Maryland, Virginia and the nation’s other shellfish-producing states are not going to have to make huge changes in the way seafood is stored and transported to protect customers from a rare but dangerous bacteria — at least for now.

Two years ago, the Food and Drug Administration required all states that have the potential to have shellfish containing a bacterium called vibrio to come up with vibrio control plans. The plans included getting the oysters under refrigeration within a certain number of hours in the spring and summer to stop the spread of vibrio, a naturally occurring bacteria that can become rampant when water temperatures soar above 80 degrees.

While the rule changes would have applied to all oyster harvesters, oyster aquaculturists would have been most affected. It is not legal to harvest wild oysters in the summer. And generally, watermen haven’t wanted to; wild oysters spawn in the summer and tend to be milky instead of the firm meat customers crave. But oyster farmers are allowed to harvest their crop all year long. Many farmers use sterile oysters, which do not spawn, so the meat is consistent all year. But even farmers who plant bars with reproducing oysters can and do harvest in the summer; they just pay attention to the animals’ spawning cycle.

Vibrio lives in the water and can contaminate tuna, sardines, shrimp and other species, but it is most known for infecting oysters, mussels and clams. If seafood contaminated with vibrio are ingested raw, the bacteria can cause gastric distress and, in rare cases, death — especially if the seafood eater is elderly or has a compromised immune system.

Each state came up with its own control plan. In Maryland, for example, oyster growers had to get their product under refrigeration within five hours of harvest in the summer months. The refrigeration takes the temperature down to 50 degrees Fahrenheit. Maryland and Virginia each have deadlines for the oysters to be under refrigeration, depending on the time of year. The latest time is noon in Virginia during September on the day of harvest and 12:30 p.m. for Maryland on the day of harvest. They have to be under refrigeration by 10 a.m. in Virginia from June 1 to Aug. 31, the height of summer, and 10:30 a.m. in Maryland from July 1 to Aug. 31. (This change accounts for the few degrees’ difference in temperatures between the states.) This information is on the lease applications for prospective oyster farmers.

But the Food and Drug Administration wanted to change the rule to just one hour, after high levels of vibrio were found in several New England states and in Washington state. The agency had been discussing the change all year and planned to introduce the new proposal at the Interstate Shellfish Sanitation Conference, which took place in January.

Changing the rule to one hour would devastate the seafood industry, said several oystermen and regulators familiar with the proposal.

“It would have put a significant number of people out of business,” said Robert Rheault, executive director of the East Coast Shellfish Growers Association.

Rheault made sure his members attended the conference in large numbers, so they could convince federal and state regulators that such a move would be devastating.

Kathy Brohawn, environment manager for the Maryland Department of the Environment, had already gotten that message. She shared the FDA’s plans at a meeting of the Aquaculture Coordinating Council in January and heard an earful from the seafood industry. Brohawn spent her time in San Antonio building alliances with Virginia regulators and members of the seafood industry there so their opposition would be heard.

“We want to reduce illness, but we want to do it smart,” Brohawn said.

In the end, the group did not vote on the FDA’s one-hour proposal, because the opposition was so great it would likely not have passed, said Keith Skiles, the shellfish growing area classification chief for the Virginia Department of Health. The FDA instead came back with a proposal to study the best methods of refrigeration in the different geographic areas and to determine which ones are best for reducing the risk of vibrio.

“We have work to do, I think everyone agrees,” Skiles said. “We need to do some more research to verify the controls.”

Oyster growers, Skiles said, use different methods to cool their oysters as quickly as possible. Some use an ice slurry bath on their boats, while others used forced-air refrigeration. In some parts of the state, the water is colder, and in others, time may be of the essence.

“We have different ideas to get us to the same endpoint,” Skiles said, “And we don’t want a requirement to stifle our growers’ innovation.”

Rheault reported a similar issue in Rhode Island, where he managed an oyster farm for two decades. There, farmers have voluntarily adopted a protocol of one hour to get oysters under ice and two hours to get them into the refrigerator, even though the rule is 10 hours. But, in Narragansett Bay, the water is cooler, so the farmers give themselves five hours to get the oysters to ice. There have been no problems with that approach, Rheault said.

Some advocacy groups, including the Center for Science in the Public Interest, have criticized the conference’s ways of making rules. In a recent report, it claimed that the FDA is too cozy with industry and that it is allowing the seafood industry to police itself.

But it would be hard to imagine how oyster growers could stay in business if they had to refrigerate their products within an hour of harvest, Brohawn said — especially because so much oyster harvesting takes place in remote corners of the Chesapeake and Coastal Bays, where there is not always access to food-quality refrigeration equipment. In Maryland, several seafood entrepreneurs complained at the coordinating council meeting that such a move would cut the legs off an industry that had barely gotten started.

Brohawn said the oyster producers were complying well with the five-hour rule. Dealers are also not allowed to accept oysters unless they came under refrigeration within five hours under the regulations. Virginia also reported good compliance with its five-hour rule last year. The state has also been working with the FDA to determine the best cooling methods.

The two types of vibrio that can afflict those who consume oysters are Vibrio vulnificus and Vibrio parahaemolyticus. Vibrio V, as it is known, is the more dangerous of the two, and can result in death if not treated quickly. There have been a few cases of Vibrio V in Maryland, but they have not come from eating seafood. They developed in individuals with immune-compromised systems who came into contact with warm water containing the bacteria. There have been serious skin infections that have required hospitalization and multiple surgeries.

Vibrio P is not life-threatening, though it is not enjoyable. It usually manifests itself as diarrhea and vomiting for about 24–48 hours. The symptoms usually disappear after 72 hours.

Vibrio in seafood is killed by either very cold temperatures or very hot ones. For that reason, people with autoimmune diseases are advised to abstain from raw shellfish, although they can eat cooked seafood.