Posts Tagged ‘invasive species’

Chesapeake Bay Invasive Catfish Research

Tuesday, May 20th, 2014

Initially introduced for sportfishing in several Virginia tributaries, blue and flathead catfish are considered invasive in the Chesapeake Bay. Since their introduction, their range and population have increased dramatically. Blue and flathead catfish are now top predators in several river systems of the Chesapeake Bay.

In order to learn more about how these fish may be affecting the Bay, the NOAA Chesapeake Bay Office has funded several studies to take a closer look at the biology and feeding habits of these fish.

Completed Projects:

A project conducted by Virginia Commonwealth University researched what kinds—and how much—prey blue and flathead catfish consume, and how that may change throughout the year. The VCU researchers found that these catfish may contribute to substantial losses of key Bay fishery species including white perch, menhaden, and blue crabs. The researchers also developed recommendations on how the effects of invasive catfish might be mitigated, including the experimental use of electrofishing to increase commercial harvest.

Researchers at the Virginia Institute of Marine Science (VIMS) focused on whether contaminant burdens in blue catfish could pose a human health risk if people eat these fish. Like other larger fish that live for a relatively long time, blue catfish may “bioaccumulate” mercury and other contaminants to such levels that cause human health concerns. The VIMS researchers explored how much of these contaminants blue catfish bioaccumulated in the Potomac, Rappahannock, and James Rivers. The research found that contaminant levels in fish under 32 inches are under current consumption advisory levels.

Another VIMS research team quantified the growth of individual blue catfish by tracking the length of fish at different ages and how much fish of a given length weighed. Fish collected and measured in the Potomac, Rappahannock, York, and James Rivers had slightly different growth characteristics—but overall, they grew to be impressively long and heavy fish. The fish that were measured sometimes reached 13 inches by their fifth year and nearly 40 inches by their 17th or 18th year. Better understanding these rapid growth rates will help fishery managers asses and identify potential impacts blue and flathead catfish could have on the ecosystem as these fish quickly approach large sizes and apex predator status.

Projects under way:

VIMS research is estimating the population numbers of blue catfish in the James River, as well as their survival rates. They are doing this by tagging blue catfish and working with a waterman to track them when they are recaptured.

Researchers at the Smithsonian Environmental Research Center are investigating how blue catfish fit into the Chesapeake Bay’s food web, including cataloging undigested fish prey items from blue catfish stomachs. Work by SERC scientists to date has been conducted in the Patuxent, Nanticoke, Sassafras Rivers and Northeast/Swan Creek/Susquehanna Flats.

Results from this research are being used by the Chesapeake Bay Program’s Sustainable Fisheries Goal Implementation Team, which brings together resource managers and other experts from around the watershed to discuss topics related to fishery management in the context of the most up-to-date science.

source: NOAA Chesapeake Bay Office

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Maryland Invasive Catfish Public Awareness Campaign

Wednesday, May 7th, 2014

In April, the Maryland Department of Natural Resources launched a statewide campaign to educate citizens about invasive Blue and Flathead Catfish, their impact on native species, and what anglers can do to help.

To kick off the effort, partners and stakeholders joined DNR staff for a catfish cooking demonstration and tasting at Smallwood State Park on the Potomac River.

“Increasing in population and range, both blue and flathead catfish are now abundant in the Chesapeake Bay, threatening the natural food chain of our ecosystem and causing concern among fishery managers,” said DNR Deputy Secretary Frank Dawson.

DNR developed the outreach program to help anglers identify and catch these invasive species, understand the importance of regulations that prohibit their transport, and encourage anglers to keep the fish instead of releasing them alive.

The Chesapeake Bay Program’s Sustainable Fisheries Goal Implementation Team and the Atlantic States Marine Fisheries Commission have both formerly recognized the need to address the threat to native species by working to reduce invasive catfish densities and range.

In addition to establishing more than 150 educational/cautionary signs at water access points and kiosks statewide, the State is escalating efforts to market Maryland’s fledgling commercial catfish fishery.

Catfish dishes from Chef Michael Stavlas of Hellas restaurant in Millersville and Executive Chef James Barrett of Azure in Annapolis provided attendees with a taste of this delicious invader.

Blue and Flathead Catfish were introduced into the Chesapeake Bay ecosystem in the 1970s and 80s. Flatheads found ideal conditions in the Occoquan River, a small tidal Potomac tributary in Virginia and were recently identified in the non-tidal Potomac River near Williamsport. Flatheads have also become established in the Lower Susquehanna River. Blue Catfish are now in most of the major tributaries of the Chesapeake Bay as a result of their natural range expansion and possibly through illegal introductions by fishermen seeking to establish fisheries in other waters.

