Possible Clues:

• Of late this will happen to die with a twist
• Calm water at dusk
• End of the day (poetic)
• Smooth variation of current towards the end of the day
• It's not so odd to get 29 across before 22 across
• Somewhat late in the day for regular diet to be altered
• Not so odd that this might ebb and flow of late
• Poetic period
• Result, fish during latter part of day
• For the poet, neither early, spring, not neap