Post by VFR on Mar 9, 2023 15:45:34 GMT -5
Virginia - Invasive Species
by the Virginia DWR
Rusty Crayfish
Really, who’s afraid of a crayfish? All Virginians should be, as the rusty crayfish’s claws may be small, but its impact on Virginia’s game fish populations as an invasive species could be large. Rusty crayfish (Faxonius rusticus) is native to Ohio, Indiana, Kentucky, and Northern Tennessee, but was first found in Virginia in 2011, probably having been used by anglers for bait and sold in the pet and biological supply industries. Rusty crayfish outcompete native crayfish for food and territory, are voracious fish egg-eaters, and reduce aquatic plant abundance and species diversity, which impacts the habitat for other crayfish and fish species. They are associated with population declines of game fish such as bluegill and bass, along with game and non-game other fish species.
Rusty crayfish are larger than species of crayfish native to Virginia, growing to almost four inches. They have a brownish-green body with dark, rusty-red spots on either side of carapace and large claws. Their size and those claws enable them to outcompete smaller, native crayfish from hiding places and for food, which they eat at about twice the volume of native crayfish. Just as native crayfish, the rusty crayfish eats almost any plant or small animal, dead or alive. But the rusty, due to its larger size and an accelerated metabolism, can eat much more than native crayfish, decimating the aquatic vegetation in whole sections of streams.
To help stop the spread of rusty crayfish, never release any individuals purchased as pets or as bait for angling into any body of water. Read more.....
Two-Horned Water Chestnut
Seriously, a plant with horns is pretty scary. And if you saw the damage two-horned trapa (Trapa bispinosa), commonly known as water chestnut, can do to a freshwater body such as tidal rivers, streams, ponds, reservoirs, lakes and wetlands, you’d be terrified! Seriously, a plant with horns is pretty scary. And if you saw the damage two-horned trapa (Trapa bispinosa), commonly known as water chestnut, can do to a freshwater body such as tidal rivers, streams, ponds, reservoirs, lakes and wetlands, you’d be terrified!
Two-horned trapa invades freshwater habitats such as ponds, lakes, and slow-moving streams. At present, two-horned trapa is found in Virginia at more than 70 sites in five counties: Fairfax, Prince William, Loudoun, Fauquier, and Charlotte. Waterfowl, particularly Canada geese, are known to move the seeds to new habitats when the barbed seed pods, the “horns” of the plant, attach to waterfowl and disperse into neighboring waters.
Like Eurasian water chestnut, two-horned water chestnut has the potential to obstruct water flow, inhibit recreational and commercial use of waterways, shade out submerged aquatic vegetation, starve aquatic species of oxygen, and outcompete native aquatic plants. A water chestnut colony can smother an entire pond or lake.
Two-horned trapa has floating leaves that are green with red undersides. Each leaf has an “inflated” petiole that allows the plant to float. Small, pink flowers with four petals emerge from the rosette center beginning in June. Two-horned trapa may flower and fruit from June until frost. The seed pod is up to 2 inches, with two opposing “horns.” Due to cold temperatures, two-horned trapa dies back in late autumn, but seeds can lie dormant for at least two years. Two-horned trapa can be confused with the invasive Eurasian water chestnut, which produces a four-horned seed pod, white flowers and entirely green leaves. Two-horned trapa has a two-horned seed pod, pink flowers and leaves with red undersides.
Two-horned trapa was discovered in Fairfax County in 2014 and is mostly concentrated in Northern Virginia, but has also been spotted in Charlotte County, Virginia, and Prince George’s County, Maryland. Two-horned trapa colonies may be removed by hand or mechanically. Hand-pulling has been shown to reduce the species effectively, but waters should be monitored yearly for plants emerging from seed. Removing all plants before they go to seed in late June to early July will help reduce the population over time. Continued control efforts will likely be necessary for several years. Plants may be left in the sun to dry out, then burned, buried, or bagged.
If you believe you have found two-horned trapa or the related Eurasian water chestnut, please report your sighting. Read more.....
Snakeheads
Native to parts of Asia and Africa, northern snakeheads have the unusual combination of an intimidating appearance and yet being delicious to eat. In Virginia since 2004, the snakehead species has shown up in the Potomac and Rappahannock rivers and their tributaries as well as in various ponds and lakes.
Northern Snakeheads grow to a maximum length of about 36 inches and 18 pounds. They’re generally tan in appearance, with dark brown mottling; body somewhat elongated; long dorsal and anal fins; jaws contain numerous canine-like teeth (similar to pike or pickerel).
This fish is an obligate air breather, using an air bladder that works as a primitive lung (not found in most fish). It’s able to hibernate in substrate including cracks and crevices during cold temperatures and to go dormant in mud during droughts.
A top-level predator, it eats mostly fish, but also eats other aquatic wildlife including frogs. Exotic species like snakeheads can disrupt natural aquatic systems and may have significant impacts by feeding on and competing with native and/or naturalized fishes.
