I've been feeding fish in shallow fresh water ponds and lakes for 28 years. Just before the passage of a front, fish feed like crazy. During the passage of a front, they feed well. Once the front passes, forget it for sometimes three or four days. I noticed this beginning 1980, when feeding catfish every day. You could see the front coming, head out on a tractor with a bin full of feed on the back and it seemed like every fish in the pond fed like it was their last meal. The day after the front passed, forget about it. We got to where we didn't even take time to feed the slimy little creatures. I believed that the fish could feel the changes coming, their instincts told them conditions would be tough (the water temperature would drop, weather would be cold)so the fish literally gorged themselves. Then, as it seemed to me, since they all filled their bellies at the same time, they weren't hungry again until that food was digested. In my feeble, young fish farmer mind, the fish didn't eat after the front because they weren't hungry. Then on or about the third day, they returned to "normal" feeding habits where about half or two-thirds of the fish ate at each setting. I don't quite understand the science behind it, other than the fish used their lateral line system to detect a change in pressure which triggered their instincts to take advantage of all offerings.
To me the interesting part is that what I learned started in catfish ponds, with only one species of fish which were totally dependent on fish food for nutrition.
But, as my career expanded, I saw the same traits in multi-species fish populations.
To this day, I watch fish feed voraciously just before the passage of a front.
I believe fish act on instinct and conditioning. They use all their senses to be able to feed. For example, when a school of shad moves, it sends ripples through the water. A bass or striper detects the movement. At first, since the school of shad moves in unison, unless the predator sees the school, it interprets it as one big fish. That's the lateral line at work. But, with conditioning, when a predator investigates, their eyes tell them that single big fish is actually the motherlode...bazillions of morsel-sized shad awaiting their roles as a snack.
Ah, but the eyes can also be deceiving. See that black dot behind the gill plate of a shad? Bass and stripers aim for the eyes and tries to swallow its prey head first. When the predator attacks the school, all kinds of dynamics are taking place and it happens fast.
The predator counts on its lateral line to find the school, its conditioning to investigate, its eyes to see individual fish. When the predator attacks, the school "flushes," immediately changing its olympic-style synchronized swimming movements to a "run for your life" attitude. When the school flushes, other predators sense it with their lateral lines and race to the scene of the activity. A feeding frenzy ensues.
The moral of this story?
Fish don't have the ability to think or reason. They are totally dependent on using their senses and instincts which are influenced by conditioning. So, methinks, while simply assuming the pressure changes trigger a feeding response may make sense, I think the bigger picture is that ALL their senses kick in to form the response to barometric pressure changes, visibility, temperature, turbidity...all that stuff.
Heck, here you guys are, talking about it and no one really knows the "truth." That's one of those cool little things that make this "fish" thing so dang much fun.
I do this for a living and I can't confidently answer the question.
