Barometric pressure is one of several factors that affect fishing. Keeping track of barometric pressure changes can mean a difference between ending a fishing trip empty-handed or going home with a cooler full of catch.
But, what does barometric pressure have to do with fishing? Even a slight change in barometric pressure affects fish behavior. Many fish species have air bladders that maintain a fish’s buoyancy and help it swim up and down the water column. Air bladders are affected by changes in barometric pressure causing the fish to alter its feeding pattern.
This post will tell you what barometric pressure is and how to measure it. You’ll also learn what the best barometric pressure for fishing is.
What Is Barometric Pressure?
Barometric pressure is the weight of the air that presses down at a given point on Earth. Barometric pressure is also called atmospheric pressure or air pressure.
Although you might not feel the effects of barometric pressure at this time, air pressure affects many things, from the weather to the feeding pattern of fish and other animals.
A high-altitude location has a lower barometric pressure than a location at sea level. There is less air pressing down on Earth at high altitudes than at sea level. Altitude, as well as low- and high-pressure systems, affect the barometric pressure.
Although barometric pressure is fairly consistent across the same climate, it is influenced by fluctuations related to local weather patterns. The movement of the atmosphere and temperature affect barometric pressure, causing low or high pressure.
Small changes in barometric pressure significantly impact the fish’s behavior because everything in the water sinks or floats through the water column. The barometric pressure changes are similar to changes in gravity, disturbing the way the fish move.
How to Measure Barometric Pressure?
Although anglers can’t predict the weather, they can predict fishing conditions by measuring barometric pressure. Using a barometer, barograph, or smartphone app is a few ways you can measure and monitor air pressure.
Barograph
The barograph is a type of aneroid barometer. Barographs have aneroid cells that constrict and expand because of small changes in barometric pressure.
When an aneroid cell is calibrated, the volume changes are transmitted by springs and levers to an arm that moves correspondingly. A barograph has a pointer on a cylinder that rotates and traces along the graphic paper. These tracings show an increase or decrease in barometric pressure.
Clock-like Barometer
A simple clock-like barometer is another type of aneroid barometer. This device works in the same manner as a barograph, except it uses a pointer to indicate low and high air pressure. The pointer moves from left to right in a semicircular motion over a dial to show the changes in barometric pressure.
Mercury Barometer
A classic mercury barometer has a long glass tube with one end open and the other end sealed. The tube is filled with mercury and sits upside down in a reservoir that also contains mercury.
The mercury barometer works by balancing the weight of mercury against atmospheric pressure.
If the weight of mercury is less than the air pressure, the mercury level in the tube rises, indicating high barometric pressure. When the weight of mercury is higher than the air pressure, the mercury level falls, showing low barometric pressure.
Smartphone Barometer Apps
There are many handy barometer apps for fishing that can help you track the weather and get accurate information in real-time. In addition to predicting the weather, a barometer app can also show your current elevation to get an accurate air pressure reading.
Barometric Pressure and Fishing
Weather conditions and air pressure have a huge effect on fish behavior. Fish are susceptible to changes in atmospheric pressure, just like the mercury in the barometer.
Many scientists believe that changes in air pressure cause pressure in a fish’s swim bladder, making the fish uncomfortable. When barometric pressure drops, the swim bladder expands, causing discomfort to fish. To relieve that discomfort, fish move deeper in the water column or absorb extra gas in their bladders to compensate for the pressure drop.
When fish experience these types of changes in barometric pressure, they aren’t interested in feeding. Most fish species will look for a spot deep enough in the water to relieve the effects of air pressure on their bladders.
Changes in atmospheric pressure don’t affect all fish species the same way. Fish with larger swim bladders, including trout, snapper, and grouper, feel the effects of air pressure more acutely.
Barracuda, Kingfish, Mahi Mahi, and other species with smaller bladders aren’t affected by pressure changes and don’t change their feeding patterns as much as other fish.
Barometric Pressure Chart for Fishing
Barometric pressure has a considerable influence on fish behavior and fishing productivity. Like sky and weather conditions, the air pressure directly impacts a fish’s holding position and behavior.
Fishing barometric pressure may seem more complicated than it actually is, especially for beginners. This handy barometric pressure fishing chart will tell you how to act in times of changing pressure.
| Air Pressure | Weather | Fish Behavior | Fishing Tactic |
| High (>30.2) | Clear skies | Fish are slower than usual, with moderate activity | Fish structures close to the surface using crankbaits and poppers |
| Medium (29.9 to 30.19) | Sunny/Partially cloudy | Normal feeding activity | Use your favorite fishing lures |
| Low (<29.9) | Cloudy | Fish are less active and bite slowly | Fish deep structures using different lures and presentations |
| Rising | Improving weather | Fish move from deeper water and are feeding slowly | Fish moving from deeper to shallower waters using brighter lures |
| Consistent | Stable weather | Fish are active, and feeding is consistent | Fish different methods using your favorite baits and lures |
| Falling | Worsening weather | Best fishing conditions, fish are fed opportunistically | Use surface and slow-running lures and a range of different fishing techniques |
Conclusion
Fishing is affected by water temperature, light levels, lunar phases, changes in water conditions, and barometric pressure. Even the slightest changes in air pressure affect the behavior and feeding patterns of many fish species.
Understanding barometric pressure and how it affects fish can help you adapt to the fishing situation and get the most out of your fishing trip.