Apparently, they are here to stay.
Recently, the Maryland Department of Natural Resources (DNR) launched a public awareness campaign to promote a “catch and cook” movement in place of the usual “catch and release” program. The agency is working with restaurants and fish processors to market these catfish. During the campaign’s April kick-off event, we were treated to samples of what these demons of the deep might taste like. I went back for seconds (several times). This is a great source of protein for those who rely on fishing for both sustenance and subsistence. And while catfish are bottom feeders, I’ve been assured that, as long as we eat fish that are smaller than 32 inches, there shouldn’t be any concern about the bioaccumulation of toxins. Good to know.
The Bay has become home to other invasive fish, as well. We all remember the northern snakehead! While this critter isn’t as pervasive as the blue catfish, it is another species that has pushed portions of the Bay ecosystem out of balance. But let me recommend a snakehead ceviche. If you can’t beat ‘em, eat ‘em! Bon apetit!
Note: The opinions expressed above are those of the author and do not necessarily reflect U.S. EPA policy endorsement or action.
The Maryland Department of Natural Resources (DNR) has launched a state-wide campaign to teach citizens about the impact of blue and flathead catfish and encourage anglers to remove the invasive species from local rivers and streams.
Native to the Mississippi, Missouri and Ohio river basins, blue catfish were introduced to the James, Rappahannock and York rivers in the 1970s and ‘80s as a sport fish. Flathead catfish were introduced to the James in the 1960s for the same reason. Over time, the natural movement and purposeful introduction of the fish into new waters have hastened their establishment in Chesapeake Bay tributaries.
This concerns scientists, who fear the fast-growing and long-lived blue catfish, in particular, could impact the region’s ecologic and economic resources. Because of its opportunistic feeding habits, the blue catfish has become an apex predator, disrupting the structure of the Bay ecosystem and eating up critical aquatic species.
Indeed, “gut content analyses” of the fish have found American shad, Atlantic menhaden, freshwater mussels and blue crabs in their stomachs. Peyton Robertson, director of the National Oceanic and Atmospheric Administration’s Chesapeake Bay Office and chair of the Chesapeake Bay Program’s Sustainable Fisheries Goal Implementation Team, compared the blue catfish to a Bengal tiger, noting that the fish eats “just about anything.”
“If left unchecked, [blue catfish] could, as top predators, start to impact other parts of our ecosystem,” Robertson said.
But its eradication isn’t feasible, and experts believe the invasive fish is here to stay. So managers hope to mitigate their spread and minimize their impact on native fish.
With support from the Bay Program, DNR has established more than 150 signs at water access points and kiosks around the state to help anglers identify, catch and keep the species, while Maryland Seafood has escalated its efforts to market the fish to restaurants and boost consumer demand.
“[Humans] are great at overfishing things,” said Maryland Seafood Marketing Director Steve Vilnit. “And [the blue catfish] is a species that we want to overfish.”
Every day, non-native plants, pests and diseases are introduced to the United States from around the world. These invaders have the power to out-compete native species, causing damaging effects to ecosystems and local economies, and the Chesapeake Bay is no stranger to these obtrusive critters.
The Bay is a vacation destination, shipping hub and home to more than 17 million people, a combination that puts it at high risk for invasive species introduction. Typically, non-native species travel to new areas by hitching rides on trade ships, travelers’ luggage and recreational vehicles. Although not all invasive species are a threat, it is important to know which ones can and have caused widespread damage. Use the list below to identify 10 invasive species in the Bay watershed.
Image courtesy rbairdpccam/Flickr
10. Blue Catfish. The blue catfish is a large, smooth-skinned fish with a bluish gray body and whisker-like barbells around its mouth. It is native to the Mississippi, Missouri, and Ohio river basins but was introduced to the James, Rappahannock, and York rivers during the late 20th century. Blue catfish are considered invasive because of their active reproduction rates and large appetite for native fish and shellfish species. The fish feeds mainly on shad, menhaden, blue crab and river herring and has few natural predators that can prevent it from out-competing native species. Blue catfish can grow up to 100 pounds, live up to 20 years and are thought to make up 75 percent of the fish biomass in some portions of the Bay.
9. Mute Swans. The mute swan is a large, aggressive bird that is native to northern and central Eurasia. It was introduced to North America in the mid-1800’s to add ambiance to parks and ponds, but individuals quickly escaped, set up nesting territories and the population spread. A single mute swan can consume up to 20 pounds of submerged aquatic vegetation daily, threatening important native aquatic plants. Mute swans are one of the most aggressive waterfowl species in the world, especially when nesting or brooding. They have been known to chase off, injure and even kill native waterfowl species.
