Wild Sea Scallops
FISHERY IMPACTS ON STOCK | HABITAT IMPACTS | BYCATCH | MANAGEMENT EFFECTIVENESS
Fishery Impacts on Stock
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.
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, according to the Seafood Choices Alliance. 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.
Extent of Bycatch
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, according to the Blue Ocean Institute. 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.
Farmed Sea Scallops
POLLUTION & HABITAT | MARINE RESOURCES | RISK TO WILD STOCKS | MANAGEMENT | ECOLOGICAL EFFECTS
Risk of Pollution and Habitat Impacts
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, according to the Seafood Choices Alliance. Scallop farms rarely use any fertilizers, antibiotics or chemicals that could negatively impact the local ecosystem, reports the Monterey Bay Aquarium.
Use of Marine Resources (Feed)
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.
Risk to Wild Stocks
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.
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 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.