I think they will head upstream on thier normal migration. (Who is to say what normal is?) When they actually spawn I believe depends on them finding the right temperature and current conditions upstream on the spawning grounds.Think I remember reading somewhere once that that temp. is around 60 deg. I could easily be wrong as my memory isn't all that good. What was the question?
i have learned from biologists and with my own eyes that some (often bigger fish) will spawn early like when water temps around 55*. however, a lot of spawning oocurs 60-70* range. problem is this: warming trends can shoot water temps bonkers delaying or speeding up. overall, mother nature tends to have spawning animals work a 25-40 day cycle. deer in the rut, strutting turkeys and fish.
one characteristic of spawning stripers is that they require oxygen rich areas. for one, the eggs free float in the water. the oxygen like in rapids or in tidal situations gives em what they need. above tidal regions, look for flats roughly 1/8 to 1/4 mile above rapids etc....eggs can mix properly with sperm and free float into the nursery areas of the river.
The spawn is temperture related along with that they spawn in fresh water. Striped Bass spawn on the surface and will start to spawn as the temp approaches 58 degrees the best temp is 62 degrees. They will spawn on a falling tide over deep water as the eggs must stay afloat for at least three days. The Hudson river provides the best conditions due to the turbidity and tidal movement. I have seen them spawn several times once it occurs the females drop out of the river and down to the ocean. The really large females are up in the spawning areas as early as the first weeks of april. They will move up stream with the tide and rest in shallow bays with little current waiting for the tide to help them swim up river. You know the spawn is over if you start catching only males on worms as they drop out on a falling tide.