There is no limit to the number of catfish an angler can catch and keep. The Maryland Department of the Environment advises limiting monthly Blue Catfish consumption for adults to: four fish under 15 inches; two between 15 and 24 inches; or one between 24 and 30 inches; and none over 30 inches due to the possibility of chemical accumulation in these species. The recommended monthly limit for children is: four under 15 inches; one from 15 to 24 inches; one fish every other month from 24 to 30 inches; and none over 30 inches.

For more information on invasive species in Maryland, visit

Maryland Department of Natural Resources

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2012 Maryland Snakehead Contest Results

Friday, March 8th, 2013

Three anglers recently won nearly $300 in prizes for catching and killing snakehead fish in the Maryland Department of Natural Resources’ (DNR) 2012 Snakehead Contest.

During the contest, 256 anglers removed nearly 600 fish from the Potomac River system. To enter, participants shared their experiences on the Department’s Angler’s Log, reporting how they caught the invasive fish, where they found them, some even sharing delicious ways to prepare them.

The contest ran from March 1 to November 30, 2012, with DNR choosing the winning anglers at random. Kasie Taylor won a $200 Bass Pro Shop gift card; Jerry Lester won a 2013 Maryland State Park Passport worth $75; and Les King won a 2013 fishing license donated by the Potomac River Fisheries Commission.

DNR launched the contest in 2010 to monitor how far the species has spread and encourage anglers to capture and remove snakeheads from Maryland waters.

The Department plans to add the snakehead to the list of species in the Volunteer Angler Survey, which uses anglers’ catch data to help fisheries managers assess fish populations. For the 2013 fishing season, snakehead anglers who log their catches on the Angler’s Log will be automatically entered in the Volunteer Angler Survey with the chance to win prizes. The single-species Snakehead Contest therefore, has been discontinued.

source: MD DNR

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Zebra Mussels Found in Upper Chesapeake Bay

Thursday, December 20th, 2012

Invasive zebra mussels have been found in the upper Chesapeake Bay. On December 3, Maryland Department of Natural Resources (DNR) biologists found young zebra mussels attached to buoys off Havre de Grace. DNR is asking boaters and anglers to be on the lookout for this harmful, invasive mussel.

Twenty live zebra mussels were found attached to the concrete anchor blocks for three channel marker buoys. DNR personnel discovered the mussels when the buoys were removed from the water for cleaning and winter storage.

DNR advises mariners who use the lower Susquehanna River and upper Bay to help prevent these harmful zebra mussels from spreading to other Maryland waters by taking several following precautions before launching and leaving the area:

- Remove all aquatic plants and mud from boats, motors, and trailers; and put the debris in trash containers.

- Drain river water from boat motors, bilges, live wells, bait buckets and coolers before leaving, to prevent these aquatic hitchhikers from riding along.

- Dispose of unused live bait on shore, far from the river or Bay or in trash containers.

-  Rinse boats, motors, trailers, live wells, bait buckets, coolers and scuba gear with high pressure or hot water between trips to different water bodies.

- Dry everything at least two days (preferably five days) between outings.

- Limit boating from place to place – particularly between the Susquehanna and upper Bay to other water bodies in Maryland

The agnecy is also asking that people who live and work on the water keep an eye out for zebra mussels and call 410-260-8615 if they find anything suspicious.

Non-native, invasive zebra mussels were first found in Maryland in late 2008 at two locations in the Susquehanna River: the Conowingo Dam and further upstream at Glen Cove Marina, Harford County.

Sporadic sightings since then indicate establishment of a zebra mussel population in the lower river and downstream dispersal, but no apparent rapid increase in abundance.

source: MD DNR

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Maryland Blue Catfish Tagged For Study

Tuesday, September 11th, 2012

A new Maryland state record blue catfish has been tagged and returned to the Potomac River as part of part of a cooperative study by Maryland and Virginia fisheries biologists.

The record setting catfish was caught on August 13 in the Potomac River near Fort Washington. The fish weighed 84 pounds and measured 52 inches in length with a girth of 36.5 inches.

Anglers who catch and report a tagged catfish will receive a commemorative Catfish Program hat and pin, while helping study distribution of catfish in area waters. Anglers must call the number on the yellow or green tags, 301-888-2423, to receive the reward.

Blue catfish are native to the Mississippi Valley and were introduced to the James and Rappahannock Rivers in the 1970s. The fish have reproduced and spread throughout the tidal Potomac River system.

Large flathead catfish, another non-native species, and blue catfish have subsequently turned up in Chesapeake Bay tributaries and waters including the Nanticoke, Susquehanna, Northeast, the Upper Chesapeake Bay and other waters.

Blue catfish are long-lived, fast growing, opportunistic feeders. Their introduction can cause irreversible changes in the food web, which could negatively impact ecologically and economically important native fish species.

