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Barometric Pressure and Bass

by Ralph Manns   |  August 24th, 2012 3

One of the most persistent myths in fishing is that barometric pressure controls the activity of bass and other gamefish. Although many researchers have tried, scientific studies have been unable to demonstrate that such a relationship exists. Every scientific report we’ve seen, in which barometric pressure was studied, reached a similar conclusion: no direct relationship is evident.

This consistency results mainly because no way has been found to isolate barometric pressure influences from simultaneous weather phenomena. We need observations of fish behavior when air pressure changes are the only variable. But significant barometric changes are rare without accompanying changes in wind, temperature, and sky conditions.

The typical weather front is preceded by dropping barometric pressure and increasing cloudiness, while postfrontal conditions usually are clear skies, bright sunlight, and higher air pressure. Although barometric pressure might directly trigger gamefish responses, no mechanism for detecting these changes has been seriously postulated by scientists.

Field Studies

Years ago, I studied bass behavior through electronic tracking and underwater observation. My team monitored barometric pressure among more than 100 variables we recorded. As in previous studies, we observed no obvious relationship between pressure readings or the nature of pressure changes and the behavior of largemouth and Guadalupe bass in Lake Travis, Texas. Nevertheless, some of our findings provide insight into the possible relationship of barometric pressure, weather, and bass behavior.

When the barometer reading was less than 29.30 (low), about 27 percent of the bass we observed fed on the surface, away from the shoreline. This percentage was greater than the 18 percent observed feeding when the barometer was higher than 29.70 (high). But when we merged the observations of apparent feeding reported by divers and trackers with the surface sightings, we found 36 percent of the observed bass were apparently feeding when the barometer reading was high, as compared to 30 percent when the barometer reading was low.

When we evaluated actual strikes and refusals of lures presented to bass observed by trackers and divers, we found 52 percent of the bass struck lures during lows compared to only 39 percent during highs. But the vast majority of our strikes took place when the barometer reading was neither particularly high nor low (between 29.30 and 29.70). High or low barometric readings, by themselves, were not consistently indicative of bass activity or catchability.

We also looked at the possibility that changes in barometric pressure were more important than absolute pressure. When the barometer was falling slowly (less than 0.21 inch per hour), 65 percent of the bass that were presented lures struck, while 35 percent did not. On a slowly rising barometer, only 30 percent struck, while 70 percent didn’t. But our fishing sample was small. In our larger sample of tracked and observed bass, 29 percent fed offshore on a slowly rising barometer, while 24 percent fed offshore on both a slowly falling and a steady barometer.

The data are confounded by other factors, however. For example, 32 percent of feeding events occurred on solunar majors, only 20 percent on minors, and 27 percent between majors and minors. So solunar influence and other factors may have affected the barometric data. These results don’t necessarily mean that falling barometers increase fishing success or that rising barometers increase offshore activity.

Continued – click on page link below.

  • darell

    Complicated and inconclusive to my thinking."but then" seems to be the consistent finding.
    Looking forward to some more info , perhaps then we can begin to figure out this thing .

  • Kennan M.

    I agree Darell. The main info I gathered from this is: overcast days are usually good times to be angling it seems, regardless of any of the other factors except if the fish have been feeding heavily for several days before. I imagine the note about the decent success in very clear/sunny skies would depend upon the combination of the tested variables a bit more, and of course the recent food intakeof the fish.

    When there are the tell-tale changes in multiple variables that, in combination, are usually found before a frontal and/or storm system moves into the area, gamefish are likely to notice and try to stock up on food intake as a precaution.
    Solunar effects are going to be just as wacky/useless to consider except that they may make what looks to be (by reviewing the other combined variables) a terrible day to fish mediocre, or make a great day to fish simply spectacular.

    It’s common sense really if I stop to think about it and correlate it to how humans are affected by certain factors. When you’re having a really bad day, one more bad thing just hits you so much harder. On a really good day, when everything’s going well, one more good thing pumps you up even more than it would have alone. But on your typical days that are a combination of good and bad things, you tend to just feel a certain way or do certain things based on your own little whimsical nature.

  • David Douglass

    Well in my Excel Spreadsheet of 13 points of criterion of every bass over 4 lbs, over the past eight years, averaging 250 days per year on the water here in Central Florida’s shallow muck lakes, like Okeechobee, Istokpoga, Kissimmee, etc, I have found that ‘extremely quick’ pressure changes no matter if there is cloudy or clear skies, or high or low pressure changes, does cause four-pound and larger bass to adjust up or down in the water column, which at times means they migrate into deeper 6-8 foot shoreline vegetation or feed in open water that is 8-12 feet deep close to the surface.
    Higher pressure for my records is at 30.20 plus In Hg, and low pressure is at 29.20 In Hg.
    Once the pressure ‘starts to move’ it’s the rate of movement that seems to cause fish to move, and this causes opprotunistic feeding to start across the food chain, If there is cloudy conditions, the fish are actively feeding in more open water with less cover while when clear sunny conditions, the fish feed within cover areas, whether it’s a deeper water tree-pile or a shoreline pencil reed patch.
    So it’s extreme changes that trigger adjustment, that triggers feeding. I believe this is due to energy expended, and the greater percentage of available food sources migrating to adjust.
    Also, if weather conditions have been unchanged for several days, depending on water temperatures, bass will feed based on lunar phases, of which the perigee overwhelming produces the better results, no matter what lunar phase is present.
    I have fished the same migration routes in the same lakes, using the same exact bait, now for the past six years. I have noted all the weather and environmental criterion the few days prior to the catch and the day of the catch and the day after, the coordinance, sizes and weights, and lake management and angler pressures that occur.
    The smaller bass under four pounds don’t seem to be as affected as the larger bass. A double-digit bass will move further than a 2 lb bass when pressure changes from 29.95 to 30.18 In Hg, which it does a couple of times per month here. If this occurs on the weeks before the new and full moons, the early morning feeding migrations on those days are very productive. If those days occur on a Wednesday through Friday, when fish have recovered from tournament pressure, the results are even better.
    Note: the pressure change sited in this article are not great enough to cause migrations sufficient enough to have a measureable difference in criterion.
    To access my fishing forecast twice weekly, visit or the newspaper out of Sebring Florida. The Center of the Bass Fishing Capitol of the World .

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