Minnesota, Carp, and Locks

By Avery Hildebrand, Community Coordinator, Conservation Minnesota

Reposted from the Conservation Minnesota blog.

We have seen the videos, heard the stories, and have been told to prepare for their inevitable arrival. I’m talking about invasive carp, commonly referred to as “Asian carp”.

Invasive carp are actually four different species of carp including the silver, bighead, black, and grass carp. Perhaps the most notable of these is the silver carp that launches itself out of the water when it feels threatened, at times as high as 10 feet in the air, and can be a safety hazard for boaters and recreationists of all kinds.

In the 1970’s these fish were imported from China to control plankton growth in agricultural and waste water treatment ponds in the southern states. Flooding in the region aided the carp in escaping into the Mississippi River in the 1990’s where they found their way into the Missouri and Illinois Rivers. Since then, we have found evidence of silver carp as far north as Taylors Falls, MN and big head carp at the mouth of the St. Croix River.

Some of the biggest threats to Minnesota’s waters are due to the size and appetite of these fish. Invasive carp can be massive. Adult bighead carp can weigh 110 pounds and on any given day they can consume roughly 40% of their own body weight. It is this appetite that has Minnesotans worried that invasive carp will change the ecosystem for native fish populations in our rivers and lakes by out competing them for food.

However, just because we have found them knocking on our front door does not mean that all hope is lost. Despite finding bighead and silver carp in our backyards, it is believed that these fish are “pioneer” carp that have traveled long distances in search of new habitat and food sources. So, the good news is that they are not yet fully established.

You may ask yourself, “How in the world can we stop invasive carp from entering our beloved rivers and lakes?” The best solution we have to this problem lies in our existing river infrastructure – the locks and dams. These structures are our best defense. The only problem is that recreationists and industry use locks to navigate the expanses of the Mississippi and other rivers in the region on a regular basis. Locks act as giant fish tanks and give invasive carp the ability to hitch a ride with boaters as they move through the locks.

Fortunately, we have an opportunity to make a difference. We are working with a coalition of organizations to stop invasive carp by encouraging recreational boaters and others on the Mississippi River no not use Lock and Dam 1 in order to protect the 6-mile stretch south of this lock called the “Gorge”.

Invasive carp have already established themselves at Pool 19 upstream from Lock and Dam 19 on the Mississippi River, which is located around the borders of Iowa, Missouri, and Illinois. If nothing is done, it is only a matter of time before they begin to move north and find themselves permanently in Minnesota’s waters.

Government agencies and researchers are developing other means of deterring the movement of the fish that include electric barriers, sound barriers, bubble walls, physical barriers, and light barriers. Invasive carp tend to be sensitive to certain sounds and light while most native fish species are not. These technologies in combination with decreased lock use will help to keep our Minnesota waters from becoming infested with invasive carp.

Now, after all this, you may be wondering, “What can I do?” The Stop Carp Coalition is encouraging people not to use Lock and Dam 1 when on the Mississippi River. Spread the word and tell everyone you know. With your help we can protect our lakes, rivers and outdoor way of life from these invasive and very detrimental carp species.

Avery Hildebrand earned his degree in Environmental Science and Management from the University of Wisconsin – River Falls. Avery is an avid fisherman and has worked as an aquatic invasive species watercraft inspector.