To be able to catch a large number of fishes at a particular period, you need to know the factors that affect the fish’s availability in the upper part of the river or sea. Every angler knows that the weather determines greatly whether your fishing adventure is going to go well or not. The atmospheric temperature determines the temperature of the water, which either encourages or suppresses the feeding behavior of fishes at a certain period.
Apart from the weather, other factors affect the availability of fish in the sea. One of these is barometric pressure. But then, how does barometric pressure affect fishing?
In this article, we’ll understand what barometric pressure is and how it affects fishing. Knowing the barometric pressure would help you determine the best time to catch fish.
In this article, we will provide detailed answers to the question,
What is Barometric Pressure?
Several gases make up the atmosphere. They include oxygen, carbon dioxide, and nitrogen among others. As you know, the gravity of the earth attracts everything that has mass. These gases which can be found in the atmosphere also have mass, so there’s a particular weight of air above you that vary depending on the time or location.
Barometric pressure which is also known as atmospheric pressure is the measure of the weight of the column of air above you. You must have experienced a change in atmospheric pressure when descending from a high altitude such as a hill, mountain, or even in a plane. Sometimes, you feel your ear pop in situations like this. This occurs as a result of the change in atmospheric pressure.
During periods of high pressure, the atmosphere is usually bright with sunny clear skies, while during periods of low pressure, you notice a duller atmosphere which most likely comes with storms and thick clouds. Very low pressure is usually associated with large storms and hurricanes.
Measuring Barometric Pressure
So, you may have heard of atmospheric pressure or even come across it in books. You would notice that there are several units of measurement that can be used for barometric pressure. In the United States, the barometric pressure is usually measured (recorded) in inches of mercury.
What is calculated is the amount of pressure the atmosphere exerts on a mercury column. It is usually carried out with a simple test using a tube that has mercury at one end while the other end is open. Air enters through the open end and pushes the mercury. At low pressure, the mercury remains at a low level, while at high pressure, the mercury rises. So, high pressure indicates a high mercury level.
Under normal circumstances, the barometric pressure at sea level pushes the mercury to a height of 29.912 inches. When the height of mercury is above 30, the pressure is high. When it is lower than 29.912 inches, then the pressure is low.
Meteorologically, atmospheric pressure is recorded as millibars (mb). According to the World Meteorological Organization, the official unit is hectopascals (hPa). Both millibars and hectopascals are the same, so no conversion has to be done to get a different value for any of them. So, 5000 millibars = 5000 hectopascals (hPa). The standard/stable pressure at sea level is 1013 hPa.
Relationship Between the Weather and Barometric Pressure
As mentioned above, every angler knows that the day’s weather determines how eventful their fishing trip is going to be. On a very bad day, you may not even catch anything at all. So, here we’ll tell you how these two major factors, weather, and barometric pressure are related.
If you watch weather forecasts, you will notice the forecaster talking about the effects of low and high-pressure systems.
Low pressures are responsible for rain, wet, and windy atmosphere. So, as the pressure drops the atmospheric temperature also drops and the weather gets more turbulent. At rising pressure, the atmospheric temperature also rises. High pressure is responsible for the calm, bright, and sunny days.
Air is pulled out from high-pressure areas, so movement is usually from these high-pressure areas to low-pressure areas. You can get out your barometer during varying weather conditions to verify this relationship.
There is usually a cycle of change of pressure around the world depending on the change in temperature and other factors. So, each factor affects each other.
How Does Barometric Pressure Affect Fishing?
Now that you know the barometric pressure affects the weather, you should also know that pressure changes also affect your fishing experience. Fish in the water can sense the barometric pressure at sea level. You may not think this is possible, but the atmospheric pressure directly affects their feeding patterns and times. Fish react to the rising or falling pressure in the same way. They sense it in their organs.
How Does the Pressure Affect Fish Feeding Times?
The best time for you to catch fish is during the pressure shift from low to high or vice versa. This implies that fishes would most likely come out to feed before the arrival of a storm (a drop in pressure) or just after a storm has passed (before the pressure rises).
When the barometric pressure changes from high to low, fishes would come out to feed. This is the best time to attach a faster bait to your fishing line because the fish would be ready to chase it down after a period of not feeding. However, as the pressure rises after a very big storm or rain, the fishes would gradually disappear. This is because they don’t adjust immediately to the rising pressure. Instead, they move into deeper water and do not feed for up to 24 hours.
Not all fishes are affected by the change in pressure. Some fishes do not feel it, but they still retreat to deeper waters because of the non-availability of fishes to prey on. So, the predatory fish may also follow the prey downwards.
Watch this video to know what day to go fishing based on barometric pressure:
How Do Fishes Sense Change in Barometric Pressure?
We mentioned above that there are organs in fishes that help detect the pressure changes. Here are the ways fish can detect pressure change:
Air bladders are also known as swim bladders. A swim bladder is an air-filled sack present in the abdomen of fishes. It is usually found in many bony fishes such as pike, muskie, redfish, largemouth bass, and tuna.
The air bladder helps them regulate their buoyancy. It helps them regulate or control their depth in the water without swimming. But when the barometric pressure changes, then the water pressure also changes. These pressure changes bring about discomfort in these fishes. So, they settle deeper into the water to adjust to these changes. They can sense whenever the water pressure rises and falls.
This is very similar to the ears in humans. When you’re swimming, your ears struggle to adjust to the pressure as you go deeper into the water.
While not all fishes have swim bladders, the swim bladders come in varying sizes and degrees of sensitivity in fishes that have them. Some fish have very sensitive swim bladders and they can adjust quickly by moving a few inches upwards or downwards in the water column, while some others that have smaller or less sensitive air bladders such as dolphins and kings are not affected by the changes in barometric pressure.
Watch this video to learn how barometric pressure could affect the Bass:
The lateral line on a fish’s body is the natural atmospheric pressure sensor. This sensitive organ runs the entire length of their bodies. Apart from the tiny changes in atmospheric pressure the lateral line detects, it also helps them detect vibrations in the water. So, they know when there’s an injured or struggling fish to prey on. Using more active and vibrating lures when fishing attracts fish because of this lateral line on their bodies.
Pressure changes cause migration in the water column. As the pressure changes, the food items like plankton and other food sources will move from their position. This pressure system also causes the fishes to follow the food. Depending on the pressure change, these food sources may either move upward. This is why sometimes, fishes that usually stay in the depth of the water column such as crappie are found higher in the column. This is also similar to other fishes that are found at the top. They are driven to the bottom due to pressure change.
As an angler, you should never forget that various factors affect fish behavior. The weather conditions, barometric pressure, and, water temperature are just some of these factors that should always be considered whenever you want to catch fish. These factors work together to determine the location of the fish and what type of lure you should use if you’re going to catch anything.
For instance, in areas of low pressure, you may not be able to catch so many fishes because they’ve migrated deeper into the water. But if you can determine their location, use slower moving bait. In this condition, the fishes are in lower sections of the water column and are trying to wait out the storm. In areas with higher pressure, the probability that you catch a fish depends less on the fish behavior and more on your skills as an angler.
During periods of stable pressure, you should also consider other factors that may predict the fish’s location such as the wind direction, currents, or lunar phases. You can have a great catch in stable conditions brought by high pressure when you fish on a kayak or boat. This is because some fishes may be hiding in deeper areas or under structures in the water.