Of the 25,000 species of fish in the world, none arouses more interest among American anglers than Micropterus salmoides, the largemouth bass. Unlike his cousin Micropterus dolomieu, the smallmouth bass, and trout, the largemouth is present in ponds and lakes in every state except Alaska. He is, by a combination of sheer weight of numbers and extent of range and fight, the most popular American gamefish.
The man who knows the most about the ecology of the largemouth bass is Dr. George W. Bennett, chief of the Aquatic Biology Section of the Illinois Natural History Survey in Urbana. And what he has to say may come as a surprise to many anglers and a number of state fish and game commissions. For instance, Dr. Bennett thinks there should be no closed season on largemouths. "I don't see how any honest biologist could back up that closed season business," he says. "Every fishery biologist knows that it's a lot of baloney. Why penalize the fishermen? You take away the best period there is, the spring. The fishermen are just paying the penalty for something not based on any fact at all."
Bennett also thinks there should be neither creel limit nor minimum legal length because it is virtually impossible to fish out a bass pond. Bennett's research has proved that the moderately fertile largemouth pond or lake supports about 50 pounds of bass per acre. This poundage averages out to about 100 bass of all sizes, with 25 of them 10 inches or more. The most successful fishermen can catch only 60% of the bass and, if other species are present to compete for the available food, the danger is too many fish rather than too few.
Now 55, Dr. Bennett has been studying fresh water gamefish, particularly bass, for more than half his life. A strapping, soft-spoken Nebraskan (he sounds like Gary Cooper playing Wild Bill Hickok), he received his B.A. at Doane College, a small liberal arts school of which his uncle was president, his M.A. at the University of Nebraska and his Ph.D. at Wisconsin. In 1938, he joined the Illinois Natural History Survey. In 1941, he took charge of the newly opened Ridge Lake laboratory for studies of largemouth bass in Fox Ridge State Park, seven miles south of Charleston in the east-central part of the state, and his findings are based on a 22-year study conducted there and at ponds and lakes elsewhere in Illinois.
August 18, 1963
Dr. Bennett has written any number of scientific papers, and his book, Management of Artificial Lakes and Ponds, which Reinhold published last year at $8, is an invaluable work on the art and science of producing the maximum annual number of wild fish. Dr. Bennett is a Fellow of the American Institute of Fishery Research Biologists and a former president of the Upper Mississippi River Conservation Committee. Besides his work at Ridge Lake, Dr. Bennett is involved in a couple of other major projects. At Dundee, in the northern part of the state, he has 15 experimental ponds stocked with largemouths, smallmouths, bluegill sunfish, bullheads and perch for a study on population dynamics. At Havana, on the Illinois River, he is attempting to reestablish lakes that were drained by the U.S. Army Corps of Engineers in a turn-of-the-century flood control project. Before the army constructed levees and upriver reservoirs, the Illinois used to yield the greatest crop of fresh-water fish in the country, 24 million pounds a year.
Ridge Lake is to aquatic biologists what the Institute for Advanced Studies at Princeton is to scholars. Eighteen acres in extent, it was especially built for the Illinois Natural History Survey by the Civilian Conservation Corps. When it was finished, Dr. Bennett stocked it with 435 largemouths. All the largemouths that have come out of that lake—and there have been 27,000 of them so far—are descendants of that original stock.
Since 1942, Ridge Lake has been open to public fishing on a highly controlled basis. Every fisherman is logged in and out of the red brick laboratory that stands on the shore of the lake. The fisherman may fish only from a boat which the survey provides free of charge, and he is required to keep every fish caught, no matter how small. Upon his return to the dock, a laboratory assistant notes, on a special yellow card made out in the name of the fisherman, the number of hours fished, the kind of fish caught, the length (to the nearest 10th of an inch), weight (to the 100th of a pound) and the bait used. The assistant also notes any fins that were clipped during periodic censuses of the lake. In addition, he takes 15 to 20 scales from each bass. These are later studied to show age and growth patterns. Fish scales can be read in much the same manner as the annual rings on a tree stump; each ring on the scale designates one year. A fish keeps the same scales throughout its life, and they grow in size as the fish grows. The annual rings on the scales are laid down in the spring, when the fish, after a dormant period, begins its yearly growth. The growth rate of the fish determines the space between the rings. When the fish grows rapidly, the space is wide; conversely, when the growth is slow, the rings are close together.
Besides all the data collected on fish from Ridge Lake, there have been innumerable studies on the lake itself. For example, biologists have investigated such phenomena as rainfall, thermal stratification, aquatic plants, plankton and bottom fauna and water transparency. In short then, Ridge Lake, under Dr. Bennett's direction, has been studied upside down and inside out. It is a fishery biologist's dream, or, as Dr. Bennett puts it, "a great toy."
