Grouper use to frequent shallow reefs just like Blue Cod. But the resident fish were quickly caught so now only* find in their deeper habitats. Well the shcoolies do still migrate into the shallows. A few remote spots, like around the Chathams still have grouper maintaining populations in shallower, more accessible spots.
I remember reading a article which mentioned larger grouper chasing baitfish around the Haast wharf.