"...Baton Rouge would be under a couple hundred feet of water within a few weeks and would be 'scoured clean')..."

I doubt so: Baton Rouge is ~50 feet above sea level. But the fishing would be great:

https://4.bp.blogspot.com/-_UCHTL-r7y4/V-l1w64zq4I/AAAAAAAAB...

or

http://3.bp.blogspot.com/-dDnJPonMvAo/UViQt1k7xHI/AAAAAAAAC2...