Almost all the Pacific oysters sold in French markets today come from a species originally found in Japan. These oysters were introduced in large numbers in the 1970s to replace a local variety, the Portuguese oyster, which had been severely affected by disease. The Portuguese oyster, known scientifically as Crassostrea angulata, accidentally arrived in France in the 19th century after a shipwreck in the Gironde estuary. However, by the 1960s, this species was nearly wiped out by two viral diseases that struck in two waves: a gill disease in 1966 and a hemocytic virus between 1970 and 1973. These outbreaks caused mortality rates exceeding 90% in some areas, leaving thousands of oyster farmers without production, oysters, or income. To address the crisis, the French oyster industry launched a major repopulation effort known as "Resur." This initiative involved importing 562 tons of adult oysters from Canada between 1971 and 1975, as well as 10,000 tons of young oysters, or "spat," from Japan between 1971 and 1977. These imports were part of a broader strategy to quickly restore the oyster population. Adult oysters from British Columbia were used to breed rapidly, while Japanese spat were brought in to rebuild the stock. Although these importation efforts began a few years earlier, the official program solidified the shift in species. The results of this effort were clear by 1975, when the first natural observations of the Japanese oyster in French waters showed that the species had adapted well to the local environment. Unlike the Portuguese oyster, the new species was resistant to the viruses that had previously devastated the industry. Its fast growth and resilience quickly won over the professionals in the oyster farming sector. Today, the Pacific oyster, also known as the Japanese oyster, dominates the French oyster industry. Its scientific name has changed over time, from Crassostrea gigas to Magallana gigas, according to recent taxonomic revisions. While the Pacific oyster now dominates production in key regions like Marennes-Oléron and Arcachon, the original Portuguese oyster is now only found in a few small areas, such as around Belon in Brittany. Interestingly, some molecular studies suggest that the Portuguese oyster may have been a local variant of the Japanese species, with the two types having diverged over centuries due to geographic separation. This finding challenges the idea of a complete break between the old and new oyster species in French waters, even though the introduction of the Pacific oyster ultimately saved the industry from collapse.