DEER ISLE — Last Thursday, the Department of Marine Resources imposed a ban on harvesting shellfish from an aquaculture lease site off Deer Isle. On Friday, Kohl Kanwit, Director of DMR’s Bureau of Public Health, explained that the harvest closure was a precautionary measure in response to a common practice in shellfish farming.
The department suspended harvest from two adjacent tracts on a lease site in Mud Cove, off Stinson Neck on Deer Isle, operated by Acadia Aqua Farms of Trenton and used for the bottom culture of mussels. The first tract includes 25.91 acres; the other, 15 acres.
According to Kanwit, DMR acted because Acadia transplanted seed mussels to the lease site from an area the state classifies as “restricted” because of potentially high levels of bacterial contamination. That kind of transfer, known as a “relay,” is not uncommon.
“A lot of oyster farmers do that,” Kanwit said.
The closure at the lease site off Deer Isle is only temporary.
With a relay from restricted waters, the closure lasts 60 days from the date of the last transfer unless the shellfish are tested for safety. If the grower does test the shellfish, the closure lasts for two weeks after a clean test to allow the shellfish to be fully purged of any possible contamination.
The closure period is longer if the relayed seed come from an area DMR classifies as “prohibited” for shellfish harvesting because of poor water quality resulting from by elevated levels of bacteria. Seed relayed from a prohibited area may not be harvested for at least six months.
In either case, according to Kanwit, once the shellfish — mussels or oysters — have been allowed to purge in clean water for the required time period they will be safe to consume.