One of Dr. Bennett's first projects in the early years at the lake was a study of the factors that controlled the size and poundage of a largemouth population. At the time, most fishery biologists believed that the largemouth population depended on the number of other fish, usually bluegill sunfish, on which the bass could prey for sustenance. The normal ratio was considered to be three or four bluegills for every one bass, and it was thought that if the bluegill population dropped, the bass would suffer accordingly.
But studies at Ridge Lake showed these assumptions to be invalid. Dr. Bennett discovered this in the following way. Up until 1943, Ridge Lake contained only largemouths. A drainage census of the lake that year revealed that each acre averaged 48.2 pounds of bass, just about what the lake should produce. In 1944, Dr. Bennett stocked the lake with 129 bluegills, and when he drained the lake the next year in 1945, the bass poundage had dipped to 39.6 pounds per acre, while the bluegills averaged 8.4 pounds per acre. He returned both bass and bluegills to the lake and, two years later, he drained the lake again. This time the bass poundage had slumped to 31.5 pounds per acre, while the bluegill poundage had jumped to a startling 193.3 pounds. All told, at the time of this census—this was in 1947, only three years after the stocking of the 129 bluegills—Ridge Lake contained the astonishing total of 67,700 bluegills. Dr. Bennett removed 66,000 of these permanently, returning only 1,700. As a result, the largemouth population once again started to increase.
The reason for the bluegill population explosion, Dr. Bennett explains, is that largemouths are not solely piscivorous, as biologists thought, but omnivorous. Only half their diet is made up of fish. Thus the bluegills were able to increase rapidly, and as they did they not only ravaged the small bass coming off nests as fry but also competed successfully with them for such food as crayfish and other crustaceans (Daphnia, Chydorus, Bosmina, Diaptomus and Cyclops), nymphs (damselflies and dragonflies) and frogs. "As the bluegills go up, the bass go down," Dr. Bennett says. He is now able to control the bluegill population by drawing the water level of the lake down 15 feet in the fall. As the water recedes, the bass dive for the bottom, but the numerous small bluegills seek cover on higher ground and are ultimately left abandoned on the shore. "When there are no natural predators, man must take their place," Dr. Bennett says.
Unless a pond owner is absolutely wild over fishing for bluegills, Dr. Bennett cautions against stocking bluegills with largemouths. The bass will do well enough on their own, though they are unlikely to grow to lunker size. For that, forage fish are necessary, and for this, Dr. Bennett recommends lake chubsuckers. He prefers them over other species of fish because they do not stir up the bottom, they feed on aquatic organisms the bass usually ignore, and they produce large numbers of young at the time small bass are coming off the nests. On no account, Dr. Bennett says, should any carp or goldfish be released in bass waters. Both are highly reproductive; in point of fact, goldfish may spawn within 36 hours after stocking. Moreover, both goldfish and carp root up the bottom for food. This makes the water turbid, and silt can prevent bass eggs from hatching. The turbidity also makes it difficult for mature bass to eat since they feed by sight.
As a result of Dr. Bennett's research, the state of Illinois has done away with closed seasons on largemouths. "I think the closed season is the silliest law ever concocted," he says. "We presume that by closing the season we're going to have a lot of bass, and that isn't true at all. The whole thing revolves around the fact that it isn't the fishermen who control the number of bass, but the other fish populations. We know from our experience at Ridge Lake that any time the bluegill population rises above 2,000 fish per acre, they're going to start depressing the bass. It's a mistake to close the season, impose a creel limit and a minimum length, and wait for the bass to build up to a big population. The bass never do on this basis.
"There's only one reason for a creel limit on bass that I can think of, and that is because some fishermen are successful and others are not. Our studies show that 10% of the fishermen—and it's consistently the same 10%—catch 80% of the bass, and the remaining 90% catch only 20%. A creel limit stops those 10% from making hogs of themselves. There wouldn't be any danger to the fish, but it would be a waste of fish. In the old days, fishermen used to catch 100 to 200 bass apiece in a day on the Illinois River. They caught so many that they just dumped them on garbage heaps.
"Legal length? What's the basis for legal length? So the bass can reach maturity and spawn. But what difference does it make, if one pair of bass is capable of repopulating a lake like this with its own spawn? We know that Ridge Lake won't support more than 2,000 bass of assorted sizes, from four inches to nine pounds. Now suppose that in some way you could take 1,900 of those bass out of here and leave only 100. And we'll assume that half of those 100 are females. Well, we know from counting eggs and checking broods of young that one of those big females is capable of producing 10,000 young. We know that this lake won't support more than 2,000 bass, and yet this one bass can produce five times that. Why impose a length limit so that each bass can reach sexual maturity? Nobody is going to catch 1,900 of the 2,000 bass here. Nobody's going to catch near that many. In our most successful seasons here, fishermen have been able to catch only 60% of the available bass, about 50% of the total poundage. And that 50%—and we think probably more—can be replaced in one season. When bass are taken out, they leave available the food they would have eaten, so the bass that are not caught are capable of growing much more rapidly.
