Understanding the Whys of Summertime Oyster Deaths
Researcher:
Andrew Y. Gracey
Biological Studies
University of Southern California
E.: gracey@usc.edu
T.: (213) 740-2288
Relevant Links:
Tools:
Revised:
August 10, 2010
Sample oysters at Totten Inlet, Wash. M. Chaney/USC
August 10, 2010
Contact: Rebecca Buddingh, California Sea Grant intern, sgintern@ucsd.edu
USC biologist Andrew Gracey has identified 60 genes in Pacific oysters that make the delectable bivalves more susceptible to “summer mortality syndrome.”
The expression patterns of these genes can be used to predict mortality rates weeks before the oysters actually perish.
Though the cause of disease is still not fully understood, Gracey's project, funded through a special nationwide competition for oyster disease research, shows that water temperatures above 36 degrees Celsius lead to higher mortality rates, as does prolonged exposure to air.
Survivorship rates from two summers of testing.
M. Chaney/USC
At shellfish farms, Pacific oysters (Crassostrea gigas – the only oyster species afflicted by the syndrome) are typically kept submerged and are fed to speed growth. Faster growth, however, could actually be a contributor to disease outbreaks, Gracey says, as smaller oysters are less likely to come down with the syndrome. Because of this, growers often harvest Pacific oysters before they are fully mature, to prevent losses that can, in extreme cases, exceed 50 percent.
Gracey hopes to one day be able to breed a disease-resistant Pacific oyster, which shellfish growers could harvest at full size. The economic implications would be staggering for the $96-million-a-year domestic oyster aquaculture industry.
“The overall goal is to help farmers alleviate the affects of oyster disease and secondly to understand the physiology of the disease,” Gracey says.
To learn more about this project, read our one page Project Profile summary at http://www.csgc.ucsd.edu/BOOKSTORE/Resources/PP2010/R-OD-1-Gracey.pdf
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