The eastern oyster is farmed in coastal waters in the Gulf and Atlantic regions of the United States. Instead of growing in clusters on the water bottom like oysters on wild reefs, farmed oysters are grown as single animals suspended in the water within cages or baskets. This method, referred to as off-bottom oyster aquaculture, improves access to food, protects them from predators, and allows for easy handling and harvest. Alabama and Mississippi produced nearly 11 million single oysters in 2024, valued at over $7 million. Locally, this industry has nearly tripled in the last 5 years, with 85 commercial oyster farms currently in operation in these two states alone.
Unfortunately, eastern oyster farming has recently been hit hard by mortality events with unknown causes. Researchers refer to these rapid, large-scale die-offs as Sudden Unusual Mortality Syndrome, or SUMS for short. SUMS specifically leads to deaths in market or near-market size oysters, preventing return on investment for the oyster farmer. As a result, SUMS is considered a substantial threat to the continued success of the oyster farming industry.
This year, three new research projects, funded by the Mississippi-Alabama Sea Grant Consortium, aim to determine the causes of SUMS as well as mitigate the damage caused by these unexplained events. These projects, led by Dr. Anna Linhoss of Auburn University’s Department of Biosystems Engineering and me, will include direct participation by oyster farmers in Alabama and Mississippi to explore a variety of potential biological and environmental factors that may contribute to these mortalities.
The projects will look at three aspects of SUMS:
- The influence of parasites (dermo and mudblister worms) and environmental factors like temperature, salinity and dissolved oxygen.
- The influence of microbes including bacteria and viruses.
- Mitigation strategies including density reductions, overwintering at low-salinity sites and in-water grading.
These studies aim to bring clarity to what is causing these mortalities, increase our ability to predict when they will occur, and provide management strategies to reduce the number of oysters that are lost. It is our goal that we will be able to reduce the economic impact of SUMS and increase the sustainability and profitability of the local oyster industry.
Be sure to follow the Auburn University Shellfish Lab on Facebook and Instagram to see updates as this research moves forward!
Meet the author
Andrea Tarnecki
Assistant Extension Professor
Andrea Tarnecki is an assistant extension professor at Auburn University's School of Fisheries, Aquaculture, and Aquatic Sciences.She connects with shellfish farmers and stakeholders to identify... Read more
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