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Ocean Quahog

Arctica islandica

Hard clam/ocean quahog

Also Known As

  • Clam
  • Quahog
  • Black clam
  • Mahogany quahog

U.S. wild-caught ocean quahog is a smart seafood choice because it is sustainably managed and responsibly harvested under U.S. regulations.

Population

Above target population level.

Fishing Rate

At recommended level.

Habitat Impacts

Fishing gear used to harvest quahogs has minimal impacts on habitat.

Bycatch

Fishing gear used to harvest quahogs is designed to minimize bycatch.

  • Availability

    Year-round. Sold processed (minced, chopped, or cut into strips) or in chowders, bisques, and sauces. Smaller ocean quahogs from Maine waters are marketed as “mahogany clams” and are sold on the half-shell market or for steaming.

  • Source

    U.S. wild-caught from Maine to Virginia.

  • Taste

    A somewhat stronger taste than other clams.

  • Texture

    Firmer than other clams.

  • Color

    Meat is pinkish.

  • Health Benefits

    Quahogs provide low-fat, high-quality protein and are an excellent source of selenium, iron, and vitamin B12.  

The U.S. Fishery

Fishery Management

  • NOAA Fisheries, the Mid-Atlantic Fishery Management Council, and state resource management agencies manage the ocean quahog fishery.
  • Managed under the Surfclam-Ocean Quahog Fishery Management Plan:
    • Fishermen must have a permit for commercial harvest ocean quahogs.
    • Individual transferable quota (catch shares) program – managers set an annual catch limit for federal waters and allocate it among individual fishermen or vessel owners. These individual quotas can be sold or leased.
    • Closed areas due to environmental degradation or to toxins that cause paralytic shellfish poisoning (PSP).
    • Fishermen harvesting ocean quahogs from Georges Bank have additional requirements under the PSP testing protocol.
    • Mandatory vessel monitoring systems.
    • Fishermen must maintain and submit logbooks of each fishing trip to document catch.
  • The ocean quahog fishery off Maine is managed separately because of differences in biological, fishery, and market characteristics.
    • The portion of this fishery in federal waters off the Maine coast is managed under a relatively small catch limit that is separate from the catch limit used to manage the rest of the quahog fishery (described above).
    • To participate in this fishery, vessels must have a separate limited access federal permit, use a mandatory vessel monitoring system, and maintain and submit logbooks of each fishing trip.
    • State authorities manage the portion of this fishery in Maine state waters.

Harvest

  • In 2019, the ocean quahog fishery produced more than 11.3 million pounds of meats, valued at more than $9.1 million, according to the NOAA Fisheries commercial fishing landings database
  • Commercial fishermen harvest ocean quahogs with hydraulic clam dredges, which use jets of water to dislodge ocean quahogs from the sandy ocean floor.
  • A smaller “dry” dredge (without hydraulic jets) is used in Maine waters.
  • Ocean quahogs burrow into sandy bottoms on the continental shelf, an environment that is thought to recover quickly after a hydraulic clam dredge passes over it.
  • The bars on commercial clam dredges are spaced several inches apart so they do not collect anything but the targeted quahogs.
  • The quahog fishery is managed under an individual transferable quota program that slows the pace of the fishery and increases its efficiency, significantly reducing bycatch.

The Science

Population Status

  • According to the 2020 stock assessment the ocean quahog stock is not overfished and is not subject to overfishing. Summary stock assessment information can be found on Stock SMART.
  • Ocean quahogs are relatively unproductive and can only support low levels of fishing.
  • Population levels are declining despite relatively low fishing rates, but remain above target levels.

Location

  • Ocean quahogs are found in the western Atlantic as far south as Cape Hatteras, North Carolina.

Habitat

  • Ocean quahogs live in water between 25 and 1,300 feet deep.
  • In the northern part of their range, they’re found in shallower water closer to shore.
  • The U.S. stock is almost entirely within federal waters (3 to 200 miles from shore), except for a modest amount off the coast of Maine and in waters between 65 and 260 feet deep.
  • Ocean quahogs are rarely found where bottom water temperatures exceed 60˚ F.
  • Eggs and larvae are found in the water column and drift with the currents until they develop into juveniles and settle to the bottom.
  • Ocean quahogs burrow in a variety of sediments, especially fine sand.

Physical Description

  • Ocean quahogs are bivalve mollusks—they have two hinged shells that enclose their body.
  • Shells are thick and oval-shaped.
  • Outside is a dull gray with growth rings that can be used to determine its age.
  • Interior is white with a purple border.
  • Most quahogs in U.S. waters are 2.8 to 4.3 inches in shell length.

Biology

  • Ocean quahogs spawn by releasing eggs and sperm into the water column where the eggs are fertilized.
  • Larvae drift with the currents for at least 30 days until they develop into juveniles and settle to the bottom.
  • Ocean quahogs spawn once a year, either in the summer or fall. The spawning season is sometimes extended over a number of months as quahogs release eggs and sperm a little at a time.
  • Ocean quahogs are among the longest-lived marine organisms in the world. Off the U.S. East Coast, where the fishery takes place, ocean quahogs can live for at least 200 years.
  • They grow very slowly and do not start to reproduce until around age 6, and do not reach a commercially harvestable size until about age 20.
  • Ocean quahogs are filter feeders. They bury themselves in the ocean floor and pump oxygen-filled water and food particles in through their siphons, which extend above the surface of the ocean floor.
  • They feed on microscopic algae.
  • Many animals prey on juvenile ocean quahogs, including invertebrates such as rock crabs, sea stars, and other crustaceans, and fish such as longhorn sculpin, ocean pout, haddock, and cod.
  • Once ocean quahogs have reached a certain size, they have a very low predation rate. They burrow in the sandy ocean floor and their thick shells close completely, providing substantial protection from potential predators.

Research

  • Scientists from NOAA’s Northeast Fisheries Science Center, along with industry and academic partners, survey clam populations every 3 years and usually follow these surveys with a full stock assessment.
  • A few species of algae cause Harmful Algal Blooms (HABs), which can have negative impacts on fish, marine animals, birds, and humans. Species of Alexandrium cause HABs in New England that are commonly referred to as “red tides.” Alexandrium toxin becomes concentrated in shellfish such as quahogs. The shellfish themselves are not affected by the toxin, but eating shellfish tainted with this toxin can lead to paralytic shellfish poisoning (PSP), a potentially fatal human illness. There are large-scale monitoring programs all along the coast to assess toxin levels in shellfish; if toxins are detected these areas are immediately closed to harvesting. Contamination from PSP has had a huge impact on fisheries for ocean quahogs. Georges Bank, where ocean quahogs are abundant, has been closed to fishing since 1990 due to the presence of PSP toxins in quahog tissue. In January 2013, a portion of Georges Bank was reopened to the harvest of ocean quahogs and surfclams by vessels using a new PSP testing protocol that was developed through the collaborative efforts of industry, scientists, and managers. This will allow safe harvest of these abundant Georges Bank resources.

Last updated: 06/04/2021