—by Steve Lekwa

The new 2014 Iowa Fishing Regulations booklet devotes several pages to a concern that seems to grow with each passing year. Invasive species have long been a problem in field and forest. Some have even been "outlawed" as noxious weeds that are to be destroyed whenever and wherever found. Common carp have long been seen as a damaging invasive species in our waterways, but a host of new alien invasive species have joined them in recent years. Some of these newcomers appear to be even more damaging than carp have been as they threaten ecosystems in our ponds, lakes, and rivers.

It is now illegal to transport not only aquatic invasive species, but any aquatic plant, invasive or not. All water must be drained from boats and live wells prior to leaving the access point to public waters. Boat hulls and the trailers they travel on are to be cleaned of any and all aquatic plants and parts of plants prior to leaving the water access area. Drain plugs must be removed and remain open during any transport of a water craft. This is to reduce the chance of spreading problem species into new waters that the boat may visit. Even small parts of some aquatic plants can remain alive for days if they don’t completely dry out and can multiply rapidly when introduced into new water. Cleaning the boat and trailer may require some hand labor to pick off plant debris.

Draining all water means the water in bait buckets, too. It is illegal to release aquatic animals from one water body into another. The only way to keep unused live bait like minnows or leaches is to replace lake or river water in the bait bucket with tap or bottled water. The larvae of some dangerous invasive species like zebra mussels are too small to notice and can easily move from one body of water to another in very small amounts of water.

Some of the new species that are threatening Iowa waters include Eurasian Watermilfoil and Brittle Naiad. These frilly rooted water plants can literally choke infested water with their growth, making boating and swimming nearly impossible. When they die back in winter, bacterial decomposition of their excessive growth robs the water of oxygen causing fish kills. People have already introduced them to several lakes and ponds in central Iowa.

Zebra mussels have now invaded Clear Lake, Rathbun Reservoir, the Okoboji/Spirit Lake complex, several private ponds and several eastern Iowa rivers. Sadly, silver and bighead carp are working their way up several larger Iowa rivers including the Des Moines and Skunk from the Mississippi where they are already established. Larger dams have stopped them at least temporarily, but all it would take is one carelessly dumped minnow bucket with a couple of little carp in it to move them even farther upstream.

Removing an invasive species from a lake or river is difficult and expensive when it’s even possible. In many cases it’s not possible. Stopping the spread of aquatic invasive species will be difficult, at best. Law enforcement will do what it can, but the dedicated effort of every user of Iowa’s streams and lakes will be necessary, as well.