How We Farm: Tumbled Oysters

Just when you thought it was too late to invent a better mousetrap - along came the tumbled oyster!

We've been farming oysters since the 1950s, but only started tumbling them in 2010. It's a relatively recent innovation, and there seems to be consensus that British Columbia farmers developed the technique. In BC and other points north, many farmers grow their oysters suspended in racks, subtidally. Subtidal oysters are always underwater and basically have 24/7 food, which can cause fast growh.[1]

Fast growth sounds great, but when an oyster grows too quickly, its shell can become brittle. Building on centuries of oyster farming techniques perfected in France (the French "rack and bag" system), BC farmers figured that by agitating their oysters they could strengthen the shells.

As an added benefit, tumbling oysters drastically improves their shape by giving them nice deep cups. The BC tumbled oysters were so nice that it didn't take long before farmers from other locales began experimenting with the technique. Farmers in Australia are credited with using tidal energy rather than diesel to do the tumbling. In South Puget Sound, Chelsea Farms first rigged up a tide tumble system.

Tumbling helps with two problems: it strengthens the shells of oysters that are growing quickly, and it prunes oysters into a more desirable shape.

We sometimes refer to tumbled oysters as oyster topiary. Think box hedges and Edward Scissorhands.

Just how bad can an oyster's shape get? If a wild oyster sets between a rock and a hard place, it can grow up all twisted:

Or, if an oyster is growing too quickly or in crowded conditions, it can get long and skinny. We have quite a few of these so-called "bananas" on our beach, remnants from the tremendous natural sets that load Hood Canal beaches with wild oysters. If you're foolhardy enough to attempt to slurp down an oyster this size, be prepared for it to slap back:

During tumbling, an oyster's delicate new growth gets broken off, causing it to put energy into forming a deep cup instead of growing longer.[2]

To tumble oysters on an intertidal farm, we attach buoys to bags of oysters, and then let the tide do the rest of the work.

When the tide comes in, the buoys float and the bags flip up. When the tide goes out, everything falls down 180 degrees. Inside the bags, the oysters roll around with every change of tide.

This is more complicated than it sounds. There are all sorts of variables: too much floatation, and you worry that the whole darn thing will rise up and float off. Not enough floatation, or too many oysters, or oysters that are too big, and you might not get the tumbling action necessary to prune the oysters. Too deep, and there won't be enough of a tidal change to tumble the oysters. Too shallow, and the oysters will spend too much time out of water and will grow slowly. Too many oysters in a bag, and they won't tumble well. Too few oysters in a bag, and you're wasting your time. And if you get a mussel set in your tumble bags, forget about it. The mussel byssal threads tie the oysters up into knots, preventing anything from rolling around.

Our tumble farm in 2010, when it was brand spanking new. This photo is interesting because you can clearly see some of the bags in the background beginning to float with the incoming tide.

And one of our tumble farms in 2018.[3] 

This isn't just cosmetic: tumbling changes the flavor and seasonality of the oysters.

For starters, the shape of the food we eat affects the experience of eating it. Think about how shredding carrots versus slicing them can change the flavor of a salad, or about how it feels to drink wine out of a paper cup instead of a glass. 

Compared to beach grown oysters, tumbled oysters have a more compact body and retain their liquor longer after being shucked. They're also - usually - easier to shuck. And because they have a different diet (more food, different kinds of food), they have different flavors and seasonality.

So when we started producing tumbled oysters, we had to come up with a new name for them. In appearance, texture, and shape they were a very different product from our beach grown Hama Hamas. We settled on "Blue Pools," a name inspired by one of our family's favorite swimming holes. For us, tumble farming has been an eye-opening exploration of our beach's merroir, allowing us to farm in previously inaccessible eddies and currents.

Here's a glamor shot of one of our Blue Pool oysters (left) compared to a beach grown Hama Hama (right). Notice the smooth, rounded, deeply cupped shell of the tumbled oyster. These are both pacific oysters - so they're the same species, and they're both from our farm in Hood Canal. The differences are entirely caused by HOW the oysters were grown, which is why we place such a high importance on growing method.

NOTES

1. Check out our friends Weatherly & Greg Bates up at Alaska Shellfish Farms to see some pictures of subtidal oyster culture. And, cold water or lack of nutrients can slow growth - so we don't mean to imply that oysters from BC / Alaskan farms grow more quickly as a rule. 

2. Oyster shell new growth comes in all sorts of colors: blue, pink, purple, dark grey, or white, as you can see in the photo below:

3. Notice the barnacle set on the bags. We spend a ton of time literally beating barnacles off the bags so that we can reuse them.