The Biology Of Crappie Fishing: What You Need To Know
By David Hart

Some 20 years ago, crappie were little more than a sideshow to any reservoir's major attraction — largemouth bass. Even stripers earned more ink in fishing magazines and more attention from fisheries scientists.

Times have certainly changed. Not only are more anglers pursuing crappie with more sophisticated gear, the biologists who manage lakes are paying far more attention to these popular panfish than ever before. What they've learned through in-depth studies can help you become a better angler.

Population Shift
After anglers expressed concern over declining catch rates of crappie on Kentucky Lake, fisheries biologists with the Kentucky Department of Fish and Wildlife implanted transmitters in both black and white crappie in the Blood River arm of the reservoir. Paul Rister, a biologist with KDFG, says Kentucky Lake anglers used to catch white crappie to the ratio of 4-to-1. Over the past five to seven years, that ratio changed. Black crappie became the predominant species, and the number of white crappie fell off considerably.

In order to figure out exactly why catch rates flip-flopped, Rister and his colleagues followed 30 black and 30 white crappie throughout a year.

"The water in Kentucky Lake really started clearing up in the 1990s as a result of changing farming practices and increases in aquatic vegetation, and that affected crappie behavior," Rister explains. "We know that white crappie favor dingier water, while black crappie favor cleaner water. What was throwing off Kentucky Lake anglers was that they were fishing the same ways they always had and using the same methods at the same times they always fished for crappie. Anglers typically head for the lake in April, and they would catch white crappie in shallow water."

However, Rister discovered that while the anglers didn't change, the population dynamics of the lake's crappie did. He also learned that black crappie and white crappie are different creatures. Blacks spawn considerably earlier than white crappie, as early as late February or early March. Whites invade the shallows in mid-April, spawn and then retreat to deeper water. They also spawned deeper in the clearer sections of the lake, as far down as 12 feet.

Rister also discovered that black crappie stay shallow much longer than previously thought.

"They often stay in 2 to 7 feet of water well into July," he notes. "Water temperatures were in the 80s."

Rister figured crappie anglers were catching fewer fish because they weren't adjusting to the clearer water. Instead of backing off and making longer casts, they were still moving close to the cover and spooking the fish, which meant they weren't catching them.

What Makes A Great Crappie Lake?
Why can one lake churn out stringer after stringer of fat, healthy crappie while another lake a few hours away produces nothing but short, wafer-thin fish that aren't worth a filet knife? Steve Miranda, a professor of fisheries at Mississippi State University, says the most important factor influencing crappie survival and growth is habitat. Although the presence of forage is important, Miranda, who has participated in numerous crappie studies, says the availability of spawning habitat determines size and age structures of a specific lake.

"Some of the best crappie lakes are ones that act like rivers," he says. "They flood seasonally, and all that flooded vegetation is critical for spawning and recruitment success and young-of-the-year survival."

The flooded vegetation not only provides cover for crappie fry, it also creates an incredible source of food in the form of insects for juvenile crappie and smaller fish that larger crappie feed on.

The study on Kentucky Lake found crappie strongly favor that flooded vegetation for spawning. Rister says fish spawned predominantly in flooded buttonbush as well as in shallow, man-made cover.

Of course, fishing pressure plays a major role in the quality of any crappie fishery, acknowledges Miranda. He points to Mississippi's Grenada Lake as a perfect example of how intense pressure can affect a crappie lake.

"Before the word got out about Grenada, it was producing some incredible fish," he says. "Now that everyone knows about it, the fishery — particularly the trophy fishery — has declined because fishing pressure has increased dramatically, and the larger fish are being removed from the population faster than they can be replaced."

Are Crappie An Unlimited Resource?
The common belief that crappie provide an unlimited and continually renewing resource is simply false. Can you take all the crappie out of a lake? Of course not, but crappie, like any other fish, are subject to intense fishing pressure, which can show in the overall population structure.

In some lakes, especially those with poor spawning habitat and lower nutrient levels, recruitment — the number of young fish that survive beyond the first year of their lives — is much lower, and fishing pressure can drastically affect the number of quality fish. Biologists try to set size and creel limits so that fisheries can sustain angling pressure, but it's still not — and probably will never be — an exact science.

