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Shellfish

A guide to producing mussels, oysters and other bivalves

Updated 9 May 2024

Establishing a shellfish farm

When setting up your shellfish farm, you need to choose the shellfish species and where you will farm it together. Not all sites are suitable for all species, and there are rules about where you can set up a shellfish farm.

Choosing a shellfish species

Farmed shellfish in Scotland are typically bivalves:

Mussels like the blue (or common) mussel (Mytilus edulis)
Oysters like the native (or common) oyster (Ostrea edulis) and the Pacific cupped oyster (Cassostrea gigas)

Choosing which shellfish to farm depends on your site. Mussels and oysters have specific requirements for growing and require clean water (see ‘Finding a farm site’).

Protected shellfish species

It is illegal to harvest protected shellfish species without a licence. Currently, the freshwater pearl mussel (Margaritifera margaritifera) is the only protected shellfish species in Scotland. Find out more and apply for a freshwater pearl mussel licence on NatureScot.

Alien and locally absent shellfish species

Farming a shellfish species that would not otherwise live in that area has a higher environmental risk and is illegal without a specific permit. Find out more about alien species control on NatureScot.

You do not need the permit for the Pacific cupped oyster (Cassostrea gigas), which is exempt.

To apply for a permit to farm an alien shellfish species, contact the Fish Health Inspectorate. Find out more about the permit process in the Alien and Locally Absent Species in Aquaculture (Scotland) Regulations 2015.

Sourcing shellfish for farming

To farm shellfish, you need a source for your stock which is different for mussels and oysters.

Mussels

To farm mussels, you need to find a site where their spat (mussel larvae) naturally occurs and will attach to the farming equipment.

Find out more:

Oysters

To farm oysters, you need to find a seed supplier or create an oyster nursery. You can also combine these. Pacific oysters do not live in the wild in Scotland, and native oysters are now rare due to overfishing.

Taking oysters from other people’s oysteries is theft and you need permission from the Crown Estate to gather oysters from the wild.

Oyster seed suppliers

You can find a supplier of oyster spat or seed (very young oysters), which you then grow out on your farm. The farming equipment needed depends on the size of oysters started with (see ‘Farming infrastructure & equipment’).

If your farm is in disease-free waters, you can purchase oyster seed only from UK-based nurseries to avoid spreading disease. To import oyster seed from Northern Ireland, Isle of Man, Guernsey, or Jersey, you need a health certificate and to notify the Fish Health Inspectorate at least 24 hours before the move. Read more and find import forms via the Marine Inspectorate.

Starting an oyster nursery

The Wild Oyster Project has a guide on creating a native oyster nursery, which will take years before becoming self-sustaining for harvest. You will still need a supplier of the initial adult oysters or oyster seed to start.

Find out more:

Finding a farm site

When selecting a farm site, you need to consider the physical requirements of your species, proximity to onshore facilities (see ‘Farming Infrastructure & Equipment), and regulation.

Mussels and oysters both need seawater or brackish water to survive. Mussels can be farmed in coastal waters, sea lochs, or estuaries and oysters can also be grown in intertidal zones.

Water quality

Mussels and oysters both eat plankton by filtering water, and simultaneously absorb pollutants. There are legal levels for contaminants in food in Scotland (see ‘End-product testing’), and two area classifications regulate water quality for shellfish farming.

Shellfish Production Areas (SPAs)

You can only harvest shellfish commercially from an SPA, which is an area that meets health standards. SPAs are designated and monitored by Food Standards Scotland (FSS).

SPA grades from highest to lowest water quality are A, B and C. Whether you need to treat your produce before selling it depends on your area grade, and you cannot sell shellfish from the most polluted waters (see ‘Shellfish depuration’). An SPA can have multiple grades depending on the time of the year.

FSS publishes updated SPA lists annually under ‘Shellfish classification documents’. SPA maps are available on Scotland’s Aquaculture.

You must apply for an SPA with this form to FSS who will then carry out a sanitary survey.

Read more:

Shellfish Water Protected Areas (SWPAs)

Scotland currently has 85 SWPAs, which are areas designated for pollution control measures to protect shellfish production. SWPAs are monitored by the Scottish Environmental Protection Agency (SEPA). See the list and maps of SWPAs.

SPAs within SWPAs benefit from additional protection and are favoured for new shellfish farm developments. There can be multiple SPAs within an SWPA.

SPA and SWPA classifications do not always match, because SWPAs are classified for larger areas over a longer time.

Read more: ‘Shellfish water protected areas’, Marine Scotland Information

Marine planning

You need to check that your planned site is acceptable within Scotland’s National Marine Plan. The Plan encourages oyster and mussel farming in principle and divides Scottish waters into three categories based on their suitability for new aquaculture farms.

View the map of aquaculture farm planning areas on Marine Scotland Information. Applications for new shellfish farms within SWPAs are favoured, and if your site is in a Category 3 area it is likely to be acceptable.

Marine Protected Areas are accounted for in the categorisations and excluded from categories 2 and 3. Read more about these locational guidelines for aquaculture farms.

You should also check the Local Development Plan (LDP) for your area. Go to the local planning authority website to search for their LDP and confirm that your site is acceptable within it. LDPs will tell you if your site in a local landscape designation, which might require you to do additional planning to minimise the visual impact of your farm. If your farm is in a National Scenic Area, contact NatureScot for visual impact advise.

Contact NatureScot or your local planning authority to get advice for most suitable location for your shellfish farm.

Find out more:

Other sea users

You need to also consider other sea users in your site area and discuss your plan with them before applying for licences. These users can include local communities and fishing operations in the area, and evidence of consulting them may be required in the licence application process (see ‘Licensing’).

