Crappies, Barometric Pressure And Weather - North To South
February 19, 2014
A gray world closed in around us in the narrow canal. Hills rose up steeply on both sides. The water was 1 to 2 feet deep all the way across and we had over 500 yards to go to reach a dead-end knob of a bay. We were forced to paddle and pole our way, trees blending into clouds overhead. The water was cooler than the air. It was an unseasonably warm April morning in Michigan. Upon reaching the little bay, we were very careful not to make noise, quietly slipping the anchor into water clear as the morning air.
The little bay was only 4 feet deep at the deepest point, held no weeds, and had only a couple fallen trees for cover in water too shallow for crappies to use. But it was the first place to warm up on the little lake, attracting big, spooky, black crappies. We slipped minnows or waxworms onto 1/64-ounce jigs 2 feet below small Rainbow Plastics A-Just-A-Bubbles and pitched beyond the deepest pool as softly as we could with 2-pound line, then reeled the floats slowly back to the pool.
And we waited for what seemed like an eternity before one of the floats would finally quiver. A minute or more later it would begin to move. Interminable moments later it would slowly submerge, the rod would bend, and a papermouth that could hold a tennis ball would open on the surface as the fish thrashed and disrupted the pool. It would be 15 minutes or so before we could get another fish to bite. If we were impatient or made too much noise, we could see the big blacks slipping out of the bay, heading quickly down the canal to the lake.
A week later we decided to try it again. This time, mist rose so thickly we could barely find the opening to the canal. The water was warmer than the air. A cold front moved through the day prior. We combed the little bay carefully with bait and with our eyes. No crappies anywhere.
That was in 1975, before we realized what was happening. Older, savvier anglers already understood that, in the gray world at ice-out, crappies respond to it. In the budding green of prespawn, crappies respond to it. During the spawn, afterwards, and all through summer, crappies respond to it, too. "It" is a change in barometric pressure. Crappies might be more susceptible to the passage of fronts and pressure changes than anything this side of a carp.
Inadvertently, Craig Bonds, Region 3 Fisheries Director for the Texas Parks & Wildlife Department, learned something about crappies and weather while conducting a tracking study on Lyndon B. Johnson Reservoir and nearby Waco Reservoir, two lakes with "disparate" water clarities.1 The study involved 28 to 30 white crappies (Pomoxis annularis) in each reservoir each year over a two-year period (2001 to 2003). Black crappies (P. nigromaculatus) are native there as well. The study was attempting to improve trap-net catch rates by studying crappie movements, and to eventually shed more light on crappie recruitment. "Each species can be difficult to manage," reads the study, "as they commonly exhibit erratic recruitment."
Sometimes that erratic recruitment, Bonds learned, is due to weather. Ultrasonic transmitters were surgically implanted into white crappies only, as black crappies are relatively rare in both lakes. "We were trying to find out when fish were closer to shore and easiest to sample," Bonds said. "Tracking revealed that often they were farther offshore than we were setting nets. White crappies move primarily between dusk and dawn." That held true, at least, until the weather changed.
"Weather changes made crappies move, especially those that included barometric pressure changes," Bonds said. "When the pressure was changing, crappies were always on the move. It soon became obvious that rapid barometric pressure changes induced movement in the fish. I don't know whether they sensed changes in water temperature, wind, or pressure, but they would move to a different location and hunker down until conditions stabilized."
Tracking the Spring Crappie Bite
The earliest prespawn activity for crappies is most often movement to shallower water for feeding rather than for spawning or staging. Crappies winter deep in many environments and undergo energy deficits before the water begins to warm. Rising temperatures in shallow bays from increasing solar energy as days lengthen stimulates plankton production and attracts baitfish, which in turn draws crappies.
Timing of this developing shallow food web depends on latitude and climate, but generally the Prespawn Period occurs over water temperatures of 50°F to 63°F. The first window opens for hot, early prespawn bites in January in southern Florida. As days lengthen, the window progresses northward at a pace of about 50 to 65 miles per week, until it reaches the northern fringe of the natural range of crappies in the Canadian Shield, during late May.
Pomoxis Vane and Compass
Having found crappies shallow during late ice, I was catching one about every four minutes or so as they slowly moved past to the fringes of a reedbed. Sitting still, waiting for the next one to appear, I felt a chilly wind hit my neck and had to pull my hood on. After 15 minutes, it became apparent no more crappies were moving through. I moved back out past the sharpest break to holes I'd drilled earlier over depths of 25 feet. The camera confirmed it. There they were, suspended in groups. I dropped tiny lures right in their faces for about 40 minutes with no response. They never seemed to move at all, in fact. Later, looking at my handheld Skymaster weather station at home, I noticed the pressure had dropped precipitously.
That was in 1998. The LBJ-Waco study verified what a lot of anglers have known for a long time. Crappies are not only sensitive to weather changes, cold fronts precipitate rapid movement followed by almost complete lethargy. "During periods of high pressure and stable weather, the crappies we were tracking pretty much stayed wherever they were," Bonds said. "High pressure follows a frontal pattern. Fish gradually move shallow during stable low-pressure periods and collect. But sudden drops in pressure would precipitate rapid movement. Once it stabilized, they would stay put. The most rapid movement would overlap the most rapid barometric pressure change. They're moving during that rapid change. Otherwise, movements had more to do with photo periods. Crappies move a whole lot more at night."
