The old oyster R-month rule

One of the more well-known, but less understood, rules about oysters says that they should be eaten only during months that have an "R," so from May to August, they should be off the menu.

This guideline goes back hundreds of years and is rooted in lack of reliable refrigeration and a need to allow oysters to reproduce during the summer months. When oysters reproduce, they become weak and may be susceptible to disease.

Today, thanks to modern refrigeration and the development of new breeds of oysters that do not reproduce in the summer, oysters are fine to eat any time. "The thing we spend most of our time educating on is that with farmed oysters, you can eat them year-round," says Tal Petty, who harvests the Sweet Baby Jesus oyster at his St. Mary's County farm, Hollywood Oyster.

"First, they're not sitting on a boat in the sun for hours on end," he says. "And two, we grow triploid oysters — hybrids. They don't have sex in the summer, which means their meat is firm throughout the season."

The Maryland Department of Natural Resources has a campaign to get diners past the R rule: "New aquaculture technology, strict harvesting standards and modern refrigeration have debunked this myth and made our Chesapeake delicacy enjoyable year-round!"

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