Virginia enacted new oyster-harvesting rules for the summer to shield fans of the briny treat from a potentially deadly bacteria in coastal waters. Other oyster-producing states will likely follow Virginia’s lead as part of a crackdown on Vibrio contamination in humans.

Two forms of Vibrio—pronounced VIB-ree-oh—occur naturally in the Bay and along the Eastern Shore seaside. While usually not a health risk, their concentrations can increase above health-safety levels in warm conditions.

When ingested in unsafe levels, these microscopic organisms can sicken people, and even cause death among those with weak immune systems. Those who have been drinking alcohol heavily are especially susceptible to infection, according to public health experts.

Virginia’s primary oyster seasons occur in fall and winter, when Vibrio is dormant. But one case of Vibrio sickness has been traced to Virginia oysters, in 2006. State officials want to avoid a second case because it would trigger tougher government scrutiny and restrictions that could include a possible ban on all harvesting from May to September—a peak time for the state’s burgeoning oyster-farming industry.

Instead, beginning May 15 and lasting through September, commercial fishermen and oyster farmers may leave their docks just one hour before sunrise and must return to shore and refrigerate their catches by 10 a.m. While on the water, fishermen must shade their captured oysters as another way of keeping the bacteria from multiplying to high levels.

If watermen want to gather oysters past 10 a.m., they must have an approved refrigeration unit or ice storage area aboard their vessel, according to regulations passed last week by the Virginia Marine Resources Commission.

In recognition of the strong tides that play a key role with oystering on the Eastern Shore, seaside fishermen may work past 10 a.m. but must refrigerate their catches within two hours of pulling them from the water, according to the regulations.

Violations can result in the destruction of all oysters gathered illegally, and the offender may lose harvesting licenses and permits until a formal hearing can be scheduled. Robert Wittman, director of field operations for the Virginia Health Department’s Shellfish Sanitation Division, said Virginia had little choice but to act.