Let's settle this.

 

On theory, on barometric pressure:

 

 

I think it depends a lot on who you ask   I wish the fish could talk. 

Its definitely not a hard fast rule

You cant push a huge swimbait in their face but yes fish do bite after a cold front

It's my opinion that low light levels during the pre-frontal stage trigger heavy feeding activity.

When the cold-front finally arrives, it's met with well-fed game fish

combined with bright sunny skies.  IMO, barometric pressure is purely coincidental,

which pales in comparison to the pressure change caused by a fish moving Up 1-foot or Down 1-foot.

 

Roger

It's my opinion that low light levels during the pre-frontal stage induce heavy feeding activity.

When the cold-front finally arrives, it's met with well-fed game fish

combined with bright sunny skies.  IMO, barometric pressure is purely coincidental,

which pales in comparison to the pressure change caused by a fish moving Up 1-foot or Down 1-foot.

 

Roger

+1

 

A clip from big mouth forever

 

https://youtu.be/ybopUwSuiS8?t=37m34s

It's my opinion that low light levels during the pre-frontal stage induce heavy feeding activity.

When the cold-front finally arrives, it's met with well-fed game fish

combined with bright sunny skies. IMO, barometric pressure is purely coincidental,

which pales in comparison to the pressure change caused by a fish moving Up 1-foot or Down 1-foot.

Roger

Once and For All no one knows for sure but it's my opinion the above is as close as it gets!

I also agree with RoLo. I'm also impressed that the news channel that made that clip was pretty unbiased and legitimately seemed education.

Once and for all nobody knows why. 

While I agree with Rolo, based on common sense, however the barometric pressure side of the debate has merit that slight changes in pressure can affect fish. My fishing experiences tells my the deeper bass, 20'+, are less affected by cold fronts or barometric changes than shallow bass, less than 8'. I have better success fishing deeper after a cold front passes.

To support we don't know side of the debate, a trip to Monterey aquarium a several years ago proved that even the deep Calico bass down to 40' can be affected by barometric changes according to the folks at the aquarium. The Monterey aquarium is a big open top tank with fresh ocean water pumped into it and out creating current. The tank has 3 levels of observation windows to view the underwater fish from, I noticed the Calico or kelp bass where laying in the kelp at all depth levels, not moving in a inactive state and asked a staff member why are the bass acting like that?

He stated they do that after a cold front for about a day or so, then wake up and start swimming around like the other fish.

The Calico bass behavior doesn't support my deeper bass are easier to catch after a cold front theory.

Tom

Well fed fish don't necessarily hug tight to cover like cold front bass seem to do so there's something else going on.  Yes, they generally feed heavily while/when the cold front is moving through but this, like not feeding much afterwards are just "symptoms" of some other environmental factor(s).  I don't have any empirical evidence to back this up but even if, for some reason, they couldn't feed heavily before/during a cold front, I don't think they'd feed at their normal or highter rate afterwards.  They'd still be tight lipped.

I dont know about any research sayin fish gorge themselves prefrontal but it makes sense

however I also know bass (esp summer) need to eat ALOT and well unless lake temps drop dramatically theyre back out the next day to feed

 

tip to those who wanna catch fish cause most of us dont have the luxury of controlling weather or fishing everyday

we get a weekend off and well if its post frontal well you gotta still fish right better than sittin on the couch and arguing with the missus

you gotta try to become proficient in all conditions..else risk gettin skunked and feelin down if gettin skunked makes you so

 

when you say tougher its relative

Post frontal IS tougher .. than immediately prefront

however, its the same (i say better) as a day or two prior to the front w/ bluebird skies

(most of the time unless a major noreaster comes and drops the lake temps 10 degrees)

if you know how to catch fish bluebuird skies you can catch fish post frontal

most have a tough time catching bluebird bass.. so obviously postfrontal will be no different for them

 

first inkling I had when I first got back to fishing was watching KVD destroy bass postfrontal

I said well if its a truism postfrontal fish cant be caught whys this guy catching fish

and he wasnt just catching he was nailing

subsequently when I got over this mental block of low confidence out postfrontal

I began to focus on becoming sucessful postfrontal

wheneve I see weather erports a fronts comin in.. baby its circled pre-post everything

Once and for all nobody knows why.

