Open and not shut
Monday is Opening day for LaSalle Lake, which suffered a significant fish kill
LaSalle Lake will be permanently etched in my memory as a piece of pandemic history. On opening day last year, March 15, 2020, I had just returned home when Curt Pazdro messaged that all Illinois Department of Natural Resources sites were closed until further notice. Opening day for LaSalle is March 15 again, as usual. I don’t expect anything that dramatic to happen this year on Monday. But I do wonder how things will be at the cooling lake south of Seneca.
In July last year, a significant fish kill hit the lake. Fish kills are a fact of life at cooling lakes, which are designed to cool generating plants. In that role, during heat waves, the cooling lakes may heat up and dissolved oxygen levels may crash, leading to fish kills. The most notorious fish kill at a cooling lake in our area was in 2008 at Braidwood Lake, but all cooling lakes have fish kills to varying degrees.
“The fish kill [at LaSalle] was pretty substantial; it put a hurting on our larger-sized fish and big blues and larger catfish, especially,” said David Wyffels, district fisheries biologist. “Fall survey for blue cats showed good numbers of fish in the 20-inch range. Those fish were able to get into a thermal area they could survive in.”
Hybrid striped bass were affected, too, but the populations still seem OK.
“Bluegills and that stuff did not seem quite as impacted or they could find that thermal refuge easier than the big guys,” Wyffels said.
There are no planned changes for stockings in 2021. There will be the usual stockings of blues, hybrids, largemouth bass and smallmouth bass. If the hatcheries have extra bluegills, there may be some bonus stockings.
(Catching bluegills on the east bank is one of my favorite times at LaSalle.)
Back to the blues. LaSalle and Powerton lakes have done really well with the decision to begin stocking blues. In Illinois, the only better place to target blues is on the Mississippi River.
“Powerton grows a little bigger fish. Not sure if it is food or because it is a peaking plant. I am not sure why,” Wyffels said.
LaSalle grows some monsters of its own, too. IDNR staff have surveyed them to 32 inches. Anglers have reported some 70-pound-plus blues. The blues are interesting enough to be in an ongoing age and growth study at LaSalle on blues and channel catfish.
“There are tagged fish out there; if [anglers] catch them, call that in,” Wyffels said. “There are lots of influences into whether a fish will grow or take off. It is going to be looked at; that is part of that study.”
When I asked if he considered the big blues the glamor fish at LaSalle, Wyffels said, “At least from what I see when I tend to be out there. [Anglers] transition to fishing for blues and hybrids. A few out there are there for those nice bluegill.
“Big thing folks may notice is catching a lot of those smaller-sized blues, not that [the fish kill] killed all those big ones. Time will tell on that when we get a couple more surveys in.”
One thing the fish kill did was open up space in the lake’s food chain, and additional food resources are available for the smaller blues coming up.
As usual, there will be some people lining up Sunday night in anticipation of opening day. The weather for opening day looks a bit challenging with a cool and damp forecast.
Site superintendent Tom Jackson said there are no changes at LaSalle. Boating on the perched lake is often restricted by high winds. Do not count on regular concessionaire service. LaSalle is open daily 6 a.m. to sunset.