Pekin, Ill. — Save for a few exceptions, most fish in Illinois were able to survive the stifling heat and drought this summer.
Sure, there were a number of fish kills, but most were minor, said Dan Stephenson, DNR’s acting assistant fisheries chief.
“I don’t know that most fishermen will see much difference,” said Stephenson.
But there was one exception, in particular.
That kill, probably the worst in the state this summer, was at Powerton Lake, a 1,426-acre lake in Pekin built in the flood plain of the Illinois River to cool a power plant.
With water evaporating at the lake, it created an unlivable situation for fish.
“The intake was at 105 degrees,” said Stephenson. “It was coming out of the discharge at 120 degrees. It cooked a bunch of fish.”
Wayne Herndon, a district fisheries biologist, said the kill was extensive.
“We did get some survival, but we haven’t appraised the damage yet,” he said.
Herndon said the DNR will do more survey work there than normal to figure out what survived, including electrofishing gear, gill net and hoop nets. That work hasn’t begun, as water temperatures at the lake were still in the 80s in the middle of September. That was still too warm to risk stressing the remaining fish any further. Herndon expected the lake would cool off enough in October to run the survey.
“We’ll base our management decisions on that population census. We’re fearful that we lost a significant amount of trophy catfish,” Herndon said.
Powerton had big channel, flathead and blue cats swimming.
“They were all affected by the kill,” Herndon said. “When you have a trophy fishery, it takes time for the fish to grow back into that status.”
Blue catfish grow fairly quickly, Herndon said, noting that it could still take 10 years before there are trophy blue cats swimming. That’s a better outlook than flathead catfish, he said, with a flathead taking 20 to 25 years to grow 40 to 50 pounds.
As for the lake’s trophy smallmouth bass fishery, Herndon thought most of those fish perished.
“The bass are almost completely gone, I’m sure,” he said.
It’s likely that, pending the results of the survey, the DNR may decide to manage the fishery at Powerton differently.
“We may want to give other species a look that we haven’t had as a part of our management scheme,” Herndon said, mentioning that the state may turn to fish that can better tolerate heat.
He was hopeful that some fish survived, finding pockets of water where they could tolerate the heat.
And fishing regulations on the lake will likely change, Herndon said.
“It’s going to affect length and limit restrictions,” Herndon said. “Things are going to change because of the effect of the hot water.”
At Spring Lake, another lake in the Illinois River flood plain northwest of Manito, there was also a fish kill of about 50 to 75 muskies, Herndon said. Spring is a natural lake.
“Because of the drought, there was less water for them to occupy,” he said. “They succumbed to low oxygen levels.”
Elsewhere around the state, there were other similar smaller kills.
On the Mississippi River, regional biologist Dan Sallee said there were northern pike kills documented in each of the pools from Lake Pepin on the Minnesota-Wisconsin border all the way down to the Quad Cities.
“It was a small kill (a few hundred per pool maximum), but we hate to see it,” Sallee said. “It was real good, quality fish, but that’s what happens when you have record heat.”
He saw dead northern pike in the 10- to 15-pound range.
“Made me sick,” said Sallee, who said there was no significant loss of walleye. “There were a few individuals, but who would know if that was hook injury or heat mortality. I only heard of two or three [fish].”
Near Chicago, there were a few small kills reported on shallow, private lakes, mostly less than 10 feet deep, according to Frank Jakubicek, a district fisheries biologist.
There was one 45-inch muskie reported dead on the Fox Chain, but “that could be hooking mortality,” said Jakubicek.
A few other private lakes in northern Illinois lost muskie, a northern fish not well-equipped to deal with hot weather.
Jakubicek said another private lake lost nearly all of its fish.