Understanding Bass Forage: Sunfish

Bassmaster / by Peter B. Mathiesen

These "go-to baits" evoke strong memories of battles won and lost, but are selectively not remembered for the many hours of casting without a hit. On your next trip, as you peer into your bait box, ask yourself if you're missing a key element that bass feed on. How often are you throwing baits that imitate sunfish?

There is a reason fish biologists use sunfish as the primary food source for bass when stocking a pond. It's as if bass live to eat them. Whether it's bluegill, green sunfish, rock bass or pumpkinseed, all of these fish play a critical role in the diet of most bass throughout the United States. Most of us have taken a child fishing for bluegill, ending with a largemouth crushing the little 3-inch sunfish and bending your kid's Mickey Mouse rod to the verge of collapse.

"The relationship between bass and sunfish is inextricably linked together as predator and prey," said Doug Beard, a USGA fisheries biologist in the Washington, D.C., area. "They are both members of the sunfish family, and they make every effort to inhabit the same littoral and sublittoral dominion. Compared to other food sources, and depending on the watershed, largemouth can ingest up to 40 percent of their annual diet from sunfish. In most impoundments, that will be bluegill," said Beard.

Living like bluegill

Adult bluegill spawn from April to midsummer and are dependent on water temperatures that must remain between 67 and 80 degrees. A female can lay up to 50,000 eggs. Bluegill start their lives much like bass, spawned in a nest guarded by the male. The risks for the new inhabitants are extreme and similar to those of young bass, as they quickly swim to grass cover before a long list of predators devour them.

The young-of-the-year bluegill fry will feed on plankton in the grass and try to avoid predation. If grass isn't available, they will head to the thickest submerged cover and brush, or if in deep lakes, treetops.

By late summer (assuming the eggs hatched in spring), the bluegill has reached postage-stamp size and has become the premier target for largemouth and smallmouth. At this stage of life, a bluegill's diet is keyed to small insects and tiny crustaceans.

A bluegill's growth rate is slower than many think. Depending on food, water quality and cover, it may take four-plus-years to produce a hand-size bluegill, depending heavily on where it lives. South of the Mason Dixon Line, most sunfish have the opportunity to spawn more than once and have a long feeding cycle that is interrupted only by cold water for just a few months. Northern bluegill have a lot of work to do in the summer and early fall to get their growth rate moving before winter shuts down their metabolism, reducing the amount of food they eat.

It takes a minimum of two full years of growth in the very best conditions in the Deep South, and up to four years in colder climates with limited growing seasons, to reach spawning size.

Impoundments that have substantial amounts of grass will usually have strong, stable bluegill populations. Lakes with changing levels and less vegetation have greater fluctuations in their sunfish populations, and often see a stronger mix of green sunfish or pumpkinseed.

A guide's view

Size is key. Once a bluegill reaches spawning size, it's only a target for the largest bass in the lake. Bill Babler, a fishing guide from Shell Knob, Mo., has spent years chucking bluegill baits in Missouri and Arkansas lakes. "I have never seen a largemouth crash an adult bluegill or sunfish on a bed," says Babler. "Table Rock is different from other lakes. It's rocky and deep, and if they've pulled down the lake, all the grass is left high and dry," said Babler. His favorite trick is to run a chartreuse spinnerbait with a gold Colorado blade through the tops of cedar trees. "On Table Rock, bluegill suspend in tree cover because there just aren't many other places for them to hide. We have few grasslines and even fewer docks, compared to places like Lake of the Ozarks, which is littered with thousands of docks."

Babler observes that bluegill behavior is completely different from other forage fish, especially in the way they move. "I watch bluegill all the time. They don't dive vertically unless they're being pursued. They seem to move more like a submarine; inflating their bladders and slowly lowering and raising vertically up and down. When they're swimming, they stop, start and stop, and start, unless fleeing from a predator. I rarely see them swim continually. Other anglers may not agree, but my favorite method for attracting bass to a bluegill bait is ripping jerkbaits above and next to brushy cover." Babler uses rebuilt Rouges by Buster Loving that are modified with different lips, hooks and brilliant paint jobs.

Other bluegill-specific techniques that Babler uses include working a 3/8-ounce black Akin's jig with a blue trailer. He also likes working square bill crankbaits. He modifies them to suspend and fishes them in short, stop-start retrieves. When he can find grass, he usually moves back to a chartreuse spinnerbait or a red, blue and gold lipless crankbait. "Bluegill are the key to most of the bass I catch when they're not caught on crawfish imitations," said Babler.

Lots of colors

Although bluegill are the prevalent sunfish in most bass water throughout the United States, other species play a roll in the mix of sunfish predation by bass. Largemouth will eat green sunfish, pumpkinseed, rock bass, longear and even crappie. Many of these other more aggressive sunfish can force bluegill out of the grass into open water. If the impoundment gets overpopulated, bluegill will eat their own eggs.

Keep in mind that every 1- to 3-inch bass is fair game in this mix. Sunfish are voracious eaters and stay active in all but the hottest and coldest conditions. Understanding where these prespawn-size fish are at any given time is critical to your success.

Myths and legends

Many anglers believe that if a bluegill or sunfish is too large, it can get stuck in a bass' throat and choke it to death. During interviews for this story, I found two anglers who said they had found bluegill stuck in the throats of dead largemouth.

However, biologist Doug Beard says, "It may be possible, but in all these years, I have yet to see it - or have someone bring a fish to me that's been choked. That would go against years of evolution."

Going blue

Today a rising tide of anglers are finding that sunfish can be a consistent key to unlocking catch rates. We continually search for the consistent reactionary strike, when more often we should be taking in information on the why, when and where. If you're fishing water that's less than 10 feet deep, with cover, and you're using a jig, swimbait, spinnerbait or crank, there's a substantial chance that the bass you just caught thought it was chasing a sunfish.

In the zone

Any pond, lake or river is scientifically divided into zones that biologists use to establish habitat - and fish behavior. Bass will move in and out of most of these zones, based on the type of water, time of year and available food. Understanding the zones enables you to know where fish are and where they are not.

Littoral: Where the shore meets the land. This zone has waves, vegetation, and lots of light penetration. It is typically very shallow and beachlike. Bass and bluegill will inhabit this area to spawn and feed. The area can be alive with invertebrates and other small fish. Even dropoffs in quarry lakes have a littoral zone; it's just extremely small.

Sublittoral: This is the preferred home for most bass and bluegill. There is light penetration, plant life, a large array of food, and in most cases, some kind of cover. Most anglers, knowingly or not, spend the majority of their time casting in the sublittoral zone.

Limnetic/Pelagic: Open water with light penetration. There are no plants or structure, but the zone is above the thermocline. This is the type of water where bass suspend or go to chase schooling baitfish.

Profundal: This is the deep water at the bottom of a lake below the effective penetration of light. Depending on latitude and water quality, this is not a primary spot for bass and bluegill. In many cases, they are completely vacant of bass and bluegill.

Benthic: Simply put, it's the bottom. In a shallow pond or lake, the benthic zone can be full of plant life and fish when it connects to the sublittoral zone. However, it is often void of plant life, bass and bluegill when it meets the profundal zone. It is a place that contains many nutrients from decomposing organisms that will eventually come to the surface during fall and spring turnovers.

Originally published in 2008.