I’m not a fisherman, so I cannot speak to that side of it.
I do go down to the Biloxi / Gulfport area for business now and then, and I can tell you that the Mississippi coast had a fishing ban for almost a year. Restaurants and wholesalers were not allowed to sell anything caught anywhere near (like a 25 mile radius) of the spill.
Any fish that was served in Biloxi was trucked in from somewhere else.
That lasted until two things happened: first, the water did actually recover fairly well and the FDA (and others) declared the fish good to eat, and clean, and second, the fishing industry nudged the powers that me to make that determination.