It has been known for a long time that the barometric pressure has an effect on fishing. How the pressure directly effects the fish is still not fully understood, but knowing how to use the barometric pressure readings can greatly increase your chances of catching fish, especially in shallow and fresh waters. Barometric pressure is the measure of the weight of the atmosphere above us. It exerts pressure on the waters we fish and even on us. In fact, it can change how well some people feel. It is believed by many, that it may have a similar and even more dramatic effect on fish effecting their feeding habits. The barometric pressure changes as the weather systems over us changes. When you look at a weather map that has those blue "H"s and red "L"s, this is indicating the areas with High and Low pressure. It is worth noting that the areas with high pressure are the areas with good weather, and the areas with low pressure are the areas with bad weather. Fishermen have used weather maps to predict the quality of fishing, and more importantly, how to fish. It is important, however, to note that the effects of barometric pressure is greater in fresh and shallow waters, than it is in deeper waters. This is probably due to the fact that the pressure of water is so much greater in deeper waters making the air pressure above it no longer having any significance. Some general rules regarding barometric pressure are: High Pressure: Clear skies. Fish slow down, find cover or go to deeper waters. Slow down and use baits more natural and attractive to fish. Fish in cover and in deeper waters. Rising Pressure: Clearing or improving. Fish tend to become slightly more active. Also fish at intermediate and deeper depths near cover. Normal Stable Pressure: Fair conditions. Normal fishing is active to slow. Experiment with your favorite baits at all depths. Falling Pressure: Degrading weather conditions. Most active fishing at this time. Drift fishing is good. Try fishing shallow water or intermediate depths. Slightly Lower Pressure: Usually cloudy conditions. Many fish will head away from cover and seek shallower waters. Some fish will become more aggressive.Use shallow water tactics and natural baits. Low Pressure:Rainy and stormy weather. Fish will tend to become less active the longer this period remains. As the action subsides, try fishing at deeper depths. It is also important to note, that the barometric pressure is just one of many factors that effect fish feeding habits. Other effects include water temperature, light, tidal forces, water clarity, the pH level, water levels, wind/surface disturbance, boat traffic, fishing pressure, and so on. Another good judging factor of fishing is the solunar effects which play a role in the tidal and illumination factors.