Eurasian Water-Milfoil
Grows in thick mats that shade out native plants.
- Produces a monoculture unfavorable to production of sportfish.
- Stunted fish can occur as a result of the heavy cover from predators.
- Late summer die-offs cause alga blooms, reducing dissolved oxygen needed by fish.
Native of Europe.
- Brought to northeastern US in 1880's. Found in 33 states by 1985.
- Common in Minnesota and Wisconsin waters.
- One plant was found in N. Dak's. Sheyenne River in the 1990's, but none since.
Eurasian water-milfoil is a rooted, submerged plant seen in shallow waters.
- Stems reddish-brown to whitish-pink
- One-eighth to one-quarter inch diameter
- Up to five feet in length.
- Leaves deeply divided, soft, and feather like.
- About two inches long.
- Arranged in whorls of 3-6 leaves about the stem.
- Leaves are limp when out of the water.
- Flowers reddish and very small.
- Held several inches above the water when the plant is blooming.
- After pollination, flower spikes sink under water.
Most infestations started by plant fragments growing into new plants or by root runners.
- Grows best on soft mud bottoms in waters with moderate nutrient levels.
- Survives for months under the ice.
Chemical or mechanical control is expensive and often unsuccessful.
- Native and desirable plants are also killed.
- Opens the area to recolonization by water-milfoil.
Eurasian water-milfoil would flourish in many North Dakota waters.
Sheyenne River boaters should watch for this plant and clean their equipment thoroughly. |
Curly-Leaf Pondweed
Grows soon after ice out and deprives later-growing plants of nutrients.
- Quickly establishes a monoculture unfavorable for fish and wildlife.
- Forms thick surface mats that inhibit boating, swimming, and wading.
- Fishing declines when mats cover much of the lake's surface.
- Mats increase escape cover for small fish in shallow waters.
- As a result small fish are not cropped by predators in summer.
- As late summer plant die-offs occur, small fish lose their protection.
- Predators begin actively feeding on them in shallow waters.
- Large gamefish become vulnerable to overharvest by anglers.
Native to Eurasia and Africa.
- Imported into the United States as an aquarium plant in the early 1800's.
- By mid-1880's was established in many eastern states and had spread westward.
- Would do well in most North Dakota waters that are not extremely salty.
- Common in Lake Audubon, Lake Sakakawea, and Missouri River.
- Isolated populations are also found in a few small lakes.
Plant stems are typically 1-3 feet in length.
- Fall/Winter: grows with smooth leaves and can over-winter as an upright plant.
- Spring/Summer: leaves oblong, reddish-green, fine-toothed edges, three inches long.
Chemical control is expensive with no assurance of effectiveness and mechanical control causes seed
pods to dislodge and float to new areas. |
Purple Loose-Strife
Grows into dense monoculture stands at water's edge.
- Mats grow so thickly that waterfowl cannot penetrate them.
- High seed production and germination rate quickly result in dense stands.
Believed to have originated in Europe and Asia.
- Hitchhiked to northeast US in a ship's hold or ballast water in the 1800's.
- Moved from eastern states in early 1900's to Washington state by the 1940's.
- Most states and provinces report purple loosestrife infestations.
- The plant is spreading in North Dakota.
- It does best in areas with moist soils.
- Found along Missouri, Red, Sheyenne, Mouse rivers as well as many other areas.
Plant is 2-7 feet tall.
- Flowers bloom June-Sept.; purple with 5-6 petals arranged in a spike.
- Stems are four-sided on young plants; multi-sided on mature plants.
- Leaves are opposite each other.
- Leaves in tightly packed whorls.
- Oblong to heart shaped, measuring 1-4 inches.
Grows best in marshes, wetlands, and along rivers or streams.
- A single large taproot may have 30-50 annual upright herbaceous stems.
- Seed heads can produce as many as 2.7 million seeds.
- A single seed is about the size of a speck of ground black pepper.
- Seeds survive for some time to sprout under favorable conditions.
- Seeds spread by water, wind, carried in feathers and fur of birds and animals.
- Seeds are tracked around on our shoes, vehicles, and boats.
Can be controlled by removing vegetation from boats, vehicles, and equipment.
- Broad-spectrum herbicides can be used to remove large stands.