^^^^^this^^^^^

While I agree with Rolo, based on common sense, however the barometric pressure side of the debate has merit that slight changes in pressure can affect fish. My fishing experiences tells my the deeper bass, 20'+, are less affected by cold fronts or barometric changes than shallow bass, less than 8'. I have better success fishing deeper after a cold front passes. To support we don't know side of the debate, a trip to Monterey aquarium a several years ago proved that even the deep Calico bass down to 40' can be affected by barometric changes according to the folks at the aquarium. The Monterey aquarium is a big open top tank with fresh ocean water pumped into it and out creating current. The tank has 3 levels of observation windows to view the underwater fish from, I noticed the Calico or kelp bass where laying in the kelp at all depth levels, not moving in a inactive state and asked a staff member why are the bass acting like that?

He stated they do that after a cold front for about a day or so, then wake up and start swimming around like the other fish.

The Calico bass behavior doesn't support my deeper bass are easier to catch after a cold front theory.

Tom

 

In my initial reply, I left out graphic detail that tends to bore the reader, but I guess that wasn't meant to be  

Not surprisingly, discussions that revolve around barometric pressure are bound to clash,

because they're dealing with the onerous task of separating “Cause and Effect”.

 

Passing cold-fronts and warm fronts are accompanied by sharp fluctuations in light level 

that run the gamut from heavy overcast to bright sunlight. To my mind at least, this supports

the strong possibility that barometric pressure is a coincidental and laggard indicator,

like driving a car while looking in the rear-view mirror. Be that as it may, rather than champion any premise,

I think it's better to provide a few valid facts and figures then let the angler arrive at his own conclusion.

 

==========================================================================================

It's all pretty basic stuff and very interesting to boot. As you might recall from science class,

the earth’s atmospheric pressure is 14.7 lb per square inch, which will vary slightly 

with the passing of a weather front (CW high cell or CCW low cell). At sea level, the mean barometric pressure

forces mercury 29.92 inches upward in a pressure test tube, which represents the barometric baseline.

This is written as “29.92 inHg” (inHg = inches of mercury), which as it were represents 'One Atmosphere'.

During an average high-pressure system (clockwise cell) the barometric pressure will climb to around 30.32 inHg,

a mean rise of 1-1/3% above normal. During an average low-pressure system (counterclockwise cell),

the barometric pressure will fall to around 29.52 inHg, a mean drop of 1-1/3% below normal.

 

Unlike air which is highly compressible, water is virtually incompressible. Consequently, when a fish swims

downward in the water column, it can easily create an overall pressure equivalent to “two” atmospheres.

This is not attainable during any meteorological event in earth’s troposphere, including hurricanes & tornadoes.

A fish at the surface of the water is unaffected by water pressure, and is only subjected to air pressure,

which is quantified as "barometric pressure". However, at a depth of 34 feet, the water pressure on the same fish

is equal to the pressure exerted by our entire 100-mile high atmosphere. In other words, in addition to

atmospheric pressure (barometric pressure), the water pressure on a fish 34 ft deep (29.4 lb psi)

exerts the combined equivalent of 'Two Atmospheres'. Due to water's density and high specific gravity,

when a fish moves just 5.4 inches downward in the water column, the increase in pressure on that fish

is equal to the pressure increase during an average high-pressure system. Conversely, when a fish moves

5.4 inches upward in the water column, the drop in overall pressure on the fish is equivalent to

the average low-pressure system. 

 

Roger

Roger I don't disagree with the science of (100 millibars) a hurricane frontal pressure change equals a few inches of water pressure, made that comparison before. Bass have air bladders they use for neutral flotation at a specific depth range and pressure changes from the water column directly impacts the size of the air bladder, like submersing a ballon 1 atmosphere dramatically reduces it's size. Using this logic lead me to believe that deeper aclimated bass should be less affected by frontal changes; pressure, light etc.

The aquarium (Calico ) bass defy this logic, thier food is provided, the lighting is natural, the bass are affected only by barometric pressure over a 40' depth range.

I still fish the deeper bass following cold fronts because that works for me.

Tom

Thanks Roger, you beat me to the punch, and saved me a bunch of typing. LOL

I've heard and read many people say bass respond the pressure increase by moving deeper. If it were only the pressure delta which caused the move they would move shallower; by a few inches.

There is some other factor at work, and, as Raul said, nobody knows.

I do know, based on my experiences, that fishing deeper structure, using lighter line, lighter weights, and smaller, more realistic baits can sometimes be the ticket for post front conditions. Not always the case, but this approach works often enough to worth a shot. Why? I have no idea.

Thanks Roger, you beat me to the punch, and saved me a bunch of typing. LOL

I've heard and read many people say bass respond the pressure increase by moving deeper.

If it were only the pressure delta which caused the move they would move shallower; by a few inches.

 

Exactly Gary!

Your response supports the "light level" theory I suggested above, while denouncing the barometric theory. 

If a fish moves deeper during a high-pressure system, it will 'increase' rather than decrease its overall pressure.