Brad Parsons, a research biologist with the Minnesota Department of Natural Resources, found that crappie in some Minnesota lakes sustained an annual harvest of as much as 30 percent of the adult population. In order to maintain viable populations of adult crappie, harvest levels need to be around 20 percent or below.

"Overharvesting clearly affects the size structure of a lake," Parsons says. "I think a lot of anglers assume crappie are an unlimited resource that can't be overharvested, but that's not the case."

Exactly Where Are The Fish?
Just as wildlife biologists can track the movements of animals, fisheries biologists can follow crappie around a lake simply by implanting a tiny transmitter into the fish's bodies, which is what Rister did on Kentucky Lake. The device emits an electronic signal at set intervals, allowing researchers to record exact locations of individual fish. Some transmitters can even determine the depth of the fish based on signal strength.

Another way to track the movements of fish is with plastic tags that are attached to the fish. A small ribbon imprinted with a series of numbers is attached under the skin, and biologists either recapture the fish or wait for anglers to catch the fish and report the tag. In many cases, biologists offer rewards for returned tags, but Parsons says a tagging study on a chain of lakes in central Minnesota resulted in a return rate of nearly 70 percent.

Parsons and fellow biologists wanted to know how far crappie and bluegills travel, so they tagged fish in four connected lakes.

"Some fish moved through a series of canals and culverts that joined this chain of lakes as much as 2 miles before they were caught by anglers," he says. "As it turned out, crappie moved from one lake to another much more than we originally thought, and most of the movement was in spring. We also determined that spawning crappie favored shoreline vegetation with little human disturbance."

A study on Ohio's Delaware Reservoir showed crappie moved and fed very little in the daytime during summer. Biologists implanted transmitters in 29 white crappie and found that the fish spent much of the day on deep structure and cover, moving shallow in the evenings where they would stay until the following morning. The fish were most active between 10 p.m. and 2 a.m., but activity was highest when light intensity was lowest. The darker the night, the more active the fish. When crappie were inactive during the day, they tended to hold in water between 12 and 18 feet deep, and were most often near or directly over a sharp drop-off.

Another common denominator was the presence of some form of cover — large rocks, logs or brush. The researchers also found that crappie were most active when barometric pressure was either steady or high.

The Human Dimension
It's interesting to note that biologists aren't just studying fish. They also study fishermen and their attitudes toward resource management. Crappie anglers were put under a microscope in Mississippi when biologists wanted to know how much money anglers spent (about $30 per trip) and how they might react to a change in creel and size limits on Sardis Lake.

"There was a negative correlation in angler effort as creel limits in our models went down," says Mississippi fisheries biologist Keith Meals. "In other words, if we set lower creel limits, fewer anglers would go crappie fishing, and they were less willing to spend as much money as they currently do now. Ironically, very few anglers actually catch limits of crappie — 4 percent or less on Grenada according to our creel surveys in 2005 — but they definitely want the ability to catch a higher limit."

In the survey, the Mississippi fisheries biologists found a significant number of anglers would stop coming to Sardis if they dropped the creel limit to 10 from 30 per day. However, guides throughout the state wanted lower creel limits so they could say their clients caught limits of fish.

Creel surveys conducted in Mississippi also found that anglers as individuals are becoming more efficient at catching fish, despite the finding that very few anglers catch a limit. In addition, Rister says a study done on Kentucky Lake found that anglers who used multiple poles caught more fish.

"There were some anglers who wanted us to set a limit on the number of poles anglers could use," Rister says. "There is no doubt those fishermen who spider-rig with 12 poles are more efficient than those who use one rod. They catch about 2½ times more fish than single-rod anglers. Biologically speaking, it really doesn't matter how many poles anglers use to catch a limit. A guy using a single rod will just take longer to catch the same number of fish using six or eight rods."

Managing crappie populations is a difficult science, and with so many uncontrollable variables at work, biologists can only do so much to help anglers catch more and bigger fish. However, there are men and women on the water or in their offices working on research projects right now. What they discover just might help you become a better angler.