Cold Storage of Eastern Oysters, Crassostrea virginca, to Reduce Winter Mortality in an Increasingly Variable Environment

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Commodities

• Animals: shellfish

Practices

• Animal Production: aquaculture

Increasingly variable winter weather coincides with increasing winter and post-season mortalities on oyster farms of the lower Delaware Bay intertidal flats.

The purpose of this project is to test whether cold reduces the incidence of Dermo disease and consequent oyster mortalities during the following spring, summer and fall. We will compare disease prevalence and intensity in oysters kept in cold storage to those left on the intertidal flats and to those kept in deep water. Oysters will be monitored for presence of shell blisters from Polydora websteri to determine if the cold dry storage provides the additional benefit of significantly improved shell quality.

Local oyster farmers have expressed an interest in this project and all results will be shared with them. If we find better overwinter oyster survival, better condition, lower Dermo disease and fewer mud blisters in the following season, then we have evidence that taking on the expense in time and resources for cold storage is worthwhile, thus providing an incentive for oyster growers to try it for themselves. Currently local oyster farmers say that their winter losses are in the many thousands of dollars.

Results will be presented locally at the Rutgers University hosted Delaware Bay Shellfish Growers Forum, which is well attended by New Jersey shellfish growers, including member farmers of the Cape May Oyster Cooperative, and regionally at the Milford Aquaculture Seminar, which draws attendees from industry, academia, and government agencies.

Should test treatments prove beneficial an informational FAQ sheet presenting information on winter cold storage will be developed and posted on the eXtension Marine Aquaculture Community of Practice website with links to NJ Sea Grant Consortium and East Coast Shellfish Growers Association and the Rutgers Haskin Shellfish Research Laboratory.

Outreach presentations and materials will be developed in collaboration with Rutgers University extension staff member, Lisa Calvo.

This project seeks to determine if cold dry storage or subtidal high salinity winter handling methods can be used as a means to reduce Dermo oyster disease, eliminate polydorid worms and, most importantly, enhance overwinter and post-winter survival of intertidal farm-raised eastern oysters, Crassostrea virginica. The comparison is among three handling methods: intertidal, subtidal and cold storage. The oysters will be monitored for mortality, growth, condition, disease, and shell blisters in each treatment. If the project is successful oyster famers on the intertidal flats of Delaware Bay and other similar regions will learn that winter cold storage improves winter and post-season oyster mortality and reduces losses to disease. They will have the incentive to invest in winter cold storage to improve profitability of their farms. In addition they may suffer fewer losses from fouling by polydorid worms.