On the other hand, if a fish moves deeper during high bluebird skies, it is moving into darker water

with reduced light-intensity, regardless of the barometric pressure. 

 

Furthermore, the average change in barometric pressure during a warm front or cold front

is handily offset by a 5.4" change in water depth. 

 

Roger

Poor of those barometrically pressured fish, they must have some sort of damage to their pneumatic conducts that can´t help them alleviate the atmospheric pressure.....  , you can´t feel it do you ? oh my I feel this pressure all over my body when it´s bluebird clear & sunny without a single cloud in the sky.....

 

That barometric pressure affecting the physiology of them fish argument got more holes than swiss cheese.

I honestly believe that the main reason largemouth bass are such a challenging gamefish is because they seem to be more influenced by environmental changes than other species. Nearly everything that happens in the air and in the water has an effect on most freshwater gamefish, especially largemouth bass. Normally two, or more fluctuating conditions are in effect at the same time - simply because they are all related - and everything that happens in the atmosphere eventually affects the watery world of fish. In all my years of fishing, one of the key things I've noticed (particularly about shallow water fishing) is the dramatic influence that barometric pressure has on fish. Ironically, this is the one influence that biologists, ichthyologists and serious fishermen have studied least. This could be because the required equipment is so delicate that it is difficult to take to the lake. And the whole pressure equation really gets complicated when you try to measure it against water pressure which also changes as fish change depth. It is a well-known fact that even minor barometric pressure changes affect a fish's swim bladder. This air-filled sac is to a fish what the inner ear is to humans. When the barometric pressure rises quickly, it exerts pressure upon the bladder, thus affecting the fishes equilibrium making it hard for the bass to maintain perfect balance. Naturally, this affects their behavior and appetite. I'm sure you've heard the term barometric pressure many, many times, but do you know what it actually means? Simply stated, it is the pressure of the atmosphere at a given point and time. And it's measured by a barometer, which is an instrument for determining the pressure of the atmosphere and predicting probable weather changes.
About 10 years ago, I started watching the barometer very closely. I had a cheap version that worked fairly well, but just to be sure, I would also check with the local weather service before and after every trip. This improved my understanding of how pressure fluctuations affect bass behavior. All serious bass fishermen know that the barometric pressure has a dramatic and immediate effect on a fish's personality and mood. Without question, it is an important element that influences fish behavior, especially shallow-water bass. Deep-water fish are not affected as much by major pressure changes and this is why they are more dependable on those days. Something to keep in mind is that barometric pressure doesn't change dramatically during a period of just a few hours unless a major storm is moving your way.
Like fish, other wildlife can predict the weather better than The Weather Channel or the National Weather Service. Mother Nature has given her creatures the uncanny ability to accurately anticipate an approaching weather system as well as knowing how long it will last. As a general rule, I concentrate my efforts in shallower water during falling pressure and in deeper water when it rises. Normally, barometric fluctuations are most important during late fall, winter, and early to mid-spring (because that is when fronts that frequently move from both the northwest and due north are strongest). Fronts that occur during the summer and early fall seem to move more from the southwest or west, and have less effect. Plus the recovery time is much quicker during these warmer periods of the year. A lot of folks think that the perfect day to be fishing is a beautiful day, when the sun is out, the sky is blue, and there's not a cloud to spoil the view. But let me tell you, most of the time these are the worst conditions for catching fish, because these conditions normally prevail just after a front has passed through. This is the type day when the pressure goes up and up - and the fish either go down or move into thick cover and seem to get lockjaw. When these conditions occur, you have to really slow down and use lures that you can work extremely slow (those that appear less likely to escape). Worms, grubs, or jig-and-pork combinations are good choices.
How many times have you heard fishermen say Wind out of the east, fish bite the least. Wind out of the west, fish bite the best. Or Wind out of the north, don't venture forth. And Winds out of the south, blows the bait in the fish's mouth. Well, first of all, the direction of the wind doesn't directly affect fishing. I've caught fish in wind of all directions except when it was blowing so hard I couldn't get out, or perhaps when it was too strong to fish a particular area. However, there is some truth about the effects of wind direction which actually has its roots in the barometric pressure. That's right, it deals with fronts. A strong brisk north or east wind will generally indicate a fast weather change; therefore, a drastic change in barometric pressure. Gusty south or west winds usually indicate a slow changing weather condition; thus minor changes in the pressure. So it's not really that the wind affects fish behavior. Instead, it's the barometric pressure that affects the wind and, therefore, fish behavior.
I think it would be safe to say that most fishermen can remember times when they were really whacking the fish and all of a sudden the wind changed direction and the fish stopped biting. This happens often, but again, it's not actually the wind that makes the difference. A dramatic shift in wind direction is the result of a frontal passage or change in barometric pressure. If I've said this once, I've said it a thousand times: the best time to go fishing is any time you can go. But if you can schedule your trips to coincide with the best weather forecast for current conditions, it will certainly pay you to do so because this is when the fish will be the most active.
Let me take a minute to explain what my experience has been with different ranges of pressure both the good and the bad. Where I live in west Tennessee, our normal pressure is 30 inches of mercury. So naturally, any reading below 30 is low and any above 30 is high. An optimum range would be 29.98 to 30.02. Without question, some of my best catches and biggest fish have come from mid-spring to early fall after several days of normal pressure were interrupted by an approaching front that caused the pressure to fall extremely fast (more than 10 to 15 points) in a few hours time. Normally during such a period, you will see bad weather moving your way, and the bass will go on a feeding frenzy. Unfortunately, these feeding sprees are short lived and to take maximum advantage of them you have to take the unsafe risk of possible high winds and lightning.

