How Does Barometric Pressure Affect Fishing?

As a dedicated angler, you would want to add more predictable factors into your fishing plans.

Nobody wants an exasperating fishing trip where fish activity varies without any explanation. As an experienced fisher, you might have already built some theories based on your understanding. In the end, though, it might be that barometric pressure and fish activity are indirectly related as pressure reflects the weather changes. Track your experiences, and you may learn that your chances can improve.

How does barometric pressure affect fishing?

Barometric pressure is the air pressure that can vary based on the temperature or height above sea level and it’s caused by the Earth’s gravitational attraction on atmospheric gases.

At this point, this is a very debated topic as there is no conclusive proof that air pressure affects the activity of fish, in general, and bass, more specifically. Some studies suggest that it is impossible to isolate the effects of barometric pressure from the weather phenomena, so any results might be unrealistic.

There are too many variables involved in such measurements to be able to prove an exact correlation between fish behavior and air pressure.

When the air pressure changes, so does the air temperature and wind. Some think that a fish can sense this type of change through their air bladder, but the fact is that only big fish seem to be affected that way.

A fish’s air bladder is squeezed by the air pressure, causing behavioral changes such as swimming deeper into the water. It is said that many marine biologists and ichthyologists agree on the fact that fish do feel barometric pressure changes in both air bladders and their lateral lines, which is basically their sensory system for water pressure. The contraction of a fish’s bladder is believed to be determined even by the slightest air pressure differences.

In this condition, we can also assume that the species with bigger gas bladders can feel the pressure more intensely than smaller fish. For that reason, it could be that under specific pressure conditions some fish would feed intensely while others would swim deeper. At least that’s what some people are claiming. In other studies, no consistent information could be collected to prove such a connection.

 

Bass behavior

Bass behavior seems to be influenced by many variables, with no single factor like air pressure, sky condition, wind speed, and direction, or even prey availability. The only reliable factor in determining the catchability of fish is the amount of time that has gone by from the moment the fish last fed.

When analyzing various weather phenomena and their effects on bass activity, cumulative factors such as wind, rain, temperature, and light indeed had an impact on fish behavior. Whether the barometric pressure is pure opinion or a science-based fact still remains a question.

Many anglers believe in this theory, and not only that, but they also believe that fish can sense barometric changes even before they occur. Even without scientific proof, though, in most situations, the predicted behavior turns out to be true.

 

Pressure variations

An increase or decrease in barometric pressure as it happens when cold weather is about to turn even colder generally means a change in the climate pattern. It could be the weather that strongly influences your fishing success. For example, casting lines when it’s raining is a bit more discreet, and so you have the chance that the insects will fly near the surface of the water right after the rain — this attracts the fish.

Another reason would be that rain makes organic matter fall on water, and again that makes fish approach the water surface to find food. That’s the reason why we could easily say that it’s weather, not the barometric pressure alone changing fish behavior.

Pressure is expressed as units of “atmosphere”. 1 atm is the amount of force/weight generated above the earth’s surface at the sea level which means 14.7 pounds per square inch. It can be measured by the height of the mercury column in a barometer. When the pressure rises, clear and stable skies should be expected, and when the pressure is low,  rain or storm are coming.

How do fish feel under these changes?

Contrary to the idea that fish feel uncomfortable under changing air pressure, another theory affirms that gas bladders adjust according to the depth a fish is swimming at. So it’s more likely that this adjustment will impact the fish much more than the air pressure above the water.

Considering that water is much denser than air, swimming deeper would expose fish to much more drastic pressure changes than the ones experienced above water. The simple movements that a fish makes can quickly change the surrounding pressure.

Even small movements determine significant pressure variations.. Knowing that every movement made by fish changes hydrostatic pressure, we must also mention that tides have the same influence.

 

Tides

A low or an increased tide usually changes the pressure by 0.09 atm, not taking into account the simultaneous effect of the moves of the fish. So within 6 hours from when the tide variations have occurred, a fish should feel a difference of .18 atm, about double of what it could be felt from a serious pressure drop right before a storm.

The same theory also claims that there is no mechanism in a fish’s body which allows it to feel water pressure in association with barometric pressure. Similarly to tides, waves make constant and fast changes in hydrostatic pressure. As a storm approaches, waves will increase underwater pressure, while the one on the surface drops considerably.

Even if the barometric pressure does influence the hydrostatic pressure, the gradual effect that it has is to give fish enough time to adjust their bodies to such mild shifts.

Based on some other observations, all pressure and weather changes are good for catching fish as long as the angler knows how to react in those specific situations and what fishing lure to choose.

When the pressure is higher, it’s said that the best fishing lures are the brightly colored ones, and that’s because fish are less active in high pressure. Lower pressure calls for flies and lighter lures as the fish begins to feed on the water surface.

No matter what theory you side with, keeping a journal with your fishing experiences during specific weather conditions could prove quite useful. In this instance, it seems that there is a battle between science and fishing experience, and probably most of us would choose to side with the scientific reasoning.

Recording all your experience will provide you later with a wealth of information that could be used in the future, even if the feeding habits or fish behavior may change over time.

 

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