In addition, they may transmit parasites and diseases to native wildlife in those systems. Biologists continue to sample snakehead-colonized waters in an effort to learn more about the ecology and biology of this exotic fish in Virginia. Migration, exploitation, food habits, growth, and behavior of northern snakeheads are being studied; and attempts are being made to determine what impacts, if any, are occurring to aquatic communities as a result of colonization.
If you catch one of these creatures, you can help in our research by reporting it at 804-367-2925. There is also a new, easy-to-use web application for reporting observations. Anglers are required to report snakeheads kept but are not required to kill them if caught and immediately released. If an angler wishes to keep a legally caught northern snakehead, the fish must be killed to be in possession, and the angler must call the hotline or other DWR contact and report the angler’s last name, date of catch, location of catch, and size. DWR does encourage harvest of snakehead. Read more.....
Zebra Mussel
What’s so scary about a fingernail-sized creature with stripes? They may look tiny and innocuous, but zebra mussels (Dreissena polymorpha) flex some powerful muscle as a significant threat to the Commonwealth’s native ecology and wildlife communities.
Virginia doesn’t currently have a known population of zebra mussels, but the state has had a few very close calls. In August 2002, zebra mussels were documented for the first time in Virginia in an abandoned quarry in Prince William County that is used for instructional and recreational scuba diving. DWR worked with a number of state, federal, and local agencies to eradicate the zebra mussel population at Millbrook Quarry, and confirmed the successful eradication of the infestation in May 2006.
In March 2021, DWR got an alert that some Virginia pet stores were selling live marimo moss balls for aquarium use that may have been contaminated with invasive zebra mussels. With a concerted awareness outreach effort and by working with pet stores directly, DWR succeeded in getting the possibly contaminated moss balls off the market.
Zebra mussels remove the food base upon which many of our native fish and freshwater invertebrates are dependent. Because of their ability to rapidly colonize any hard surface, zebra mussels also pose a significant risk to many bottom-dwelling species, including our rare and endangered freshwater mussel populations. Zebra mussels can attach themselves to the native mussel shells, making it impossible for these animals to open or close, burrow in the stream bottom, or feed. Zebra mussels also can damage boat hulls and engines. Colonies of zebra mussels lodged in pipes can cause millions of dollars of damage to water and power plants. You can help keep Virginia zebra mussel-free! Report any zebra mussel sightings and make sure to inspect, clean, and dry boats and equipment thoroughly when transferring from one water body to another. Read more about the zebra mussel and what you can do. Read more.....
by the Virginia DWR
Rusty CrayfishReally, who’s afraid of a crayfish? All Virginians should be, as the rusty crayfish’s claws may be small, but its impact on Virginia’s game fish populations as an invasive species could be large. Rusty crayfish (Faxonius rusticus) is native to Ohio, Indiana, Kentucky, and Northern Tennessee, but was first found in Virginia in 2011, probably having been used by anglers for bait and sold in the pet and biological supply industries. Rusty crayfish outcompete native crayfish for food and territory, are voracious fish egg-eaters, and reduce aquatic plant abundance and species diversity, which impacts the habitat for other crayfish and fish species. They are associated with population declines of game fish such as bluegill and bass, along with game and non-game other fish species.
Rusty crayfish are larger than species of crayfish native to Virginia, growing to almost four inches. They have a brownish-green body with dark, rusty-red spots on either side of carapace and large claws. Their size and those claws enable them to outcompete smaller, native crayfish from hiding places and for food, which they eat at about twice the volume of native crayfish. Just as native crayfish, the rusty crayfish eats almost any plant or small animal, dead or alive. But the rusty, due to its larger size and an accelerated metabolism, can eat much more than native crayfish, decimating the aquatic vegetation in whole sections of streams.
To help stop the spread of rusty crayfish, never release any individuals purchased as pets or as bait for angling into any body of water. Read more.....
______________________________________________________________________
Two-Horned Water ChestnutSeriously, a plant with horns is pretty scary. And if you saw the damage two-horned trapa (Trapa bispinosa), commonly known as water chestnut, can do to a freshwater body such as tidal rivers, streams, ponds, reservoirs, lakes and wetlands, you’d be terrified! Seriously, a plant with horns is pretty scary. And if you saw the damage two-horned trapa (Trapa bispinosa), commonly known as water chestnut, can do to a freshwater body such as tidal rivers, streams, ponds, reservoirs, lakes and wetlands, you’d be terrified!
Two-horned trapa invades freshwater habitats such as ponds, lakes, and slow-moving streams. At present, two-horned trapa is found in Virginia at more than 70 sites in five counties: Fairfax, Prince William, Loudoun, Fauquier, and Charlotte. Waterfowl, particularly Canada geese, are known to move the seeds to new habitats when the barbed seed pods, the “horns” of the plant, attach to waterfowl and disperse into neighboring waters.
