Atlantic Surfclam (Spisula solidissima)

• Population levels of Atlantic surfclam are high, and no overfishing is occurring.
• Atlantic surfclams were one of the first species to have a fisheries management plan as directed in 1976 by the Magnuson-Stevens Act, and they are currently managed under an Individual Transferable Quota (ITQ) system.
• Surfclams provide a low-fat, high-quality protein and are an excellent source of selenium and niacin. For more on nutrition, see Nutrition Facts. (USDA)
• Surfclams are used to manufacture processed clam products such as breaded clam strips, minced clams, stuffed clam products, chowders, and broth.

Sustainability Status

Biomass: Biomass is 30% above the biomass that supports maximum sustainable yield (B_MSY).
Overfishing: No
Overfished: No
Fishing and habitat: Atlantic surfclams burrow into sandy bottoms on the continental shelf. This is a "high energy" environment and is thought to recover quickly following the passage of a hydraulic clam dredge. The area actually disturbed by surfclam dredges is an extremely small percentage of the total sandy bottom of the Mid-Atlantic bight. Any impacts from fishing gear are considered temporary and minimal; the habitat's functions are not likely to be affected.
Bycatch: The surfclam fishery is managed under an individual transferable quota (ITQ) management system that reduces the "race to fish" and therefore significantly reduces bycatch. Surfclam fisheries are extremely clean - surfclams constitute nearly 90% of the total number of animals caught during surveys. Commercial clam dredges have bars that are spaced several inches apart so as not to collect anything but the targeted surfclams; however, large fish, mollusks, and crabs that are too large to pass through the bars are retained in the dredge.
Aquaculture: There is currently no commercial aquaculture of Atlantic surfclams in the U.S.

Science and Management

The fishery for surfclams in the U.S. Exclusive Economic Zone (EEZ) (waters 3 to 200 miles offshore) is managed under the Surfclam-Ocean Quahog Fishery Management Plan (FMP) of the Mid-Atlantic Fishery Management Council. Current management measures for the fishery include a Total Allowable Catch (TAC) and an individual transferable quota (ITQ) system, which were adopted in 1990 under Amendment 8 to the FMP. A single annual TAC (a regulated amount of catch) for surfclam applies to the entire United States EEZ. The ITQ system allocates individual fishing quotas to fishermen or vessel owners that can be sold or leased.

State-managed surfclam fisheries in territorial waters (less than 3 nautical miles from shore) of New Jersey, New York, and southern New England occasionally contribute significantly to the overall surfclam harvest.

Federal surveys are conducted by NOAA's Northeast Fisheries Science Center (NEFSC) every 3 years. According to the most recent stock assessment for the Atlantic surfclam (2006), the stock is not overfished nor is overfishing occurring. The clam survey was conducted aboard NOAA research vessels until 2008 and is expected to be conducted on a cooperative basis from a commercial fishing vessel in the future.

Life History and Habitat

Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed.

• Geographic range: In the Western North Atlantic from the southern Gulf of St. Lawrence to Cape Hatteras, North Carolina. Commercial concentrations are primarily found off New Jersey, the Delmarva Peninsula, and on Georges Bank.
• Habitat: Adult beds are found from beach zones to an average of 164 feet deep. Adult surfclams prefer turbulent waters at the edge of the breaker zone. Some can be found in estuarine areas, but their distribution is limited by salinity. Juveniles prefer medium to fine, low organic sands in waters 29.5 to 82 feet deep; adults prefer medium- to coarse-grained sand and gravel and bury themselves just below the sediment surface. Adults often remain in their juvenile burrows unless they are displaced by storm events.
• Life span: Surfclams can live up to about 35 years. On average, surfclams living in open water live longer than those living inshore.
• Food: Surfclams are planktivorous filter feeders, meaning they strain tiny plants and animals out of the water to eat. Larval surfclams eat algal cells; adults primarily feed on diatoms, green algae, and naked flagellates.
• Growth rate: Grow to about 1.8 inches by the end of their first year of life and reach a harvestable size in about 6 years at 5 inches. Their growth rate is fairly rapid until about age 7. Surfclams' growth is variable and seems dependent on water temperature; southern surfclam populations in warmer water grow more slowly than more northern populations.
• Maximum size: Surfclams can grow up to 8.9 inches, but clams larger than 7.9 inches are rare.
• Reaches reproductive maturity: Some are capable of reproduction in their first year of life, although most spawn by the end of their second year.
• Reproduction: Surfclams shed their eggs and sperm directly into the water column. Larvae spend about 3 weeks in the water column as plankton before moving to the bottom to live.
• Spawning season: Two spawning periods: the first from mid-July through early August and the second from mid-October to early November
• Spawning grounds: Fertilization occurs in the water column above the spawning bed.
• Migrations: None
• Predators: Predators include boring snails, ducks, haddock, and cod.
• Commercial or recreational interest: Commercial
• Distinguishing characteristics: Surfclams have thick, slightly triangular, yellowish-white shells with rounded edges and concentric ridges. The shells do not fully close and therefore gape slightly.

