Atmospheric Pressure
North America has no shortage of storms and other extreme weather events. These usually occur when the air masses over the ocean meet those that come from the continent. Depending on how vast the temperature difference (and, therefore, difference in barometric pressure) of those air fronts are, we either get a light breeze of a heavy storm. The most basic way wind affects fish is by affecting the behavior of the water. High wind disturbs the water, creating waves and currents that increase turbidity of the water (in simple terms, makes the waters murkier). This makes fish less attracted to the surface of the water and whatever may come from it because thanks to all of this disturbance the nutrients usually locked in the resting soil of the water body’s floor are now all around in the water. It also makes your bate or fly less visible.
But the amount of wind can also be indicative of atmospheric pressure, which has a more significant effect on the fish due to the anatomical specifics that they have. The main organ in question is the swim bladder. The swim bladder is like a bag of air inside the fish that allows it to more easily change depth and remain at that depth with little expenditure of energy. This evolutionary adaptation is present in most with, with some oceanic exceptions, such as sharks for example. The larger the fish – the bigger the swim bladder. The bigger the swim-bladder – the more sensitive the fish is to atmospheric pressure. The amount of air pushing down on the water body determines how much effort the fish needs to achieve buoyancy to rise closer to the surface.
Low pressure usually means that clouds are brewing up a storm as the high pressure air is drawn in. With the significant difference in temperature between the high-pressure and low-pressure fronts, condensation occurs. That time when the storm is gathering is an opportune time to fish as the air pressure is low and fish are in higher numbers towards the surface. The slower the storm formation process is, the greater your time window for getting a good catch. It is time to head home once the storm starts, however, because of the high winds we’ve already discussed. Once the storm clears, it is usually followed by clear skies. Clear skies means high pressure, so while the sunny weather factor will make the fishing trip that much more pleasurable, it won’t make for a good catch. Depending on how long the clear skies endure, the fish will be relatively dormant. However, the behavior of the fish is affected but not completely determined by air pressure. After about three consecutive days of clear skies you can go out on the lake with high chances of a good catch, because during that time the fish wasn’t actively searching for food and is getting pretty hungry by that point. To summarise, what you want to look for is a rapid decrease in air pressure before and during your fishing trip. Likewise, if the air pressure rises rapidly, it is best to save yourself the trouble of the trip and engage in another activity.
