Our Mussels & Technology

Engineered for Offshore Performance. Built on Natural Processes.

Offshore Shellfish combines engineered offshore aquaculture systems with the natural biology of blue mussels (Mytilus edulis) to produce nutritious protein with minimal environmental input.

Our farm uses rope-based longline technology, specifically adapted for high-energy offshore environments. Longline systems consist of buoyant backbone lines anchored to the seabed, from which hundreds of vertical droppers carry millions of juvenile mussels into the water column. This configuration maximises exposure to nutrient-rich flows, supporting efficient natural growth and high meat yields.

Advanced Offshore Engineering

Operating 3–6 miles offshore in Lyme Bay presents unique challenges — strong tides, swells and wind forces require robust design and precise marine engineering. All structural components, moorings and ropes are selected and engineered to withstand these conditions, ensuring:

  • Structural resilience in high-energy seas
  • Optimised hydrodynamics for nutrient delivery and waste dispersal
  • Low-density cultivation, improving mussel health and growth rates
  • Scalability and modular expansion as production grows

This technical foundation enables production at meaningful scale — up to 10,000 tonnes annually — while keeping operations efficient and robust against marine forces.

Mussel Biology & Environmental Integration

Our mussels settle naturally on suspended ropes, feeding exclusively on plankton drawn from surrounding waters. No external feed, fertiliser or freshwater inputs are required — making rope-cultured mussels one of the lowest-impact sources of animal protein available.

Mussels also capture carbon through biomineralisation, converting dissolved carbon and minerals into stable calcium carbonate shells. This contributes to low lifecycle emissions and strengthens the case for mussel farming as part of climate-aligned food systems.

Scientific Monitoring & Habitat Interaction

Our partnership with the University of Plymouth underpins continuous ecological monitoring and long-term research. Since the farm’s establishment in 2013, multiple integrated studies have evaluated how offshore rope systems interact with the marine environment — from plankton dynamics to benthic and pelagic biodiversity.

The Ropes to Reefs Fisheries Industry Science Partnership (FISP) project extends this work, assessing whether offshore mussel infrastructure provides wider ecosystem benefits such as:

  • No feed
  • No fertiliser
  • No freshwater
  • No antibiotics

This research demonstrates how engineered mussel farms can function as biogenic reefs, contributing both to food production and to ecological restoration. Independent analyses also show increases in species such as bass and horse mackerel around offshore rope infrastructure.

Mussel Farm Consulting & Site Selection Services

Beyond production, Offshore Shellfish offers technical consulting services for organisations and investors exploring mussel farming and offshore aquaculture development. Our expertise includes:

  • Detailed site assessment and selection, evaluating water quality, hydrodynamics, depth profiles, and regulatory constraints
  • Farm design optimisation, matching structural systems to marine conditions and production goals
  • Environmental monitoring frameworks, integrating oceanographic and ecological data collection
  • Operational planning for offshore logistics, health and safety, and maintenance

We leverage our years of offshore experience and academic partnerships to guide practical, science-informed decisions at every stage — from feasibility studies to full-scale implementation.

Offshore Shellfish is a family run business, founded by John and Nicki Holmyard, who have been involved in the mussel and seafood industries for 30 years.

Offshore Shellfish are building the UK’s first large-scale fully offshore, rope cultured mussel farm off the coast of South Devon.

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