Bull Bluegills and Optimal Foraging
September 30, 2014
When it comes to bluegill fishing, dinks just don't cut it. It's bull bluegills surpassing 9 inches with muscular humps on their heads and enlarged chests that are what many panfish anglers obsess over. Paraphrasing the comedic words of Brian Fontana from Anchorman, if someone tells you they have a secret potion for trophy bluegills that 60 percent of the time works every time, be skeptical and amused. My recent experiences have tended toward fishing larger baits — both livebaits and artificial lures — to fool and provoke strikes from bull bluegills. To weed out smaller 'gills, jumbo leeches, whole nightcrawlers, swimbaits, and crankbaits have become staples. Bruce Condello, a bull 'gill expert, has fished most of the best bluegill fisheries in the country and has caught as many 2- to 3-pound 'gills as anyone. When he's not putting smiles on faces as a dentist in Lincoln, Nebraska, he's busy as an aquaculturist breeding bluegills and sharing his love for the species with like-minded anglers on his website bigbluegill.com. When asked about catching trophy bluegills on larger baits, he recounted memories of his childhood to offer an analogy for pursuing trophy 'gills. He says the grocery store is where he first had the epiphany of reconciling competing points of view regarding selecting proper bait sizes for fish.
"As I entered the grocery store, the first thing I saw was the magazine rack," he recalls. "All the magazines were nicely ordered with dramatic cover photos and bold-lettered writing inviting you to spend your pocket change for a chance to become more informed. There were always three different outdoor magazines but they might as well have all had the same name because their stories were similar. But something struck me this particular month. I noticed a serious conflict in the cover headlines of two of them. One read, "Go Big for Spring Largemouths," and the other read, "Smaller is Better for Spring Bass." Clearly, somebody is mistaken, I thought. Whatever the case, I bought both magazines.
"The two articles couldn't have been more different, and today a Google search yields multiple arguments on each side of the debate. So which is better, big or small? Turns out they were both right — whether you're after bass or bluegills. Trophy fish often are less concerned about whether a food item is big or small than if it fits in their mouth, that there's room in their stomach, and that they can capture and consume it with fewer calories expended than gained."
Years spent as an aquaculturist and observer of bluegills have convinced Condello that 'gills go crazy for bigger baits like fathead minnows. "I've watched 100 bluegills in a 300-gallon tank go through 200 fatheads in less than 24 hours," he says. "Growth rates of bluegills on fathead minnows are about as good as they get. Big 'gills are carnivores. The scientific literature on bluegill diets shows that even big dragonfly larvae, sometimes 20 to 30 millimeters long, can be a staple in the diet of big bluegills. So why wouldn't you always 'go big' for trophy bluegills? The answer is that it depends. Water temperature, prey abundance, and fish temperament all factor into it.
"If a big bluegill's sole reason for existence was to grow at the most rapid rate, you could make the inference that a 10-calorie minnow would always be the target," Condello explains. "But a bluegill didn't get to bull proportions by being stupid or frivolous. He got that way because he's programmed to maximize the calorie-gained-to-calorie-expended ratio.
"If the pursuit of a fathead minnow expends one calorie, he'd better have a better than 10-percent success rate in capturing that prey. If not, there's a net loss of calories and the fish doesn't grow, or even starves or dies. To grow bigger, targeting vulnerable minnows — those that are slow, injured, or lacking awareness — is more efficient. This is a theory known as 'optimal foraging.' All organisms must make more deposits than withdrawals over time to survive."
Condello studies bluegills in an 11-acre quarry pond in his backyard. "My observations of the feeding habits of big bluegills have shown that they almost always study a food item before attempting to consume it." Bluegills are suction feeders in open water, so they need to get close to their meal. They then open their mouth in less than 1/25th of a second, creating a vacuum as their mouth cavity expands. This causes the surrounding water and prey to rush into their mouth. Anyone who's sight-fished for bluegills has seen this feeding behavior and knows how quickly bluegills can also expel the water from their mouths and reject an unwanted offering. Fooling trophy 'gills isn't easy.
Condello says that almost any reasonable presentation within a bluegill's sight path gets a solid look. "A bluegill is able to assess the size-to-vulnerability ratio from a distance. Hundreds of times I've seen big bluegills turn and watch a small jig from at least 6 feet away, only to make no effort to pursue it. If that same jig pauses for just a moment, perhaps suggesting it's injured, bluegills charge over for a closer look from about an inch away. It seems at that point that they evaluate whether the bait is recognizable and vulnerable, and also if it's the proper size." This suggests the need to create presentations that take all of these factors into account. While the outcome may be up to fate, Condello suggests that anglers must first put themselves in a position to succeed if they want to catch trophy 'gills.
Optimal foraging theory explains why trophy bluegills sometimes feed on small prey. Tiny foods, like phantom midges, mosquito larvae, and zooplankton are more abundant and easier for bluegills to capture and consume than minnows. These small prey items, however, must yield more calories than the expenditure of energy to capture them.
