The worst time to buy scallops is after they have spawned because the adductor muscle is soft and discolored and sheds moisture easily. The best time to buy scallops is in the late summer when prices are low and the quality has improved following the spring spawn. Scallop meats are sold by count per pound, with a premium being paid for larger size meats (lower count per pound). The trick to sea scallops is to not pay $10/lb. for water. Dry scallops will feel sticky whereas a soaked scallop will feel soapy or slick. Although very small quantities of U.S. scallops are harvested inshore by divers, the term “diver” scallops refers to a dry scallop that has not been treated by sodium tripolyphosphate. The phosphates allow the scallop to hold more water, sometimes 20% more. Most scallops are treated using phosphates and even dry scallops are often washed in tripolyphosphate. Sea scallop raw meat coloration varies due to different types of algae they consume from a creamy white to a soft orangish color.
Key sustainability sourcing notes for wild-caught U.S. and Canadian sea scallops based on 2014-2015 landings and the most recent MSC certifications and current Seafood Watch assessments:
~90% of U.S. and Canadian sea scallop landings are MSC-certified (2 Canadian fisheries, 1 U.S. fishery) and meet the "Good Alternative (yellow)" rating (U.S. and Canada dredge-caught)
~25% of the landings data does not include enough information to match the relative sustainable portion to the corresponding U.S. states (~75% from Massachusetts)
For known landings, and within both the MSC-certified and "Good Alternative" category, ~35% is landed in Massachusetts, ~30% from Canada-offshore, ~15% from New Jersey, ~10% from Canada-inshore, and ~5% from New Jersey. Other U.S. states landing sea scallops include: Connecticut, Maine, Maryland, New Hampshire, New York, North Carolina, and Rhode Island which accounts for <5% combined landings within the MSC-certified and "Good Alternative" category.
Scallops are bivalves and their shells are held together by the adductor muscle, which is what American diners typically eat. The upper shell is a red-pink or brown color, and the lower shell is white or cream. Very few sea scallops (5-10 percent) are albinos. Unlike other bivalves, sea scallops can use their adductor muscle to open and close their shells, propelling themselves through the water. Scallops have about 60 eyes that line their mantle and can detect light and motion.
Sea scallops can live up to 20 years, growing quickly for the first few years of their life. Most grow up to six inches (15 cm) in height, although the largest scallop ever reported was nine inches (23 cm) in shell height. They reach maturity at two years; however, sea scallops don’t produce egg or sperm until about four years old. They are very fertile, and females produce 270 million eggs per year. Output is greater for scallops in shallow water, where the temperature is higher and food supply is greater. Spawning season can be spring, late summer, or fall depending on the scallop’s location. After hatching, larvae remain in the water column for about five weeks before settling onto the ocean floor.
In aquaculture operations, larvae and juvenile nurseries are usually pearl nets or fine-meshed shellfish bags set in bottom racks. Greater depths reduce fouling rates of the fine mesh products. Grow-out can take between one to three years. Improper stocking densities, feed, temperature, or salinity conditions can affect production success. Typically, 30 to 60 percent bottom coverage is an appropriate stocking density. Bottom-cultured scallops take longer to reach market size than those grown in suspended culture, up to one year more. Scallops are fully-grown within two to three years after hatching.
Atlantic sea scallops range from the Gulf of St. Lawrence and Newfoundland, Canada to Cape Hatteras, North Carolina. Major aggregations of sea scallops occur in the Mid-Atlantic from Virginia to Long Island, Georges Bank, the Great South Channel, and in the Gulf of Maine. They are generally found living in large concentrations called “beds” on sand or gravel bottoms in waters between 65 to 390 feet (20 to 119 meters) deep. Sea scallops tend to be found in shallower waters in Maine and Canada while in the Mid-Atlantic and Georges Bank they occur in deeper waters between 100 to 300 feet (30 to 91 meters) deep. They are sensitive to high water temperatures and are therefore restricted to deeper, coolers waters (generally less than 20 degrees Celsius (68 degrees Fahrenheit)) throughout their southern range. Spawning occurs in US waters as a single peak in late summer or early autumn. Adult sea scallops do not disperse widely throughout their range, though larval are planktonic for their first five weeks, before settling on the sea floor.
