For as long as Due West Anglers has been writing articles, there have been two white-whale topics nagging us: the influences of moon phase and barometric pressure on fishing success. I've taken deep dives into literature on each topic, learned nothing conclusive, and tabled each topic repeatedly. But the time is finally upon us, and we're goin' myth-busting. Let's look at the Barometric Pressure debate and dive into one of the most enigmatic topics of the modern fishing community. I'll try to give a fair representation to both sides of the argument, but the emphasis will be on which side is supported by facts.
Note: Most of this discussion uses trout as an example species, but this isn't a trout-specific conversation. I tried to interject information about other game fish whenever applicable.
What is Barometric Pressure?
Atmospheric pressure (also known as barometric pressure) is caused from the downward force of air in the atmosphere. Generally, pressure is minimal in the higher atmosphere, and greatest at the Earth's surface. But even at Earth's surface, pockets of high and low pressures can be found, and are caused by heat convection and Earth's rotation. Air wants to flow from areas of high pressure to low pressure. Rising air leads to low pressure at the surface, while sinking air leads to high pressure. These movements of air due to pressure changes create weather. With high pressure cells, descending air suppresses weather development. Usually calm, clear, and sunny conditions are associated with high pressure systems. During low pressure, wind circulates upwards. As air rises, it cools and the moisture held in the air condenses, creating clouds, causing wind and sometimes precipitation. Many anglers believe changes in pressure influence fish behavior, mainly in their feeding aggression. Therefore, theories have been developed about which types of pressure are best for getting a fish to bite.