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Home > Communications > Newsroom > 2003


California Ban Affects Louisiana Oyster Industry
May 6, 2003

A California ban on raw oysters harvested from the Gulf of Mexico in the spring and summer months is affecting Louisiana's oyster industry. Louisiana supplies about 70 percent of its harvested oysters to California, and industry leaders say this ban could mean a loss of about $20 million.

"Obviously, it's going to stop shipment of some product right now - which is the slow time of the year for oysters, but we do ship a lot in the summer time," said Mark Schexnayder, Sea Grant Extension Agent in the LSU Agricultural Center. "If other states adopt the ban, or if other people hear about it and stop eating oysters because of what happened, it could have a huge effect."

California health officials have banned the sale of raw oysters from the Gulf of Mexico from April to October, citing six deaths from raw oyster consumption last year, as well as deaths in previous years, among the reasons for the ban.

"Generally, the primary concern is with a certain pathogenic bacteria, Vibrio vulnificus, which is usually present in the Gulf and other ocean waters where oysters are grown," said Jon Bell, Sea Grant Extension Seafood Technology Specialist in the LSU Agricultural Center. "The risk of illness increases with the increased number of bacteria present in the water and oysters."

Although the amount of Vibrio vulnificus in raw oysters can become quite high during warmer summer months, the bacteria generally will not make people with normal and healthy immune systems ill, Bell says. However, individuals who have a compromised immunity can be affected. They should not consume raw oysters at any time of the year.

"I want to point out that the people who have become ill or who have actually died in California from consuming raw oysters have been identified as people at a high risk," Bell stressed.

California will accept raw oysters that have been treated by approved methods to kill bacteria. "Currently, two processing methods have been accepted by the FDA and the state of California as post-harvest treatments to reduce Vibrio vulnificus to non-detectable levels," Bell said. "Oysters that have been processed by these methods are acceptable to be imported and eaten raw year-round in California."

One method, low-temperature pasteurization, involves placing the oysters in warm water, which is below the temperature that would cook the oyster, and then immediately placing the oysters in cooler water. "This combination has been scientifically validated to destroy the V. vulnificus bacteria, " Bell said.

Another validated method, high-pressure processing, subjects the immersed oysters to very high pressures that destroy the bacteria without affecting the oyster, Bell explained. A third method, very low temperature freezing, is currently under review for this designation.

Officials in Louisiana believe more education is needed instead of outright bans on sales like this one in California. But the ban is in effect, and Schexnayder says the industry needs to look at other ways to add value to their products, such as smoked oysters.

"I think we really need to look at the Louisiana oyster industry as a whole and explore possibilities to make more money from the raw product that we produce instead of just shipping them out raw," Schexnayder said. Louisiana harvests about 60 percent of the Gulf oysters and produces about a third of the country's oysters. The state has led the nation in developing ways to kill the bacteria in raw oysters without actually cooking the oysters. Louisiana Sea Grant currently supports research at LSU on this topic.

For more information, contact Mark Schexnayder at (504) 838-1170 or mschexnayder@agcenter.lsu.edu or Jon Bell at (225) 578-5190 or jonbell@agcenter.lsu.edu.

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