In Maryland, it is illegal to transport live blue and flathead catfish for the purpose of introduction into another body of water. Additionally, DNR officials are asking anglers to remove and kill any blue and flathead catfish that they catch.

source: MD DNR

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Chesapeake Bay Invasive Catfish

Saturday, March 17th, 2012

State and Federal fisheries managers recently identified blue and flathead catfish of the Chesapeake Bay Watershed as invasive, non-native species, and have begun developing strategies to mitigate their impact.

Blue catfish are native to the Mississippi River Valley and were introduced to the James and Rappahannock Rivers in the 1970s. Since then, the fish have reproduced and spread throughout the tidal Potomac River system. Flathead catfish and blue catfish have since been identified in the Nanticoke, Susquehanna and Northeast Rivers, Upper Chesapeake Bay and other waters.

The Chesapeake Bay Program’s Sustainable Fisheries Goal Team, which includes representatives from Virginia, Maryland, the Potomac River Fisheries Commission, District of Columbia, National Oceanic and Atmospheric Administration National Marine Fisheries Service, and Atlantic States Marine Fisheries Commission, recently adopted a Chesapeake Bay blue and flathead catfish policy to reduce these catfish populations and to stem their spread.

In August, 2011, The Atlantic States Marine Fisheries Commission approved a resolution expressing concern about the impacts of blue and flathead catfish to Atlantic coast migratory fish species.

source: MD DNR

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Zebra Mussels Now Established In Susquehanna River Below Conowingo Dam

Monday, July 19th, 2010

On July 6th, a team of biologists from the Maryland Department of Natural Resources’ (DNR) Monitoring and Non-tidal Assessment Division spotted several suspected zebra mussel adults for the first time in the lower Susquehanna River below the Conowingo Dam.

These recent findings indicate that a population of this non-native, invasive mussel is established in this part of the Susquehanna. The first-ever sightings of zebra mussels in Maryland occurred in the lower Susquehanna River upstream of the Conowingo in November 2008.

“Most of the specimens were the largest I’ve ever seen, ranging up to 38 mm (almost 1-1/2 inches) in shell length, and they were probably three to four years old,” said DNR Biologist Ron Klauda.

Zebra mussels (Dreissena polymorpha) have caused over five billion dollars in damages and economic losses in North America since they were introduced into the Great Lakes during the 1980s. Based on studies conducted in the Hudson River Estuary, New York, the potential impacts of zebra mussels on the freshwater to slightly brackish portions of Maryland’s aquatic ecosystem could be substantial, with effects on all aspects of the food web from plankton to fish by outcompeting native species, filtering all available plankton and rapidly colonizing large areas.

“The good news is that, at least for now, the density of zebra mussels appears to be low,” said DNR Natural Resource Biologist Jay Kilian.

Boaters, anglers and other recreational water users who enjoy the lower Susquehanna River can help stop the spread of harmful zebra mussels to other Maryland waters by taking these simple precautions before launching and before leaving:

(1) Remove all aquatic plants and mud from boats, motors, and trailers, and put the debris in the trash.

(2) Drain river water from boat motors, bilges, live wells, bait buckets and coolers before leaving to prevent aquatic hitchhikers from riding along.

(3) Dispose of unused live bait on shore far from the water body or in the trash.

(4) Rinse boats, motors, trailers, live wells, bait buckets, coolers and scuba gear with high pressure or hot water between trips to different water bodies.

(5) Dry everything at least two days (preferably five days) between outings.

DNR urges boaters to do their part to stop the introduction and spread of zebra mussels and other invasive species in Maryland. Citizens who find what look like zebra mussels should seal them in a zip lock bag, put the bag in the freezer, record where and when they were found and report the find to DNR at 410-260-8615.

For more information about zebra mussels and other invasive species in Maryland, call 1-877-620-8DNR or visit

source: DNR press release

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Maryland Study Finds Native Crayfish Threats

Monday, April 26th, 2010

A new study by Maryland Department of Natural Resources (DNR) biologists finds that several of Maryland’s native crayfish species have declined due to the introduction and spread of invasive species. This new study highlights the need for increased public awareness of invasive species issues and public participation and support to prevent the spread of problem animals.

“It’s been over 45 years since the last comprehensive study of Maryland’s crayfish, and a lot has changed in that time” said Jay Kilian, a biologist in DNR’s Resource Assessment Service and one of the authors of the study. “Maryland is now home to five non-native crayfish, all introduced as unwanted pets, through their use as bait by anglers, or as a result of escapes from aquaculture operations.”

The threat looms large, especially with the first-ever discovery of the Rusty Crayfish, one of the most notorious invasive species, in three Maryland watersheds in 2007 and 2008.

