Green mussels come from two distinct parts of the world, depending on the species. The New Zealand green-lipped mussel (Perna canaliculus) is found only in the coastal waters of New Zealand and has never established populations anywhere else. The Asian green mussel (Perna viridis) is native to the Indo-West Pacific, ranging from Southeast Asia through the Indian Ocean. Both species share a bright green lip along the shell edge, which is how they got their common name, but they are genetically distinct species with very different stories.
Two Species, Two Origins
The genus Perna contains three recognized species, two of which are commonly called “green mussels” or “green-lipped mussels.” Perna canaliculus is endemic to New Zealand, meaning it evolved there and exists nowhere else naturally. Perna viridis is native to the waters of Southeast Asia and is widely distributed along coastlines from Malaysia and Thailand through the Indo-Pacific region. A third species, the brown mussel Perna perna, is native to South America and Africa but isn’t typically called a green mussel.
The distinction matters because the two green mussel species show up in very different contexts. If you’ve seen green mussels on a restaurant menu or in a supplement bottle, that’s almost certainly the New Zealand species. If you’ve read about green mussels as an invasive pest in Florida or the Caribbean, that’s the Asian species.
New Zealand’s Native Green-Lipped Mussel
Perna canaliculus lives along both the North and South Islands of New Zealand, attached to rocks, wharf pilings, and other hard surfaces in subtidal waters. The species holds deep cultural significance for Māori and has become one of New Zealand’s most important aquaculture products. These mussels grow up to 26 centimeters long, though farmed mussels are typically harvested at about 10 centimeters after roughly 18 months of growth.
The life cycle starts when adult mussels release eggs and sperm into the water. Fertilized eggs develop into tiny swimming larvae that drift in the plankton for up to six weeks. When larvae reach about half a millimeter, they settle onto a surface and metamorphose into recognizable mussel shapes called spat. From that point, growth is rapid under the right conditions.
No confirmed populations of this species exist outside New Zealand. It is not considered invasive anywhere, and molecular studies have verified that it forms a genetically distinct group separate from its tropical and subtropical relatives.
The Asian Green Mussel’s Expanding Range
Perna viridis thrives in warm tropical and subtropical waters, with an optimal temperature range of 26 to 32°C. It can tolerate water as cool as 12°C for short periods, but chronic exposure to temperatures around 10°C causes significant die-offs. This temperature sensitivity is what keeps the species from spreading further north along the U.S. Atlantic coast.
Unlike its New Zealand cousin, the Asian green mussel has spread well beyond its native range. It has established invasive populations along the Atlantic coast of North America, in parts of Australia, Jamaica, Trinidad and Tobago, and Venezuela. In Florida, populations attach to floating docks, channel markers, and mooring buoys on artificial reefs 6 to 23 miles offshore. The species likely traveled to new regions as larvae in ships’ ballast water or as adults attached to hulls.
In the southeastern United States, the northern limit for established populations appears to be around northeast Florida, where average winter water temperatures hover near 13 to 14°C. Charleston, South Carolina, with average winter temperatures around 10°C, is too cold to support permanent populations. Offshore waters at the same latitude can be several degrees warmer than coastal waters, which creates pockets where the species can survive further north than expected.
How Green Mussels Are Farmed
New Zealand’s mussel farming industry harvested over 93,000 tonnes in 2023, making it the country’s largest aquaculture sector. Between October 2023 and September 2024, frozen half-shell mussels alone accounted for $257.3 million in export value, with mussel oil (used in joint health supplements) adding another $56.8 million.
Farming takes place on longlines, typically 110 meters long, consisting of two parallel ropes suspended by plastic floats and anchored to the seafloor at both ends. Cultivation rope hangs in loops 5 to 10 meters deep from these longlines. A single cultivation rope runs about 3,500 meters and can carry 40 tonnes of mussels at harvest. Farms range from 1 to over 20 hectares, with most falling between 3 and 5.
The industry relies entirely on wild spat rather than hatchery-bred seed. Some farmers hang spat-catching lines in areas with high concentrations of settling larvae, but the majority of spat arrives in a more unusual way: young mussels that have settled onto seaweed wash ashore on beaches near Kaitaia, at the northern tip of the North Island. Local collectors gather the seaweed and transport it quickly to growers around the country. At the farm, workers wrap the seaweed against nursery ropes using a light cotton stocking. The tiny mussels attach to the rope within hours, and the cotton biodegrades once they’re firmly anchored. Optimal seeding density is 1,000 to 5,000 spat per meter of rope.
Their Role in the Ecosystem
In the wild, green mussels are filter feeders that pull phytoplankton and organic particles from the water column. Dense mussel beds can significantly improve water clarity in the areas where they grow. They also serve as a food source for predators, particularly sea stars, which aggregate around mussel beds and increase their feeding rates when they encounter dense patches. The consistent food supply from mussel farms can boost reproductive output in local predator populations by increasing growth rates and energy storage.
On mussel farms, material that falls from the lines (shell fragments, waste, dead mussels) accumulates on the seafloor below, creating a localized food subsidy that reshapes the surrounding benthic community. This is one reason sustainability assessments look carefully at habitat effects beneath farm sites.
Sustainability of Farmed Green Mussels
Monterey Bay Aquarium’s Seafood Watch program rates farmed mussels worldwide, including green-lipped mussels, as a “Best Choice” with an overall score of 6.68 out of 10. The highest marks go to effluent (a perfect 10, since mussels don’t require feed inputs that pollute surrounding water) and feed (also a perfect 10, because the mussels eat naturally occurring plankton). Chemical use scores well at 8 out of 10, as mussel farming requires minimal to no antibiotics or pesticides. The weakest scores relate to the risk of escapes introducing non-native species to new environments and interactions with wildlife predators attracted to farm sites.