Atlantic Sea Scallop (Placopecten magellanicus)

• Atlantic sea scallop population levels are high; overfishing is not occurring.
• Scallops are managed using a combined approach of effort reduction and rotating harvest areas, which maximizes scallop yields while protecting beds of young scallops.
• Scallops are a good low-fat source of protein and are high in selenium and B vitamins. For more information, see Nutrition Facts. (USDA)
• Over 60 percent of the sea scallops sold in the U.S. are caught in U.S. fisheries; the rest are imports, mostly from Canada.

Sustainability Status

Biomass: Scallop biomass stood at 7.8 kilograms per tow for 2005, above the biomass target of 5.6 kilograms per tow. This level is 39% above the biomass needed for maximum sustainable yield (B_MSY).
Overfishing: No
Overfished: No
Fishing and habitat: Scallop dredges can have long term effects on habitat. In some cases, areas are closed to scallop dredges to protect sensitive habitats and scallop populations. For more information, see Fisheries Gear.
Bycatch: Bycatch of finfish (such as yellowtail flounder, skates, and monkfish), sea turtles, and undersized scallops have been identified as concerns in this fishery.
Aquaculture: There is currently no commercial aquaculture of sea scallops in the U.S.

Science and Management

The New England Fishery Management Council manages Atlantic sea scallops in cooperation with the Mid-Atlantic Fishery Management Council under the Atlantic Sea Scallop Fisheries Management Plan (FMP), which was implemented in 1982 to restore and stabilize adult scallop stocks. The scallop FMP has evolved since, incorporating new management techniques as scientists learn more about the fishery. NOAA's National Marine Fisheries Service (NMFS) determined that the scallop fishery experienced overfishing in 2003, and the New England Fishery Management Council subsequently implemented measures to reduce fishing effort. The Atlantic sea scallop population is now rebuilt to sustainable levels, as a result of effort reductions, gear restrictions, and closed areas established to reduce fishing mortality.

Most fishermen in the Northeast use dredge gear to harvest scallops; some in the Mid-Atlantic use trawl net gear. Ongoing research and experimentation with different techniques and gears and education efforts have helped to reduce bycatch. For example, temporary and seasonal closures in areas where species like yellowtail flounder and sea turtles congregate reduce catch of these untargeted species. In addition, NMFS, in collaboration with industry, has tested and implemented changes in dredge design to minimize injuries and capture of sea turtles. Additional studies are examining the feasibility of turtle excluder devices (TEDs) for scallop trawls.

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. High reproductive potential in sea scallops means they may respond to management actions more rapidly than species that reproduce slowly and in small numbers.

• Geographic range: In the Northwest Atlantic Ocean, from Newfoundland to North Carolina
• Habitat: Adult scallops form dense aggregations called "beds" on the ocean floor. Commercially valuable scallop beds are usually found at depths between 59 and 360 feet.
• Life span: Up to 20 years
• Food: Scallops filter small organisms out of water column
• Growth rate: Sea scallops grow rapidly during the first half of their lifespan. Between the ages of 3 and 5, sea scallops commonly grow to 50 to 80% of their shell height and may quadruple their meat weight.
• Maximum size: Usually not larger than 6.7 inches in shell height
• Reaches reproductive maturity: At age 2, but do not significantly contribute until around age 4
• Reproduction: Sea scallops have high fecundity (potential reproductive capacity); a single sea scallop can produce as many as 270 million eggs during its lifetime.
• Spawning season: Most spawn late summer to fall, but timing varies according to latitude.
• Spawning grounds: Bottom habitats with a substrate of cobble, shells, coarse/gravelly sand, and sand in the Gulf of Maine, Georges Bank, southern New England, and middle Atlantic
• Migrations: None, but scallop can use its adductor muscle to open and shut its two shells to propel itself in the water column. Scallop larvae also drift in the current.
• Predators: Predators of larval sea scallops include numerous pelagic fish and invertebrates that eat zooplankton; predators that target juveniles and adults include cod, wolffish, eel pout, flounder, crabs, lobster, and sea stars.
• Commercial or recreational interest: Commercial
• Distinguishing characteristics: A bivalve mollusk harvested for the muscle that holds its two shells together

Role in the Ecosystem

Sea scallops are filter feeders - they filter their food out of the water, which can help to improve water clarity by removing suspended materials from the water column. However, water quality is not really an issue where sea scallops occur in large numbers.

Additional Information

Market name: Scallop
Vernacular name: none
Several other species are also marketed as Scallop.

