a bait in the water may change the chemical buidup of all the water in the river.
Hi Fred,
I am sorry to take so long over this response. Unfortunately I had other things that had to be done immediately.
I accept that that some kinds of chemical change take place; bait companies have been making such claims for years. Hitherto I accepted that as a reasonable and plausible claim with regard to lakes. But a river is not a lake.
Even with a lake it must take some time, though it may be a very short time, for a flavour or scent to spread from the local point of entry. Baits are not energy - they are neither radioactive nor electrical so any effect they have will need time and a medium to spread. Water is the medium but what is the means of transfer, via the medium, to the rest of the lake?
Are you saying that some species of fish have a sense of smell so acute that a minute chemical change is detected by them as a sound, or a beam of light might be detected by human sensory equipment?
We know fish detect sound and other vibrations over long distances extremely quickly. Even for humans, sound travels faster underwater.
With a river, as you say yourself, the effect, whatever it is, is limited in its transfer upstream. I suggest it is almost certainly absent from upstream, because the water is moving all the time. Let's take the Trent, a river we both know. It has an immense flow rate so the water is gone, almost as soon as it arrives. There was a Greek philosopher, Heraclitus, who said, according to Plato,
“You could not step twice into the same river; for other waters are ever flowing on to you.”
For Heraclitus, the river’s flow was a perfect example of his view that the only constant in the universe is change – so there!
Getting back to the baits and how fish become aware of them, could you point me at sources that support what you say, as I am genuinely interested?
One more point. I certainly do accept that fish will detect the arrival of pellets, as the sound vibrations [and the smell] are carried, in the water, downstream to them, from upstream, by the current. They then swim, upstream, to investigate.
But would fish swim downstream, [from upstream] having “heard” pellets chucked in twenty yards downstream of them?