Aquaculture will continue to show promise in providing a healthy, domestic source of seafood and creating jobs at working waterfronts. Plenty of domestic demand exists to support growth of mussel aquaculture – the United States imports about $30 million of mussels annually (compared to the $6.7 million in blue mussels cultured domestically). Some fishermen in the Northeast are moving into mussel aquaculture to supplement their incomes. To do so requires only minor modifications to their boats and allows them to continue to work on the water as independent operators, sell to buyers they already deal with, and support local coastal industries. The blue mussel is a prime candidate for culture in federal waters off of New England. To encourage domestic production of the blue mussel, NOAA is working with researchers, industry, and federal and state regulators to explore the permitting process in federal waters.
- Ocean perch
- Sea Bass
- Turbot (Greenland)
ALSO KNOWN AS:
- Edible Mussel
Domestically farmed; mainly New England and Washington State
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Mussels are an excellent protein source that contain heart- and brain-healthy omega-3 fatty acids.LAUNCH GALLERY
Known for its sweet, tender meat, the blue mussel is gaining popularity in the United States, but has been farmed worldwide since the 19th century. This mussel does not always have a blue shell, sometimes it is purple or brown. The first mussel farm in the United States was established in the Damariscotta River, Maine in 1973 and since then, the domestic mussel industry has grown slowly.
Mussel farming improves water quality through the process of filtration. Mussels filter algae (small aquatic plants) out of the water. In the United States, mussel farmers adhere to strict environmental and food safety regulations. Mussel farming occurs mainly along the northern Atlantic coast and in Washington State.
In 2009, the world aquaculture supply of mussels was 1.8 million metric tons (4 billion pounds). The U.S. contribution was 333 metric tons (700,000 pounds), amounting to roughly $6.7 million.
LOCATION & HABITAT
Native to Europe, blue mussels are also found in the northern Atlantic and Pacific coasts of North America and in many temperate and polar waters worldwide. Blue mussels can live in inter-tidal waters (between the high and low tide) and sub-tidal waters (always below the water surface) within a temperature range of 40 and 70°F. Mussels anchor themselves using many tiny, thread-like fibers called byssal threads that allow them to attach to almost anything, including other mussels. Mussels form groups to help protect individuals from predators and to remain attached to the substrate. This tendency to clump together also makes mussel harvesting efficient compared to other shellfish.
Mussels are bivalve mollusks, which means they have a hinged shell-like clams, oysters, and scallops. Blue mussels produce hundreds of thousands of eggs. Once hatched, larvae are highly mobile and drift around in the water column for 2-3 weeks before attaching to a substrate. Wild mussels can take several years to reach market size (2.5 inches). With efficient culture methods, they may reach that size in 12 to 18 months on a farm.
Mussels are suspension feeders, so they get their nutrients from particles, mainly algae (small aquatic plants), suspended in the water column. Mussels are highly efficient at removing algae and provide a better aquatic environment for other organisms by improving local water quality. Scientists are studying how to take advantage of this to remove excess nutrients such as nitrogen from polluted bodies of water, a strategy referred to as “nutrient bio-extraction.” Mussels from polluted areas will not be eaten by humans, but can be used for other purposes such as fertilizers.
Blue mussels range in size from 2 to 4 inches at maturity, although some can grow up to 8 inches depending on food availability and age. The shell is almost tear-drop shaped and has concentric lines marking the outside. The inner shell is white, while the outer shell can appear black, blue-black, or brownish. The ‘beard’ of the mussel is actually the byssal threads that allow the mussel to attach to the substrate.
Mussel farming provides a sustainable and affordable way to increase production, as well as an environmentally friendly method to produce healthy domestic seafood. Because mussels are suspended in open water offshore, there is a continuous supply of algae. Farms engineer their structures to reduce the possibility of entangling protected species. However, there have been no reported cases of this occurring and protected species have rarely been spotted near mussel farms. A major environmental benefit of any type of mussel culture is that it provides habitat for many other organisms such as seaweed, invertebrates, and small fish.
Current research at laboratories such as NOAA’s Northeast Region and Woods Hole Oceanographic Institution provide information to make mussel culture even more efficient and environmentally sustainable.
In the future, other species of mussel may be farmed for other purposes. For example, researchers from NOAA’s Northeast Fisheries Science Center started a 2-year project assessing the efficiency of the ribbed mussel (Geukensia demissa, a species not for human consumption) for improving water quality in the Bronx River.
Large numbers and high motility of larvae in the environment are contributing factors to the success of farming blue mussels. Farmers collect spat (larval mussels) from wild populations and then transfer them to a farm for grow-out to market size. More recent technologies have allowed for culturing spat in on-shore hatcheries to increase farm efficiency.
There are two types of mussel farming: on- and off-bottom. On-bottom mussel farming is exactly what it sounds like—mussels are seeded on rocky or stony sea bottom areas and form ‘beds’ that cover the area, mimicking natural conditions. With on-bottom farming, mussels are harvested by dredging fully-grown mussels.
