· The Florida oyster aquaculture industry is rapidly growing but growers have experienced unexplainable mortality events in recent years.
· A new UF/IFAS program monitored oyster production at four farms in Florida.
· Results helped researchers understand basic but important relationships between health of cultured oysters and environmental factors as well as set
goals for future research and grower support.
Florida’s oyster industry has grown rapidly, but not without its share of challenges. In recent years, Florida growers in certain areas of the state have faced significant oyster mortalities during the spring and early summer.
UF/IFAS researchers are on a mission to find answers and make science-based recommendations for growers with a monitoring program that began in 2020. Through the program, supported by UF/IFAS SEEDIT research funding, researchers analyzed two genetic stocks of oysters grown at four farms in two oyster farming areas in the Panhandle.
“With more than 125 growers, the industry has grown rapidly,” said Leslie Sturmer, UF/IFAS Extension and Florida Sea Grant aquaculture specialist. “It’s amazing how fast it has developed but growers have run into production problems due to these mortalities and we want to understand why this is happening.”
Over the past several years, growers in other regions have also faced summer mortalities, but in Florida, this event typically occurs in the spring. Because Florida oysters grow so fast, growers lose them just as the oysters are reaching market size. These losses stem from a combination of environmental and physiological stressors.
“It’s extremely difficult to provide management practices for this industry,” said Sturmer. “Growers are continually planting and harvesting to meet market demands. It’s hard to target that window of potential threat in late spring or early summer and give advice as to how to avoid large losses.”
Researchers monitored overall production at oyster farms, water quality and abundance of phytoplankton — which oysters need to consume to thrive. They also studied the prevalence and severity of two common oyster ailments, shell parasitism and dermo disease.
In the study, scientists found environmental factors such as salinity, temperature and phytoplankton quantities strongly influence oyster performance. Elevated salinity was associated with faster growth, but also higher mortality, dermo disease, shell parasitism and reduced oyster condition.
Scientists observed differing rates of mortality between the two stocks of oysters used in the study. This indicates a potential for development of oyster lines with higher resistance to environmental stressors and Florida’s spring mortalities.
“Our suggestion is for growers to monitor temperature and salinity for site selection, but we are working with oyster breeders at Auburn University and other universities to develop stocks that would thrive here in Florida,” said Sturmer. “Mortality differences between the genetic stocks demonstrate the potential for selective breeding that would have a higher resistance to environmental stressors and spring and summer mortality events. Seeing these results is a response in the right direction.”
Researchers hope to expand the study by increasing the number of farms to provide a greater understanding of how environment factors impact mortality rate and expand the data set.
“These production relationships were from just one year of data. We really need to look at this annually and seasonally to really sink our teeth into it,” said Sturmer. “Hopefully, we will garner additional funds to keep working with these growers.”
For more information, you can view the full report on the UF/IFAS Florida Shellfish Aquaculture website. This research was conducted in tandem with market research to help oyster farmers increase their regions of sale and value of their product.