Littleneck clams are farmed in protected bays and estuaries from California to Alaska, which is within their native range. Alaska, where many farms are located, has strict controls over the leasing and harvesting process. Destructive mechanical harvesting is prohibited, requiring that clams be harvested by hand.
Clams are a great source of calcium, and are also high in protein. They are also very high in heme iron – found only in red meat, poultry, fish, and seafood – which is much more easily absorbed by the body than free iron. Clams are also an excellent source of vitamin B12 and copper, which may help maintain good blood status for delivering oxygen to working muscles. Their levels of zinc and selenium assist in the proper functioning of the body’s immune system and its antioxidant defenses.
Here's what the various seafood rating websites have to say about it:
From the Monterey Bay Aquarium's Seafood Watch Program: ""
From Environmental Defense's Oceans Alive Guide: "Pacific littleneck clams are a native species, and populations are not in decline. Harvesting littlenecks clams does not appear to jeopardize intertidal habitats or other animals."
From Monterey Bay Aquarium Seafood Watch Program: "Because these shellfish filter their food right out of the sea water, farming them requires no input of feed. Shellfish farms cause little impact on the environment, putting farmed shellfish on our “Best Choices” list."
• One Fish, Two Fish, Crawfish, Bluefish: The Smithsonian Sustainable Seafood Cookbook (Smithsonian Books) by Carole C. Baldwin
• Ocean Friendly Cuisine: Sustainable Seafood Recipes from the World's Finest Chefs (Willow Creek Press) by James Fraioli