I agree with Bruce. Have you noticed most here have said they catch one fish before the rest stop ? I have posted this before. It has been noted in many fish species ,that when one of its kind is subjected to a strong negative stimulus (hooked and dragged around) the hooked fish releases a chemical warning response into the water. The rest of the fish take notice and become wary .

Having said that some fish species are harder to get to bite . There are even differences between sub-species and individual (genetics) of the same type , and I am sure age and conditioning can be a factor.

One fish biting a hook and that act being a conditioning event on all the others there who have not bitten a hook and who have successfully filled their gut with pellets many times -- I don't know. More likely there is another warning method at work. \:\)