"Fish have indeterminate growth. When you buy a pup, you can say that within a year he will reach mature size, and after that he won't be any larger in bone structure, whether you feed him well or poorly. But a fish keeps growing throughout its life, depending on the amount of food it can swallow and digest. It doesn't grow an inch this year and an inch next year. A fingerling bass in this part of the country can, with good food, get up to 11 inches in one summer. If it has poor feeding, it may be only two and a half inches long at the end of the summer. We've seen bass nine years old and only nine inches long. The only thing that grows are the eyes. Why the eyes grow, I don't know. They're oversized in a stunted fish.
"The danger in the average lake or pond is too many fish rather than too few. The idea is sometimes hard to sell to fishermen. But the fact is, overpopulated ponds often seem to contain no fish. The exceptional fishing found in a naturally primitive environment—before man comes in, settles down and spoils it—is the result of predation and growth. Predators prevent any one species offish from becoming overabundant, because they're continually being thinned out. Those that survive grow rapidly.
"In evolution, fishes represent a very old group. They've been around millions of years. As they evolved, predators came along and evolved with them. As new forms of predators evolved, such as fish-eating birds, reptiles, amphibians and mammals, the fish evolved to compensate for this, probably by laying more eggs. So over the years, relatively high predation and relatively high production of young became the norm. The welfare of the fish population actually depended on this high predation. If there were not this high predation in primitive areas, the fish would overpopulate the natural environment.
"Here is a good example. When I was out at McCook, Nebraska, we used to take trips to the primitive northern part of the state to fish and hunt. We located a lake, five miles long and about a mile wide, that was filled with thousands of bullheads. They were whoppers, for bullheads. Most of them went to a pound, a pound and a half. We'd go in with hip boots and use worms, and the limiting factor as to how fast you could catch them was how fast you could put a worm on. They were all big. You'd catch so many that you'd get to the point where you could hardly drag your stringer out of the lake. Now, bullheads are notorious for overpopulating and stunting. So it was very unusual to have such consistently large ones.
"One year we got the idea of going duck hunting up there. So we drove all night and arrived just before daybreak. We really thought we were going to have some good shooting, but we never used a shell. We saw no ducks, only the fish-eating, fish-tasting American mergansers. They're rough. You can't eat them. So we had to move to another lake to get mallards. Now a rancher there told us those mergansers came through that bullhead lake, spring and fall, regularly. They'd stay a couple of weeks, and obviously they were culling the small bullheads, thus leaving the big ones for us to catch.
"The only places where fish-eating birds do damage is in hatcheries or in trout streams where there are concentrations of hatchery-reared trout that have been stocked. And, of course, both of these are artificial situations."
Water temperature plays a major role in governing the life of bass. With the approach of winter, they become quiescent. "You're dealing with a coldblooded animal that just can't function well when it's cold," Dr. Bennett says. "A bass is dormant because of the low temperatures. A bass's temperature is the temperature of the water, and until the water gets above 60°, bass are not active. Their metabolic systems are slowed down by cold, their digestion works slowly, the nervous system is slow. Smallmouths apparently hibernate, in a sense, in the winter. They have a tendency to pile up in crevices or logs. Largemouths don't generally follow that procedure. They tend to concentrate in deep water toward the bottom. But they don't stop feeding. The bass will still grab a minnow, but then the bass might take 10 days to two weeks to digest it. When you ice fish, weight a live minnow and lower it to the bottom. Then lift it up a few inches. The minnow can't move around because it is restricted and so the bass doesn't have to move quickly to get it. It's mainly a matter of finding where the fish are concentrated. You look for the deep pockets."
The water temperatures also have an effect on the life expectancy of largemouths. "The higher the temperature, the shorter the life of the bass," Dr. Bennett says. "It's just as though you wound them up quickly, and they ran down fast. A real southern largemouth—I'm not speaking of the Florida largemouth, but of the Louisiana bass—probably has a shorter life span than he would have here in central Illinois. They live to 8, 9, 10. Here bass live to 10, 12, maybe 13, at the maximum. A northern largemouth, one in northern Wisconsin or northern Michigan, lives to 14 or 16. The smaller fish, like bluegills and crappies, have shorter lives. Most bluegills here die at 4, some live to 6. You can't accumulate fish by just letting them live."
