Gloucester - The Massachusetts Division of Marine Fisheries has notified the city of Gloucester that a red tide closure is in effect for the harvesting of all shellfish, including all soft shell clams, mussels, razor clams, sea or surf clams, quahogs, oysters and carnivorous snails.

Gloucester Shellfish Constable Dave Sargent said Thursday that they are not yet sure how long the closure will be in effect.

"We have no idea when they're going to peak and then start to subside. That gives us a better idea as to how long it will last," Sargent said. Southern Maine and New Hampshire's waters are also closed for harvesting, and the red time bloom has not yet peaked in New Hampshire.

With an early warning system from the Division of Marine Fisheries, Sargent was able to intervene and prevent anyone from going out clamming yesterday. Shellfish harvested locally are sold locally, and are served in many of Cape Ann's restaurants.

Sargent said people should be very comfortable with eating shellfish that are already on the market. "They're a healthy, nutritious, and safe food product," he said, adding that it is probably the most closely monitored food product.

Once their shellfish stocks are gone, local restaurants will have to look to buy product that has been harvested out of state.

"Many tourists who come here expect to have steamed clams or fried clams as part of their experience," Sargent said, adding that consumers "should be aware that their food product is safe, and it's healthy, and enjoy their North Shore experience."