 

Bill Dance

 

I thought everybody knew,  Bill explained this years ago.

I honestly believe that the main reason largemouth bass are such a challenging gamefish is because they seem to be more influenced by environmental changes than other species. Nearly everything that happens in the air and in the water has an effect on most freshwater gamefish, especially largemouth bass. Normally two, or more fluctuating conditions are in effect at the same time - simply because they are all related - and everything that happens in the atmosphere eventually affects the watery world of fish. In all my years of fishing, one of the key things I've noticed (particularly about shallow water fishing) is the dramatic influence that barometric pressure has on fish. Ironically, this is the one influence that biologists, ichthyologists and serious fishermen have studied least. This could be because the required equipment is so delicate that it is difficult to take to the lake. And the whole pressure equation really gets complicated when you try to measure it against water pressure which also changes as fish change depth. It is a well-known fact that even minor barometric pressure changes affect a fish's swim bladder. This air-filled sac is to a fish what the inner ear is to humans. When the barometric pressure rises quickly, it exerts pressure upon the bladder, thus affecting the fishes equilibrium making it hard for the bass to maintain perfect balance. Naturally, this affects their behavior and appetite. I'm sure you've heard the term barometric pressure many, many times, but do you know what it actually means? Simply stated, it is the pressure of the atmosphere at a given point and time. And it's measured by a barometer, which is an instrument for determining the pressure of the atmosphere and predicting probable weather changes.

About 10 years ago, I started watching the barometer very closely. I had a cheap version that worked fairly well, but just to be sure, I would also check with the local weather service before and after every trip. This improved my understanding of how pressure fluctuations affect bass behavior. All serious bass fishermen know that the barometric pressure has a dramatic and immediate effect on a fish's personality and mood. Without question, it is an important element that influences fish behavior, especially shallow-water bass. Deep-water fish are not affected as much by major pressure changes and this is why they are more dependable on those days. Something to keep in mind is that barometric pressure doesn't change dramatically during a period of just a few hours unless a major storm is moving your way.

Like fish, other wildlife can predict the weather better than The Weather Channel or the National Weather Service. Mother Nature has given her creatures the uncanny ability to accurately anticipate an approaching weather system as well as knowing how long it will last. As a general rule, I concentrate my efforts in shallower water during falling pressure and in deeper water when it rises. Normally, barometric fluctuations are most important during late fall, winter, and early to mid-spring (because that is when fronts that frequently move from both the northwest and due north are strongest). Fronts that occur during the summer and early fall seem to move more from the southwest or west, and have less effect. Plus the recovery time is much quicker during these warmer periods of the year. A lot of folks think that the perfect day to be fishing is a beautiful day, when the sun is out, the sky is blue, and there's not a cloud to spoil the view. But let me tell you, most of the time these are the worst conditions for catching fish, because these conditions normally prevail just after a front has passed through. This is the type day when the pressure goes up and up - and the fish either go down or move into thick cover and seem to get lockjaw. When these conditions occur, you have to really slow down and use lures that you can work extremely slow (those that appear less likely to escape). Worms, grubs, or jig-and-pork combinations are good choices.

How many times have you heard fishermen say Wind out of the east, fish bite the least. Wind out of the west, fish bite the best. Or Wind out of the north, don't venture forth. And Winds out of the south, blows the bait in the fish's mouth. Well, first of all, the direction of the wind doesn't directly affect fishing. I've caught fish in wind of all directions except when it was blowing so hard I couldn't get out, or perhaps when it was too strong to fish a particular area. However, there is some truth about the effects of wind direction which actually has its roots in the barometric pressure. That's right, it deals with fronts. A strong brisk north or east wind will generally indicate a fast weather change; therefore, a drastic change in barometric pressure. Gusty south or west winds usually indicate a slow changing weather condition; thus minor changes in the pressure. So it's not really that the wind affects fish behavior. Instead, it's the barometric pressure that affects the wind and, therefore, fish behavior.