- It is very expensive and is not always effective.
- Most herbicides kill desirable plants along with targeted plants.
- Spot treatment with specific herbicides may eliminate small stands.
- Remove young plants by hand cutting, if the taproot has not been formed.
- Biological controls (flea beetles or weevils) reduce but do not eliminate plants.
- Must be closely monitored to prevent a new set of problems.
- Result in repeating cycle of high and low bug and plant populations. |
Salt Cedar (Tamarisk)
Out-competes native plants such as willow and cottonwood.
- Drops salt-laden leaves in fall that poison soil and prevent other plants from growing.
- Site renovation may require removing contaminated topsoil, replacing it with new soil.
- Dense stands are difficult to penetrate and of little benefit to wildlife.
- Uses up to 300 gallons of water daily, 10-20 times the amount used by native plants.
- Thick taproot penetrates up to 50 feet into the ground to reach water.
- Can easily deplete underground seeps and springs.
Native to Eurasia and Africa.
- Introduced into inter-Mountain Region of western United States in early 1800's.
- Used as erosion control in areas disturbed by agriculture or overgrazed by cattle.
- Original seed source in North Dakota appears to have been from Montana.
- Found in Missouri and Yellowstone rivers and Lake Sakakawea.
- May already exist in Missouri River below Garrison Dam.
- A plant was found in Sargent County in southeastern North Dakota.
- Would do well in most North Dakota waters.
Grows as shrubs or trees 12 -15 ft tall.
- Bark of young plant smooth and reddish-brown.
- Branches slender with gray-green foliage.
- Bark of older trees brownish-purple, furrowed, and ridged.
- Leaves less than 1/8 inch long and overlap the stem in a fish-scale pattern.
- Flowers from late spring to early fall.
- Large bunches of 2-inch spikes of pink-white flowers appear on the tips of branches.
- A flower produces thousands of seeds that wash downstream and colonize an area.
- Seeds hitchhike in feathers of birds and the fur of animals.
- Seeds tracked in mud on our shoes, the feet of animals, and by vehicle tires.
Chemical spraying programs can be used for control.
- Hand cutting may be effective if the plants are young, small, and few in number.
Biological controls under consideration, but are just beginning.
- Require close monitoring to prevent a new set of problems.
Preventing the spread of ANS - Equipment cleaning guidelines:
Hitch, live-well, mud & water on floor, transom
Anchor rope, trailer frame, boat hull, rollers, bunks, axle, wheels, boat motor
Equipment cleaning and bait guidelines:
Remove plant fragments from boats, personal watercraft, trailers, fishing, hunting, or scuba gear
before leaving the boat ramp.
Drain water from the boat motor, live-well, bilge, and behind the transom before leaving the boat ramp.
Disinfect boat, live-well and bilge, trailer, and other equipment by power washing with water 110 degrees
Fahrenheit or hotter. Rinse with a solution of one part chlorine bleach to 20 parts warm water. Or air dry boat
and trailer for five days in hot, dry weather; longer if it is cool or damp.
Learn to identify legal baits and check bait buckets for carp and other species. It is illegal to bring bait fish into
North Dakota without a permit from the Game and Fish Department.
Do not release bait or bait water into a lake or move fish from one lake to another. Put excess bait in a fish grinder,
the garbage, or bury it at home. Return fish only to waters they came from.
Replace bait bucket water with well water clear of plants or plant fragments. |
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Common Carp
A very prolific fish that out-competes native and desirable fish.
- Roots on bottom for animals and plant roots, making water turbid.
- Competes with young sportfish for food.
- Can grow to eight inches by end of first summer.
- At five inches long, carp are too big for most predator' s to eat.
A native of Asia.
- Imported to Europe by Roman legions.
- Brought to North America to raise as a food fish in the 1870's.
- By 1900 they were established in most states.
- Found in many North Dakota waters.
A large, hardy fish.
- The current state record is 31 pounds.
- Color varies from almost black to dark-brownish yellow, which is most common.
- Fins pale yellow with bright orange edges.
Survives high-nutrient waters, alga blooms by loading blood-hemoglobin with oxygen.
- Only bullheads tolerate lower oxygen levels.
Sexually mature at age three.
- A five-pound female can produce a half million eggs.
- A 20-pound fish can produce more than two million eggs.
