InTrans / Sep 23, 2015

Oh carp! How to manage invasive species with early prevention, control

Go! Magazine

Zebra mussel cluster. Photo taken by D. Jude, Univ. of Michigan.

posted on September 23, 2015

In conjunction with our Go! Explore series about the transport and travel of animals, and in this case, invasive species, I wanted to speak to someone that actually tries to prevent their spread specifically in Iowa—my home state.

So, I talked with Kim Bogenschutz of the Iowa Department of Natural Resources (DNR) to learn more about the types of invasive species now commonly found in the Midwest, and what effect they have on people and the environment.

Kim is the aquatic invasive species (AIS) program coordinator for the Iowa DNR, which means that she is responsible for the prevention, management, and control of AIS in Iowa. She is also responsible for doing outreach to teach the general public about AIS already prevalent in Iowa lakes and rivers.

To better learn about some of the more prevalent invasive species and how they can be managed, I spoke with her about two of the most important tactics: control and prevention.

A conversation with Kim Bogenschutz

Can you name some of the invasive species in Iowa and that exist largely in the Midwest?

Some plants in the Midwest include Eurasian watermilfoil, hydrilla, and starry stonewart. Some of the aquatic animals that we have include zebra mussels, which are a huge threat in the Midwest and across the country. In terms of fish, Asian carp is a big one as it continues to move up the Mississippi River. Additionally, a species called rusty crayfish, which is originally native to the Ohio River, has since spread into several states’ waters and is competing against other native crayfish.

How do invasive species spread?

One of the main ways (or the only way in some instances) is by plants. Even commercial boats that are building bridges or dams can get pieces of plants attached to their boats. For instance, a piece of watermilfoil can get caught on the side of the boat and then, once in a new body of water, that piece can regenerate into a new plant. That is why cleaning the boat before entering new bodies of water is so important.

Zebra mussels can also attach to boats and can be spread when they are transported from one body of water to the next. When zebra mussels are juveniles and adults, they have sticky threads that allow them to attach to the boat or equipment. Additionally, if plants get caught on the boat, zebra mussels may be attached to those plants and be spread that way. When zebra mussels reproduce, their offspring are microscopic, and so if you don’t drain the boats’ water before transport to another body of water then they could be introduced without even seeing them.

Crayfish are often used as bait, and sometimes fisherman dump their bait into the water and thus they spread. The same goes for Asian carp, though it is less likely because most people at bait shops can identify the minnows. It’s illegal to dump bait; instead, you should throw it in the trash.

What can be done to stop invasive species?

In Iowa, you are required by law to clean off all plants, mud, zebra mussels, etc., from your boat before you leave a water body. And this law applies to cleaning off all plants, not just known invasives. Boaters are also required to drain their live wells, bilges, ballast tanks, or any other water in the boat. Actually, most states require you to leave the drain plug open while driving your boat to make sure you’re not carrying any water.

What are the consequences of letting invasive species spread?

Well, by definition, invasive species reproduce quickly, grow fast, and take over an area, which causes problems. Eurasian watermilfoil, for instance, outcompete native plants. It is also hard to travel through with your boat. Also, fish don’t like it and tend to not do well when it is present.

Zebra mussels attach to native mussels and kill them, because they can’t filter water and get food. Additionally, zebra mussels clog pipes for irrigation or drainage. And since zebra mussels also filter water to get food—like other native mussels—they directly compete with the native species for food.

The same goes for Asian carp; they also filter water to get their food and compete with native fish for food such as algae and other microscopic water plants and animals. Carp can get to be 100 pounds and have huge populations. Today, certain parts of the Des Moines River and Illinois River are 90 percent Asian carp! Silver carp in rivers can even hurt people that are on boats by flipping out of the water and slapping them.

Overall, invasive species cause problems for native species by competing with them for food, can hinder recreation, and even affect industry that use water bodies (i.e., zebra mussels clogging pipes. It costs a lot of money to deal with them, and most often you can’t get rid of them. Once they are introduced, the best you can do is control them.

What are some of the controlling mechanisms for dealing with invasive species?

For plants, like watermilfoil, the most successful tactic is to use aquatic herbicides that control them while still allowing natives to come back. Another tactic, which is less effective, is to go in and harvest plants. When you harvest the plants, they come back next year, but at least people can boat for the season.

Right now, for zebra mussels, the only way to kill them is with chlorine and ozone. Since this is a pollutant, this tactic can’t be used in rivers or other water bodies. So right now we have no controls for zebra mussels that will kill just them and not other mussels (including natives). Scientists are working on options that will control them. One product, Zequanox, is made from dead bacteria and will kill them, but it is not meant for a whole water body.

There are some physical measures to help stop the spread of Asian carp. For instance, there is an electric barrier in the Chicago canal to prevent carp from spreading, which seems to be pretty effective. Those dealing with invasive species hate to say anything is “completely effective.” Another tactic to stop carp include water guns, which create high flow in the water to keep carp away from docks and dams. There are also bubbles that help deter carp. There are various physical control options to try to prevent carp from moving upstream or that herd them in an area to then effectively harvest them out.

One of the current nationwide efforts involves working with the American Boat and Yacht Council to manufacture boats and trailers that are easier to clean and drain (or not allow invasive species to attach to them in the first place). All of this takes time! But the better we can prevent the spread of invasive species, the less water bodies we have to control.

How can you detect invasive species?

There are various ways. Some states, like in Iowa, have a crew that goes out on the water to try and detect species early. It may be that DNR staff survey the vegetation or rocks in a water body to see if they find anything suspicious. Many states have online forms as well. If you see something, we ask that you contact me or your local DNR office to report what you saw. The earlier we find things, then the better chance we have to eradicate it. We take public reports seriously and immediately try to go out and verify the reports.

How much money is spent to prevent invasive species in Iowa?

Some estimate it costs over a billion dollars nationwide to control and prevent the spread. States vary, however, in their individual budgets. In Iowa, we have a budget of $800,000, but for Minnesota the number is in the millions. Industries have also spent a considerable amount around the Great Lakes, because it costs a lot to keep their infrastructure clean.

We just want people to be aware of the fact that they could be transporting invasive species. Firstly, so they don’t get a ticket but also to further protect lakes and rivers.

By Jackie Nester, Go! Staff Writer

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