During the 1940s and '50s our Great Lakes systems in the Midwest were very polluted. The only lake that still had some pure water was Lake Superior.

Locally, Lake Michigan still had a population of yellow perch and smelt. Lake Erie was considered the "dead sea" at that time.

Soon after the early '50s the Clean Water Act was put in place and all municipalities were under orders to construct waste treatment plants. The government was concerned because of typhoid and other water-born diseases coming from our waterways. They instituted deadlines for completion with $10,000 per day fines for nonconformance. There were also laws that followed for industries that discharged chemical wastes into waterways.

It didn"t take long to start seeing an improvement in rivers and lakes. The soap suds generated by the roller dams on the Illinois River disappeared. New native fish species began to show up on the rivers, and angling began to take place like never before. Rivers started freezing at higher temperatures due to water clarity. (Stained waters draw more heat from the sun.)

Waterways continued to improve, and in 1959 the Saint Lawrence Seaway opened. This was a great engineering feat and allowed the largest ships to deliver goods from abroad into the interior of the country. This had never been accomplished before. Raw materials from all over the world opened up markets and provided an employment boom. As the ships became larger they required ballast water to be pumped into the vessel or discharged to compensate for water conditions and loads.

However, with the good comes the bad. That scenario was the start of invasive species being introduced into most all of our waterways, something that still haunts us today.

The first species that entered our Great Lakes systems through ballast water discharges were the alewives. They resembled large gizzard shad and were present in most salt water environments. With no natural predators they multiplied in great numbers, perished, and then washed ashore. They were in such large numbers they had to be moved off Chicago beaches using snowplows.

To remedy the alewives problem, coho and Chinook salmon, as well as brown trout, were stocked in the lake in large numbers in the 1970s. This was a combined effort of Illinois, Wisconsin and Michigan. In less than two years the alewives were brought under control.

The growth rate of the salmon and trout was phenomenal. With the large amounts of available food these fish grew at a rate of five to seven pounds per year. It also created one of the best sport fishing areas on the planet.

A few years later another invader entered the Great Lakes in the form of the lamprey eel, a species that lives on the blood of other fish. They are eel-looking but their head contains a large leech-like suction disk with rotary teeth. They attach themselves to a host fish and live off their blood, sometimes even destroying internal organs in the process. Many fish caught have had disk-like scars from lampreys. Some fish died as a result of these parasites.

Biologists discovered eels were spawning in small tributary streams entering the Great Lakes. They discovered a chemical treatment that destroyed the lamprey"s spawn but didn"t harm native species. This is done each year to control the eel population, but does not kill them all.

It wasn"t long before another invader was discovered in the Great Lakes. Enter the round goby. The round goby is a small fish, 6 to 8 inches in length. It destroys the spawn of most native fish. If an angler catches one, it is illegal to retain it alive. It was responsible for almost annihilating smelt and yellow perch in Lake Michigan.

Again, biologists went to work to solve this dilemma and soon discovered our native smallmouth bass loved to feed on gobies. Smallmouth were stocked in the lake in huge numbers. They were so efficient they have kept the gobies in check. There is even a fishing lure that resembles a goby, and it is very effective.

Another invader is the snakehead fish, which looks somewhat like a snake but is smaller in length with large teeth. It also destroys other native fish.

The snakehead has had some difficulty surviving winters in our Northern states and seems to have declined. The snakehead entered our systems from pet owners releasing them into a waterway after they got tired of them or they outgrew their aquariums. This practice is illegal.

Most of the aforementioned invaders came from salt water environments. Unfortunately it doesn"t end there.

As a result of flooding in the last 20 years, many Arkansas farmers near large rivers took up aquaculture, raising marketable fish species for sale throughout the country and abroad. They dug or blasted lakes and ponds on their properties and discontinued crop farming.

Business started to boom and other industries started up such as fish food companies and refrigerated vehicle drivers to haul the product.

While the fish farmer prospered another problem arose. Algae growth in the lakes and ponds became so great it was choking out dissolved oxygen needed for fish to exist. Farmers began to lose a lot of fish so began to look for ways to control algae growth.

Research led to an idea from Asian commercial fishermen.The Asians had a native fish that consumed plankton, weeds and algae, so farmers inquired about a purchase of bighead and silver carp.

Bighead and silver carp are hardy fish that are fast growing and feed constantly. To the farmers this seemed like a blessing in disguise. Multitudes of these fish were imported for the aquaculture"s lakes and ponds. The idea worked until the year 1996.

In 1996 our Midwest had the largest amount of rainfall that fell in a single storm. This occurred from Central Illinois all the way into Wisconsin. The Mississippi overflowed as well as the aquaculture ponds in Arkansas. As a result a quantity of bighead and silver carp entered the Mississippi River.

Around 1999 commercial fishermen and anglers started catching a very strange looking fish. It was small, about eight inches long, with eyes very low on its head. Biologists identified them as bighead and silver carp but didn"t seem to be overly concerned. Eventually these fish started to turn up in big numbers and in very large sizes.

We discovered them in the Illinois River"s backwater areas less than a year later. Our local biologist was contacted and identified them also. Again there seemed to be very little concern.

Presently, these fish are in the millions in the Illinois River and are threatening to destroy its entire ecosystem. Some of the fish we have caught exceed 35 pounds. They have consumed so much plankton the native bait fish such as gizzard shad are almost nonexistent in some river pools. Other species such as emerald shiners are not as plentiful as they were.

All native fish in our river system depend on plankton to survive shortly after hatching. Some of our larger predator fish are now in fewer number also.

I don"t really know if this is a result of the invasion but speculation tells me it is. These fish are also a threat to human safety as the sound of watercraft makes them jump high into the air, sometimes hitting boats' occupants, causing serious injury.

Currently there is no known control for these invaders. There is talk of bringing back commercial fishing as a form of control.

There also is an experimental plant in Havana, Ill., that is going to try to use these fish to produce omega 3 health capsules for human needs and also a farm fertilizer. The plant produces no offensive odors and could offer some fine employment. A similar plant is in the planning stages near Spring Valley.

These invaders threaten the world class salmon and trout fishery in the Great Lakes.An electronic barrier was installed more thana year agonear Romeoville to stop the fish from entering Lake Michigan.

I feel the electronic barrier at Romeoville is nothing more than lip service. If invaders entered Illinois from Arkansas in a little over a year, they also entered Lake Michigan long ago. These are the worst invaders we have had to deal with.

No one has come up with a remedy to protect our world-class walleye and sauger fishery on the Illinois River except to try commercial fishing and the processing plants. This needs to be done soon. In the past it was illegal to commercial fish from Route 89 all the way to Lake Michigan. This has to change. In our present economy these fish could also be used to feed the hungry.

Our Illinois River that has turned into great fishery could eventually be destroyed.