Can the opportunities for shellfish and seaweed aquaculture growth in Scotland be fully realised? Read our report for Crown Estate Scotland.

Farming of seaweeds and bivalve shellfish can provide both beneficial ecosystem services whilst also having the potential to produce commercially valuable crops. Aquaculture is an important industry for Scotland, helping sustain economic growth in rural and coastal communities.

The majority of mussel production occurs in the Shetland Islands, which has generally increased in the past ten years, while production on the mainland has mainly stagnated.

Seaweed farming is an emerging sector, with increased interest in its development, although commercial farming in Scotland is still in its infancy. Currently there is at least one commercial farm producing seaweed for the supply chain in Scotland, several trial sites cultivating seaweed, and nine where a marine licence has been consented for seaweed farm development.

There is ambition for the Scottish aquaculture industry to grow, given its socio-economic importance, and its potential to contribute to national and global food security and the provision of healthy nutritious food. It also plays an important role in providing employment in remote and island communities.

Crown Estate Scotland (CES) commissioned ABPmer to assess the prospects and opportunities that may exist for large-scale shellfish and seaweed farming, and potential co-location of these sectors.

Areas of potential mussel and seaweed cultivation off the Scottish coast

Two study areas were defined: one on the West coast, and one on the East coast (Figure 1). Physical and environmental spatial data sets were mapped to identify potential resource areas where offshore mussel or kelp farming may be suitable, based on the natural resource requirements of the species to be cultivated and the physical conditions (in relation to tidal current and wave height) required for farm-related operations.

^{Figure 1: Scotland aquaculture opportunity study areas (full resolution)}

A total of 24,295 km² of potential resource area for mussels between 20-100 m water depth were identified within the areas of interest, and 25,742 km² for kelp.

The model outputs also enabled identification of potential resource areas which may be suitable for the cultivation of either or both farmed species, a total of 24,293 km².

Interactions between aquaculture activities and local fishing interests

Following identification of the potentially feasible development areas for cultivating mussels and kelp, key fisheries stakeholders were invited to discuss:

• Fishing activity in these areas
• Potential impacts of aquaculture developments on commercial fisheries
• Views on the potential for some fishing activities to co-exist within mussel or kelp farm installations

Displacement of fishing vessels from important inshore fishing areas was the key impact of concern, due to safety concerns over gear entanglement with farm equipment. This led to the consensus that fishing and farming activities should be kept apart, with recognised separation distances.

The concept of access channels for fisheries to be able to work within the farms was explored, but these were expected to encourage all vessels to transit through them, making it even less practical for static gear fisheries to operate there.

A preference was stated for an intensive farm design where feasible, i.e. producing higher volumes of mussels or kelp from a smaller area, therefore minimising the spatial impact on the fisheries sector.

It was also queried whether such aquaculture development could occur within Marine Protected Areas (MPAs), when compatible with their protected features, to reduce competition for space with commercial fisheries outside MPAs.

Further considerations

As part of this study, a spatial model was developed to identify potential resource areas to develop large-scale mussel or kelp farms based on their physical, environmental and operational requirements.

Marine spatial planning factors relating to other marine sector activities, infrastructure and nature conservation were then considered to identify potentially feasible development areas for such installations.

For any proposed mussel or kelp farm development, its interactions with (and impacts on) all marine sectors and receptors would need to be considered, at a site-specific level, through the existing consenting process for seaweed and shellfish aquaculture, or at a regional or national level for regional marine plans or sectoral plans respectively.

Download the full report at the CES website.

^{Image: Offshore Shellfish Ltd (used with permission)}

ABPmer supports policy-makers, regulators and the fisheries and aquaculture industry on marine environmental policy matters, assessment and management, including interactions between fisheries, marine protected areas (MPAs) and other marine developments.