The largemouth bass is the top piscine predator in the Chicago River. You’ll also find it in Lake Michigan, as well as in the Des Plaines, Illinois, Fox and Kankakee Rivers. The largemouth is pale green or olive, even lighter on the underside, and is distinguishable by the uneven dark horizontal stripe that runs the length of each side of the body. But its key characteristic, says Kurt, the one for which it is named, is its long jawline, which extends beyond the rear edge of the eye. He adds that the corresponding gape as a largemouth goes after prey or bait has earned the species another name in some regions: bucketmouth.

The force with which this foot-long, 2- to 3-pound fish will strike a lure or bait makes largemouth bass a fisherman’s favorite. According to the International Game Fish Association, the species also may be the most intelligent freshwater fish for its ability to recognize and avoid a specific lure after one experience with it. (A smart largemouth can live 10 years and reach a length of 20 inches and a weight of more than 5½ pounds. Uncommonly smart 10-pounders are common in Illinois.)

Smallmouth bass, as their name indicates, have a shorter jawline than the largemouth. “It only extends to the middle or the end of the eye,” Kurt says, pointing out examples of both species swimming in the “healthy ecosystem” habitat of the Great Lakes Invasive Species exhibit in his gallery. If you still can’t tell the difference, however, look for this fish’s dark broken vertical stripes on a medium brown background and red or orange eyes. They fit their nickname: bronzeback.


“This is another popular sport fish. In fact, the smallmouth bass fishery in southern Lake Michigan has
increased so much,” he continues, “that about a decade ago, what’s called the Bassmaster Classic was held at Soldier Field. That’s like the Super Bowl of bass fishing.” It turns out Kurt is an avid fisherman as well as an expert native freshwater fish biologist. 

He’s also a concerned conservationist, and he explains that the smallmouth resurgence may be the result of ecological disruption in the lake. “Biologists think that there are two reasons why the smallmouth have increased so much. One is the establishment of the round goby, an aggressively invasive species, in Lake Michigan. It turns out to be an excellent food source for smallmouth bass. The other reason is another invasive, zebra mussels, which have cleared—not cleaned, but cleared—the water so much that smallmouth bass, which are primarily sight feeders, can see all the gobies, which have become a forage base for them. So biologists are seeing bigger smallmouth and more smallmouth.”

Like largemouth bass, smallmouth are also found in the Des Plaines, Illinois and Fox Rivers, “and the Kankakee River is really well known for smallmouth,” the aquarist says. Smallmouth bass are intolerant of poor water conditions; their presence in a river or lake indicates decent or better water quality, with good levels of dissolved oxygen, the form that fish breathe. Their repopulation of their historic range, he says, is largely due to the long-term benefits of the Clean Water Act.

The largemouth and smallmouth together are also called black basses, says Kurt. They are the largest members of the sunfish family, Centrarchidae, which also includes our next soloist.

Rock bass (one is pictured at the top of the page) get their common name not from their musical tastes or talents, but from the rocky nearshore lake habitats they prefer. Kurt notes that they’re very common along the Lake Michigan shore, so rock bass might be hanging out at the edge of the harbor, enjoying Jazzin’ along with Shedd’s guests on the lakeside terraces. Rock bass do not seem to be perturbed by human activity: They can be found living under docks and near swimming areas in inland waters. 

“But they’re one of the species that we see being affected by the round gobies,” Kurt says. “We don’t see the numbers of rock bass that we used to.” Where the larger smallmouth bass preys on them, the 6- to 8-inch, half-pound rock bass are being chased out of their native haunts by the territorial invader. Gobies also consume the eggs and fry of these bottom-nesters, a quick way to decimate the rock bass population. Visit our rock bass at the Local Waters Streams habitat with other sunfish. (And see round gobies a few habitats over.)

You might be surprised to find white bass in with silver and bighead carp—the so-called Asian carp that make other aquatic invaders look like welcomed guests. “This habitat tells an ecological story that not every fish is being wiped out or is having a problem with invasive species,” Kurt says. “Some, like the white bass, could actually thrive. Unfortunately, it could become a monoculture, where maybe one native species survives. We might be seeing that with the increase in smallmouth bass. Could they start overpopulating and create an imbalance and new problems? Invasives aren’t going to affect everything, but they certainly lessen the diversity.”

The white bass on exhibit were collected in the Illinois River. “These are a very popular game fish,” Kurt says, “but only when their spawning run occurs. People throughout the Midwest travel to Wisconsin to fish for these, especially on the Wolf River, which is well-known for a big white bass run. White bass is a good-eating fish.” He is quick to add that rock bass, largemouth bass and smallmouth bass are all good table fare. “I’ve eaten plenty of fish, including the basses.”

Kurt then explains, “The term bass is kind of generic. The rock bass and largemouth are in the same family, but they’re not that closely related. The rock bass are more related to bluegill and green sunfish. And the white bass aren’t even in the same family.”

And on that taxonomic note, the bass solos go out.

See cool fishes and hear hot music every Wednesday evening through Sept. 5 at Jazzin’ at the Shedd. New this year, chill in air-conditioned comfort in the Aqua Lounge. This special ticket includes live jazz, a small-plates buffet, a complimentary cocktail and an indoor view of the evening’s fireworks.

Karen Furnweger, web editor