I think it would be safe to say that most fishermen can remember times when they were really whacking the fish and all of a sudden the wind changed direction and the fish stopped biting. This happens often, but again, it's not actually the wind that makes the difference. A dramatic shift in wind direction is the result of a frontal passage or change in barometric pressure. If I've said this once, I've said it a thousand times: the best time to go fishing is any time you can go. But if you can schedule your trips to coincide with the best weather forecast for current conditions, it will certainly pay you to do so because this is when the fish will be the most active.

Let me take a minute to explain what my experience has been with different ranges of pressure both the good and the bad. Where I live in west Tennessee, our normal pressure is 30 inches of mercury. So naturally, any reading below 30 is low and any above 30 is high. An optimum range would be 29.98 to 30.02. Without question, some of my best catches and biggest fish have come from mid-spring to early fall after several days of normal pressure were interrupted by an approaching front that caused the pressure to fall extremely fast (more than 10 to 15 points) in a few hours time. Normally during such a period, you will see bad weather moving your way, and the bass will go on a feeding frenzy. Unfortunately, these feeding sprees are short lived and to take maximum advantage of them you have to take the unsafe risk of possible high winds and lightning.

 

Bill Dance

 

I thought everybody knew,  Bill explained this years ago.

 

Rolo made an excellent point questioning this theory:

 

It's my opinion that low light levels during the pre-frontal stage trigger heavy feeding activity.

When the cold-front finally arrives, it's met with well-fed game fish

combined with bright sunny skies.  IMO, barometric pressure is purely coincidental,

which pales in comparison to the pressure change caused by a fish moving Up 1-foot or Down 1-foot.

 

Roger

If the barometric pressure rises, meaning there is added pressure on the swim bladder and the fish wants to relieve some of that pressure, it could just move up in the water column. As RoLo pointed out it would be a very very minor change in depth- less than a foot probably. Anyone who has free dived or even just swam to the bottom of a pool knows the pressure difference between 10 ft and 15 ft is very remarkable.

Maybe there is some physics going on that is over my head...We are talking liquids vs gases. But if it really is the pressure then it should have been explained at some point. Someone had to create these theories. I'd like to see what the real idea is behind this. No offense to Bill Dance but I am tired of settling for the lay person version from fishing celebrities, I'd like to hear the scientific account.

Imo the barometric pressure factor is another myth

 

Also, our northern bass up here in the northeast are a bit hardier than those cousins from the south and west.. ours need to survivelarge temp fluctuations and ice-over

..and our conan bass likely shrug off cold fronts alot better than those from the south and west

I guess the thing is we will never no.  Alls I know is I have a harder time catching fish after a cold front moves through. Be it shallow or Deep, I just have a harder time after a cold front period.

My head is spinning

Unfortunately, like so many things in the natural world, there just isn't a "once and for all". It's too complicated out there. We seek simplicity -which has its merits- but don't exist in such a world. The bottom line on "cold fronts" is that many factors associated with weather changes affect fish behavior. The trick is to know which one(s) are most important when. There are almost as many possible scenarios as there are hours in the day. There certainly are patterns out there, which is why we study the natural world, which in turn is why we have enormous brains. If yours is spinning, well it's doing what it's meant to do. If it hurts you're probably expecting simple, or single, answers to complex questions. Simplifying is the narrowing of real probabilities, not settling for less.

If we call the days in between fronts normal conditions with few clouds, light wind or breezes, constant air temperature variation, the ecosystem is stable. Along comes a weather system with low pressure, clouds and wind, the lighting is reduced form the clouds or rain, the air temperature drops a little or a lot depending on the strength of the system, the ecosystem is unstable. Terrestrial creatures like insects are forced to land or end up on the waters surface, the baitfish start feeding and the predators start hunting prey. The barometric pressure is a small factor compared to the ecosystem changes that activated the shallow water bass.

The weather passes, the backend of the low is called the cold front being pushed by a high pressure system with warmer compressional wind and cloudless skies clearing out any airborne insects, the ecosystem is transitioning back to normal, the predators are less active.

Deeper water bass are less affected by light changes and weather systems, the bass fishing doesn't get better for deep water bass during pre frontal conditions or worse during post frontal conditions, it stays stable has been my experience.

Tom

I'm just posting so I can read this when I get home from work.