Mussel, Chilean (Farmed)

Mytilus chilensis

Method of production — Farmed
Production country — Chile
Production method — Suspended Rope Culture and Bottom Culture
Certification — All
Picture of Mussel, Chilean (Farmed)

Sustainability rating one info

Sustainability overview

Updated: August 2019.

Mussels farmed in Chile in suspended rope culture and bottom culture have little environmental impact and do not require any commercial feed sources as they get all of their nutrient requirements from the surrounding water. Mussel aquaculture is entirely sea-based and habitat concerns are minimal. Recent mussel culture generally does not involve the use of chemicals and there is no concern about the impact of effluents. Spat used for farming are either collected from the wild or settle naturally and research into development of a hatchery is ongoing. Disease risk and parasite interactions are thought to be minimal and do not threaten regional level populations. Both independently certified (ASC and MSC) and uncertified mussels are available.

This rating is based on full compliance with certification requirements. Commercial buyers should therefore ensure that full compliance has been achieved in order for this rating to be applicable.

Feed Resources

Criterion score: 5 info

Farmed mussels do not require any commercial feed sources as they get all of their nutrient requirements from the surrounding water. They feed by filtering mainly microscopic algae (phytoplankton), but also some organic detritus in sea water.

Environmental Impacts

Criterion score: 4 info

Overall, Chilean Mussel aquaculture performs well on environmental impacts. Mussels used in aquaculture can be found naturally in marine and brackish areas and therefore culture is entirely sea-based. Habitat concerns resulting from the physical infrastructure associated with suspended mussel culture are minimal and include the alteration of hydrodynamics, current velocities, and reduced flow rates. For bottom culture methods, dredging has the potential to have significant habitat impacts. However, tows for farmed mussels are generally much shorter than for wild-caught and farming takes place in shallow coastal areas which can recover from major disturbances within a few weeks or months. A variety of shellfish predators exist among mussel farms, including oyster drills, sea stars, crabs, benthic fishes, seabirds, and mammals. Methods used to harvest mussels in suspended rope culture generally do not result in direct impacts to predators. Mussel harvesting by dredge can result in an immediate decline in abundance and biomass of all species, but the decline is often followed by rapid benthic recovery. Passive and benign barrier netting can be used to prohibit any type of predator and is usually species specific. Duck deterrents are also used, with varying results.

Recent mussel culture generally does not involve the application of chemicals (e.g. antibiotics, pesticides, herbicides, fertilizers) to control fouling and predators or to prevent disease. The amount of chemicals used in mussel culture is thought to be minute, if at all. In addition, the water in which chemicals would be used is generally not released into the marine environment and therefore, there is no threat of chemical contamination to adjacent waters or organisms. As farmed mussels are not provided external feed and there is no nutrient fertilisation, there is no concern about the impact of effluents. However, there can be a concern over changes in the sedimentary environment around mussel farms due to bio deposition and sediment trapping. These changes are limited to the farm site and are not considered to extend beyond the immediate vicinity of the farm. Furthermore, mussel farming has been shown to increase water quality at the farm site through removal of excess nutrients and phytoplankton.

Mussel juveniles or ‘spat’ used for farming are either collected from the wild or settle naturally on purpose-made collectors. Research into and the development of a mussel hatchery is currently ongoing in Chile and three companies have built hatcheries and produced Chilean mussel seed at an experimental level. However, none of them yet producing seed commercially and at present, the cultivation of mussels does not rely on hatchery production of seed as wild spatfalls are usually of sufficient quality and reliability and are not overexploited. Aquaculture systems that are open to the environment tend to pose a risk for disease and parasite interaction with wild populations. However, there have been few mass mortality events described for adult blue mussels and good management practices ensure that the risk is low and does not threaten regional level populations.

Fish Health and Welfare

Criterion score: 1 info

Animal welfare is not applicable for shellfish as it is not covered by EU regulations on welfare. Humane slaughter has been carried out by RSPCA definitions.


Criterion score: 4 info or 1

As this assessment covers both mussels independently certified to ASC and MSC standards, and uncertified mussels, two different scores have been awarded for this section. A score of 4 is awarded for certified mussels and a score of 1 is awarded for uncertified mussels.

In Chile, the administration of marine conservation is complex, with multiple state agencies having the power to establish, veto, and administer the governance and management of ocean and coastal resources. At present, there is no strategic environmental planning in place, however, this could be subject to change in the future as Chile has been active over the past 5 years in designating MPAs in its marine waters and this is often a precursor to the development of a plan to cover all national marine waters.

In Chile, there is regulatory framework in place to address farm level environmental impact assessment, protection of valuable habitats and species, use of land and water resources, discharges, biosecurity and disease management. These all appear to be fully effective in minimising negative impacts of mussel farming.

Production method

Suspended Rope Culture and Bottom Culture

In Chile, mussels are grown by suspension rope culture and bottom culture. Mussels grown by suspension rope culture are generally harvested by hand-gathering methods. Mussels grown by bottom culture are usually dredged.


Chilean mussels are bivalve molluscs found on shores throughout Chile, Argentine, Uruguay, the Falkland Islands and the Kerguelen Islands. They normally live in large aggregations, attaching themselves to rocks and each other with sticky threads known as byssus. Size and shape vary widely, and colour differs from light brown through greenish or dark blue and black. Shell up to 18cm but usually much smaller. Mussels mature when one year old and may live 10-15 years or more.


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Charles Ehler, personal communication via email, 26.08.2019.

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