"Even if these smaller items are excessively vulnerable, a trophy bluegill can't haul his big body around a lake just to plink a few Daphnia," Condello says. "A 0.1-calorie expenditure eventually shrinks and kills a big bluegill over time if the gain is only .05 calories. If you want to catch a big bluegill on a small bait, you need to present the offering right in front of his face, and the presentation needs to represent an item it knows has almost a zero chance of escaping."
Science into Practice
To mimic tiny food morsels, use weighted flies and micro-jigs in the 1/80- to 1/100-ounce range and copy the motions of these critters. Among the most common microscopic animals on the bluegill's menu are Daphnia, a type of Cladoceran (larger zooplankton often called water fleas) that can grow to several millimeters and swim in small hopping motions. Other small foods include copepods, which are small zooplankters that move quickly with a backward kicking motion, and amphipods, larger invertebrates measuring 0.5 to 2 centimeters that include scuds and freshwater shrimp, which move in darting, side-swimming motions.
Replicate movements of these small foods with small jigging maneuvers, stop-and-go jerking retrieves, and darting motions with a jig, weighted fly, or softbait. While it may be necessary to fish small at times, if prey is abundant and a big bluegill is presented with food items of different sizes, studies indicate it favors larger prey, which offers a greater calorie return per calories expended.
At first glance it might seem that optimal foraging theory gives bluegills just a little too much credit. But it's not that they do complicated calorie calculations each time they eat. Rather, feeding behavior and food choices are driven by innate behavior and past experiences.
It reminds me of my house cat, Tiger, who can stare deliberately for 20 seconds or more at a countertop or book shelf while seemingly making a complicated physics calculation to determine the exact amount of force and angle of trajectory necessary to propel himself to his desired perch. He never misses. Yet this cat chases and bites his own tail — clearly not a Rhodes Scholar.
Condello suggests that if a bluegill angler wants to put this science into practice, goal number one should be to identify waters that hold trophy 'gills. Then show big fish something that they would ordinarily pursue. "Your powers of observation can go a long way," he says. "You may be able to determine if big dragonfly larvae, or possibly young-of-year bass or other fish are regular diet items of big bluegills.
"If you use a lure that represents a fish, make it as easy to capture as possible," he says. A 1.5- to 2-inch floating minnowbait such as a #5 Original Floating Rapala fished in a slow, irregular fashion mimics an injured minnow. Alternatively, since large insect larvae are generally easy targets for big 'gills, try a 1- to 2-inch black or dark green soft-plastic grub on a 1/32- or 1/16-ounce jighead. Fish it slowly across the bottom and between stalks of vegetation. Tip the jig with a plump redworm to fool even the most discriminating 'gills. "Give bluegills something they like, where they like it, and make it big enough to create a good gain to effort ratio," he says.
Knowing feeding behaviors and favorite food items of bull 'gills increases your odds of connecting with them, but it's also helpful to know how to bully a bull. There are times when big bluegills can be provoked into striking, even though their intention isn't to eat. Throw out optimal foraging theory and replace it with another basic compulsion of bull 'gills — to breed and guard their territory.
During the Prespawn Period and extending through postspawn, big male bluegills establish and defend a territory. While they may ignore a small offering and allow it to go unharassed as it proceeds through their territory, a larger fish or lure on their turf gets bulls seeing red. They charge and pursue such an intruder for 10 or more feet when they typically won't budge more that a couple inches to inspect a small offering. This same behavior is displayed by other fish species such as bass, trout, and salmon.
Once bulls are working a bed, this approach is less effective. During the Prespawn and Postspawn periods, a small swimbait such as a 3-inch Storm WildEye Rippin' Swim Shad or crankbait like the 2-inch Bandit 100 Series fished across 3- to 6-foot flats in front of traditional spawning areas can be good.
Condello agrees and has been successful using the Strike King Bitsy Minnow in Baby Bass pattern. "We call it the revenge lure," he says. "Some of the hardest strikes I've ever had from bluegills came on this little true-running crankbait. When a 10-inch bluegill hits the Baby Bass pattern, it's almost as if he's using vengeance as a motivator. Perhaps seeing your brothers eaten by bass your entire life creates this aggression.
"I've caught dozens of bluegills over 2 pounds, and five fish over 3 pounds using these techniques. Two of the five 3-pounders came at the famed Richmond Mill Lake in North Carolina using slow and erratically twitched Lucky Craft Pointer 100s. A big 'gill, especially one near his spawning nest, shows enough aggression and guile to attack a fish that he'd have to fold in half to swallow."
Theories concerning how and why bluegills target their prey provide anglers with keys to catching trophy 'gills. When prey is abundant, appeal to a bluegill's instinct to target a bigger meal that offers a greater caloric return on the feeding investment. If prey options are scarce and generally consist of zooplankton and other small invertebrates, downsize your bait and make it easy to catch and consume. And when bulls have their minds on something other than eating, appeal to their guarding instincts with oversized lures that make them attack.