What is the best pressure for fishing

Where the weatherman begins, the fisherman ends

Fishing wisdom

Surely many anglers in a burst of enthusiasm tried to keep a diary, where they recorded weather conditions and fish activity. The main purpose is obvious: if you find a pattern of pecking from weather conditions, you can choose the most successful days for fishing just looking at the weather forecast.

For some reason, the main parameter affecting the catch of fish is considered to be atmospheric pressure. The Internet is full of abstract articles on the subject of “what pressure is better for fishing?”, which say general words, unsubstantiated conclusions of anonymous authors often contradict each other. There are, of course, also common theses. They all boil down to the fact that allegedly fish can not quickly adapt to a sharp jump in pressure, due to the fact that it has little blood and it has to long pump air into the bubble to compensate for the difference. Therefore, the optimal pressure must be constant over a long period of time. What a “spike” is, how sharp it is, and what pressure is considered normal for catching fish, the author must guess for himself.

Ichthyology

Let’s try to figure it out with a scientific approach. First, let’s turn to ichthyology. Almost all species of fish inhabiting the territory of the Russian Federation, have such a hydrostatic organ as a swim bladder. It is a rather voluminous outgrowth of the intestine, which appears at the stage of embryonic development.

Initially, the swim bladder is connected to the intestine air channel, but in the process of further development of the embryo in some species of fish this channel is overgrown, they are called closed-bellied. Closed-bellied fish include: perch, pikeperch, burbot, burbot. Open-bellied fish include: catfish, pike and all carps. The fundamental difference between these groups of fish is that in closed-bellied fish swim bladder increases only due to the gas gland, and decreases due to the oval (a small hole in the inner shell). Because of this, the volume of the bladder changes slowly. Open-bellied fish are able to change the volume of the swim bladder more rapidly with the help of the air channel.

Pressure fluctuations and its effects

You don’t have to be a fisherman to realize that different species should react differently to pressure. But how noticeable are atmospheric pressure fluctuations to fish? Let’s turn to physics. The pressure at a certain depth of the liquid is calculated by the following formula:

P=Pa+ρgh,

where Pa is the pressure of the air column above the surface of the liquid, ρ is the density of the liquid, g is the acceleration of free fall, h is the given depth. For example, if the atmospheric pressure is 750 mmHg, then at a depth of 3 meters there will be a pressure equivalent to 971 mmHg. What do you think? Obviously, if the atmospheric pressure, for example, increases by 20 mm.Hg, then underwater it will become greater by the same amount. Such a “jump” in atmospheric pressure would be equivalent to a 27 cm change in depth. That is, fish can rise 27 cm higher and compensate for this difference. Thus, a perceptible jump in pressure, at first glance, seems almost insensible underwater. For example, a pikeperch, living at a depth of 10 meters, experiences such a tremendous pressure that for him 20 mmHg will only change the total pressure on the body by 3%.

From all of the above, it may seem that atmospheric pressure does not affect fish at all. But this statement would also be wrong. The whole point is that the swim bladder of fish performs in addition to its main hydrostatic function and barometric. If the external pressure changes, the volume of the bladder changes, and the nerve endings in the walls of the bladder transmit the appropriate signals to the brain. This function is needed fish primarily to monitor the water level.

If the water level decreases – this is a serious reason to change its habitat to a deeper, that is, safer. When the pressure rises, perhaps the opposite processes operate, in any case, this would explain the active catch of fish in the morning and evening, when the atmospheric pressure rises.

Atmospheric pressure for fishing in winter

It is also worth touching on the topic of atmospheric pressure for fishing in winter. After the ice age, the pressure in the reservoir does not change and does not depend on atmospheric pressure. Probably many people are familiar with the situation when, after drilling a hole, water begins to flow out of it. This indicates a pressure difference. But this happens only on “unpressurized” reservoirs, where fishermen are extremely rare. Usually a huge number of holes negates the effect of isolation and the same principles that apply to summer fishing begin to work.

Conclusion

Summarizing, from a scientific point of view, we can safely say what pressure is better for fishing. If all other factors are equal, a constant, elevated or pressure with small, about 5-7 mm Hg, drops are preferable. This corresponds to a change in depth of 5-10 cm, which is equivalent to a small wave on the surface of the water. The deeper the fish dwells, the less susceptible it is to atmospheric pressure variations, perhaps deep-sea species do not notice its changes at all.

Do not forget that fish – it is a complex and primarily a living organism, whose feeding activity depends on a variety of factors that together affect behavior: water temperature, light, water oxygen saturation, and predators also from the activity of victims. All parameters of this huge equation is simply impossible to calculate. Therefore, it is better to enjoy fishing, not clogging your head with extraneous thoughts and not writing off your fishing failures on the change in pressure or the phase of the moon. Remember, all a fisherman needs is a rod and a river!

Author: Bob Nudd is an expert fisherman with over 20 years experience and winner of many competitions.