Science & Management
NOAA’s Northeast Fisheries Science Center has surveyed sea scallop populations off the northeastern US coast every year beginning in 1979. The survey area is divided into zones, based on depth and habitat, and a dredge and HabCam camera is towed to randomly sample and document marine life and other conditions in the area. Each catch is sorted and counted, providing indices of the average density of animals, and information about bottom type and habitat. Scientists use this information, as well as data from other surveys and commercial fisheries, to estimate biomass abundance, and assess the health of the population and the sustainability of the fishery.
The NOAA’s Scallop Research Set-Aside Program uses a fraction of the allowed scallop harvest each year to fund scallop and habitat research and surveys in order to provide better information for future management decisions. Participating scallop vessels fund research through the sales of the scallop they harvest. 2016-17 projects include: finding innovative ways to prevent yellowtail flounder bycatch, understanding the impacts of scallop fisheries on loggerhead sea turtles, an assessment of sea scallop abundance in the Nantucket Lightship Closed Area, Georges Bank Closed area, and surrounds, and age structure and growth rate in the sea scallop.
NOAA Fisheries and the New England and Mid-Atlantic Fishery Management Councils manage the Atlantic sea scallop fishery under the Atlantic Sea Scallop Fishery Management Plan (FMP). Implemented in 1982 to restore adult sea scallop stock and reduce yearly fluctuations in stock abundance, the Atlantic Sea Scallop FMP has been successful in the recovery of scallop populations along the US Atlantic resulting in increased landings and revenue.
The fishery is divided into a limited access fleet that includes larger boats that make longer trips, and a general category fleet for smaller boats that make shorter day trips. The majority of the annual catch limit (95 percent) is allocated to the limited access fleet. Sea scallops are managed as single stock in the US Exclusive Economic Zone (EEZ) although four regional components (Mid‐Atlantic from Virginia to Long Island, Georges Bank, the Great South Channel, and the Gulf of Maine) are recognized which are subsequently divided into six resource areas: Delmarva (Mid‐Atlantic), New York Bight (Mid‐Atlantic), South Channel, southeast part of Georges Bank, northeast peak and northern part of Georges Bank, and the Gulf of Maine. The majority of US assessments and management efforts focus on Georges Bank and the Mid-Atlantic as they account for the largest concentrations of sea scallops along the US Atlantic and therefore the majority of the fishery occurs in these regions.
Among management measures for Atlantic sea scallops are:
A total allowable catch that is allocated to different groups within the fishery and dependent on permit type and historical catch;
Days at sea limits and limits to special access areas;
Crew size limits;
Requirements for the use of vessel monitoring systems;
Year-round area closures and rotational closed areas to protect young scallops;
Additional seasonal closures to protect finfish congregations;
Gear modifications to reduce bycatch of sea turtles and finfish;
A total allowable catch (TAC) limit for yellowtail and windowpane flounder bycatch; and,
A individual fishing quota catch share program (general category fleet only).
There is an Atlantic sea scallop fishery in the Gulf of Maine that operates in both federal and state waters. This particular fishery occurs primarily in state waters and is managed by the State of Maine. NOAA and the fishery management council manage the federal component of this particular fishery.
In 2014, the US Atlantic scallop totaled 33.8 million pounds of sea scallop meats and was valued at more than US $424 million. A 2015 stock assessment indicated that Atlantic sea scallops are not overfished, nor subject to overfishing.
Sea scallops are managed by the Department of Fisheries and Oceans (DFO) in Canada. The majority of the fishery occurs off the coast of Nova Scotia and part of the southern coast off of Newfoundland. Georges Banks accounts for 80 percent of the offshore scallop landings. Among measures the DFO has in place for sea scallops are:
A limited entry program;
Total allowable catch quotas for each of the six Scallop Fishing Areas (ranging from the St. Pierre Bank off the south coast of Newfoundland to Georges Bank off the southern coast of Nova Scotia);
Electronic vessel and dockside monitoring; and,
Farming for Atlantic sea scallops has been explored using both suspended, on-bottom, and polyculture techniques in New England and Canada. These efforts have been successful though they occur at a small scale. In the US, the Army Corps of Engineers issues aquaculture permits before a farm can be established, which requires consultation from NOAA’s National Marine Fisheries Service, the US Fish and Wildlife Service, and state governments. Additionally, the US Department of Agriculture, US Food and Drug Administration, the Bureau of Ocean Energy Management, and the US Coast Guard provide some degree of oversight regarding shellfish aquaculture farms. US shellfish farms must also adhere to federal regulations as outlined in the Magnuson-Stevens Fishery Conservation and Management Act, the National Environmental Policy Act (NEPA), and the Clean Water Act (CWA). Additionally, US shellfish farmers often implement best management practices (BMPs) to reduce, minimize, and mitigate the effects of farming on both aquatic and terrestrial resources as well as with interactions with other marine resource users.