Crayfish play important ecological roles in nature. They serve as prey to many terrestrial and aquatic predators and are important processors of organic matter, the basis of aquatic food webs. However, several non-native crayfish species have flourished, become invasive, and are now widespread in the state. These invasive species represent the greatest threat to Maryland’s 14 native crayfish species.

Invasive crayfish can become very abundant in the streams, rivers, and lakes in which they are introduced. They often out-compete native crayfish for shelter habitats and food. These invasive species can also reduce the quality and quantity of food and habitat available to other aquatic animals.

“The most important thing we can do to protect our native species is to prevent the further spread of invasive crayfish already in Maryland and keep other invasives out,” Kilian said.

The study’s results were recently published in a special issue of Southeastern Naturalist, the product of a scientific symposium on the conservation, biology, and natural history of crayfish from the southern United States. It is available online:

This information is provided as a public service of the Maryland Department of Natural Resources.

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DNR Asks Public to Help Stop the Introduction and Spread of Zebra Mussels

Thursday, April 30th, 2009

The Maryland Department of Natural Resources (DNR) has launched an education and outreach campaign to inform the public about the threats posed by zebra mussels. More than 20 years ago zebra mussels were introduced into the Great Lakes in ship ballast water. Now this non-native, invasive mussel has found its way into Maryland. The mussels were discovered last fall in the Susquehanna River, at and upstream from the Conowingo Dam.

“We want boaters and anglers who use the lower Susquehanna to know that zebra mussels likely now live there,” said Ron Klauda, a biologist with DNR. “We’re again asking everyone to take a few precautionary steps now to hopefully head off the potentially devastating environmental and economic impacts in Maryland that this small, invasive mussel has had in other parts of the country.”

DNR convened a Zebra Mussel Information Exchange in Annapolis in January 2009, where it formed the Mid-Atlantic Zebra Mussel Working Group to continue the discussion on zebra mussel ecology, distribution, monitoring and control technology and to develop a response plan.

The agency recently posted STOP AQUATIC HITCHHIKERS signs at boat ramps and marinas along the Harford and Cecil county sides of the Susquehanna between the Pennsylvania-Maryland border and the river mouth as a part of the response plan.

The large “hot pink” signs ask boaters and anglers to follow these five simple steps before launching and leaving:

(1) REMOVE aquatic plants and mud from your boat, motor and trailer, and put the debris in a trash can (or at least on shore, far from the water).
(2) DRAIN river water from your boat, motor, bilge, bait buckets, live wells and coolers.
(3) DISPOSE of unused live bait on shore far from the water or in a trash can.
(4) RINSE your boat, motor, trailer, live wells, bait buckets, coolers and SCUBA gear with high pressure or hot water.
(5) DRY everything for at least 5 days between outings.

For personal watercraft, impeller areas can harbor zebra mussels and aquatic plants with attached mussels.

When your watercraft is on the trailer, run the engine for 5-10 seconds to blow out excess water and any associated mussels and plants.

Before leaving the area, inspect and REMOVE any zebra mussels, plants, mud, and other debris from the intake, steering nozzle, hull and trailer.

The only place zebra mussels are currently found in Maryland is the lower Susquehanna. Zebra mussels threaten fish and other aquatic life by consuming available food and smothering native mussels. They can ruin boat motors by clogging their cooling systems and jamming steering components. A single female mussel can release up to a million eggs each season, quickly increasing the population. They can encrust walls of intake structures and clog pipes at drinking water facilities and power plants. The U.S. Army Corps of Engineers calculated economic losses related to zebra mussel infestations at more than $5 billion between 1993 and 1999, not including the costs of ecological damages.

“Nobody can say for sure how zebra mussels found their way into the lower Susquehanna, but experiences with them in other parts of the country have taught us they are effective hitchhikers on boats and trailers,” said Klauda. “We also don’t know how long zebra mussels have been there or if they’ll become established and start to reproduce in great numbers this summer. We are concerned that the mussel population in the lower Susquehanna could take off like they did in the Hudson River back in the early to mid-1990s and we could be dealing with billions by the end of 2010.”

In addition to taking preventive measures to stop the spread, DNR is also asking boaters and anglers to be vigilant and contact the agency if they find anything that they suspect to be zebra mussels in the lower Susquehanna or elsewhere in the state. While young mussels are too small to see, newly settled young feel like fine sand paper on boat hulls and other smooth surfaces. Adult mussels are usually about the size of a fingernail and commonly have alternating dark and light stripes. Anyone spotting a suspected zebra mussel should put it into a zip-lock bag, place a paper label inside containing the collection site and date written in pencil, freeze the bag and its contents and report the finding to DNR toll free at 1-877-6208-DNR extension 8615 or 410-260-8615.

For more information on zebra mussels and other invasive species, visit DNR’s website:

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    Chesapeake Bay: Nature of the Estuary