Why just oysters? There are plenty of farmable bivalves, notably the New Zealand green lipped mussel, which are farmed out in the open ocean. One advantage with mussels is that there's no need to cage them; if attached to supports (like ropes hanging down from buoys) when sprats, they'll stay attached as they grow. In the case of green-lips, they use ropes for supports. Each rope has mussels of the same age, and the entire rope with attached mussels can be taken to an onshore processing station.

I first started eating (standard Atlantic) mussels in France in the 70s. At the time, they weren't a thing back home in the US - I didn't even need a license to harvest as many as I wanted. Also, no such thing as bottled water then - but that's a different subject.

Back to oysters. I learned in New Orleans that the secret to successfully broiling them is to make sure they're very cold first.

Finally, with soft shell clams (sand dwelling bivalves), the secret to getting all the sand out from inside is to put them in a large container of clean seawater (I used a big washtub) and throw some cornmeal in. They'll eject the sand in favor of the cornmeal. Doesn't seen necessary with the hard shelled variety (e.g. quahogs).