Role in the Ecosystem

Surfclams are filter feeders, straining plankton from surrounding waters. They serve as prey for species such as shrimp, horseshoe crabs, snails, sea stars, Jonah and Lady crabs, and fish.

Additional Information

The Georges Bank region has been closed to the harvesting of surfclams since 1990, due to the risk of paralytic shellfish poisoning (PSP). However, Georges Bank accounts for the largest fraction of stock biomass and is becoming more important as biomass declines in southern regions.

Market names: Clam, Surfclam
Vernacular names: Hen clam, Bar clam, and Sea clam
Several other species are marketed as Clam and Surfclam.

Biomass

Biomass refers to the amount of Atlantic surfclam meats in the ocean. Scientists cannot collect and weigh every single surfclam to determine biomass, so they use models to estimate it instead. These biomass estimates can help determine if a stock is being fished too heavily or if it may be able to tolerate more fishing pressure. Managers can then make appropriate changes in the regulations of the fishery.

The stock as a whole is at a relatively high biomass level, but there have been declines in biomass in southern areas in recent years due primarily to poor recruitment and slow growth rates associated with warm water conditions. The surfclam stock is not considered overfished and overfishing is not occurring, nor is it likely that these conditions will occur in the near future.

Landings

Landings refer to the amount of catch that is brought to land. The federal fishery has seen considerable consolidation over the last few decades. During 1990, 128 vessels participated in the U.S. EEZ fishery for surfclams. The number of vessels in the fishery declined to 75 in 1991 with adoption of Amendment 8 and implementation of individual transferable quota (ITQ) management. Between 2005 and early 2007, vessels harvesting surfclams again declined from 36 to 25 vessels. Total landings from the EEZ stock during 2005 were less than the quota due to market factors, based on industry sources.

Note: The landings presented are domestic commercial landings.

Biomass and Landings

Are landings and biomass related? Landings are dependent on biomass, management measures in the fishery, and fishing effort.

Data sources:
Biomass and landings from 44th Northeast Regional Stock Assessment Workshop - Assessment of Atlantic Surfclam

Important Dates

1977 – Original FMP for surfclam (and ocean quahog) approved
1979 – Amendment 1 extends moratorium in surfclam fishery through 1979
1981 – Amendment 3 extends FMP indefinitely; also imposes a 5.5 inch minimum size limit, expands fishing week, and puts quota setting on a framework basis
1984 – Amendment 5 extends size limit and requires that cages be tagged
1988 – Amendment 8 establishes an individual transferable quota (ITQ) system; also allows minimum size to be suspended from year to year, merges the New England and Mid-Atlantic areas into one management area, and authorizes an experimental fishery for information purposes
1991 – Size limit suspended for the year's fishing season due to the relatively low abundance of pre-recruit-sized clams (less than 4.3 inches) and the likely incentive under Amendment 8 to target beds of larger surfclams
1996 – Amendment 9 revises overfishing definitions in response to scientific review by NOAA's National Marine Fisheries Service (NMFS)
1998 – Amendment 10 places a moratorium on entry to the Maine EEZ fishery
1999 – Amendment 12 establishes new overfishing definitions, identifies and describes essential fish habitat, adds framework adjustment procedure, and implements Operator Permits
2004-2006 – Industry downsizes the portion of the fleet harvesting surfclams
2004 – Amendment 13 revises surfclam overfishing definition, addresses gear impacts to EFH, allows for multi-year quotas, provides for a reversal of the suspension of the surfclam size limit, and allows mandatory implementation of a mandatory vessel monitoring system (VMS)
2005 – Industry has lowest harvest since 2000, at 2.744 million bushels of surfclams, 81% of the 3.4 million bushel quota, due to market conditions
2007 – Final rule implements Framework 1 of the FMP, requiring a vessel monitoring system (VMS) for vessels participating in the surfclam fishery to monitor closed areas and borders between state and Federal jurisdiction

Notes and Links

General Information:
NOAA Coastal Services Center Benthic Habitats of NY/NJ Harbor study - Surfclam information page

NOAA Northeast Fisheries Science Center Report from the Atlantic surfclam aging workshop (2005)

NOAA Northeast Fisheries Science Center Results from the 2004 Cooperative Survey of Atlantic Surfclams (2005)

NOAA Technical Memorandum NMFS-NE-142: Essential Fish Habitat Source Document: Atlantic Surfclam, Spisula solidissima, Life History and Habitat Characteristics (1999)

NOAA's National Marine Fisheries Service (NMFS) Northeast Regional Office

NOAA Northeast Fisheries Science Center

Mid-Atlantic Fishery Management Council

Fishery Management: 
Mid-Atlantic Fishery Management Council Surfclam and Ocean Quahog Fishery Management Plan - History of FMP development

Framework Adjustment 1 to the Atlantic Surfclam and Ocean Quahog FMP Regarding Vessel Monitoring Systems (VMS)

Stock Assessments:
NOAA Northeast Fisheries Science Center Status of Fisheries Resources off the Northeastern U.S. Atlantic surfclam summary

44th Northeast Regional Stock Assessment Workshop - Assessment of Atlantic Surfclam