Knocked the Crappie out at 29.93 one evening. Cold front moved in that night and the next morning three of us only caught 2 crappie between us and we fished for a longer period of time in the same spot. Pressure had moved up to 30.27. Chalked it up to the pressure. Thought to my self I should test this a little bit further so I went back out by myself again that evening and fished the same spot at the same time I had the evening before and slayed the crappie again pressure was now at 30.32. I used the same technique each time. By the way the crappie turned off at the same time both evenings. Some times we think pressure is correlated with the bite when in fact it is other things effecting the bite. In this case it was the time of day, not the pressure change, or the 30 degree reduction in air temperature.

Eric, I guess I missed the intent of your question. And, are you saying that while you are out on, say, a clear day, fish are biting very actively and then, boom, the bite is off . . . that you are registering a significant change in barometric pressure from one moment (or hour) to the next?

I think I can answer if I understand the sorts of readings you are registering.

Look forward to hearing back!

Just generally speaking, those two anecdotes I listed (top water bites and clouds rolling in) ARE siding in my direction, that a change in weather variables without a significant change in barometric pressure can and do turn off fishing, or else require you to change up presentations. Pro bass guys mention this all the time, that they are catching them up on the banks, then the bite dies so they head out to deeper water to find where the fish have moved to.

Just in general, low pressure "pulls" weather in and is associated with: rain, temperature change, wind, clouds, rougher water. High pressures, say especially those in summer months, are associated with hot days, dead air, clear bluebird skies, flat water. Odd, too, that to the general public, they would see the latter description of clear skies and calm water and see it as likely great fishing. We know that those very conditions can be very tough as fish move deeper, they become lethargic, and more.

Anyway, what of the range of barometric readings you have seen on clear days?

Brad

Sure! SweetRay sees it for what it really likely is: a combination of many factors including time of day, cold weather effects, and so much more.

For daily ranges of barometric pressure readings, if some are further implying that even the very slight changes intra-day suddenly turn fish on and off, irrespective of weather, TOD and other factors, the actual range of pressure changes are just too small.

For Lake Athens, here are the barometric readings, averages and highs and lows for each day for the first 15 days of the month of January 2017. The average total range, from high to low each day over these 15 readings? Just .25 inches of mercury. So, a fish would literally only have to adjust its position 1.5" up or 1.5" down from the "average" pressure to offset any effects that are supposedly bothering it enough for it to start or stop eating.

C'mon guys!

Brad

Correct, I fish at night a lot so an example would be: it is an hour after dark, I get to my spot and catch 3 keeper crappie and 5 unders in 30 minutes then the bite stops. I keep fishing for 15 more minutes then move to my next spot. I catch 1 6 inch crappie and nothing else. The water is 2-4 feet deep so it's not like they moved deeper on the cover and I'm missing them. Over the next 2 hours I move to spots 3 and 4 and catch nothing, I then move back to spots 1 and 2 and still catch nothing and call it a night. There is no change in wind speed or direction, no beaver scaring them off, no change in cloud cover, etc etc. I then check the air pressure and the hour the bite turned off the pressure dropped .06. I can consistently go and catch a dozen crappie in 2 hours with minimum 4 keepers any given night EXCEPT when the pressure is high, low, or make a sudden fluctuation. There are no other factors we can detect. Duh, off/odd nights happen, but when you go enough you pick up on patterns. What you're saying is that "every time must be attributed to something, each time there must be something else causing it" which may be (and I would like to know what obv...) but the INDICATOR that we see is the change in pressure. It correlates directly over hundreds and thousands to observed trips ("tests").

Same thing with what Carey is saying about crappie in the winter in the creeks and sand bass in the spring. He's been beating the banks for 6 months out of the year for over 10 years and would pick up if a bite turned off because of a notable weather change like shade, wind, time of day... When you see hundreds of instances when you catch a sand bass every 45 seconds, and within 1 cast the bite stops, you can still see the school of fish but they won't bite, you spend the next four hours fishing a dozen holes where you can still see the fish but not a one will bite. You check the pressure and exactly when the bite turned off the pressure went from being stable to making a significant jump. It then stabilizes and you go back in the afternoon and start catching a butt ton again. No one can write off having this happen that many times.

Based off of the field studies either 1) the pressure does effect the fish to some capacity or 2) there are one or more factors that happen the same time as a pressure change. Either way, we can still watch the pressure change and use it as an indicator whether it is the cause or not...

