Monte Burke combines historical anecdotes and personal experience on the Miramichi in an attempt to answer the question.

To the list of life’s great mysteries — the primacy of the chicken or the egg, who shot J.F.K., why there is an s in the word “lisp” — I would add one more: how long should an angler wait to cast again to an Atlantic salmon that has come up for, but not taken, a fly?  Via: The NY Times LINK