Wild sea scallops are primarily fished in the U.S. and Canadian Atlantic while a small number come from Mexico and Peru. They grow quickly and mature young, which makes them particularly resistant to fishing pressure. U.S. sea scallops were overfished in the past, causing extensive areas to be closed in the 1990s. Since then, some of the areas have been reopened to controlled fishing. American sea scallop stocks have recovered following years of strict conservation measures and is operating at sustainable levels, according to the National Marine Fisheries Service.
Habitat impacts (Wild)
Most sea scallops fished in the U.S. are collected from the sandy or cobbled ocean floor with dredges, trawls, or rakes. Dredging for sea scallops often levels structural marine habitat. Some sea scallop habitats in the U.S. have been closed to dredging for several years, which is helping them recover. Some gear modifications that reduce contact with the ocean floor have been implemented, according to the Monterey Bay Aquarium. In Mexico and Peru divers collect them by hand, a method that results in little habitat impact, according to the Monterey Bay Aquarium.
The dredges commonly used to harvest scallops along America’s Atlantic coast can result in the bycatch of sea turtles and finfish such as yellowtail flounder, skates and, to a certain extent, monkfish, according to the Monterey Bay Aquarium. Bycatch can also include undersized scallops as well as bottom-dwelling species such as cod and monkfish. In the mid-Atlantic region, endangered sea turtles have been caught in scallop gear. A gear modification involving rock chains may reduce sea turtle interactions but more data is still needed. In New England, dredges are required to have a minimum ring size and minimum twine top mesh size to reduce the amount of groundfish and juvenile scallop bycatch.
The sea scallop fishery in the U.S. has been highly effective at recovering stocks through closed and rotational closed areas as well as gear restrictions and maximum fishing days per year, according to the Monterey Bay Aquarium. The risk to sea turtles is being addressed through restrictions on the number of fishing trips, according to the U.S. National Marine Fisheries Service. The NMFS also reported that starting May 1, 2013, scallop vessels in the Mid-Atlantic must use a turtle deflector dredge in areas where sea turtles occur on scallop grounds. In Peru, where sea scallops are hand-collected by divers, there are few regulations and little enforcement to protect the stocks, according to the Monterey Bay Aquarium.
Conservation Criteria - Farmed
The U.S. and Canada have strict rules for aquaculture, but China has been struggling with water quality and pollution problems in its coastal environment, according to the Monterey Bay Aquarium. Shellfish farmers there have little control over industrial and agricultural pollution, so it’s unusual for there to be management processes in place to deal with the problem. There is little information available about best management practices for sea scallop farming operations in Asia, according to the aquarium.
The majority of sea scallops available in the United States are wild-caught but a small percent comes from farmers in Japan and China. Sea scallops are also farmed in Peru and Chile. In Japan, sea scallops are frequently grown in lantern nets suspended from buoys, which has a minimal impact on the environment, according to the Environmental Defense Fund. However, sea scallops farmed using vacuum dredging from the seafloor can cause environmental damage, killing or injuring bottom-dwelling organisms. Scallop farms rarely use any fertilizers, antibiotics or chemicals that could negatively impact the local ecosystem, reports the Monterey Bay Aquarium.
The majority of farmed scallops are raised “off-bottom,” a method where they are harvested by hand, according to the Monterey Bay Aquarium. Some scallops are raised “on-bottom” in culture plots, meaning they are removed using a heavy net dredge that can harm ecosystems and negatively impact marine life, causing diversity to decline, according to the Monterey Bay Aquarium.
Scallops are filter feeders that don’t need any fishmeal or fish oil-based feed because they survive on tiny particles drawn from seawater. Sea scallops actually help improve water quality and clarity, according to the Monterey Bay Aquarium.
Escapes and Introduced Species
Since scallop spawn are transplanted to sites that are usually better than the areas where they’d naturally settle, the capture of wild scallop spat for aquaculture doesn’t appear to harm natural sea scallop populations, according to the Monterey Bay Aquarium. However, the aquarium did report that there is concern about wild spat collection in China because of a generally low abundance of wild scallops. There is little information to suggest that cultured sea scallop escapes negatively affect wild stocks in China and Japan, according to the aquarium’s 2006 report.