Farming infrastructure & equipment

Once you have selected your species and site, you need to plan your farming infrastructure and equipment. You will need this information to apply for the necessary licenses (see ‘Licensing’).

Farming equipment

Your farming method will depend on your farm site (for example, how sheltered it is) and there is different equipment for different farming methods.

Mussels can either be farmed on the seabed or on a suspension system, such as rafts and ropes, which is more common in Scotland. The equipment you need depends on whether you plan to start from seed or source partly grown mussels.

Farming methods differ for Pacific and native oysters. Pacific oysters are commonly farmed on the foreshore in trays or bags, whereas native oysters are farmed on the seabed where young oysters are laid on a growing substrate. Sometimes oysters are also grown on rafts or other suspension.

The Seafish technical guides are a good starting point for assessing what equipment you will need:

Second-hand equipment can transfer disease and should be cleaned carefully before moving and use. Fisheries Research Services has published a guide to disinfecting aquaculture equipment.

For seabed cultivation, it can be helpful to get exclusive management rights for the species on your site (see ‘Licensing’).

Depending on the scale of your production or for ease, you might also need a purpose-designed vessel for managing your stock (see ‘Boats’).

Boats

You need a service boat to manage a mussel farm but oyster farms in intertidal zones may be accessed from land. A service boat for a smaller scale shellfish farm can usually be under 24 meters long, and is legally classified as a small commercial vessel.

To operate a small commercial vessel, you need to:

Get the correct training and certifications, which will be different if your boat is over 16.5m long. Read the Maritime and Coastguard Agency guidance on training and certifications.
Arrange your boat to be surveyed by a Maritime and Coastguard Agency approved surveyor. Read about small commercial vessel surveys on gov.uk.

Register your boat with the UK fishing register.
Secure a berth in a nearby harbour that also has infrastructure for loading and unloading cargo. A map and list of UK ports is available on ports.org.uk.

Onshore facilities

You need onshore facilities to process, store and package your produce. Only produce from Class A production areas can be dispatched directly and must meet hygiene standards (see ‘End-product testing’). Facilities can include depuration systems (see ‘Shellfish depuration’) and wet or cold storage.

Onshore facilities should be near the harbour to ensure ethical and hygienic handling of produce and will need to be approved by Food Standards Scotland (see ‘Registering as a food business’).

You will also need chilled transport of produce to onshore facilities. If this is done by you, no additional permits are needed but if you outsource transport the company needs to be registered as a Specialist Transport Business.

Licensing

Before applying for licences, you need to arrange and be ready to provide details of your proposed location, infrastructure and equipment, development timeline, and budget.

Shetland has a different licensing process and you can find more information on the Shetland Shellfish Management Organisation website.

This Marine Directorate review has an overview of the consenting process for shellfish farms and you can read more about aquaculture consents their website.

Seabed lease

The Crown Estate owns all seabed within 12 nautical miles from the shore in Scotland, and you will need to apply to rent an area from them for your shellfish farm. Check aquaculture sector rents.

Before applying, contact Crown Estate Scotland and ask for a ‘conflict check’ to ensure there are no conflicting seabed interests in your selected area.

Then apply for a lease option agreement, which has a fee. The Crown Estate will not give you a lease before your planning permission and Marine Licence are in place, but the lease option agreement gives you an exclusive interest to the seabed area for three years while you are going through the licensing processes. Apply for a lease option agreement.

After you have secured required licences, you can apply for a seabed lease. Once you are granted a lease, you will have to pay rent and have a reporting duty (see ‘Crown Estate reporting’).

Planning permission

Once you have secured a seabed lease, apply for a planning permission from your Local Planning Authority to build the farm.

You can contact your Local Planning Authority for pre-application advice, which usually has a fee. Argyll & Bute Council has an example of what the pre-application advice service provides.

There is a planning fee for shellfish farms, which depends on the area size and is the same across Scotland. Read more about marine planning fees on the Shetland Council website.

Shellfish farm applications do not require an Environmental Impact Assessment but if your site is in a Marine Special Area of Conservation or Special Protection Area, your application will be subject to a Habitat Regulation Appraisal.

If you want to alter your farm in the future, your planning permission gives you ‘permitted development rights’ which means you do not need a new permission for certain alterations. Read more about permitted development rights on gov.scot.

Marine Licence

You need to apply for a Marine Licence to assess potential hazards to maritime navigation and interference with other sea users. You can apply while applying for a planning permission, but the Marine Licence will only be issued when your full planning permission is provided.

Marine Scotland may be able to coordinate with other regulators on your various licences to return them all together, and you should contact Marine Scotland to discuss this.

Marine Licence application documents and guidance.

There is a fee for the application which needs to be paid before your application is processed. Check marine licensing fees and how to pay. The Marine Licence is usually valid for 6 years, and you will need to renew it at least two months before expiry.

As part of the application process, you will need to advertise your plan in a local newspaper.

Aquaculture Production Business Licence

Before starting any farm development, you are legally required to apply for an Aquaculture Production Business Licence (APB licence) and from the Fish Health Inspectorate. You will also need to complete an Aquatic Animal Holding Site form.

Application forms and guidance for APB licences. You can ask guidance on the licensing process from the Fish Health Inspectorate. There is no fee for the application.

Several Orders

Several Orders give exclusive management rights to a specific species within a designated area. They can be made for areas within 6 nautical miles of seashore in Scotland and can be helpful for various purposes including seabed farming.

Find out more about Several Orders and how to apply:

Shellfish