Trout and Barametric Pressure

[shortcaster]

I only fish when I'm alone or with someone.

[dudley]

The minimal effect of a barometric change on a fish underwater isn't even close to the pressure change that they feel moving just a couple of feet up and down in the water column
Something most fish do everyday

Just sayin'

[Marco]

AND, expanding Dudley's statement, fish can't feel barometric pressure on the water since water, a liquid, is NOT compressible.
My experience while fishing is that fish react to temp and and light penetration of water. I cannot, however, say with certainty just WHAT that reaction might be, positive or negative with regard to fishing. I also note that different species of fish react differently under those conditions.
I go fishing regardless.


Mark

[thorarinna]

Hi MarkF.
I asked this question once (nothing new under the sun)
Here are the answers:
http://www.flyanglersonline.com/bb/s...ad.php?t=14688

Regards,
Thorarinn.

[Soft-hackle]

Hi MarkF,
I've been fly fishing 47 years, and I once thought the barometer affected fish activity and feeding. This, I discovered was not true. More influential is water temperature because it affects metabolism and insect activity. Some time back FF Magazine ran an article by the late Leonard M. Wright, Jr on "When Trout Feed". Mr Wright found that water temp 63 degrees F to be the magic number. As the temperature approaches 63 from either the higher or lower side is when the best fishing occurred on freestone waterways. I have tested this out, myself, and found it to be right on. The highest insect activity took place at that temperature as well. It's nice how Ma Nature makes things coincide with one another.

Use a thermometer more than the barometer and you'll see a difference.

Mark L.

[Chuck S]

From above I noted that, "AND, expanding Dudley's statement, fish can't feel barometric pressure on the water since water, a liquid, is NOT compressible."
That's incorrect, as it's the very incompressibility of water that allows all pressure changes from the atmostphere to be felt underwater. In shallow water the change is comparably greater due to the lowered water pressure above the fish. I'm not aware of any research that shows that fish can feel the barometer change and how they might react.

My experience drawn for years of fishing and diving is that sometimes the change causes huge responses with the fish and other u/w life. I once dove a reef area on a Pacific Island that was teaming with life. We decied to come back that evening and do a night dive for lobster only to find that the fish, lobsters and more had vacated the area following a fast moving cold front that hit about 5 pm. The entire area was a ghost flat--sort of spooky really!

The author of that first statement went on to say:
"My experience while fishing is that fish react to temp and and light penetration of water."
Here's I heartily agree and personally think that this is precisely the mechanism driving a fishes apparent reaction to barometric changes.

Usually, following a sudden pressure change, or a front, the skys clear, get clearer, or get cloudy coupled with possible blue bird skys or rain/snow. At times this also occurs prior to the front arriving as the clouds and weather often overrun the front or occur just in front of it.

Less light means less heat felt by a fish near the surface, a visibility change and more. Blue bird skys mean more heat and light and the predator factor goes way up as anyone who has sight fished knows. Those fish hawks make hay when the sun shines. The fish react to all these factors be it in a stream or ocean. For certain a small stream canopied by trees will see less change as far as light changes but may well fell the temperature change that goes along with the baro change/front.

[dudley]

Here are the facts from Dr. David A. Ross of the Woods Hole Oceanographic Institute

http://www.midcurrent.com/articles/s...sure_myth.aspx

it is the change in the weather, not any fluctuation in barometric pressure

[Marco]

ChuckS,

With all respect, I did not understand your point disputing my statement. Water pressure is NOT caused by compressing molecules into each other creating a smaller volume of same.That cannot be done with liquids. Water pressure is simply caused by it's weight stacked above the measuring device. NO amount of atmospheric pressure can alter that. A fish varies the pressure on it's bladder by either submerging ( more water above it) or surfacing ( less water above it). If a fish is at a 1' depth constantly, it dose not feel ANY change in it's internal bladder regardless of the barometric pressure above the water.

Mark

[Silverexpress]

If anything, I think CHANGING light conditions, and or a quick movement will put down fish faster than a rising or falling barometric pressure.

OP (Original Poster) - the day you got skunk could have been caused by a multitude of things.

1. The food base in the area you fish was probably depleted; the fish aren't going to hang around. They'll move up or down the river or even travel for miles till they find another source of food. It could be that of all the times you've fished this area, this time you coincided with this natural event.

2. Changing light conditions - With the cold front coming, were there large patchy clouds? Was it sunny earlier, and then a sudden cloud cover blow in? Or vice versa? Fish adjust to changing light conditions by moving their rods and cones back and forth. It takes them awhile to adjust to changing light. And they do feed on bright sunny and cloudless days (This is proven by research!)

On a day that is patchy. Fish will adjust to the brightest condition - when the sun is shining thru, and then when a moving cloud casts its shadow directly above, the fish will be unable to see. Surface feeding fish will stop feeding momentarily because they cannot see as well. Days like this are an opportune time to snatch a fish in the shallows by the tail!

3. Wrong fly. It could also have meant that you were using the wrong fly. There may have been a massive drift going on below, possibly caddis pupaes, BWO nymphs, or is this a tailwater you speak off? If so maybe a drawdown for winter was occurring, this will release an enourmous amount of nutrients, and whatever lives below the impoundment. The fish could have then been conditioned to feed on whatever those are.

4. etc etc etc....

Best to keep a log or diary, and train your eye to become keenly observent of the surroundings since trout are unfortunately a product of their environment. They can't jump into a air conditioned car and sit around until things get better.

Nevertheless, this was a great question you posed, and I learned from all who replied.