Off-bottom farming may use one of several techniques, including longline culture, raft culture, and bouchot culture. Each of these methods involves suspending the mussels in the water column and may result in a cleaner and more uniform product.
Because mussels are suspension feeders, there is no cost associated with feed.
Blue mussel farming is a multi-million dollar industry in the U.S., providing many jobs both on farms and at processing plants. In 2009, over 333 tons (700,000 pounds) of mussels were cultured in the U.S., bringing in $6.7 million.
Who’s in charge? Permitting for marine aquaculture is governed at the federal, state, and local levels and involves many regulations. The primary federal agencies involved are the Army Corps of Engineers (lead agency), National Oceanic and Atmospheric Administration, U.S. Fish and Wildlife Service, U.S. Department of Agriculture, U.S. Food and Drug Administration, and the U.S. Coast Guard.
What regulations are in place? Marine aquaculture permits must adhere to over 20 different laws including the Magnuson-Stevens Fishery Conservation and Management Act, Endangered Species Act, National Environmental Policy Act, and the Clean Water Act.
NOAA’s Mussel Watch Program has monitored numerous contaminant levels in mussels across all U.S. coastal waters since 1986, making it the longest continuous monitoring program in these waters. The program spans 300 coastal sites in the Pacific, Atlantic, and Gulf of Mexico.
Programs and regulations enforce regular monitoring of aquaculture practices. Mussel Watch is one program that works to ensure ocean-friendly seafood to consumers. Together, these programs and regulations address a broad suite of environmental, food-safety, and human-health issues. In the U.S., environmental regulations protect water quality, fish habitat, endangered species, and marine mammals, while consumer laws certify the safety and quality of the final product.
Once shellfish are in the environment, they do not require feed because they acquire all of their nutrients from natural plankton in the water column. Mussels benefit their local environment by filtering the water and enhancing water quality.
The main pathogen of concern for both animal and human health is Vibrio spp. Close monitoring of farmed and wild mussels and area closures, if necessary, ensure that no contaminated products are sent to market and that any infected animals are removed from the population so pathogens are not spread.
Mussels (and all filter-feeders) remove plankton and organic matter from the water column and have an overall restorative effect on water quality. Mussel farming, like most shellfish aquaculture, has a benign impact at the footprint level (disturbance of sediments and aquatic vegetation, etc.), which disappears once any structures are removed. Shellfish aquaculture is widely accepted as having a “net positive” environmental benefit.
Three concerns about mussel farming are that 1) collecting spat by dredging could impact the bottom-dwelling community and deplete natural populations of mussels, 2) a high density of shellfish in one area can deplete algae levels, and 3) high densities can also create large deposits of waste beneath farms, leading to organic sediment enrichment and low oxygen levels in the water. These issues are addressed through best management practices and innovative technology. For example, proper siting helps relieve potential nutrient depletion and waste buildup. Suspended collectors gather spat from the water column, taking pressure off of wild populations and eliminating the need to dredge.
Mussels are a healthy protein source and contain heart- and brain-healthy omega-3 fatty acids. Blue mussels tend to have tender meat and a sweet flavor. Mussels are usually served cooked.
For consumer tips and information, see the Pacific Coast Shellfish Growers Association website.
The health of mussels is not only important to the mussels themselves, but to the humans who eat them. Mussel farmers take great care in maintaining the health of their mussels by monitoring the surrounding water and checking for common parasites and diseases.
Farm-raised mussels are monitored by the Interstate Shellfish Sanitation Conference (ISSC) in cooperation with the Food and Drug Administration (FDA), which oversees monitoring of biotoxins. The National Shellfish Sanitation Program (NSSP) was established in 1925 and is the FDA program that ensures the safety of shellfish sold to consumers.
State agencies administer certification programs requiring all wholesale shellfish dealers to handle, process, and ship shellfish under sanitary conditions, and maintain records verifying that the shellfish were harvested from approved waters. Programs like NOAA’s Mussel Watch are vigilant in identifying potential risks to mussel populations from toxic pollutants.
Paralytic shellfish poisoning
Paralytic shellfish poisoning (PSP) is a serious illness that can occur after one eats contaminated shellfish. PSP originates from several dinoflagellate algae species that develop harmful algal blooms. These dinoflagellates produce harmful toxins that shellfish assimilate when filtering the water for food and then build up in the shellfish’s tissues.
When people eat contaminated shellfish, their neurological system is affected, initially manifesting in numbness or tingling of lips, fingers, toes, or limbs. PSP can result in paralysis of the chest and abdomen muscles, which eventually can lead to death. If you feel any tingling or numbness after eating shellfish, go to the hospital immediately. Monitoring programs for PSP and other biotoxins are in effect in all coastal states to prevent contaminated shellfish from being marketed.
If you are collecting wild mussels, always be aware of current closures and areas where harmful algal blooms have occurred to avoid getting sick. For more information visit FDA’s Consumer Updates.
Farmed mussels are available year-round.