Biomass

Biomass refers to the amount of Atlantic sea scallops in the ocean. Scientists cannot collect and weigh every single scallop 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. In 1994, 1998, 2004, and 2007, NOAA's National Marine Fisheries Service closed extensive areas to scallop dredging. These closures, in conjunction with significant reductions in effort and increases in recruitment, have led to a ten-fold increase in scallop biomass since its low point in 1993.

Note: Biomass for some species, like scallop, is estimated indirectly if good estimates of actual biomass are unknown. Relative sea scallop abundance from year to year is estimated by weight of scallops per tow from annual surveys by scientists (e.g., kilograms per tow). Such indirect measures often serve as a good proxy for total biomass.

Landings

Landings refer to the amount of catch that is brought to land. Scallops were declared overfished in 1997; stricter management followed in 1998. Now, the scallop fishery supports the largest amount of landings in its history. U.S. sea scallop landings averaged about 26,000 metric tons meat weight during 2002-2006, about twice their long-term average.

Note: The landings presented are domestic commercial landings.

Biomass and Landings

Are landings and biomass related? Landings are heavily dependent on biomass, management measures in the fishery, and fishing effort. Following low biomass and landings in the 1990s, strict management and productive scallop seasons led to the current levels of higher biomass and landings.

Data sources:
Biomass and landings from 45th Northeast Regional Stock Assessment Workshop - Assessment of Atlantic Sea Scallops

Important Dates

1982 – Atlantic Sea Scallop Fishery Management Plan implemented, requiring that harvestable scallops meet a minimum weight requirement
1994 – NMFS closes areas on Georges Bank and Nantucket shoals to groundfish and scallop fishing
1994 – Amendment 4 changes protocol for collecting commercial fishing data for Northeast U.S. fisheries and requires increase in dredge ring size from 3.0 to 3.5 inches by 1996
1997 – Report to Congress declares scallops are an overfished stock
1998 – Amendment 7 establishes a more stringent "days-at-sea" limitation and a plan to rebuild stocks within 10 years; maximum crew size capped at seven
1998-2001 – Extensive areas in Mid-Atlantic Bight region closed to scallop fishing
1999-2001 – First limited reopenings of closed area on Georges Bank
2001 – Mid-Atlantic biomass continues to increase as a result of above-average recruitment coupled with better size selection by the fishery and gear. Mid-Atlantic areas closed since 1998 reopen to controlled fishing.
2004 – Amendment 10 updates other measures and implements "area rotation management program," or rotating open and closed areas to maximize scallop yield. A new rotational area (the "Elephant Trunk" area) was closed to fishing for three years.
2004 – Biomass peaks at 9.6 kilograms per tow
2004-2006 – Limited portions of Georges Bank closure areas reopen to controlled fishing
2005 – Dredge ring size increases to 4.0 inches
2006 – Chain mats required in sea scallop dredges used in the Mid-Atlantic, May through November, to prevent sea turtles from entering gear
2007 – Amendment 13 implemented, continuing the industry-funded observer program through a TAC and days-at-sea (DAS) set-aside program that helps vessel owners defray the cost of carrying observers; necessary to monitor bycatch of finfish and interactions with threatened and endangered species
2007 – The Elephant Trunk area reopens to fishing, and a new rotational closure (Delmarva) is implemented.
2008 – Amendment 11 is approved and implemented, establishing limited access and individual quotas for the general category fleet of scallop vessels, as well as other important measures to control fishing mortality and capacity in the general category scallop fishery

Notes and Links

General Information:
NOAA Technical Memorandum NMFS-NE-189 Essential Fish Habitat Source Document: Sea Scallop, Placopecten magellanicus, Life History and Habitat Characteristics, Second Edition (2004)

NOAA Northeast Fisheries Science Center Estimated bycatch of loggerhead sea turtles (Caretta caretta) in U.S. Mid-Atlantic scallop trawl gear, 2004-2005, and in sea scallop dredge gear, 2005 (2007)

Fishery Management:
New England Fishery Management Council Sea Scallop Fishery Management amendments and information

New England Fishery Management Council Atlantic Sea Scallop Fishery Management Plan

Amendment 10 of the Atlantic Sea Scallop Fishery Management Plan was passed on June 23, 2004. This amendment calls for an "area rotation management program" among other measures to ensure the sustainability of this fishery.

Stock Assessments:
45th Northeast Regional Stock Assessment Workshop - Assessment of Atlantic Sea Scallops