In large Southern reservoirs, crappie tend to have cyclical ups and downs in their population, which makes them much more challenging to manage than other species.
Crappie have "boom-or-bust" reproduction, meaning that a single "boom" year can result in a large fishery and high catch rates for several years. At the other end of the spectrum, several "bust" years in a row can mean almost no crappie fishery for an extended period of time in a particular body of water.
Biologists have not been able to specifically identify what causes these "boom or bust" cycles in crappie. There's some evidence that high-water levels before and during spawning may mean more spawning success, but this relationship isn't consistent. Understanding this relationship, and learning more about factors that affect the reproductive success of crappie, would help biologists manage crappie populations more effectively.
Most black crappie that anglers catch and keep are only 3- or 4-year-old fish. Only 20 percent or fewer live to age 5. In the southeastern U.S., the total annual mortality ranges from 48 to 94 percent. In heavily fished lakes, fishing mortality can be more than 40 percent.
Mortality rates influence the effectiveness of various harvest regulations, so biologists need a good understanding of catch rates, catch-and-release mortality, and other factors that affect fish population numbers.
Florida is undertaking a management plan to better maintain and enhance crappie fisheries in the state.
"Part of our management plan is to try to get a better handle on what the factors are in the population cycles," said Ryan Hamm, Section Leader of Freshwater Fisheries Management, Hatcheries and Resource Biologists for the Florida Fish and Wildlife Conservation Commission (FWC). "Then we can determine what we can do to manage them. A lot of the research on crappie in the Southeast is in reservoirs, and they see some correlation between water levels and water regimes and their cycle, but Florida's water bodies aren't big, deep reservoirs. They're shallow lakes, and although our larger systems actually have water management done for flood control, they don't have greatly fluctuating water levels.”
Florida biologists will be looking at a number of factors in lakes with crappie fisheries, including the forage base at different stages of a crappie's life.
"It may be that some of this is density dependent reproduction, where a system will only support so much," Hamm said. "In a good year, that may push a good year class through.”
Hamm said Florida is unique in its number of broad, shallow lakes and a very long warm season.
"Where we have good crappie, we also have nutrient rich waters," he said. "That's not unique to Florida, but the heat and the number of broad, shallow lakes is."
Within the management plan, there are a number of different management actions that biologists want to undertake.
"When you see more submersed plants in the system, there's less catching effort," Hamm said. "Whether that's because there are fewer crappie or they're less vulnerable to being caught, or anglers don't want to fish out there because it's a different way of fishing, cleaning out those plants is a management action that can be looked at.”
Although much of the crappie management plan is in the research phase, biologists do take the needs of crappie into consideration when they undertake various plant treatments or habitat projects.
"We also have some water-body specific regulations," Hamm said. "We will be taking a look at those regulations to see where they're working and where they aren't." What it amounts to is that the FWC is on a mission to make their crappie management more sophisticated than what they're doing now.
Chris Greene is Chief of Fisheries of Alabama Wildlife & Freshwater Fisheries Division. He said in Alabama, research has shown that strong crappie year classes are often produced in connection with high winter water levels, especially when followed by relatively dry summer conditions.
"Crappie populations are primarily managed through angler creel and length limits in Alabama," he said. "Habitat enhancement work and supplemental stockings are also utilized, but to a lesser extent.”
Decisions about management strategies are based on fall surveys, Greene said.
"If fall trap-net sampling data indicates a poor year-class of crappie based on a low abundance of young-of-year fish, then supplemental stockings may be conducted," he said. "However, there's no guarantee that stocked fish will recruit to the fishery in the future. It's important to understand that a strong year-class of crappie can frequently sustain the fishery for several years, so mitigating for weak-classes is often not even necessary. Supplemental crappie stockings are not conducted every year, since they are often unnecessary. When they are utilized, stocking rates are typically based on past experience and the availability of fingerling crappie at our state fish hatcheries.”
In Arkansas, biologists stocked lakes across the state with two species of crappie in 2018. They stocked 120,000 fingerling white crappie and 400 adults, and another 22,000 fingerling and 250 adult black crappie.
North Carolina has both black crappie and white crappie. White crappie are not native to the state, and mostly likely were introduced into the state in the 1880s. They seem to prefer more turbid and warmer waters than the black crappie. They're common in many reservoirs in the Piedmont area of North Carolina.
Black crappie have been widely stocked across North Carolina. They're common in clear ponds and natural lakes and reservoirs with moderate vegetation.
Although Oklahoma biologists don't recommend stocking crappie in ponds, many landowners still do it. Good crappie fishing in ponds usually is short term. Usually the pond has only a few large fish either stocked as adults or from the initial spawn from stocked adults. Most of the time, stocking crappie in ponds creates an overcrowded crappie population and poor fishing for all the species in the pond. This situation is hard to fix; the best solution is to treat the pond, or drain and restock it.