Early in Kevin Irons’ 19 years with the Illinois Natural History Survey — he began in 1991 as a large-river ecologist on the lower Illinois River — he had a prophetic encounter.

‘‘I remember a bighead carp was brought in, and it was, ‘What is this thing?’ ’’ he said.

He knows quite well now. Since 2010, he has been the manager of Illinois’ aquatic nuisance species program. He is at the forefront of halting the advance of bighead and silver carp (commonly lumped together as Asian carp) and keeping them out of Lake Michigan and the Great Lakes.

Silver carp found June 22 within nine miles of Lake Michigan:
Credit: Asian Carp Regional Coordinating Committee

That effort again made worldwide news when an 8-pound silver carp was found nine miles from Lake Michigan on June 22 below the T.J. O’Brien Lock and Dam. It triggered an intensive two-week search by multiple agencies with multiple methods that turned up no more bigheads or silvers.

‘‘We are keeping our bar high,’’ Irons said. ‘‘One fish is a concern.’’

There have been only two found past the barrier — one bighead and one silver — in the last decade.

The electric barrier on the Sanitary and Ship Canal was originally there to stop another invasive, the round goby, from coming from Lake Michigan toward the Illinois River and Mississippi system.

As silver and bighead carp made their much noted advance up the Illinois River, the barrier became the final stopper from them coming from the other direction toward Lake Michigan.

It’s that zone downstream of the barrier that is the focus of the most attention in the Starved Rock, Marseilles and Dresden Island pools.

‘‘That is important because we don’t want them up in the Brandon Road pool near the barrier,’’ Irons said.

Basically, they’re doing a helluva job in those three pools at reducing the quantity of carp.

‘‘But we are not resting on our laurels,’’ Irons said. ‘‘We are defending it because Lake Michigan is our great lake.’’

‘‘Contract fishers,’’ which Irons points out are different from commercial fishermen, are removing about a million pounds of silvers and bigheads from there.

Silvers and bigheads have a dominant presence in the lower Illinois River, but a report this month noted they had dropped by half in the upper Illinois. There are the usual academic caveats.

Southern Illinois used hydroacoustic sonar, cross-referenced with other methods, to determine how many Asian carp were in each pool.

The study found that in 2012-14 there was a 68 percent reduction (error boundaries from 50 to 75 percent) in Asian carp in the Dresden Island pool and about a 58 percent reduction in the Marseilles and Starved Rock pools.

‘‘We are standing tall in Illinois by working with our federal partners,’’ Irons said. ‘‘It is probably a model program with the U.S. Fish and Wildlife Service and the Army Corps of Engineers.’’

Irons would like more economic partners.

‘‘If industry becomes our partner, we can do bigger things,’’ he said.

He points to Asian carp as an ingredient in hot dogs, the Chicago company working on dog treats made from Asian carp and sweet potatoes and the boneless fillets from Carter’s Fish Market.

About the fillets, Irons said, ‘‘I would challenge a fish eater to tell the difference between that and bluegill or crappie.’’

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