Fishermen are probably some of the keenest weather watchers you will meet. Not just because they spend a lot of time outdoors, but because of how the weather will impact the appetite of the fish. It is common knowledge that animals can easily sense and respond to changes in weather, often before it occurs. Atmospheric pressure changes are one of these factors that could have an effect on fish too.
When I was a teenager, I was intrigued by how the fish could go off the bite from day to another. I wondered if it was air or water temperature, atmospheric temperature or some other weather change. Being a science student, I decided to do a simple study over a couple of months to see if there was any correlation between fishing and weather. Gathering the weather data over a period of time was a simple process, even before the internet. The big problem was how to quantify a day's fishing activity. How do you compare fishing and a numeric value like temperature.
I tried to resolve this by rating the fishing quality of the day, on a scale from 1 to 10, with 1 being really poor, and 10 being outstanding. I also needed to get this data every day, and sadly enough was not able to fish each day, and discover it for myself. For this information I turned to the radio (again pre-internet). Each evening a coastal fishing report was broadcast, summing up the day's fishing up and down the coast. The geographic range of the report was small enough to fall within the regional weather patterns.
Having listened to the
fishing reports for many years, I was very aware of the sources of information and consistent nature of the reporter. I felt this was a stable enough source of anecdotal information that I could quantify the results. Each evening I would listen to the report and based on information, would give the day's fishing a number on my scale. I was very careful to keep the recording of this data separate from any weather data, so as not to bias myself into following a weather trend. For the weather data, I simply clipped the detailed weather conditions from the newspaper each morning and filed it away without reading it. By the end of the two months I felt that I had collected the two sets of data independently from each other.
My biggest concern was over the numeric assignment of fishing quality. When I finally compiled the data, I was astonished by the results. Air and water temperature, showed no correlation to the fishing quality. Atmospheric pressure, however, mimicked the fishing with uncanny precision. From then on, I planned my trips based on atmospheric pressure, with much improved results. It did not stop me from trying to fish in the middle of a cold front with rain and wind, pushing through ahead of a trough of low pressure.
While there are a number of people who share my belief in the effects of atmospheric pressure, their are many who disagree. Having examined the scientific explanations dispelling this theory, there are certainly some valid points to be made. The most notable is the relative effects of hydrostatic versus atmospheric pressure. Because water is much denser than air, the pressure under water increases rapidly with depth. At 32.8 feet below the surface, the pressure is equivalent to 2 atmospheres of pressure. This hydrostatic pressure is effected by wave height, tidal action, and atmospheric pressure. The differences between high and low pressure extremes is about 0.1 atmospheres (only about 3.28 feet in water depth). This is a relatively small change compared to that of a fish simply swimming from 20 feet up to 5 feet in depth and so shouldn't push the fish into not feeding. In shallow fresh water bodies, atmospheric changes may be more noticeable, yet my original study was on saltwater fishing, where this dispute has more credibility.
This scientific logic certainly makes sense. Given the anecdotal evidence, like my boyhood study, and others who swear by barometric pressure effects, there seems to be something relating fishing and pressure. What that is, and how it effects the fish
biologically, still remains to be concluded. When keeping a log on your fishing trips, keep track of the pressure and see how it effects your fishing.