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Silver Carp
Live in large river systems.
- Produce huge numbers of eggs that quickly hatch.
- Found below Gavins Point Dam and the lower James River in South Dakota.
An indirect competitor with sportfish.
- Eats phytoplankton, a food item used by zooplankton needed by small gamefish.
- Even when eating only single cell plants, they can reach 60 pounds or more.
- Concentrates below dams and can drive out desirable fish.
Easily spooked by noises and flee.
- Many times they will jump out of the water to get away.
- A 60-pound fish becomes a cruise missile aimed at a boater or water skier .
In large rivers there is no simple solution for eliminating or controlling them.
- Chemical treatment would affect nontarget species such as gamefish.
- Preventing introduction far easier than trying to control or eliminate them. |
Exotic Fishes: Rudd, Ruffe, and Goby
All three species would out-compete native or desirable fish for the same niche.
All three species measure less than 10 inches long and have no sport fishing value.
Originally found in Europe's Baltic Sea region and in Asia.
- None of these fish has yet been reported in North Dakota.
- Would do well in our waters.
Eradication is the only treatment for a water infested with these fish.
- This not only eliminates the target species but also more desirable fish.
- It takes 3-5 years to restore a water's sport fishery after eradication.
Ruffe
Ruffe resemble small perch or walleye.
Few predators eat them because of the sharp spines on the dorsal fins and gill flaps.
- Known to out-compete walleye, yellow perch, and even bullheads.
- Called the "bait stealer" because it takes the bait from a walleye angler's hook.
Arrived in US in early 1980's in ballast water from a trans-Atlantic cargo ship.
- Now a dominant species in parts of the Great Lakes.
A prolific species that matures sexually at age one.
- Females spawn several times a season, producing up to 82,000 eggs a year.
Goby
Goby are similar in appearance to sculpin.
- Resemble tadpoles.
- Have large heads, soft bodies, and appear to be pot-bellied.
- Dorsal fins free of spines.
Linked to declines in yellow perch populations.
Arrived in United States in ballast water of a trans-Atlantic cargo ship.
- Now range throughout much of the Great Lakes and their tributaries.
Female produces between 200-10,000 eggs and spawns multiple times a season.
- Male builds a nest and tends to eggs.
- Multi-spawning females and nest-tending males results in high survival of young.
Rudd
Rudd resemble golden shiner.
Carry parasites, diseases, and viruses that infect desirable gamefish.
- In one Minnesota lake, about one in five yellow perch is infected with a virus thought to be carried by rudd.
Originally found in Europe's Baltic Sea region and in Asia.
- Brought to US in 1920's and propagated in southern states as batfish.
- By mid 1980's were found throughout eastern and southern United States.
- Now found in South Dakota, Minnesota, and some Rocky Mountain states.
Females may spawn two or three times in a year and with different males.
- A large, one-pound female can produce 200,000 eggs a year. |
Northern Snakehead
Provided by USGS, artist Susan Trammel
A very hardy fish.
- Survives extended periods of cold temperature and marginal water conditions.
- Brought to US as aquarium fish or as a food item in some cultural markets.
- Released into the wild, survived, and established populations.
A very good parent.
- Adults guard their nest and the newly hatched fry.
- Can spawn 3-5 times a year, with as many as 15,000 eggs per spawn.
A well fed Northern Snakehead can grow to 30 pounds or more.
- It has simple food preferences – it eats about everything.
- Eats other fish, invertebrates, small waterfowl, and baby muskrats.
- Competes for food with yellow perch, walleye, and northern pike.
- Preys on fingerling sportfish, obviating benefits of fish stocking programs.
Eliminating this species would be very difficult.
- Infested waters would require rotenone treatment, which kills all fish species.
- Would take 3-5 years to reestablish the recreational fishery.
- Prevent introduction by not releasing aquarium fish into the wild or using illegal baits. |
New Zealand Mudsnail
Compete with small sportfish for macro-invertebrates.
- Eat all vegetation, algae, dead animal material, and bacteria.
- Snail closes up when eaten by a predator and passes through the intestines unharmed.
- This ability to hide in the shell allows them to survive out of water for a few days.
All New Zealand mudsnail are females.
- They are born alive, already carrying fertilized eggs.
