I Want Oysters but There’s No “R” in May (or June, or July…)

r month oysters, oyster season
Forget the “r” months. Oyster season never has to end!

Many misconceptions and lots of outdated information about oysters swim around in the world. Few are more pervasive than the “r” month oysters rule. Most of us were taught that oysters and other shellfish should only be eaten in months with names that include the letter “r.” Hot, summer months (May, June, July and August) included no “r” and thus, no oysters.

Thankfully for oyster-lovers, this rule is FALSE or at least outdated. Commercially harvested oysters are fine to consume year-round.

Two factors shaped the “r” rule: summer can bring toxic red tides to some areas, and oysters spawn in warm weather. Red tide results from algae blooms that produce toxins which can be carried by oysters and other shellfish. Commercial oyster operations and state health departments are vigilant in tracking red tides and other potential toxins.

When oysters are spawning, they put all of their energy into reproduction. They can lose more than 60% of their body weight, making them thin, soft and milky. In summer months, look for oysters from colder climates or farmed, all-season, triploid oysters. Triploid oysters are infertile so they stay fat and yummy all year. Many people note that another “r,” refrigeration, makes the most difference in summer-harvested oyster safety.

Closely monitored commercial harvesting produces reliably safe oysters year-round. So when you’re in the fish market or a restaurant, ignore the “r” rule! If you plan to harvest your own oysters from public grounds, check with the local or state health department for news on bed closures and warnings.

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More about the “r” month oysters myth:

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  • Great post above regarding “non-R-month” oyster consumption. In addition to the reasons for this “rule of thumb” I would add that mechanical refrigeration is a relatively new technology – prior to which it was very difficult, if not impossible to do a credible job of transporting oysters even a few miles from point of harvest. Back in the good ol’ days, inland from the coast, oysters often arrived via riverboat or train, which necessitated cool weather for reasonable shelf life of the product. Another point I would add is the realization that certain naturally occurring bacteria are more abundant in warmer weather in our estuaries along all coasts, including the Gulf Coast. These bacteria can cause illness, especially if oysters are improperly refrigerated. Serious illnesses occur from these natural bacteria if the consumer is particularly susceptible to infection due to liver disease, diabetes, cancer therapy which suppresses the immune system, etc. To learn more about how to avoid those more serious infections visit beoysteraware.com or safeoysters.org The vast majority of consumers are not at risk of serious illness. However, we all have to be careful of wound infections from contact with warm seawater, which are now the majority of incidences along the Gulf Coast. Hope this is all helpful.