Lefty: There is no simple answer. For example, if there is a spring tide and the water is rushing out of the estuary, baitfish caught in the outgoing current may not be strong enough to resist being carried along, and predators will recognize this. Also, the water on the lower stage of a tide is often dirty or roiled, especially on spring-tide periods. The theory that predatory fish will wait outside an estuary to feed on baitfish being swept to them by a falling tide is most effective when the estuary empties completely, forcing the bait out. If several feet of clean water remain, you are correct in assuming that the predatory fish will enter to feed.