- Under extreme conditions a few become functional males and mate with females.
Eggs are tough, withstanding long periods of dewatering and freezing.
- Eggs hatch when conditions are favorable.
- Eggs less than 3 millimeters long.
- As many as 30,000 eggs per square meter have been found.
May have been brought to the US through Great Lakes' ports.
- Hitchhike on dirty equipment that is not allowed to completely dry out or freeze.
- Because of their small size they are not easily noticed.
- Found in trout streams of Colorado, Montana, Wyoming, and in the Great Lakes. |
Zebra Mussel
Note byssal threads on lower left.
Byssal threads attach to hard surfaces such as rocks, boat docks, and bridge pilings.
- Zebra mussels cover rocks walleye use for spawning.
- Can out-compete native bivalves.
- More than 44,000 mussels per square yard have been documented.
- In large numbers they can plug municipal water intakes and similar structures.
Feeds by filtering water of organic materials.
- Consume small zooplankton needed by young gamefish.
- Adults filter up to a liter of water of organic materials daily.
- In large numbers, they can strain an entire lake in a short period.
A native of Asia.
- Hitchhiked to Great Lakes in ballast water of trans-Atlantic freighter.
- Spread to Mississippi River and eastern US lakes via recreational boats.
- Have not yet been found in North Dakota.
- Potential infestation areas are Lake Sakakawea, Missouri River, and Devils Lake.
Named for their black and white stripes.
- Colors vary from sharply contrasting to subtle gray and off-whites.
- Adults are small, from 1/8 to one inch long.
Females spawn twice a year and produce 40,000-1,000,000 eggs.
- Life expectancy is about four years.
Adults and free swimming larvae brought aboard a boat in lake water hitchhike to other areas.
- Survive in bilges, live-wells, or other damp places such as boat trailer rails.
- Can live more than two weeks under moist conditions. |
Exotic Water Fleas: Spiny Water Flea and Hooked Tail Water Flea
Exotic Water Fleas
Spiny Water Flea Hooked Tail Water Flea
Spiny Water Flea
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Hooked Tail Water Flea |
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Feed on smaller zooplankton, the same food items needed by small gamefish.
- No natural predators in North Dakota waters.
- Not eaten by fish because of the spines on their long tails.
- Adults hitchhike to other waters when tails tangle in fishing lines, nets, etc.
- Adults or eggs survive for extended periods under damp conditions.
- Egg masses can be transported in live-wells, bilges, and on equipment.
A native of Europe.
- Hitchhiked to US in ballast water of trans-Atlantic cargo ships.
- Found throughout the Great Lakes and in some inland lakes.
- Have not yet been found in North Dakota.
- Would do well in North Dakota's major recreational waters.
Adults of both species measure less than half an inch in length.
- Have a distinctive long tail covered with sharp barbs.
Mature sexually within a short time of hatching.
- Reproduce frequently in the summer.
- Female produces up to 10 offspring every two weeks.
- Eggs will lie dormant all winter and hatch the following spring.
Great Lakes' boaters should disinfect their boats before bringing them to North Dakota. |
Preventing the spread of ANS
Places where aquatic nuisances species can hide and hitchhike to new waters:
Hitch, live-well, mud & water on floor, transom
Anchor rope, trailer frame, boat hull, rollers, bunks, axle, wheels, boat motor
Equipment cleaning and bait guidelines:
- Remove plant fragments from boats, personal watercraft, trailers, fishing, hunting, or scuba gear before leaving the boat ramp.
- Drain water from the boat motor, live-well, bilge, and behind the transom before leaving the boat ramp.
- Disinfect boat, live-well and bilge, trailer, and other equipment by power washing with water 110 degrees Fahrenheit or hotter. Rinse with a solution of one part chlorine bleach to 20 parts warm water. Or air dry boat and trailer for five days in hot, dry weather; longer if it is cool or damp.
- Learn to identify legal baits and check bait buckets for carp and other species. It is illegal to bring bait fish into North Dakota without a permit from the Game and Fish Department.
- Do not release bait or bait water into a lake or move fish from one lake to another. Put excess bait in a fish grinder, the garbage, or bury it at home. Return fish only to waters they came from.
- Replace bait bucket water with well water clear of plants or plant fragments.
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