From Animal's TPFR post...
I just spoke with Gordon Leisch. He is a former marine biologist and VERY long time Potomac fall line angler. His logs go back 50 + years. We averaged the date of the first bite for a few species. Based on his records they are as follows.
Blue Catfish Year Round 20 - 40 pounders being caught now on the sandbar
Gizzard Shad March 1 in numbers but always around
White Perch March 15th
H Shad March 30th
River Herring March 30th
Striped Bass (big) April 1st
Snakeheads Insufficient data Usually around the 1st of April with a high water event
A Shad April 15th