While the levees were breeched they didn't magically become desirable habitat. The former freshwater/terrestrial forms need to die and decompose, the marine and estuarial forms need to invade, establish, and form new ecosystems.

It will probably take 5-10 years for the estuary to establish and begin to fully function. Say that this year, 2017, the new area hit 100% super functionality. First chum to benefit will be 2017 brood when they invade as fry. The first adults to have that benefit will be the 2020 age-3s.