Could those concrete frames double as buoys and ocean fencing?
Surveillance, testing and feeding equipment might have something to hold on to that way reducing either propulsion or lines, or the need of a boat
Permanently operating the above support boat on below´s conditions doesn´t look either profitable or fun
in this context the picture of Ekofisk looks like a giant version of existing aquculture pens.
The bottom could be mostly solid (if trapping sediments, scrap food and waste, is desired) like an artificial seabed where lobster, sea urchin and cucumber might dwell and take shelter,
Closed Containment could also be an option to further alter-control conditions
Indeed it would be helpful to listen to the opinion of someone already doing open ocean aquaculture.