By Doug Leier
With boat fishing season picking up and recreational boating just around the corner, we need to again focus on the role anglers and boaters play in reducing the impact of zebra mussels and other invasive species. Ben Holen, North Dakota Game and Fish Department aquatic nuisance species coordinator, answers some common ANS questions.
Q: What can water recreationists do to eliminate the spread and introduction of ANS in North Dakota?
A: Whether you are an angler, hunter, water sports enthusiast, or a pleasure boater, play a part in preventing the spread of aquatic nuisance species. It is important to clean, drain and dry all watercraft and water recreational equipment. Many boat owners practice these steps between every launch. However, other common items such as anchors, watersports equipment, decoys, canoes and kayaks are all possible vectors that can also spread aquatic nuisance species. Large equipment, such as boat lifts, docks and barges can be high risks for spreading ANS, especially if they are moved from one lake to another. It is important to remove any vegetation, mud, or residual water left on equipment, because it may harbor an aquatic nuisance species. Cleaning gear with hot water for 10 seconds between recreational trips can eliminate the risk of spreading ANS.
Q: Much is made about zebra mussels and the problems they can cause. What is the fallout for a body of water with zebra mussels?
A: It is hard to say the exact effects zebra mussels will cause at any given waterbody because of the great variability that can exist in a lake’s water chemistry, nutrient input, aquatic organisms and population levels of mussels. Some common impacts observed in lakes are clearer water and a shift of nutrients to the lake bottom, which causes an increase in plant growth and benthic macroinvertebrates. Some lakes see an increase in the severity of harmful algae blooms because zebra mussels selectively feed against them. The changes in fish abundance and growth and water quality can also be highly variable. Zebra mussels cause major problems to infrastructure, they can clog water intakes, foul boating equipment and damage property.
Q: Other than zebra mussels, what other invasive species are a concern in North Dakota? And if there are some, where are they found?
A: Other than zebra mussels, North Dakota has just a few aquatic invasive plants and animals including curly leaf pondweed, Eurasian watermilfoil, bighead, silver and common carp. Curley leaf pondweed can be found throughout the Missouri River System, Lake Metigoshe, Sheyenne River in Barnes County, and a few small reservoirs. In the last five years, Eurasian watermilfoil has only been documented in the Sheyenne River in Barnes County. Bighead and silver carp are only found in the James River, while common carp are widespread and are found in many waters across the state. Any ANS has the potential to cause harm to the aquatic ecosystem.
Q: While we don’t think about common carp as aquatic nuisance species, are these fish becoming a bigger issue as high water connects drainages and natural lakes?
A: The increased connectivity between water bodies allows for the natural movement of fish from drainages into natural lakes. Spring runoff acts as a highway for fish to travel to new water bodies, and common carp take full advantage of this opportunity. It is engrained in carp DNA, as well as many other fish species, to follow running water to its source, to look for viable spawning habitat and food resources. Fortunately, the Game and Fish Department works with both public and private entities to identify points of water connectivity and then set barriers to prevent their upward movement. Game and Fish staff have created earth berms and stock dams to prevent carp from getting into Devils, Alkaline and Rice lakes. Temporary block net barriers are placed yearly at various district lakes when a more permanent structure is not feasible.
Featured Photo: Despite their small size, zebra mussels cause major problems to infrastructure when they colonize a water: they can clog water intakes, foul boating equipment and damage property. NDG&F Photo.