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CONSERVATION CORNER
For the week of July 9, 2007
Fish and Barometric Pressure
by James L. Cummins

A barometer measures the weight of the air above us. Air pressure, as indicated by the barometer, has a definite effect on the behavior of most game fish. By observing the action of a barometer, it is possible to predict the probability for good fishing or for poor fishing at any particular time.

The information below summarizes the generally accepted relation of barometric conditions and fishing prospects. This information is correct only if the barometer is adjusted to the altitude of the locality where the barometer is being used.

If your barometer is showing high pressure (29.8 and above) and rising, very good fishing can be expected. If reading is below 29.8 and rising, fishing will be poor but improving.

So what if there is basically no change in pressure? If the reading is 29.8 and above, good fishing can generally be expected. If the reading is below 29.8, fishing will be poor, but may improve if the barometer remains steady for several days.

What about falling pressure? If the barometer reading is 29.8 or above and falling, fishing will become poor. If it is low, below 29.8, and falling, very poor fishing is likely.

Ordinarily best fishing will occur when the pressure is 29.8 to 30.2 and is rising or steady.

Remember, the most important feature in the use of a barometer to predict catching fish is barometer trend, that is, whether the barometer reading is rising or falling.

It is necessary to become familiar with the method of reading a barometer in order to determine if the atmospheric pressure is "rising" or "falling" or in other words what the "trend" is. To determine the direction of change in barometric pressure, first take note of the pressure. To determine the barometer "trend," wait several hours and then note the pressure again. If the barometric pressure is increasing, we say the "barometer is rising." If the barometric pressure is decreasing, we say the "barometer is falling." After determining the trend by taking the two readings, as above, note the pressure for future trends. Very small changes in pressure are not too important, but a series of small changes in the same direction on consecutive readings taken at short intervals will be significant.

James L. Cummins is Executive Director of Wildlife Mississippi, a non-profit, conservation organization founded to conserve, restore and enhance fish, wildlife and plant resources throughout Mississippi. Their web site is www.wildlifemiss.org.