Checking the weather before fishing is common practice, but other atmospheric elements besides rain and wind can have a critical impact on fish behavior as well. Perhaps the most important to consider is barometric or atmospheric pressure (both rain and wind are affected by this). Barometric pressure is defined as “the measurement of air pressure in the atmosphere, specifically the measurement of the weight exerted by air molecules at a given point on Earth.” This pressure can be felt more significantly by creatures living underwater, where pressures are already greater than those of the air which can really mess with fishing. To break down the barometer in simple terms and what it means for fish and fishing, we visit with Brian Brosdahl of Bro’s Guide Service.
Brosdahl admits he is not a meteorologist but has spent enough time on the water while following the barometer to make some accurate correlations between air pressure and fishing. Air pressure affects fish by dictating how they use their air bladders. When the pressure is low, they shrink their air bladder and sink to the bottom, awaiting more comfortable levels. When the pressure is high, the air bladder expands and they rise higher in the water column away from the higher pressures near the bottom. Old adage agrees that fish often become more “lock jaw” during a high pressure system setting the stage for those frustrating outings where you mark lots of fish, but they refuse to eat. Brosdahl remarks that anything below 29.90 is on the low end, and anything above 30.12 is high. When the pressure is high, Brosdahl switches to more finesse presentations like lighter lines and smaller baits. What you’re looking for is pressure stability. Think about it: if the pressure constantly fluctuates, the fish have to adjust their air bladder often, making them uncomfortable. Would you want to eat if you had a belly ache? Stable pressures from 29.90 to 30.05 are key to watch for, so use weather apps with accurate barometric readings to get a good sense of when fish are feeding and dial in exactly when the fishing is going to be top-notch!