The crappies Bonds tracked seemed much less active after a pressure drop. "It's tougher to make them bite," he said. "Their strike zone shrinks, and you have to drop something vertically right in front of their nose during stable, high-pressure periods. The highest levels of spawning activity took place during stable low-pressure periods. Fish are cold blooded, of course, so if environmental conditions aren't good they can shut down and not eat and it doesn't adversely affect them much."
Bonds implied we don't yet know how crappies might sense changes in barometric pressure, but he indicated that crappies seemed to seek areas where they experience less distress after a front. "The most obvious changes in location occurred in and around cold fronts," he said. "The changes would be different according to season, but the most dramatic took place during the spawning period and when crappies were in prespawn mode, when moving out of deeper winter habitats to spots closer to shore where they spawn. When a cold front moved through, they moved back to deeper water. I believe those deeper areas are more stable. We watched what happened when barometric changes precipitated weather with a lot of rainfall. Crappies would move away from flowing water and get out of the flow. Crappies do not like flow, especially when it's increasing. It was dramatic in spring, up in the upper end of the flow.
"Not all fish behave the same way at the same time," he said. "People have idiosyncrasies and fish do to. Some people go out and play in cold weather, some people never do. Some crappies were shallow and some were deep at the same time. You can make generalities because most of the crappies did seem to move in sync, but there are always exceptions to the rule. Some fish are shallow and some fish are deep at any given time of day or night under any conditions. You see fish moving in or out, too, under all conditions. When anglers say the fish are all on the banks spawning, well — that might never be exactly true. Not all female fish spawn every year anyway."
Bonds liked the idea that spawning fish could be left alone by anglers, if they so choose, without slowing down catch rates. When it seems like "all the crappies are spawning," some are staging in prespawn mode and some are moving out to postspawn locations at the same time. And some crappies, as Bonds indicates, make no effort to spawn at all, waiting for the next year or even the year after that before nesting again. '©The study also revealed white crappies in prespawn mode used "broad areas of the reservoir, traveling up to 51â„2 miles from their transmitter-implanting locations. Although some fish used well-defined core areas (exhibiting "site fidelity," as the study referred to it), several exhibited nomadic behavior and were seldom found within several hundred yards of previous locations. A crappie tracking study by Dr. Chris Guy in South Dakota showed that some white crappies did not establish preferred home ranges, but used the entire 290-acre lake."
Crappies roaming around like caribou? Moving eight klicks at a time? Using entire reservoirs as a home area? Talk about here today, gone tomorrow. Crappies may be quite susceptible to rapid changes in barometric pressure, but that might not be the only reason we can't always find them where they're "supposed to be."
Typical Spawning Months
The Spawn Period occurs over a general range of water temperatures of about 64°F to 72°F. Although temperature is important, daylength also is likely a contributing factor, so spawning might occur in cooler temperatures during abnormally cool springs and vice versa in springs that warm early.
The crappie spawn in an individual water body might last several days to several weeks, depending on conditions and size of the water body. Spawn periods continuously interrupted by unstable weather such as cold fronts can become extended. In some waters such as larger reservoirs, spawning can occur at different times, from upstream in headwater zones to downlake near the dam. (In-Fisherman)
Finding Spawning Crappies
Ideal crappie spawning habitat is generally described as having thick cover, moderately firm bottom substrates, and in areas that warm early and are protected from wind and wave action. Several studies on black crappies show, however, that the spawning habitat formula depends on what features a lake has to offer.
In three Minnesota lakes, biologists found black crappies are more likely to nest near undeveloped shorelines with emergent vegetation (hardstem bulrush) and shoreline canopy cover. Crappie nests near developed shorelines were significantly deeper than those found near undeveloped shorelines.
Emergent vegetation, in the form of cattail stands, also was an important factor in nest-site selection of crappies in an 800-acre eastern South Dakota reservoir. Most nests were in the middle of the stands, not on the edge, and were protected from wind and wave action. Eighty percent of nests were located in one of two reservoir arms. The arm containing most nests had a well-defined creek channel with cattail stands off to either side. The arm with few nests had extensive cattail stands with no defined creek channel. Perhaps a well-defined creek channel serves as an avenue for movements to spawning areas.
In a South Dakota natural lake, researchers found that crappies spawned in a protected bay off of the main lake. Most nests were located under fallen trees, usually within about 10 feet of cattails. Only one nest was found in the middle of a cattail stand, and cattail stands were less common than in the reservoir.
In a small southern Illinois impoundment, nesting black crappies didn't appear to show a preference for any particular vegetation type (coontail, curlyleaf pondweed, cattails, and reeds were present), but they selected areas with low vegetation height and density as well as firm stubtrates. The researchers speculate that nest construction and nest protection may be easier in low vegetation densities. Areas with maximum wind fetch and south fetch were just as likely to contain nests as protected areas. The researchers suggest that this impoundment was small enough where wind and wave action wasn't a factor in nest-site selection. Temperature and dissolved oxygen, however, was higher at nest sites than at non-nest sites.
At Kentucky Lake, crappies outfitted with transmitters moved from deeper water to flats less than 8 feet deep during the spawn. The study suggests that shallow flats adjacent to secondary creek channels were the most common habitat for spawning. Black crappies made greater use of flooded shoreline brush than white crappies. During the spawn, both species were often found along rocky banks, not a classic spawning location according to Ryan Oster, the biologist who tracked the crappies. Rocky banks rarely attracted fish except during the spawn.
Cover, substrate, water temperature, and protection from wind and waves — all are important variables in the formula for finding spawning crappies. These studies show, however, that habitat availability, lake size, layout, and local features affect where crappies spawn. Consider the variables, look at the unique circumstances a water has to offer, and you should get close. (Rob Neumann)