View single post by kAtOnKeL88
 Posted: Mon Mar 22nd, 2010 07:46 pm
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Joined: Sat Mar 6th, 2010
Location: Naboom, South Africa
Posts: 3
Barometric Pressure

by Raymond de Bruyn (Photos by Brenna Bales-Smith and Dean Pretorius)

This is an exceptionally “scientific approach” in the whole angling arena. Many enquiries have been mailed to us regarding this subject and exactly how it affects our love, angling. Let’s take a look at the intricacies of it and work from there.

To help us understand the words ‘barometric pressure’ lets turn to the dictionary definition: Barometric pressure - a noun describing atmospheric pressure, indicated to us by a barometer.

Now that seems fairly straight forward and simple to understand but if we dig a little deeper we will see there is a little more to it as far as angling is concerned. The scientific definition of the words Barometric pressure states - it is a measure of the weight of the atmosphere above a surface averaging approximately 29, 2 inches of mercury/1013 millibars (mb) at mean sea level, which corresponds to 14, 7 pounds per square inch.

Now that is a little more complex but still, with the help of an instrument simple enough to understand its not all that complicated. A barometer is an instrument used to measure atmospheric pressure. Basically, in general terms, changes in barometric pressure indicate weather changes, these changes can be good or bad, and this can all be defined by what the barometer is doing. For example is it dropping or rising?

Bad weather usually occurs when the barometer is falling where as good weather on the other hand can usually be predicted by a rising barometer. Through this simple method one has the advantage of being able to predict the weather.

Anglers have their own ideas, opinions and theories about the marine environment that don’t necessarily always stand up to scientific analysis. We generally believe that as pressure changes so the effects are felt by the fish, causing them to feel uncomfortable or resulting in fish on the bite. According to scientists atmospheric pressure has no significant effect on fish feeding habits but, it does have an effect on the depth or structure where a fish would prefer feeding during high and low pressures. According to scientists the weather conditions indicated by a fluctuating barometer have more effect on feeding patterns than the air pressure itself. Usually a high barometer means clear weather and a rising barometer is the result of clearing or improving weather. A stable barometer would suggest fair weather conditions where as a slightly low level barometer indicates cloudy weather and a lower reading indicating rain and storms.

 Another way of looking at the changing weather we experience with changes in the air pressure we could look at the winds which are known to affect a fish’s behavioral patterns. One theory is that high pressure will result in clear skies and little wind. A rising barometer indicates, improving weather with the usual light south-westerly or south-easterly. Stable pressure generally shows fair weather with a light north-easterly. A falling barometer is the result of bad weather approaching, usually with strong north-easterly winds, a slightly low barometer means that a south-west is coming and low pressure indicates rain and storms along with gusting south-westers.

Winds play a huge role in the effects of fish feeding patterns and therefore also on the species we can expect to catch.

Affects of winds on marine conditions.

The theory is that wind from the left i.e. a north easterly, will make things more productive whereas with the wind in your face, a south easterly, the fish don’t tend to eat. This is commonly known as the poison wind. Wind from the right, namely a south westerly often results in good fishing on the first day of south west but then deteriorating as it continues to blow.

Let’s put some facts to theses theories to prove why these different winds affect angling.
One straight fact is that oxygen content in water plays the most important role in the fish behavior. Oxygen can be gained or lost depending on what conditions regarding wind and air pressure are present. Generally high pressure forces more oxygen into the water and low pressure removes oxygen from the water. Wind also plays a role in the amount of oxygen available in the water, with the north-easter generally making the swell shorter causing the sea to become choppy thus infusing more oxygen into the water. The southwest on the other hand, makes the swells longer creating a less choppy sea and thus resulting in less oxygen being infused into the ocean. With that being said there is one more element to throw into the equation. The water temperature also has its role to play… Colder water, usually blown inshore by a north easterly wind, has higher oxygen content than warmer water, caused by south westerly winds.
What causes a fish feeding frenzy?

Fish notice the decline in the oxygen content of the water. This oxygen starts depleting because of the air pressure and the sea conditions present. As the pressure climbs so the oxygen levels increase making the fish more active and going about their normal behavior. Once the air pressure stabilizes, the oxygen levels reach their highest levels. This climb in the barometer usually coincides with a south westerly wind. Once the weather stabilizes, the north easterly begins to blow filling the water with even more oxygen leaving the fish happy and comfortable. This is called the ‘lag’ period. The north easterly wind means a low pressure system is moving up the coastline and the pressure starts dropping as this low pressure comes closer. As the pressure drops so the oxygen levels also begin to deplete causing the “smash” as fish begin to feel the depletion in oxygen causing them to panic almost and thus resulting in the fish eating as much as possible before the bad weather conditions arrive.

Now you can see the complexity of all these factors really do keep us guessing on where what when and how the fish are going to be feeding. In short, using the above information we can conclude that, the barometer does play a significant role in indicating what the fish feeding patterns may be, taking many more aspects into consideration than just the air pressure. In fact we can actually say that generally, a high barometer reading means that the fish are content and will feed at leisure not really going out of their way to actively pursue food and a dropping barometer will indicate an out come, resulting in the conditions sending the fish into a feeding frenzy because due to the conditions of the elements we have discussed, combined with a low pressure the fish will sense the possibilities of bad weather approaching, thus forcing them to eat. A low barometer will show that the conditions present will slow down their feeding and finally a rising barometer will tell us of good conditions approaching, slowly making the fish more active and less panicked, thus returning them to their normal feeding patterns.

In short there are many other factors involved in finding fish and their feeding spots. As a good friend of mine once said, fish bite best when your bait is in the water. If you are not fishing then you can’t be getting any bites! There is only one thing that will suffice other then than not working and catching fish and that is being on the beach early in the morning when the sun is just rising, the fish are jumping and the birds are starting to wake up. I reckon God made early mornings especially to enjoy everything about being near the water, not necessarily just what’s in the water.