Have you ever listened to a weather forecast and wondered what the heck a falling or rising barometric pressure meant? Recently my girlfriend and I were having a conversation on this topic and decided to pull out the old Google machine. Our findings were interesting especially to me as one of the articles we found talked about barometric pressure and the impact on fishing. I thought it might useful to the group so here goes....
What is Barometric Pressure? (from Setra.com)
Simply put, barometric pressure is the measurement of air pressure in the atmosphere, specifically the measurement of the weight exerted by air molecules at a given point on Earth. Barometric pressure changes constantly and is always different depending on where the reading takes place.
What does barometric pressure tell you?
A barometer that has a high reading — meaning high pressure — and is stable, indicates good weather. You're in the midst of a high pressure system. A barometer that is falling indicates that a low pressure system is moving in, and you can expect poorer weather.
A barometer reading of 30 inches (Hg) is considered normal. Strong high pressure could register as high as 30.70 inches, whereas low pressure associated with a hurricane can dip below 27.30 inches (Hurricane Andrew had a measured surface pressure of 27.23 just before its landfall in Miami Dade County).
Low means slow (from the Weather Channel)
According to Woodward, fish are much more comfortable when there's stable high pressure, and tend to feed actively most anywhere within the water column. He also acknowledges the general cycles of high and low pressure and how fish react to them.
"Let's say we're experiencing a prolonged period of high pressure and the fishing has been good. Then a cold front heads our way. Ahead of the front is low pressure. The fish can sense that the barometer is about to drop. So, right before the high begins to dissipate and the barometer falls, the fish respond with a change in feeding patterns. They'll often feed heavily right before the pressure drops. As it does, they become more uncomfortable and feed less aggressively. When the front passes and high pressure moves back in, the fish may not feed aggressively for at least 24 hours, since they're still adjusting.
"However, it's a different story a day or two after a high settles back in. The fish will have had time to stabilize and an intense bite can occur. When the pressure changes again, such as when another front moves in, the cycle repeats itself."
When the barometer sinks below 30 inches off his home coast of Georgia, Woodward doesn't bother fishing for big kings in less than 70 feet of water, even if the fishing had been good in previous days. Instead, he fishes farther offshore, in deeper water, where he believes the pressure change may be less pronounced and the kings less affected than those closer to shore.
He also recognizes that the fish may be holding deeper in the water column during this period, and that he may have to experiment with the depth of his baits to score.
As Woodward mentioned, baitfish are also affected by barometric pressure. For example, falling pressure may force the bait to hold deeper and become less active, which would impact the fishing in the middle and upper levels of the water column.
Bass by the barometer
In New Jersey, Captain Terry Sullivan experiences similar behavior with striped bass. "There's nothing like it when we get inside that high-pressure bubble during the spring," says Sullivan. "That's when those brilliant, sunny days warm the bottom in the shallow backwaters. Usually on the third day of the high, the fish really turn on. These highs usually last three or four days before the weather changes."Sullivan points out that one of his best nights of fishing came before an approaching front. With lightning flashing in the distance, the stripers turned on and aggressively struck the flies Sullivan and his charter clients were dead-drifting from their anchored boat.
"I've seen striped bass go on a wild feed right before the barometer began to drop," says Sullivan. "During summer, we get an upwelling effect ahead of a front. Right before our southeast wind shifts more southerly and begins to blow, which precedes the front, it triggers a hot bite locally. The fish sense that a change in weather is about to occur and feed heavily right before the front. Once the wind goes hard south, they shut down. I guess they know they won't be eating for a few days, so they have to gorge themselves."