Defra may close parts of Lyme Bay's £2m-per-year scallop fishery to save the rare pink sea fan coral that grows there.
The government is consulting on proposals to ban dredging in 60 sq miles off the Dorset and Devon coasts where fishing activity has destroyed large parts of reef.
There are concerns over the economic cost of restrictions to local fishermen but local environmental organisations say the fishery is worth more intact.
"Sustainable activities such as angling, diving and hand-caught scalloping generate two-and-a-half times more income than dredging," said Paul Gompertz, director of the Devon Wildlife Trust.
Diver-caught scallops are also more valuable than trawled ones because they are less stressed, don't contain sand or have broken shells. They sell for an 80% premium in local markets. Gompertz said prices and availability for scallops nationally would not be affected by the proposed measures.