Aquatic Nuisance Species - The Animals

The common carp is found in many North Dakota waters too numerous to list.

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.

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

Exotic Fishes

Rudd	Ruffe	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

Illustration 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

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.

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.

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:

1. Remove plant fragments from boats, personal watercraft, trailers, fishing, hunting, or scuba gear before leaving the boat ramp.
2. Drain water from the boat motor, live-well, bilge, and behind the transom before leaving the boat ramp.
3. 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.
4. 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.
5. 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.
6. Replace bait bucket water with well water clear of plants or plant fragments.