The mahogany clam masquerades under several monikers: ocean quahog, mahogany quahog, black clam and golden neck clam. According to the online food magazine "The Nibble," mahogany clam is simply a marketing name. Whatever this clam is called colloquially, its scientific name is Arctica islandica, and it's an undisputed fixture on the ocean floor: Bangor University scientists have discovered an ocean quahog specimen that's 500 years old.
The purple varnish clam -- Nuttallia obscurata -- is also often called a mahogany clam, but it's a different species and is not commercially sold in markets like Arctica islandica is. Nuttallia obscurata is considered an invasive species that's found on the West Coast of North America, primarily in Washington and British Columbia. Arctica islandica are harvested in the New England region of the United States and in Newfoundland and Labrador in Canada. The large ocean quahog also found in seafood markets is another common species of clam: Mercenaria mercenaria.
The mahogany clam is a hard-shelled bivalve mollusk. According to the National Oceanic and Atmospheric Administration, this clam matures very slowly, on average reaching maturity when it's 9 years old. It sports a round, dark brown shell and grows up to 3 1/2 inches in length. Mahogany clams are medium-sized; expect 18 to 24 mahogany clams per pound compared to large ocean quahogs, which typically yield 10 per pound. Mahogany clams' flavor is described as sweet and briny, and a bit stronger compared to large ocean quahogs.
Don't expect to dig mahogany clams on beaches. Although these clams burrow in the sand in fairly shallow water, they can't be found in the intertidal zone, where the ocean and land meet. According to the Northeast Fisheries Science Center, mahogany clams are primarily harvested off the coast of Maine. Mahogany clams are also found in Massachusetts, but harvest is prohibited because of high levels of paralytic shellfish poison toxin, commonly known as red tide.
According to Fish Watch, a program of the National Marine Fisheries Service, the mahogany clam fishery is well managed, and the clam is not overfished. Mahogany clams are harvested from the sandy sea floor with the use of a hydraulic dredge. Fish Watch notes that this method of harvest has little impact on vegetation of the habitat of other fish and organisms living in this area. California's Monterey Bay Seafood Watch program suggests that since mahogany clams are wild-caught, they are a sustainable seafood choice. However, Ocean Wise, a similar Canadian nonprofit organization, points to dredging methods as a reason to regard the mahogany clam as an unsustainable seafood choice.
- National Marine Fisheries Service; FishWatch: Ocean Quahog
- Ocean Wise: Clams Seafood Items
- The Festival of Science and Arts; Summer Science Exhibition: Arctica islandica, the longest-lived animal on Earth
- "The Nibble"; Fish & Seafood Glossary
- University of Washington; Nuttallia obscurata: The Purple Varnish Clam or the Purple Mahogany-Clam; Claudia Mills; 1998
- U.S. Department of Commerce; National Oceanic and Atmospheric Administration; Ocean Quahog, Arctica islandica; 1999
- Photo Credit Thomas Northcut/Photodisc/Getty Images