Your info on the fish being able to move in the column to compensate is 100% accurate, I agree completely, and they definitely do that. Everything that you are saying about the fish being able to regulate their pressure is absolutely true. That doesn't change though that there is an OBVIOUS correlation between pressure and fish feeding. Whether we understand or not these pressure differences happen the same time as a bad bite and we can use it to help us be more productive. Maybe like I said before, the fish habitually shut down because of the "possibility" of a coming storm because they detect pressure changes every time there is one. Or anything else I mentioned.

If you can say what is actually causing this we obviously want to know so we can use it; but for now we know we can rely on watching the barometer.

Eric

I will withdraw from this conversation my degree in science may not be big enough.

scruboak, your science is plenty big enough! Hang in there!

Eric, just in general, barometric pressure is high in the AM and drops down to a low in the late afternoon. It "lags" the effects of temperature and sunlight a bit. The cool night air becomes dense so it is heavier; the sun warms the air and it expands and become less heavy.

This lag is well known in the field of science.

Most of us who occasionally fish from the bank like to get out early. I often catch several fish very early, very quickly then it slows down. I have always assumed I am simply catching them as they are out for breakfast! Another popular time to catch fish is in the late afternoon, the sun drops down, often if it has been windy, the wind dies down. Different presentations work that didn't work at other times and barometric pressures are not the same as earlier.

Then, throw in a thousand weather variables.

Fish moving around, say like the ones in one of Carey's videos, you will see some swimming "above" others in a pack like sardines, say some 3" higher in the water column . . . tummies to dorsal fins. Maybe, later, they turn and drop down a few inches. But, they move here and there, their position in the water column changes . . . as we both agree.

I don't know how to be any more clear about a fish's inability to discern a .06 change in a baro reading. It would be . . what, the equivalent of 1/4" of water column height? How would a fish be able to distinguish this tiny change in pressure owing to the atmosphere pushing down on the water, or letting up on it, from just floating along or moving along in the water? I know you don't believe they hold some isometric position in the water at an exact depth.

So, this is certainly not to impugn Carey's observations or his fishing prowess; I know he is a top notch guide; but, do you believe that my math is accurate? You either do or you don't.

What I think is a whole lot of you thought, before being presented with how very little the effects of barometric pressure really affect fish in the water, how little they have to move to offset it, that a reading change from, say, 29.75 to 30.00 somehow gave the fish the equivalent of a pounding headache, so they stop feeding.

Anyway, though my math doesn't have to answer the why behind the bad bites, just the reality of barometric pressure effects on fishing, but,

here is what I think:

A watch is a MUCH more valuable gauge than a barometer;
That weather conditions and changes account for most of the good and bad days on the water fishing;
That fish, when all weathers and pressures are stable, simply get enough to eat and just stop. You do, most animals do, so can fish.

I'd throw hormonal rhythms into the mix, the signals a fish gets to feed and fatten up before winter, the post-spawn feed to fatten up after being off food for a bit, those sorts of things, too.

Hey! On a positive note, I managed to catch about a dozen fish in a little cove off of the bay in Galveston today, Crash Cove or some name like that. Bros in law had a canoe, fishing was just so-so. All my thoughts about watches and barometers were a million miles away. I had no idea what the pressure was, no idea what the time was.

We've beaten this topic to death. Off to another!

Brad

Well first. Fish has an overall better sense in hearing, feel, and sight.
So just imagine. Even a small pressure driplike you said 1/4inch. Make a huge difference in shallow water and the fish will know. Like the front today. Shut down the bite for a good hour with pressures falling at a quick pace. Pressure is everything in shallow water fishing. Trust.

Mr. Fish,

The depth of water as it pertains to barometric readings has no effect. An inch up or down in the water column in 2 feet of water has the exact same incremental effect of pressure as an inch, up or down, in 33 feet of water. It is very close to totally linear as water doesn't "compress" much. Air does so atmospheric pressure is not nearly as linear.

I am totally with you, I agree, about fish and their ability to hear, feel and see.

And, I buy the idea that the front (weather) might have been the reason for them to stop biting. Again, weather. Your watch, too, as in time of day.

