New Zealand Green Mussels
Seafood guides quicktabs
- Seafood Profile
- Biology & Habitat
- Science & Management
- Conservation Criteria
- Sustainability Summary
Seasonality is generallly not a concern and these mussels are typically individually frozen on the half shell. New Zealand greenshell mussels are 30% larger than blue mussels.Generally, rope-grown mussels have thin, clean shells and high meat content. Some producers hold mussels in tanks of water that are treated with ultraviolet light which destroys harmful bacteria, a process known as "depuration."
- Meat (cooked)
Health & Nutrition
- Total Fat2.50g
Farmed green mussels have elongated shells that are brown-green on one end and green at the broad lip, with dark brown striations in the middle. Wild mussels are more dark purple and black with the distinctive green lip along the inside margin. Juveniles have bright green shells. The insides of the shell are milky white and slightly iridescent. They can grow up to 6 in (15 cm) but market size is typically 3.5-4 in (9-10 cm). When farmed, they can reach market size within 18-24 months, about twice as fast than in the wild.
Green mussels’ shells are slightly open in their natural state, which New Zealanders refer to as “smiling.” However, the shells will close tightly when there is stress, freshwater, or rough handling. In general, they can withstand large fluctuations in salinity, desiccation, temperature, and oxygen levels.
New Zealand green mussels first mature as males and later develop female reproductive capabilities. There is no set season for when green mussels will spawn. General onset and length of the spawning season can vary and is directly driven by food availability and temperature.
They are semi-mobile suspension feeders, feeding on phytoplankton like green algae, dinoflagellates, and diatoms. As filter feeders, they help remove pollutants from the water. New Zealand green mussels are prey to various fish species such as snapper, spotty, and leatherjacket fish.
The green mussel is endemic to New Zealand. They occur throughout the country but are more common in the North Island, where the water is warmer. They are benthic organisms and in the wild, can be found in temperate waters from 0-328 ft (0-100 m). They prefer moderately exposed environments with full salinity levels.
Mussel farms are restricted to sheltered in-shore areas that are suitable for these high subtidal requirements. Most farms are set to depths between 16-98 ft (5-30 m). The major growing areas include Coromandel, Marlborough Sounds, and Stewart Island.
New Zealand green mussels are also known as green mussels, greenshells, or greenlipped mussels. A considerable amount of research takes place in the mussel industry in order to enhance production and environmental management. This research is carried out by government agencies, universities, and private research organizations, and is regarded as the most progressive and advanced of its kind. Since 2000, New Zealand’s Cawthron Institute has been carrying out a selective breeding program, which small-scale commercial hatcheries established after 2005 have been taking up the benefits from the project. In 2003, research was also conducted to adapt longline technology to exposed offshore waters. A biotoxin monitoring research program is also taking place in New Zealand.Management:
New Zealand green mussels are farmed exclusively in New Zealand and have been exported to the United States since 1979. Other major importers are Japan, Australia, and Europe. In 2016, production harvest was 94,037 tons. The 2002 harvest of 78,000 tons was worth USD $85.8 million. In 2000, there were 605 farms in New Zealand.
Green mussels are cultivated on ropes, rafts, and longlines and are harvested using specially designed harvesting vessels. Farming methods are mechanized and are highly cost-effective. The New Zealand government tightly regulates growing standards like water quality and production levels. Because of this, product quality is considered consistently high.
Seed, or spat, for the mussels comes from wild sources. Farmers have a spat settlement monitoring program, where they will suspend spat catching lines in areas where there are high numbers of planktonic mussel larvae ready to settle. This method is expensive and only represents a small portion of total spat collected, but the mussels are high quality. Farmers will also take advantage of a natural phenomenon occurring on the North West Coast of the North Island. At irregular times throughout the year, the area provides considerable quantities of newly settled spat attached to washed up pieces of seaweed, creating a major source of spat. The seaweed is collected by locals and distributed to growers throughout the country.
Overall, mussel farming in New Zealand has minimal ecological impact near or on established farm sites because most farms are sited in areas away from cities and where green mussels occur naturally. The presence of mussels may actually benefit many other marine life and also provides a flow-on benefit for recreational anglers. No harmful chemicals or additives are used during the farming process.
Mussels are often raised on ropes submersed in coastal areas, a system considered to be one of the most environmentally friendly forms of aquaculture. They are also bottom cultured and harvested by dredging, which can degrade sediment and cause a decline in biodiversity. However, dredging cultured beds causes less damage than dredging natural ones. Although they are filterfeeders that improve water quality, mussels will only thrive in a healthy environment. Harmful algal toxins in the water have caused some mussel farming areas to be closed temporarily.
Mussel farms tend to be protected from duck predators with fine mesh that is heavily weighted to avoid problems there with entanglements.
Mussels are filterfeeders that take in plankton so no extra feed is needed to grow them.
Disease, Pathogen and Parasite Interaction
Disease incidence among mussels is low.
Escapes and Introduced Species
Mussels are generally farmed in areas where they are native and interbreeding between wild and escaped mussels doesn’t threaten the wild populations. Mediterranean mussels farmed in the U.S. are considered a naturalized species.
|46° South Fish Co. Ltd.||Canada||British Columbia|
|Catanese Classic Seafood||United States||Ohio|
|Channel Seafoods International||United States||Florida|
|DiCarlo Seafood Company||United States||California|
|Euclid Fish Company||United States||Ohio|
|Export Packers Company Limited||Canada||Ontario|
|Frobisher International Enterprise Ltd.||Canada||British Columbia|
|Lee Fish USA||United States||California|
|Lotus Seafood Inc.||United States||California|
|Lusamerica Foods||United States, United States, United States||California|
|Macgregors Meat & Seafood Ltd.||Canada||Ontario|
|Mark Foods, Inc.||United States||New York|
|New Zealand Seafood Marketing||United States||California|
|OM Seafood Company||United States||Oregon|
|P.H.R Processing Ltd||New Zealand|
|Pacific Fresh Fish Ltd.||Canada||Saskatchewan|
|Pacific Harvest Seafoods||United States||California|
|Royal Hawaiian Seafood||United States||California|
|Sammy's Seafood Inc||United States||Florida|
|Santa Monica Seafood, Inc.||United States||California|
|The Fish Guys Inc.||United States||Minnesota|
- Food and Agriculture Organization of the U.N. (FAO)
- Seafood Watch Program