Real Food Encyclopedia | Clams

Like many seafood delicacies, clams, at first glance, are not something that beg to be eaten. They are not pretty or inviting. Buried as they are in layers of sand or mud, they are not easily accessible. But for many, particularly those with the sea coast in their history or in their veins, clams are not only delicious, they are rich with memories of summers at the shore, steaming mugs of chowder on a wintery New England day or memories of digging for your own dinner. Each year, more than 112 million pounds of clams are harvested so, looks aside, a lot of eaters are digging their clams.

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What to Look for When Buying Clams

There are lots of different kinds of clams from which to choose, but no matter which variety you seek, there are a few rules that apply. You never want a broken clam. Clams should smell of the sea, so any “fishy” odor or whiff of ammonia should send up a red flag. Clams should show some vigor. Hard shell varieties should be firmly closed or snap shut when disturbed. A touch to any visible siphons should cause the clam to retract them immediately.

Here are some types of clams you may see at the market:

Hard-shell clams (Mercenaria mercenaria): come from the Atlantic Ocean along the East Coast of the US and Canada in intertidal areas. They are often called by different names to connote their size. Littlenecks are the smallest, then topnecks, cherrystones and chowders.

Manila clams (Venerupis philippinarum): were accidentally introduced in Washington State in the 1920s. They are widely farmed in the Pacific Northwest, mostly in Washington State and British Columbia. Their sweet flavor often makes them the preferred clam for cooking.

Soft-shell clams (Mya arenaria): aren’t soft as much as they are simply brittle. They are commonly called steamers or Ipswich clams and have more of an oblong shell than hard-shell clams. Soft-shell clams live in tidal flats on the eastern shore of Canada and the US as well as across the Atlantic in the UK, where they are also known as Essex clams. Soft-shell clams are notoriously sandy. Often served steamed, eaters give them a rinse in a cup of broth served alongside to give them a final bath to remove any lingering grit before eating.

Razor clams (Siliqua patula): are popular in Oregon and Washington. They have long, thin shells and plant themselves in the sand vertically.

Geoducks (Panopea abrupta or Panopea generosa): are found on the Northwest coast of the US and Canada and are popular there and in parts of Asia. They are rumored to have aphrodisiac properties. (And they’re pronounced “gooey-ducks” in case you were wondering!)

Other, less common types of clams you may come across include: Ocean quahogs (Arctica islandica), which are different from quahogs of the East Coast and have a distinctive black shell. Surf clams (Spisula solida) live on the eastern coast of the US and Canada. They are often used in clam strips and chowder. The giant clam of Asia (Tridacna gigas) has a giant shell with a frilly edge and bright colors. The harvesting of wild giant clams for their meat and shells has led to destruction of marine habitat, such as reefs, which are often ground by poachers’ boat propellers to release the shells that can become encased in reefs.

Sustainability of Clams

Overall, clams are considered one of the most sustainable types of seafood to eat. Most clam populations are healthy and, unless they are mechanically dredged, there is little by-catch in the harvest. Seafood Watch recommends that you eat farmed clams (“hamaguri” in sushi). If you’re buying wild clams, look for “Best Choice” sources of geoduck, Northern quahog, Northern razor and soft-shell clams that reflect best harvesting practices.

Clam Cultivation and Harvesting

Clam digging is a recreational seaside activity. It doesn’t require a lot of equipment — a rake and a bucket; some wellies if you don’t want sandy feet. However, you do need a license in some areas, so best to check with the local authorities before you gear up. You may also want to check for any area closures due to conservation or contamination such as red tide, a harmful algae bloom that can compromise the wholesomeness of your catch and your health.

Some commercial clammers boat out to heavily populated clam beds and use hand-held rakes that reach more than twenty feet into the water to scratch at the ocean floor and capture clams in an attached basked. It’s a painstaking process that causes some disturbance to the environment but isn’t terribly disruptive.

Hydraulic dredgers, however, are more controversial. These machines pump water into the sand to loosen it and a mechanical rake follows behind, gathering clams and other sea life that get caught in the machinery. Proponents say that hydraulic dredgers are used in shallow waters that experience this type of upheaval on a regular basis during storms, for example, and easily and regularly rebound from it. Detractors believe that the force of the process is too disruptive to animal life and habitat producing grasses that are essential to a vibrant ecosystem.

In clam farming, clam farmers start with “spats,” baby clams that don’t yet have a shell. These are spread on an area of sea floor, usually in a bay or estuary that has a strong tide but no crashing waves. The spats are then covered with netting to discourage predation. Because they are filter feeders, clams clean the water they inhabit. They rely on the minuscule organisms that the tide brings their way so, unlike farmed fin fish, they don’t require any inputs — not even food and certainly not antibiotics — to thrive.

Eating Clams

Storing Live Clams

You can keep clams the in the refrigerator, but for no more than two days. Place them in a colander set over a bowl and cover with a damp paper towel and a layer of ice. Soft shell and razor clams need to be purged of the sand that they not only live in, but also eat. An overnight soak in salted water will flush this out of their digestive system. Just before using, scrub the shells with a brush and rinse thoroughly.

Cooking with Clams

The general rule when eating clams is that the smaller clams are eaten raw, larger clams are better cooked. But they can be served in any number of ways: grilled, steamed, in ceviche or in soups. And of course, in a classic New England chowder. But first, you have to open them!

Preserving Clams

Clams are often canned commercially. Clams can be frozen shucked or in the shell. You can pressure can your own clams, but never use the Boiling Water Method for meat, fish, dairy or any non-acidic preparation.

Clam Nutrition

A three-ounce serving (85.04 grams) of steamed clams contains 22 grams of protein, four grams of carbohydrates, and less than two grams of fat. The same serving has 18 milligrams of Vitamin C, as well as Vitamins A and B-12, calcium, potassium, selenium and zinc, along with 24 milligrams of iron. They are high in omega-3 fatty acids and, being low on the food chain, are free from high levels of mercury. However, clams are naturally high in sodium (three ounces contain 1,022 milligrams) and have 57 milligrams of cholesterol.