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 weâ€™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.
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 didnâ€™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 donâ€™t necessarily mean that falling barometers increase fishing success or that rising barometers increase offshore activity.
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