Like Eurasian water chestnut, two-horned water chestnut has the potential to obstruct water flow, inhibit recreational and commercial use of waterways, shade out submerged aquatic vegetation, starve aquatic species of oxygen, and outcompete native aquatic plants. A water chestnut colony can smother an entire pond or lake.
Two-horned trapa has floating leaves that are green with red undersides. Each leaf has an “inflated” petiole that allows the plant to float. Small, pink flowers with four petals emerge from the rosette center beginning in June. Two-horned trapa may flower and fruit from June until frost. The seed pod is up to 2 inches, with two opposing “horns.” Due to cold temperatures, two-horned trapa dies back in late autumn, but seeds can lie dormant for at least two years. Two-horned trapa can be confused with the invasive Eurasian water chestnut, which produces a four-horned seed pod, white flowers and entirely green leaves. Two-horned trapa has a two-horned seed pod, pink flowers and leaves with red undersides.
Two-horned trapa was discovered in Fairfax County in 2014 and is mostly concentrated in Northern Virginia, but has also been spotted in Charlotte County, Virginia, and Prince George’s County, Maryland. Two-horned trapa colonies may be removed by hand or mechanically. Hand-pulling has been shown to reduce the species effectively, but waters should be monitored yearly for plants emerging from seed. Removing all plants before they go to seed in late June to early July will help reduce the population over time. Continued control efforts will likely be necessary for several years. Plants may be left in the sun to dry out, then burned, buried, or bagged.
If you believe you have found two-horned trapa or the related Eurasian water chestnut, please report your sighting. Read more.....
______________________________________________________________________
SnakeheadsNative to parts of Asia and Africa, northern snakeheads have the unusual combination of an intimidating appearance and yet being delicious to eat. In Virginia since 2004, the snakehead species has shown up in the Potomac and Rappahannock rivers and their tributaries as well as in various ponds and lakes.
Northern Snakeheads grow to a maximum length of about 36 inches and 18 pounds. They’re generally tan in appearance, with dark brown mottling; body somewhat elongated; long dorsal and anal fins; jaws contain numerous canine-like teeth (similar to pike or pickerel).
This fish is an obligate air breather, using an air bladder that works as a primitive lung (not found in most fish). It’s able to hibernate in substrate including cracks and crevices during cold temperatures and to go dormant in mud during droughts.
A top-level predator, it eats mostly fish, but also eats other aquatic wildlife including frogs. Exotic species like snakeheads can disrupt natural aquatic systems and may have significant impacts by feeding on and competing with native and/or naturalized fishes.
In addition, they may transmit parasites and diseases to native wildlife in those systems. Biologists continue to sample snakehead-colonized waters in an effort to learn more about the ecology and biology of this exotic fish in Virginia. Migration, exploitation, food habits, growth, and behavior of northern snakeheads are being studied; and attempts are being made to determine what impacts, if any, are occurring to aquatic communities as a result of colonization.
If you catch one of these creatures, you can help in our research by reporting it at 804-367-2925. There is also a new, easy-to-use web application for reporting observations. Anglers are required to report snakeheads kept but are not required to kill them if caught and immediately released. If an angler wishes to keep a legally caught northern snakehead, the fish must be killed to be in possession, and the angler must call the hotline or other DWR contact and report the angler’s last name, date of catch, location of catch, and size. DWR does encourage harvest of snakehead. Read more.....
______________________________________________________________________
Zebra MusselWhat’s so scary about a fingernail-sized creature with stripes? They may look tiny and innocuous, but zebra mussels (Dreissena polymorpha) flex some powerful muscle as a significant threat to the Commonwealth’s native ecology and wildlife communities.
Virginia doesn’t currently have a known population of zebra mussels, but the state has had a few very close calls. In August 2002, zebra mussels were documented for the first time in Virginia in an abandoned quarry in Prince William County that is used for instructional and recreational scuba diving. DWR worked with a number of state, federal, and local agencies to eradicate the zebra mussel population at Millbrook Quarry, and confirmed the successful eradication of the infestation in May 2006.
In March 2021, DWR got an alert that some Virginia pet stores were selling live marimo moss balls for aquarium use that may have been contaminated with invasive zebra mussels. With a concerted awareness outreach effort and by working with pet stores directly, DWR succeeded in getting the possibly contaminated moss balls off the market.
Zebra mussels remove the food base upon which many of our native fish and freshwater invertebrates are dependent. Because of their ability to rapidly colonize any hard surface, zebra mussels also pose a significant risk to many bottom-dwelling species, including our rare and endangered freshwater mussel populations. Zebra mussels can attach themselves to the native mussel shells, making it impossible for these animals to open or close, burrow in the stream bottom, or feed. Zebra mussels also can damage boat hulls and engines. Colonies of zebra mussels lodged in pipes can cause millions of dollars of damage to water and power plants. You can help keep Virginia zebra mussel-free! Report any zebra mussel sightings and make sure to inspect, clean, and dry boats and equipment thoroughly when transferring from one water body to another. Read more about the zebra mussel and what you can do. Read more.....