Cold fronts seem a never-ending plague for springtime anglers, and they provide a time-honored excuse for poor fishing. The connection between barometric pressure—the actual weight of the atmosphere pressing upon us—and fish behavior has been a hotbed of discussion and puzzlement since the days of Izaak Walton in the 17th century.

In our rational minds, we tend to minimize such effects because changes in air pressure are impossible to see and difficult to envision. Air, after all, seems weightless. Biological researchers have not devoted much attention to the effects of barometric pressure on fish. When they have, results have been unclear and often conflicting.

As a result, the effects on fish remain mysterious, a source of endless curiosity, bringing frequent questions to In-Fisherman staff at fishing seminars, in letters to the editor, and on our Web forums. Some anglers suggest that biologists should do studies to better define how such slight changes in our atmosphere could affect creatures living below the water’s surface. But with many more urgent projects, intense research into this topic isn’t likely anytime soon.

It’s reasonable to assume that any direct effects of air pressure, along with wind, cloud cover, solar radiation, and other atmospheric changes that coincide with barometric fluctuations, would be more pronounced in shallow water—generally the domain of crappies, especially early in the year. Moreover, crappies are common throughout the U.S. and southern Canada, a huge landlocked region boasting some of the most tumultuous weather changes on the planet.

Weather Effects

In-Fisherman researcher Ralph Manns downplays the direct effect of barometric pressure on fish behavior. “A fish with a gas bladder needs only to swim up or down a foot or two to experience as great or greater a pressure change as that created by all but the largest natural pressure changes—say, a hurricane.

“A fish might notice itself floating or sinking a few inches in response to a change in air pressure, but it experiences larger pressure changes as it shifts depth several feet while hunting prey, escaping predators, or changing location.

“Black bass and other species with closed gas bladders use their bladders to achieve neutral density and thereby hold at constant depths. This weightlessness conserves energy by reducing the need to swim to hold position. If air pressure or depth changes, a fish with a gas bladder slowly and naturally adjusts bladder pressure to re-establish equilibrium.”

Weather expert Irvin Decker adds, “Freshwater fish, including largemouth bass and crappies, shift depths from the surface to 15 feet or more in their feeding activities. This difference in depth represents a pressure change many times greater than the maximum barometric pressure change ever recorded on earth.

“I believe that barometric pressure changes associated with fronts bring with them secondary effects—wind, thunderstorms, cloud cover, changes in temperatures, and changes in light intensity—that do affect fishing success. Actual pressure changes alone do not have any direct effect on fishing, as is so often stated.”

Manns concludes: “Biologists have never identified physical mechanisms or sensory systems that would specifically allow fish suspended at neutral density to sense relatively small changes in water pressure associated with barometric pressure shifts. Biologists have, however, long postulated that clouds, waves, and changes in lighting affect hunting success by predators, by favoring species with eyes sensitive to low light levels, such as crappies.” Research into bioenergetics suggests that fish conserve energy by not foraging when their likelihood of success is reduced, then begin actively feeding when conditions are more promising. How they know this remains unstudied.

Be the Weatherman

If you’ve heard one joke about weather prognosticators, you’ve heard 100. But let’s face it—the job’s not easy. Try your hand by acquiring weather testing equipment: There’s no arguing the benefits of consulting a barometer regularly and being prepared to adjust locations and presentations accordingly. Tacklebox barometers are available from Airguide, Cabela’s, and Bass Pro Shops for under $20. Be sure to tune your barometer to local altitude by checking a nearby weather station, airport, or weather website. Set the marker arrow (usually red) to match the local current barometer level.

The Anglers’ EDGE PLUS from Speedtech (speedtech.com) is a pocket-sized weather guide that graphs 24-hour trends in barometric pressure, along with listing sunrise and sunset times, weather forecasts based on barometric pressure, and feeding activity charts. It’s programmed with the next 96 years of solunar and sunrise data for future reference. Throughout the day, check for rising and falling barometric conditions and approaching solunar periods. Larger and more sophisticated weather stations can be set up indoors with equipment mounted on buildings to gauge wind speed and direction, humidity, UV index, and other factors. For a large selection of models from under $100 up to $1,000, check weathershack.com, weatherconnect.com, or bestnest.com.

Dealing with Change

In most cases, the best time to go fishing is right now. If you wait for prime conditions, you’ll likely find more pressing commitments spiking your trip.

Understanding the barometer’s effects on bass can help you to select key depths and the most promising lure presentations. Though consensus is lacking on reasons for a tough bite following a cold front, there’s little disagreement that fishing will be more challenging now than some days after the front has passed.

Cold fronts—Watching the barometer can help you tune your presentations to the mood of the fish. In general, best results after frontal passage come by fishing deeper. Another important modification is to use smaller baits and lighter line during postfrontal conditions. Livebait fished near the bottom continue to work, and for artificial lures, try vertical baits like minijigs that are effective when fished in cover and worked slowly.

Crappies typically aren’t active or chasing prey under high-pressure conditions, but they will feed if an easy opportunity presents itself. Faster-moving horizontal baits like spinner jigs and mini-crankbaits usually don’t produce well during high-pressure conditions.

Thin monofilaments or castable fluorocarbons hide the presentation better than heavier lines, and also allow small lures to move more naturally. Reduced line visibility also helps tempt bites from inactive fish. Naturally colored lures also are best. In short, fish deeper with smaller, slower-moving, natural-appearing lures.

Descending barometer—A falling barometer signals the approach of a front and often spurs a fast bite. Crappies often move shallower, following baitfish, and they feed toward the surface. It’s a great time to fish small spinners or other fast-moving baits. Moreover, plankton rising in the water column in response to the falling barometer are concentrated on windblown banks, creating a great feeding opportunity for various species. In short, fish shallow with faster-moving baits.

Stable conditions—When the weather is stable and the barometer shows little fluctuation, fish tend to be scattered, as are preyfish. Fish hold at various depths, in different forms of cover, and show unpredictable activity levels. Various presentation patterns work, though none may produce outstanding catches.

If the barometer is falling from 30.1 or so, plan on covering water fast to find actively feeding fish, possibly near the surface. Once you find concentrations, expect a great catch. Focus on areas where crappies can corral baitfish, such as main-lake coves, bluff banks, tributary inflows, and necked-down areas. Carry crankbaits, rattlebaits, spinnerbaits, and buzzers.

If, on the other hand, the barometer is rising after a front has passed, pushing into the 30.4 range and beyond, switch presentation styles. Focus on smaller, natural-appearing baits that can be fished deeper and slower. Tune down your expectations, but fish hard, watching your sonar and your line carefully for soft bites.