The raft belonging to Jack and Sue Blake lies on Katama Bay, surrounded by a field of mooring balls and strings of rubber markers. It’s the one with the tall wind turbine whirring at one end, cages piled high on the platform, and a winch bolted to the deck. Unlikely as it seems, this is a farm where oysters grow.

Sweet Neck Farm – as Jack and Sue call their business – is one of eight oyster farms occupying eight acres at the heart of Katama Bay. Established in 1996, Sweet Neck is among the oldest, most elaborately engineered, and successful aquaculture operations on the bay.

Jack is a former house builder and shell fisherman who came to the Island from Marshfield; ashore Sue also works as a dental hygienist. The Blakes start their growing season each year with 600,000 seed from a certified nursery in Maine – about three fistfuls, fine as dust – and look after their oysters all year-round as they grow in boxes beneath the raft and in cages set ten feet down on the bottom.

“We’re known to have a large cocktail oyster,” says Jack. “Everybody’s farm is a little different. Everybody’s color is a little different. But to me, I want a full mouthful.”

Below the raft, a tide-powered upweller – a nursery of sorts – funnels nutrient-rich water to the seed. A sorter on deck separates the growing crop according to size, and a tumbler cleans the shells and helps them grow to an appealing depth and roundness – each device designed and built by Jack and powered by the wind turbine. If all goes well, Jack and Sue can grow a crop of market-sized oysters in fifteen months, while in the wild it may take up to three years. They supply restaurants, caterers, and customers across the Island and on Nantucket. Wholesale, the oysters fetch roughly 85 cents each; if there is a surplus, Sweet Neck Farm can also ship to the mainland, and restaurants in Boston will charge their patrons as much as $3 per oyster.

When the section of South Beach known as Norton Point gave way and the breach opened Katama Bay to the Atlantic during a storm in April 2007, Sweet Neck Farm lay as close to the newly opened hell gate as an oyster farmer would ever want his raft and crop to be. Old-timers told Jack that shellfish thrive when Katama Bay is opened to the sea; the currents scour and clean the bottom and bring in more nutrients from the Atlantic. “Be careful what you wish for!” says Jack. “I think we came down on April 17 [the day Norton Point opened], Sue and I, and we got seasick. On this raft we got seasick, because the currents were so strong. We still had a surge coming right through the opening. The raft was going sideways.”

The opening has also exposed the farm to unpredictable phenomena and pests, such as mud, mussels, barnacles, and worms that cling to cages and shells, all of which must be cleaned by machine and by hand before harvest. With the tide running so hard through the bay – up to three times faster than it once did – the algae that feed the oysters hurtle by, and the bay is not quite so abundant with nutrients as it was when Norton Point was closed.

“They’re not quite as sweet, I think,” says Jack of his crops since 2007. “And the water temps are way different – way colder. We lost probably three weeks of growing down here when that thing opened, because of the water temps. But you know, the consistency, I’d say, is better. They’re meaty, they’re plump, they always taste the same – which is still a good, salty taste. Which, in a marketing sense, is great, because chefs love consistency.”

Jack and Sue have learned how to deal with the Atlantic Ocean reaching into the bay where they tend their farm. “It’s working. The oysters don’t seem to mind it. I’d say leave everything alone. But I would like to live long enough to see it closed,” Jack says with a laugh. Like any good farmer on the water, he is “ready for both.”