
Originally Posted by
Moveon
How can you separate the effects of Barometric Pressure from the front coming though. Are they not one and the same or so related to one another that they are inseparable?
Air Pressure changes are brought about by changing air masses (fronts) moving though the area. Changing air masses are nothing more than heavy or light air (Density wise) and air masses of different temperatures.
PV=nRt
Changing light, air temperature, air density (pressure) all are part of a frontal system.
The overall changing weather pattern does affect the fishing and hunting. But how or what actually causes the fish to bite is a mystery to me.
Would a fish changing it's depth in the water make it more likely to bit you bait? Think about this for a while before you answer this question. What's the difference in a fish going 10 ft deeper in the water from a cold front passing though with higher barrometer readings? Look at this from the Fish's point of view in 30 ft below the surface of the water.
What would happen to a ballon that was blown up to half it's potential size at the surface and then sunk down to a depth of 33 ft. If the air volume of the ballon was ONE LITER at the surface with a BP of 760 what would the air volume of the ballon be at 33 ft deep? Think of this formula PV=nRt. R= Renoylds number; P= pressure in mmHg;V equal volume in liters, n= ? [Look it up]; and T is temperature in Kelvin Deg. or C deg plus 273 deg = Kelvin deg.
Think of Charle's law and of Boyle's Laws when you figure this one out.
Then remember that the air bladder in a fish is not a separate organ and in some fish it's tied to the mouth and also has blood vessels that wrap around the air badder and that allow exchange of gases between the blood vessels and the air bladder. I'm not sure how much air can pass between these blood vessels and the air bladder in a short amount of time but eventually the air in side the air bladder can be expanded or contracted by exchanging it's air with the blood vessels. This is how a fish regulates it's bouyancy in the water.
Rapid changes in light intensity are important in feeding of the fish. The yellow perch and many other fishes exhibit circadian rythms in feeding activity adn movement with peaks of dawn and dusk. There are manysubtle changes in the environment tied to day and night or tidal conditions; included are not only light, but also temperture, salinity, pH and current. The variation of any one of these factors by itself or in combination with others are discernible by fishes and may influence activity and feeding pattern. Innate timing mechanisms, termed physiological clocks, independend of , or unrelated to environmental stimuli may exist in fishes. In nature, however, timing landmarks such as diurnal light, pH, temperature and other changes are rarely absent and usually trigger levels of activity.
Let me note that changing sunlight conditions will directly affect the water's temperature. Changing sunlight will also affect the water's pH. As the sun goes down the plants start to respire and stop producing Oxygen and photosynthesis and start giving of CO2. This will make the water more acidic as CO2 gas in water will form carbonic acid which lowers the pH of the water quickly. One can blow air into a glass of water with a straw and watch the ph of the water drop instantly. The ph of the water can drop by many factors of ten.
The amount of oxygen in the water can change with the amount of light as the aquatic plants that live in the water depend on the sun's energy to produce oxygen by photosynthesis. As the sun goes down the plants turn off the produciton of oxygen. However as the sun goes down the surface of the water can cool off and therefore hold more oxygen. Cold water holds a lot more dissolved oxygen than hot water.
The point I am making in all this is that many factors can work together to influnce how and when a fish will feed.
Hunger, quality of the last feeding, smells and sight and vibrations all have an effect on when and where the fish will feed.
It's been my experience in over 60 years of fishing that fish will bite good right before a front or storm moves into the area. Fish may know that the air pressure is changing and that that means a storm is coming in and the environmental conditions will be changing. Like we humans they may put on the feed to prepare for the changing condidtions much like we humans rush to the grocery store to stock up on food before the snow storm hits. We are warned by the weathermen who look at the sky with satellites and doppler radars. But the fish have to note the darking skies and the changing surface conditions caused by the winds and waves. Both of these decrease the amount of light getting to the depths.
Then there is the position of the sun and moon in relations to the earth and their changing gravitational effect on the earth. Solunar tables are made to predict when the sun and moon are in the right spots to produce the best fishing. So they say.
When ever I catch a limit of crappie I like to check the solunar tables after my fishing trip and note the times of best fishing to see if they match the time of day that I did well. I was surprised to see how well the match up.