Dr. Bennett rates the largemouth as the most intelligent of freshwater fish. "Smallmouths," he says, "are not as smart. They are so excitable and high-strung that they'll actually die of fright in an aquarium from sudden exposure to light." Largemouths can often be caught on a lure they have never seen before. They are inquisitive, and their curiosity may get the better of them. "There was a spinner lure that had never been used in Ridge Lake," Dr. Bennett says, "so a man here tried it, and he caught 52 bass in one day. He tried it again, and he got hardly anything. The bass had learned. It's a matter of education. They become aware of what's going on and respond accordingly. For instance, the first morning of opening day here, the rate of catch is a half to one pound of bass per man hour. By afternoon, that is reduced by at least half. By the third day, the fishing is as bad as it ever gets. On the average, it takes one man 10 hours to catch one pound of bass. The bass have learned."
Educated bass are sometimes the reason why fishermen complain that a pond has been fished out. "A fished-out pond usually contains bass," Dr. Bennett says. "Nine-tenths of the time the fishermen just can't catch them. One pond on which we worked belonged to a fishing club of the Owens-Illinois Glass Company. There were several hundred members. They actually overfished the pond, but even then they didn't overfish the bass. The fishing pressure was heavy, about 1,500 man hours per acre per season. The ideal is 50 to 60 man hours per acre per season. The pond was small enough so that a good bait caster could reach every part of it without moving. Yet that pond contained 12 bass that were two to six pounds and several hundred bass of catchable smaller size. But they couldn't be caught at all. What you do is let them alone one winter, and they'll be hot to bite in the spring."
Even though bass soon become wary of lures and baits, there are three, according to the statistics compiled at Ridge Lake, that are generally effective. These are, in order, a blue jig, a yellow popper and a nightcrawler on a harness. Uninformed bass fishermen avoid the color blue in lures. Back in the '30s, Frank A. Brown of the Illinois Natural History Survey conducted experiments on vision in bass. He discovered that their vision was comparable to that of human vision through a strong yellow filter. Consequently, bass have the poorest vision at the blue end of the color spectrum. And that is possibly why the blue jig is so successful. "The bass can't determine what it is," Dr. Bennett says. "It's difficult for him to see it. So he'll go up to take a swipe at it to satisfy his curiosity. Our experience here with the blue jig is that it is far superior to anything else. It is better in the spring than at other times, but it is generally good the year round. A smallmouth will pick up a blue jig when it's right on the bottom. Why any self-respecting bass would do that I don't know. The best way to fish smallmouths is just to put the blue jig on the bottom, let it stay there for 30 seconds, then pull it up a couple of feet and let it settle again. Now, a largemouth will want that blue jig moving just as fast as you can crank your reel. And while you're doing that, raise your rod tip at intervals so it moves in an underwater wave."
For surface lures, poppers are more effective than plugs. Bright yellow is the most effective color for a popper, and after that, the best colors are red, brown, black and white. For a plug, red and white is the best color combination. Plugs are not as deadly as poppers, but the bigger bass tend to hit plugs more readily. "I knew a painter—he's dead now—who fished strip mines," says Dr. Bennett. "He caught more big bass than anyone I know. He used big, deer-hair bugs with lots of colors. He made the bugs himself. He'd cast one out and let it sit just like a bale of hay. He'd let it sit for 5 minutes. Then he'd give it a little twist and let it lie again, worrying those big bass onto the hook. Most of the bass he caught ranged from four and a half to six pounds. He never caught more than two on a trip, but over the season he caught more big bass than anyone else.
"You know there are fishermen who consistently take fish. As I said, our records show that 10% catch 80% of the fish. First of all, they handle their tackle well. They are able to hit where they want to hit. That's a simple matter of practice. But from then on, it's a matter of an extra little something—the certain twitch you can give a popper or the way the lure is presented. There's an indefinable something that makes the bass decide to strike or not to strike."
By far the most effective live bait are nightcrawlers. The worms far surpass minnows, crickets, grasshoppers and crayfish. A nightcrawler in a harness of three hooks is the most consistently successful live bait.
As every bass fisherman knows, there are times when the bass just will not bite. When this happens, Dr. Bennett suggests, "Take a flat board and shake them up by whacking the water. Go out and make a lot of noise. The fish will be curious. Pull the boat away for 5 minutes, and then go back in and catch bass. It works on some occasions." But exactly why bass bite or do not bite is a question that eludes even Dr. Bennett. It may be that the hot biting periods are associated with the availability of some food organism in the water. But then, Dr. Bennett is not certain. "There's nothing very consistent," he says. "That's why fishing is interesting."