Yesterday I touched on tides, temperature, light and the moon, re our success rate and one other factor is Barometric pressure. This has a big effect on Fish Behaviour.
Trout have large bladders and when the air pressure is dropping their bladders expand and the fish becomes uncomfortable. They relieve their discomfort by moving deeper in the water. When this happens they are not worried about eating (or as we say, they go off the take). *George Poveromo.
It has been my experience that when this happens sea trout go to the bottom and feed only on shrimp and I suspect the sand eels and herring fry return to the bay.
Pilots understand the science of this much better than us groundhogs, as one explained, imagine a giant hand pressing down on the globe and tides failing to reach predicted levels. No wonder the poor fish are off form!
What is Barometric Pressure?
According to Dr. Stephen Baig, an oceanographer at Miami Hurricane Centre, barometric pressure is defined as the weight or mass of an entire air column on a unit of surface area at sea level. Liquid mercury is used in a berometer to measure air pressure changes.
“Imagine a U-shaped tube” says Dr. Baig. “At one end is liquid mercury, whereas the other end is open to the atmosphere. When the air pressure rises, it pushes the mercury higher. When the air pressure drops, so does the mercury level”.
As a very general rule, cold, wind and rain are associated with low atmospheric pressure. When high pressure settles over an area it often means bright days and relatively calm seas.
According to Spud Woodward, Angler and Assistant Director for the Georgia department of NRCR Division. “A fish senses pressure changes through its air bladder, well in advance of humans. Many things they eat have air bladders and that alone could have a big impact on where you might find them and how they’ll behave”.
“Fish with large bladders quickly sense when the air pressure is dropping, because there’s less pressure on their bladders. With less pressure their bladders expand a bit and fish become uncomfortable. They relieve their discomfort by moving lower in the water or absorbing extra gas in their swim bladders”.
According to Woodward, “fish are much more comfortable when there’s stable high pressure and they tend to feed actively most anywhere within the water column”.
*George Poveromo is Editor-at-Large for Salt Water Sportsman Magazine and Host of the TV series “World of Saltwater Fishing” on NBC Sports.