Most anglers know that specific conditions like temperature, tide, light levels, wind, and rainfall affect fishing. But did you know that barometric pressure has a significant effect on fish behavior and feeding patterns?
So, how does barometric pressure affect fishing? Fish have natural pressure-sensing organs, including swim bladders and lateral lines. As barometric pressure drops, the fish’s swim bladder inflates, and as the pressure rises, the bladder shrinks. These changes are painful and spur the fish to move down in the water column to alleviate discomfort.
Keep reading to find out everything you need to know about atmospheric pressure and how it can affect fishing.
What Is Barometric Pressure?
Also known as atmospheric pressure or air pressure, barometric pressure is the weight of the atmosphere pressing down on everything on Earth.
Barometric pressure isn’t the same across the Earth’s surface. At high altitudes, there’s less air pressing down on Earth than at sea level, which means that high-altitude locations have a lower barometric pressure than sea-level locations.
Besides altitude, low- and high-pressure systems both affect barometric pressure. For example, a rise in barometric pressure implies that a high-pressure system with sunny weather and clear skies is coming. A drop in the barometric pressure points that a low-pressure system with overcast and rainy weather is forthcoming.
Even the slightest change in barometric pressure affects fish behavior. Knowing the barometric pressure at your fishing location can help you predict the fish’s feeding patterns and have a successful fishing trip.
Effects of Barometric Pressure on Fishing
Although fish live far below the water’s surface, they aren’t immune to the effects of barometric pressure. Fish have several pressure-sensing organs, including lateral lines and swim bladders, also known as air bladders. These organs help fish notice even the slightest barometric pressure changes.
A swim bladder is an inflated sack that helps the fish maintain buoyancy. When barometric pressure drops, a fish’s swim bladder inflates to compensate for the pressure difference. But, when the barometric pressure rises, the swim bladder shrinks.
The shrinking and expanding of the swim bladder, caused by barometric pressure changes, is painful for the fish. The fish may also struggle to stay balanced if they are in pain. The fish will swim down the water column to reduce the pain and discomfort caused by the change in barometric pressure.
Smaller fish usually feel the changes in pressure more acutely than bigger fish. These fish will retreat to deeper waters when the barometric pressure drops, to alleviate any pain and discomfort.
Besides causing the fish to change its location in the water, the rise and fall of barometric pressure also affect the fish’s eating habits. Most fish will go into a feeding frenzy just before the storm moves in and the barometric pressure starts to fall, and when the storm front is moving out.
Are Fish Sensitive to Barometric Pressure?
Some fish aren’t affected by weather and changes in barometric pressure as much as other species. Although smaller fish are the most affected by the changes in the barometric pressure, with time, the bigger fish will start feeling the difference too.
Larger fish might not physically feel the pain caused by expanding and shrinking swim bladders. But large predatory fish will notice smaller bait fish heading to deeper waters and decide to follow them there.
The changes in barometric pressure cause anatomical and physiological stress to fish, reducing their appetite and making them uninterested in food and your skillfully presented bait. At this point, fish are more interested in finding the depth at which they can stabilize their swimming bladders and reduce pain.
What Is a “Normal” Barometric Pressure?
Barometric pressure can be measured in millibars (Mb) or inches or millimeters of mercury (Hg). The normal barometric pressure at sea level is 1013.3 millibars of 29.92 inches of mercury.
Changes in barometric pressure are usually a sign of weather conditions. For instance, a falling barometric pressure indicates imminent stormy weather, while a rising barometric pressure signifies improving weather conditions.
Barometric pressure is easily predictable based on the norms for any given area. Lower pressure is normal for areas with higher altitudes, so a baseline air pressure of 29.92 inHg won’t necessarily be considered normal by people living at high altitudes.
Keeping track of your local weather conditions and air pressure will help you determine your baseline barometric pressure.
What Barometric Pressure Is Best for Fishing?
Learning about how barometric pressure affects fish can help you identify optimal times for fishing. The falling barometric pressure and degrading weather offer the best conditions for fishing. During the falling barometric pressure, fish go into a feeding frenzy, increasing your chances of going home with a catch.
The second-best barometric pressure for fishing is medium and stable air pressure. The stable pressure is accompanied by fair weather and normal fishing conditions.
In high-pressure conditions, fish are less active and can be found in deeper water, hidden near a cover. To catch a fish in these conditions, anglers must use slower fishing techniques to pique the fish’s interest and elicit a bite.
The same can be said for low-pressure conditions associated with rainy and cloudy weather. In these weather conditions, the fish are holed up in deeper water and are much slower to bite than usual. If you decide to wet the line in low-pressure conditions, fish slowly in deeper water or near cover.
Fish are affected by barometric pressure, which allows anglers to predict fishing conditions based on the changes in air pressure. A barometer, handheld weather meter, or a phone app can keep you updated on any changes in barometric pressure, increasing your chances of fishing success.
Falling barometric pressure that indicates poor weather conditions is the best time to hit the water. Inclement weather makes fish very active and likely to feed on any bait that comes their way.