What's for dinner? If you are a largemouth, smallmouth or spotted bass, the answer might be easy: anything that doesn't try to eat you first. That's good to know if you like to catch bass because with so many food choices, finding a lure that works is sometimes as easy as choosing one that looks good to you.
Biologists who study largemouth bass sometimes examine the stomach contents of fish to learn more about them. John Odenkirk, a fisheries biologist with the Virginia Department of Game and Inland Fisheries, says he looks at what bass eat to determine the health not only of an individual fish but all the bass that live in the same body of water.
"There are three things that determine the overall health of a lake's or pond's bass population: recruitment, which is how many baby bass grow to adults; growth, or how fast they grow and how healthy they are as they grow; and mortality. In other words, what kills bass, how long do they live, that sort of thing," he explains. "By looking at the various foods in their stomachs, we can determine how well they are eating. If they aren't getting big fast enough, we might be able to help them out by providing more food."
Biologists help bass eat better by stocking forage fish such as shad, herring or alewives in a lake that doesn't have enough food to help bass grow big. Who doesn't like to catch big bass? Most of the time, however, bass do pretty well on their own. Almost every lake, pond and river has at least some food bass will eat, because, well, bass will eat pretty much anything that comes by them.
Odenkirk says what he finds in bass stomachs is limited only to what foods are available and what they can fit in their mouths. Insects, crayfish, frogs, lizards, snakes, other fish and even baby birds end up on the dinner menu. Bass will even eat each other. The name of the game is survival, and if a bass has to eat another bass in order to live, he won't think twice about it.
Florida Fish and Wildlife Conservation Commission biologist Fred Cross says bass are opportunistic feeders. So what they eat is often determined by what swims in front of their mouths. In other words, they eat whatever is available where they live. He's found eels, snakes and baby ducks in bass stomachs.
Bass also choose their food based on their size. The bigger the bass, the bigger the meal. Largemouth in California often eat rainbow trout 10 to 12 inches long, and Cross once found a 12-inch gizzard shad in the stomach of a 10-pound largemouth. He has, however, examined stomachs of big largemouth that were crammed full of tiny grass shrimp, proof that bass will eat whatever is easy to catch.
"If they are available, threadfin shad are probably the favorite food of largemouth bass. We find them in bass stomachs more than anything else," says Cross. "Shad are soft-rayed fish, which means their fins aren't as spiny as, say, a bluegill's. Soft-rayed fish are easier to swallow."
But threadfin and other shad don't live in every lake or pond. In fact, they need water with plankton in order to survive. Plankton are tiny plants that suspend or float in the water. How can you tell if your lake has plankton? Look at the water color. Lakes with a green or light brown tint probably have plankton, but clear lakes don't. If your favorite bass lake doesn't have any threadfin shad, don't worry. There are probably bluegill, crappie, minnows and other fish.
Both Cross and Odenkirk say insects are a vital food source to young bass. Without little bugs, baby bass can't grow into big bass. Most healthy lakes, ponds and rivers have an abundance of aquatic insects, or insects that live under the water.
"Largemouth bass switch from a diet of mostly insects to a diet of fish and other larger prey when they reach about 8 inches," says Cross.
Hold the vegetables, please.
One thing bass don't eat, says Cross, is plant matter. Although he finds aquatic plant life in bass stomachs frequently, he and other fish experts think it ends up in bass' mouths when bass are feeding. They don't eat it on purpose.
"Bass suck in their prey, and their prey often live in and around aquatic vegetation. When they grab a shad or a bluegill, they don't want to open their mouths to get rid of the plant matter, so they just swallow everything," he says. "Bass don't need nutrition from plant matter the way you do."
Odenkirk says he often finds hooks and pieces of fishing lures in bass stomachs. In some cases, the fish will pass those items that don't digest. Other objects, like hooks, disintegrate in the stomach thanks to the strong acid that helps digest food.
Figuring out exactly why bass eat what they eat is still a mystery, notes Odenkirk. He studies smallmouth bass in several rivers in Virginia and has seen many big fish with madtoms, a small member of the catfish family, in their stomachs.
"I have no idea why a smallmouth would eat a madtom, which has three sharp, barbed fins, when it has so many other options. The rivers I work are loaded with shiners, sunfish and other forage fish that aren't as spiny as madtoms, but they seem to prefer madtoms," he said.
Biologists think bass (and other fish) will choose one type of food over another because it provides them with the vitamins and minerals they need to grow.
The good news is that you don't have to match real fish and other creatures perfectly the next time you go fishing. Look in any professional bass angler's tacklebox and you'll see an assortment of lures that don't look like anything in nature. Spinnerbaits, buzzbaits, and a variety of wild-looking soft plastic lures all catch bass. Largemouth, smallmouth and spotted bass are as curious as any other animal and will take a close look at something that seems out of place.
However, while you might pick an object up with your hand to take a closer look, a bass would grab it with its mouth, chomp on it a few times and decide if it's something worth eating. In other words, just because your favorite lure doesn't look like a real creature doesn't mean it won't work. Sometimes, bass will eat anything!
What eats bass?
Little bass have a pretty tough time. Many are just another source of food for larger bass and other fish, and all kinds of other predators eat largemouth and smallmouth bass. John Odenkirk says a baby bass has about a 10 percent chance of growing into an adult. That is, nine out of 10 little largemouth never make it to their third or fourth birthday. The bigger the bass, the better its chances of survival, but those that do survive can still get eaten.
Plenty of big predators love the taste of fish. Turtles, alligators, herons, otters and of course, people, eat bass. Although many anglers practice catch-and-release, sometimes people keep a few for dinner. There's nothing wrong with that. Fisheries biologists set size and harvest limits to allow anglers to keep bass while still maintaining a healthy and abundant fishery.
Originally published in August 2007.