The question isn’t whether more fish and species live in the Chicago Area Waterway System (CAWS) since the Clean Water Act, but are they getting bigger?
The simple answer is a qualified yes from Shedd Aquarium research biologist Austin Happel, Ph.D., and U.S. Army Corps of Engineers project manager Patrick Kennedy.
They published “Increased fishing quality of Chicago’s waterways following the Clean Water Act” in late May in “Fisheries Management and Ecology.” It “analyzed 35 years of historical electrofishing data (1985-2020) to determine if there were any body size changes in the available fish populations throughout Chicago’s waterways.”
It gave me a good reason to talk with Happel.
Let’s start south.
“Something super unique is happening in the South Branch, something in the barge slips and Bubbly Creek,” Happel said. “Something is happening down there in biodiversity.”
The old barge slips are shallow enough to function in a similar way that wetlands or connected ponds do to wild rivers. Of course, that is with the caveat unless the Racine Avenue Pump Station is having a dumping event.
“Our research suggests that the barge slips are being used as refuges and nursery areas much like how wetlands connected to rivers operate,” Happel emailed later. “I think these remnants of industries being analogs of important natural habitats is a cool story worth studying and talking about more.”
Absolutely. I remember the sense of discovery in 2000 when Rich Pinkowski showed me the largemouth bass, not huge but good ones, stacked in the slips near Bubbly Creek.
On habitat, I wondered if the floating islands of vegetation, one change in recent years along the Chicago River, help.
“It’s not hurting,” Happel said. “There are lots of benefits, some are easier to track.”
You can see plants growing and birds being attracted to them.
“It’s harder to see fish populations change,” he noted.
They’re trying to figure if more larval fish are around the islands. A telemetry project with the Metropolitan Water Reclamation District of Greater Chicago on adult fish, primarily common carp, largemouth and bluegill, started on June 12. That will help answer such questions as whether fish spawn around the floating islands, use them during poor water quality events or come regularly to feed.
Receivers will be placed near the splitting points, such as Wolf Point, and by the Wild Mile.
One of the odd findings is that while most species and populations trend up, common carp and gizzard shad dropped.
On carp, Happel said, “They tend to be very large old fish, very few juveniles. We find tons of [larval fish], but are not finding those young classes, that is leading to a population decline.”
The decline of gizzard shad may be an anomaly It’s related to the area on the Calumet from the T.J. O’Brien Lock and Dam to Lake Michigan. Gizzard shad remain the most abundant species in CAWS.
Another thing that caught Happel’s (and my) interest is a handful of walleye surveyed this year in the North Branch and North Shore Channel last month and one more on the South Branch this month, but Happel cautioned, “Not like enormous numbers.”
That jells with what dedicated river anglers such as Jeffrey Williams have seen downtown this spring.
When it comes to anglers, walleye are the goods.
The most famous catch remains the 6.75-pound walleye (weighed on the certified scale at the former Henry’s Sports and Bait) Toni Pellegrino caught Oct. 8, 2007 on the Chicago River near DuSable Harbor.
‘‘I remember it was about 2 or 3 in the morning,’’ she recalled. ‘‘I was fishing for salmon, and then I caught the big one. She was beautiful. I couldn’t believe that I caught such a fish. It was amazing and exciting.’’
Less exciting, but maybe more significant, Happel mentioned an increase in yellow bullhead, which are “pretty sensitive” to what is happening in the substrates.
“Every system has a capacity limit,” said Happel, which is why he is looking at things such as habitat to take the fisheries in CAWS to the next level.
He cites the Calumet, which over the 35 years of data, went from a few skinny bass to some memorable or trophy bass.
A doorway to more is at onlinelibrary.wiley.com/doi/10.1111/fme.12635.
