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Invasive Bottom-Feeding Fish Threaten North Dakota Waters

JAMESTOWN, N.D. (AP) — As North Dakota continues through a wet cycle of seasonal changes, the threat of undesirable and possibly invasive species threaten to contaminate the state's waterways, state officials say.

"Population density can increase to the point where it's almost impossible to re-establish other fish,'' said Gene Van Eeckhout, southeast district fisheries supervisor for North Dakota Game and Fish Department.

Undesirables, or rough fish, such as carp and bullheads are bottom feeders and take food from game species like walleye and northern pike, Van Eeckhout said. Nursing habitats can also be altered by certain rough fish destroying rooted plants, taking away structural cover.

"It's been a chronic problem forever, it's nothing new,'' he said of rough fish.

What is new is that those fish have been moving north to new bodies of water because of existing high water in North Dakota.

Some parts of the southeast district are worse than others like McIntosh and Dickey counties, Van Eeckhout said.

"Virtually every road ditch is now a water course and the fish will move through that stuff,'' he said.

Sanborn Lake is within two feet of entering the Sheyenne River, which is connected to other lakes abundant with rough fish, Van Eeckhout said.

"There are some pretty significant questions that need to be answered,'' he said.

There is also no way to dispose of invasive species without destroying game fish. No chemical exists to kill off one type of fish without killing the others, said Lynn Schlueter, aquatic nuisance species coordinator with fisheries division for the North Dakota Game and Fish Department.

Arrowwood National Wildlife Refuge does employ a method that works but kills all fish in the process. Water levels are lowered so a deep-enough winter freeze kills all fish in the refuge, said Kim Hanson, refuge manager.

The same method has been used in Lisbon to eliminate Eurasian water milfoil, a nuisance plant, with some fish surviving because the water level was high enough, Schlueter said.

It takes three to five years after a freeze or a total kill before game fish can be restocked and grow to a desirable size, he said.

One threat North Dakota has never seen is making its way north on the James River, and it could change game fish in the state forever.

The big head and silver carp, varieties of Asian carp, have been spotted on the James River, said John Lott, chief of aquatic resources with South Dakota Game, Fish and Parks. One big head carp was caught in Huron, S.D., and the silver carp has been spotted by the mouth of the James River near Yankton, S.D.

Asian carp feed on a different type of plankton in the middle of the water instead of the bottom, which could throw off the food chain, Schlueter said. The fish also can grow to 60 pounds and can suddenly leap out of the water injuring boaters or water skiers.

The Jamestown area has several things in its favor that could keep Asian carp varieties out of the area, he said.

The journey up the James River from Huron has many dams and wetlands that need to be passed. The invasive species would also have to winter up stream in a different ecosystem, he said. Jamestown waters also have blue-green algae while Asian carp feed on zooplankton.

"These things have a reduced chance of surviving,'' Schlueter said. "Notice how I said reduced, I'd never close the door on these things, they are too hardy, too much of a survivor.''

Game and Fish officials offer simple tips to keep invasive species out of North Dakota waters.

Boaters and anglers should clean boats, equipment and lures after each use. They should not bring plants, water or bait to a new body of water and use common-sense practices like draining live wells before entering a new body of water. At-home treatments like hot water and bleach also clean boats.

Hopefully Asian carp never make it this far up the James River because if they do the results in this ecosystem are unknown.

"We don't know, the bottom line is we don't want to know,'' said Greg Powers, fisheries chief for the North Dakota Game and Fish Department. "That's why our emphasis is on prevention.''

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