But, following Eric's earlier logic in an anecdote he shared that no weather had changed, but that the barometric pressure had altered by just .06, 6 ticks, and it was the sole change in conditions he was aware of . . . and it shut down the bite . . .

just explain to me how a fish can discriminate between the added or lessened pressure of +/- .06 from the equivalent added or lessened pressure from its movements in the water column up or down of less than an inch?

Even if we can all agree that a fish can sense these pressure changes, I buy that, that they affect its daily routines including eating . . . exactly how does it differentiate the 6 ticks from .79 inches as it swims here and there feeding actively?

Here is the math. I moved the decimal place over so 29.92 is 2992, gave the results in inches related to each tick of baro pressure. 6 "ticks" of barometric pressure (I illustrate increasing pressure but it would be the same in either direction) is equivalent to .79 inches of change in water depth. Less than an inch! I also drop down to show two atmospheres . . . the 33 feet every scuba diver in the world knows represents 2 atmospheres, a doubling of pressure.

So, a fish is swimming around and eating one moment, it is likely moving up or down in the water column way more than .79 inches . . . and it is supposed to be able to differentiate between the pressure changes from its own movement . . . and the pressure from changes in air pressure pushing down on or letting up on the water?

Now, that is some tuned in fish!

Brad

Chart

Here is a great article that may help explain better than I could. It all has to do with Air Bladders and what pressure changes do to the air bladder.
https://weather.com/sports-recreation/fishing/news/fishing-barometer-20120328

My barometer is the cows...if they are lying down, I ain't fishing.

But, after reading all this, I'm buying a barometer!!!!!!!!!!!!!!!

Perfect. Crappiefan.

$

Eric

I suppose it is all about how one reads it, certainly though next to nothing about bladders. Bladders sure become an issue if you catch really deep fish, then release them bloated. But, here, we are talking about a sudden change of something approaching 1 atmosphere.

It starts out, as articles often do, by quoting an expert. And expert on weather, not fishing. He does great.

Then, it goes off track with Spud Woodward's poor logic and absurdities. He does say, "While Woodward admits that there's no definitive answer for how a rising or falling barometer affects fish behavior" so he gives himself an out I guess. Spud is just another guy who doesn't get how little a fish need move up or down to totally offset any desired pressure relief. He, too, fails to help understand how it is fish aren't bothered moving around in the water column chasing dinner, yet are super sensitive and discerning regarding the tiny pressures from air.

Again, how can a fish discern the differences between pressures owing to the levels it swims, and the tiny pressures exerted from air?

I like Captain Sullivan who says, "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."

Yep! He attributes it to . . . weather and its effects on water temps.

Sullivan then reports, "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."

Yep, the wind changes. Weather.

And, again here, "With the storm still miles away, a light, cool breeze sprang up" meaning the bite turned on owing to a sudden development of wind.

Weather, again.

I do like Ray Rosher's comments on sailfish migration using the wind to fight the dominant currents. Cool! He says it is high pressure but what he really should say is high pressure means winds from the north helping sailfish push against the current. Here: "When high pressure moves in, we're in a cold front and the wind is from a northerly direction."

Weather.

More in the form of an anecdote from him: "A good example occurred recently when my co-captain, Alex Castellanos, caught five sails in calm conditions. The next day, the barometric pressure increased and the wind shifted around from the north. Alex caught and released 15 out of 16 sailfish in less than four hours!"

Yep! Calm conditions then the wind shifted around from the north (high pressure) and the feed was on.

Weather.

Anyway . . . Eric, have you come up with an idea how fish can discern changes in pressure, from just moving around or chasing dinner and changes in air pressure?

Brad

I'm guilty,been watching the pressure today. We are low low right now. 28.67 and was 28.64 3hrs ago. Rain showers in sperts. Looking just north at canyon lake,it's higher 29.41 but haven't been tracking it. Debating some night fishing but don't want to get skunked OR soaked. HAS to start climbing,can't go much lower right?
UPDATE,Dang Weather.com is listing wrong info! Ah man,I have to buy a gage of my own!

This has been the interest topic on TFF
I love the fact we have two biologists discussing this topic.

My question to both :

How does barometric pressure affect spawning activities?
I walk the shore during lunch see largemouths bass locked on beds just this week

So if water temp is above 63 and barometric pressure is bad . These fish are spawning in 1 to 2 foot of water
What affect does pressure have on these fish?

Anyways have a good weekend fishing going this afternoon.