Record waterfowl numbers and native fish thriving at Dixon Refuge

With no traces remaining of any invasive carp, numbers of migratory waterfowl visiting the Wetlands Initiative's Dixon Waterfowl Refuge at Hennepin & Hopper Lakes this fall are the highest ever recorded, and populations of reintroduced game and native fish are thriving.

An aerial survey conducted by the Illinois Natural History Survey on October 28 found nearly 70,000 ducks present that day, in addition to more than 46,000 American Coots.

The successful removal of the common carp from the lake system in 2012, combined with the hemi-marsh restoration TWI completed in summer 2013, has created prime conditions for resting and feeding waterbirds. The lakes and their aquatic vegetation have swiftly recovered and, through the hemi-marsh effort, thousands of wild celery plugs were planted, along with other native species that are excellent food sources for waterfowl.

The 2013 fall migration has exceeded many of our previous records for individual species counts. Single-day counts for Ruddy Duck, Gadwall, Redhead, Green-winged Teal, Blue-winged Teal, Mallard, and Northern Pintail are all higher than they've ever been since the first year of restoration in 2002 (see chart above). The number of coots, a great indicator species for healthy lake vegetation, is nearly three times that of the next best year.

"It looks like we've hit a home run," said TWI senior ecologist Gary Sullivan. "2013 is turning out to be the best waterfowl year at Hennepin & Hopper ever."

Meanwhile, IDNR fishery biologists conducted electrofishing and netting of fish in Hennepin & Hopper Lakes in October to determine how well the new fishery is developing. The limited survey found that many large-mouth bass, northern pike, and walleye were present and rapidly growing. Native fish species such as pumpkinseed and the state-endangered star-headed topminnow were also numerous, and bluegill and bowfin, a rare ancient fish of the Illinois River backwaters, were both found to be reproducing in good numbers.

“All fish observed during the surveys were in excellent condition,” said Sullivan. “They were averaging around 120 percent of peak condition; that is, they were fat, happy, and growing.”

Fishing at Hennepin & Hopper Lakes continues to be closed to allow the fishery to recover. Public fishing is expected to reopen in 2015.