Image courtesy of Chrisdetmer/Flickr
8. Zebra Mussels. The zebra mussel is a tiny bivalve with zebra-like stripes and a triangular shell. It lives in freshwater lakes, rivers and reservoirs in parts of the Bay watershed. It was introduced to the Great Lakes region in the 1980s, most likely via ballast water from a European ship, and quickly spread throughout the United States. Once introduced to a waterway, the zebra mussel attaches itself to hard surfaces and can produce millions of offspring annually. Zebra mussels compete with native bivalves, fish and invertebrates for plankton and are responsible for the drastic decline of native clam, mussel and oyster populations in some areas.
Image courtesy of Bernd Loos/Flickr
7. Nutria. The nutria is a large, brown, semi-aquatic rodent that looks like a beaver and lives in marshes and wetlands on the Delmarva Peninsula and other parts of the Bay watershed. Native to South America, the nutria was introduced in Maryland to Blackwater National Wildlife Refuge in 1943 for fur farming. Escaped animals soon began to reproduce, bearing up to three litters of four offspring each year, spreading rapidly. In Maryland, nutria is the greatest threat to salt marsh habitat because it eats sediment-holding plants and causes significant erosion.
6. Phragmites. Phragmites is a perennial plant with feathery plumes at the top of tall, stiff stalks. It grows in wetlands, along roadsides and along shorelines throughout the Bay watershed. Although its origin is unclear, it is widely distributed across Europe, Asia, Africa, North America and Australia. It was introduced to North America inadvertently in the 19th century from the ballasts of Eurasian trade ships. Phragmites crowd out native plants by creating tall, dense stands in wetland habitats.
Image courtesy of Lisa Roukis/Flickr
5. Purple Loosestrife. Purple loosestrife is a perennial plant with spikes of bright purple flowers that bloom in mid-to late summer. Native to Europe and Asia, the plant was both accidentally and intentionally introduced in the 18th and 19th centuries. Ship ballasts unintentionally carried the tiny seeds to North America while others planted it for its aesthetic value and healing properties. The plant is considered an invasive because it quickly establishes itself in wetlands, crowding out native plant species and producing up to 2 million seeds per year with no known natural predators.
Image courtesy of U.S. Department of Agriculture/Flickr
4. Emerald Ash Borer. The emerald ash borer is a green, shiny beetle that lives on ash trees in certain parts of Virginia, Maryland and Pennsylvania. Native to Asia, the emerald ash borer was discovered outside of Detroit in 2002 and made its way to the Bay watershed in 2003 when a Michigan nursery shipped ash trees to Maryland. Adult beetles cause little damage to ash trees but larvae feed on the inner bark, disrupting the dispersion of water and nutrients throughout the tree.
Image courtesy of Smithsonian Environmental Research Center/Flickr
3. Chinese Mitten Crab. The Chinese mitten crab is a light brown crustacean with a distinctive pair of hairy, white-tipped claws. Native to East Asia and a member of LaFondation’s top 100 worst invasive alien species list, it has recently been found in small numbers in the Bay. In abundance it not only competes with native species for resources and threatens populations through predation but also damages fishing industries by feeding on fish in nets and damaging nets and other equipment. It is also known to erode soft sediment banks, dykes and costal protection systems through excessive burrowing.
2. Veined Rapa Whelk. The rapa whelk is a large, predatory marine snail that inhabits the lower Bay. It is native to the Sea of Japan and the Bohai, Yellow and East China seas in Asia. It was first discovered in the Bay in 1998 by a trawl survey group from the Virginia Institute of Marine Science (VIMS) and is believed to have been transported in larval form through ballast water from trade ships. It poses a threat to the Bay because it preys on native bivalves like clams, oysters and mussels, which are vital to the region’s economy and ecosystem. It feeds by wrapping itself around the hinge of its prey’s shell, then feeding between the openings.
Image courtesy of Sergey Yeliseev/Flickr
1. European Gypsy Moth. The European gypsy moth is one of the most destructive pests that has ever been introduced to North America. Moth larvae gorge themselves on the foliage of shrubs and trees, leaving the plants bare and susceptible to disease and damage from other pests. The gypsy moth was accidentally introduced to the United States in Medford, Mass., in 1869, by a professor conducting silk research. It has been established in parts of eastern North America for more than a century.