Frequently asked questions about Maine oysters

What is an oyster?

An oyster is a marine invertebrate animal that lives in salt and brackish water. Oysters are bivalves: two shells connected by a hinge enclose and protect their muscles and organs.

Are Maine oysters all the same species?

All oysters grown in Maine are the same species, Crassostrea virginica, the American or Eastern oyster, which ranges along the East Coast of North America from the Gulf of St. Lawrence to the Gulf of Mexico, Caribbean, Brazil, and Argentina. Maine consumers might occasionally see European (flat or Belon) oysters, Ostrea edulis, on the menu. These were introduced to Maine waters in the mid-twentieth century and developed self-sustaining populations in some parts of midcoast Maine. Other species of oyster grow on both sides of the Pacific and in Australia and New Zealand.

What do oysters eat?

Oysters eat algae, mostly, and other bits of microscopic detritus. They pump water through their gills and extract the nutritious particles. Through this filtering action, oysters help keep water clear.

Why do oysters from different farms vary in appearance?

Even though all of Maine’s cultured oysters are the same species, they vary widely in size, shape, color, etc. due to their growing conditions. The look and taste of oysters varies from river to river depending on what kind of algae they eat, culture technique, and water flow, temperature, and salinity.

How do oysters grow?

Oyster farmers purchase juvenile oyster “seed” or spat from one of two hatcheries in the state, and raise the oysters to market size in several ways. Some place the juvenile shellfish in plastic mesh bags or cages that float on the water surface; others suspend oysters in trays or cages in the water. Some growers may take small hatchery seed and grow it bigger in bottom cages or bags before free planting on the bottom.

How long does it take for oysters to reach market size?

Oysters typically are ready to harvest in two to three years, depending on temperature and other local conditions.

When is the best time to eat oysters?

If oysters are on the menu, they are safe to eat in any month. The old adage about not eating oysters in months without an ‘R’ comes from the days when refrigeration was much less available than today. Water quality is one of the biggest concerns of the oyster farmer. While the filter-feeding oysters themselves actually help to keep the water clear, oysters are vulnerable to bacterial pollution, chemical contamination, and harmful algal blooms (red tide), especially spring through fall. Check with the Department of Marine Resources for shellfish growing area closures; 1-800-232-4733 or 207-624-7727.

Keep oysters cold! Purchased oysters should be stored in the refrigerator, packed loosely and covered with a damp towel. Eat within 14 days.

Eating raw oysters does come with some risk of exposure to viruses and bacteria, especially for people with compromised immune systems.

What is oysters’ nutritional value?

Oysters are low in fat and calories and provide an excellent source of zinc, iron and selenium, and a moderate amount of protein.

Where can I buy oysters?

Oysters are available from select seafood markets and, in some cases, directly from growers. See the Oyster Trail of Maine for the latest listing.

Keep oysters cold! Purchased oysters should be stored in the refrigerator, packed loosely and covered with a damp towel. Eat within 14 days.

Where can I eat oysters?

The availability of oysters is growing in Maine. See the Oyster Trail of Maine for the latest restaurant listing, and be sure to ask your server where your oysters were grown (which farm/what kind are they?).

Where can I see an oyster farm?

Some oyster farmers, including Abigail Carroll at Nonesuch Farm, offer regular tours of their growing operations. Others offer tours by request. In the Damariscotta region, Damariscotta River Cruises and Midcoast Kayak offer boat tours of the farms and surrounding environment. See the Oyster Trail of Maine for the latest listing. Oyster farms are private businesses. Please call ahead before visiting and be respectful of farmers at work on the water.

How many farms are there in Maine?

Approximately 80, as of August 2017.

How big is the industry?

In 2016, oyster growers operated in 600 acres of water leased or permitted from the State of Maine, growing two million pounds of oysters valued at more than $5 million.

Does farming oysters harm the environment?

Generally, no. Oysters actually help keep water clear as they filter algae and other food particles from the water—which is why people are trying to restore oyster reef habitat in many areas, and why water quality is one of the biggest concerns for an oyster farmer.

Where do oysters come from?

Oyster farmers purchase tiny baby oyster “seed” or spat from one of several commercial hatcheries around the state. In the wild, oysters are “broadcast spawners” – males and females release sperm and eggs into the water. Fertilized eggs form larvae, which spend about three weeks in the water before settling to rocks and other hard surfaces.

Is it ok to bring my kayak or small motor boat near an oyster farm to get a closer look?

Oyster farms are private businesses. Please call ahead before visiting and be respectful of farmers at work on the water. If you are boating, give farms a generous berth as lines can tangle into propellers or kayak paddles.

Who are the farmers?

Maine oyster farmers are small, private business owners of all ages and backgrounds. A few grow oysters full time but most have other occupations, including fishing for lobster and other sea foods. Some farmers have been working the water for more than two decades, while a new generation of growers is just getting started. For some, oyster farming involves the whole family. Others grow oysters to supplement incomes from other employment. A few are exploring cooperatives and other partnership models.

Are oysters a native species?

The American or Eastern oyster, Crassostrea virginica, is native to Maine. Learn more about oyster history at the Downeast Fisheries Trail.

How are Maine oysters different than those from other states or Canada?

Clean, cold waters are key to the quality of Maine oysters. According to In A Half Shell’s Julie Qiu, “Objectively speaking, I think the pristine environment and bracingly cold waters of the Gulf of Maine make the oysters here taste a cut above the rest. You just can’t deny the crisp brininess and bone-broth savoriness of the oysters that come out of these waters.”

Do oysters grow in the wild in Maine?

Yes. There are pockets of oysters that have persisted in the upper reaches of estuaries since the last Ice Age. More recently, cultured oysters began reproducing on their own, leading to self-sustaining populations. Read more about wild oysters in Maine Boats, Homes & Harbors.

Can I harvest wild Maine oysters?

No. Tempting as it might be to forage for wild oysters, both recreational/subsistence and commercial shellfish gathering requires a license. The towns of Newcastle and Damariscotta work with the state to manage the only commercial fishery in the Damariscotta River. In terms of taste, wild is not necessarily better: cultured oysters are tended in closely monitored conditions and are subject to closures for harmful algal blooms and bacteria (learn more from the Department of Marine Resources,

Can I explore an oyster shell midden?

Yes! Visit the Whaleback Shell Midden State Historic Site, an 11-acre property owned by the Maine Bureau of Parks and Lands and operated cooperatively with the Damariscotta River Association.

Do Maine oysters have pearls?

Yes, but they are not usually pretty (or valuable). Almost all shell-bearing mollusks can make pearls when a grain of sand or other irritant gets next to their shell, prompting the release of irridescent nacre. But cultured and natural pearls come from Pearl or feathered oysters in the family Pteriidae.