Fish Fry Day: “Fishes of Wisconsin” Challenge – Largemouth Bass

Happy Fish Fry Day! For those of you just tuning in, last week we embarked on a crusade to share a little bit about ALL 183 species on the amazing “Fishes of Wisconsin” poster.

Panorama is a must for a poster this epic. Kandis Elliot's "Fishes of Wisconsin" poster.
Panorama is a must for a poster this epic. Kandis Elliot’s “Fishes of Wisconsin” poster.

Fish #1 was the suckermouth minnow, and we learned all sorts of fun stuff, like the fact that not all small fish are  minnows and not all minnows are small. But now on to a new species: Today, we introduce the beast lurking beneath the suckermouth minnow (on the poster at least) – the largemouth bass.
Largemouth Bass on the Fishes of Wisconsin poster.
Largemouth Bass on the Fishes of Wisconsin poster.

Micropterus salmoides, or the largemouth bass, is a top predator in many freshwater ecosystems. In fact, it’s so good at its role in the food web that it is one of the most successful fish across the globe. In other words, either occurring naturally in an ecosystem or being introduced by humans, the largemouth bass has no problem being king of the hill.
A lot of that has to do with its namesake mouth – which, unlike smallmouth bass, extends beyond the back of its eye. That mouth is useful for pursuing all sorts of prey – from crayfish, to bluegill, to the occasional, unlucky mouse! (Note to mice: stay out of the water!) It also has a lot to do with the fish’s “personality.” Largemouth bass are aggressive, energetic fish and fight hard on a fishing line, making them one of the nation’s most popular sport fish.
We could go on and on with fun facts about largemouth bass, but, well, we don’t have all day. So here are three morsels to chew on:

Largemouth Bass Play a Pivotal Role in Our Research

Batt adds largemouth bass to Peter Lake to force the "trophic cascade" documented in his study. Photo: Laura Smith
Batt adds largemouth bass to Peter Lake to force the “trophic cascade” documented in his study. Photo: Laura Smith

One well known study conducted by Center for Limnology scientists, Steve Carpenter and Ryan Batt, owes much of its success to largemouth bass. And that study may someday lead us to be able to predict major ecosystem changes. The experiment involved our favorite “real world” laboratories – Peter and Paul Lakes.
The two small lakes, located on Wisconsin/Michigan border in the University of Notre Dame’s Environmental Research Center,  were once connected bodies of water, but we long ago separated them so that we could do whole-lake experiments. In one lake, we’d add nutrients, or fish or whatever the experiment called for. The other would serve as the control (where we didn’t change a thing).
Our “trophic cascade” research involved stocking largemouth bass into Peter Lake. Researchers kept adding bass into the lake until its food web regime completely shifted and, as the largemouths ate everything they could get their mouths around, became a food web dominated by bass. Throughout the process, the scientists recorded data on all sorts of variables, like dissolved oxygen, pH levels, and chlorophyll, a measurement of plant and algal abundance. What they found was that the lake gave early warning signs of its eventual food web collapse. Someday, thanks in no small part to largemouth bass, we may be able to heed an early warning and head off an ecological catastrophe, using what we’ve learned from this study.

Largemouth Bass Are Good Fathers

When water temps hit about 60 degrees Fahrenheit (15.5 Celsius) in the spring, male largemouth bass begin to clear a circular nest. After spawning, the males guard the nest and, even after the eggs hatch, they will guard their new fry for as many as four weeks, swimming around with the “brood swarm” or large school of their little offspring and chasing off any potential predators.
Largemouth guarding his nest with eggs. Courtesy Illinois DNR

Parental care like this is probably another reason largemouth bass do so well wherever they live – not every newly hatched fish species gets its own security detail!

Largemouth Bass are Horrible Gluttons

Unfortunately, the “good Dad” award will only get you so far. A different Center for Limnology study, led by Jereme Gaeta, looked at what happens in northern Wisconsin lakes when water levels drop (in this case, due to an extended drought) and leave near-shore habitat, like fallen trees, sitting high and dry, out of the water.
In that scenario, the research found, prey species of fish, like bluegill, have nowhere to hide and are quite quickly consumed by the lake’s resident predators, especially largemouth bass. The end result is that the bass pig-out on any available fish and end up eating themselves out of future meals. Once they’ve exhausted the other, less fortunate, species in the lake, bass were  forced to turn to terrestrial sources of food, like dragonflies and the occasional, unlucky shrew – meals that forced them to spend more energy to get less, stunting their growth. Oh well, no fish is perfect!
Thanks for tuning in to this week’s “Fishes of Wisconsin” Challenge! Next week, the stickleback!
Thanks to University of Wisconsin Sea Grant Institute, the Wisconsin Department of Natural Resources, and The University of Michigan for info.