CASE STUDY

Novel Offshore Fish Pen Design

Phase 2

THE CHALLENGE

Most marine aquaculture farms are located in sheltered nearshore waters for reasons of safety, accessibility, power supply, and transport efficiency. However, as coastal zones become increasingly busy, the availability of suitable space for aquaculture expansion is constrained. For industry, this limits scale and long-term certainty. Offshore sites provide opportunities for growth at larger scale, with greater separation from other coastal activities and improved environmental conditions for farming.

Operating in these more exposed environments does introduce new engineering and operational challenges, including higher energy demands, stronger wave climates, and increased weather exposure. But it also creates pathways to greater productivity, reduced user conflict, and stronger investor confidence in the long-term sustainability of marine farming. This requires robust infrastructure, specialised vessels, and updated design and safety standards. The industry’s central challenge is to develop reliable, efficient, and cost-effective offshore farming systems capable of operating safely in these conditions.

Novel Offshore Fish Pen Design

Phase 2

THE CHALLENGE

Most marine aquaculture farms are located in sheltered nearshore waters for reasons of safety, accessibility, power supply, and transport efficiency. However, as coastal zones become increasingly busy, the availability of suitable space for aquaculture expansion is constrained. For industry, this limits scale and long-term certainty. Offshore sites provide opportunities for growth at larger scale, with greater separation from other coastal activities and improved environmental conditions for farming.

Operating in these more exposed environments does introduce new engineering and operational challenges, including higher energy demands, stronger wave climates, and increased weather exposure. But it also creates pathways to greater productivity, reduced user conflict, and stronger investor confidence in the long-term sustainability of marine farming. This requires robust infrastructure, specialised vessels, and updated design and safety standards. The industry’s central challenge is to develop reliable, efficient, and cost-effective offshore farming systems capable of operating safely in these conditions.

The solution / outcome

The solution to farming fish offshore is to develop pens that can protect stock in energetic waters, even during storms. Recent advances in offshore pen technology have produced massive structures such as Ocean Farm 1 (69 m high, 110 m diameter, 1.2 million fish) and HavFarm 1 (380 m × 59 m, 10,000 t salmon), but these cost over USD 100 million each. A more cost-effective approach is submersible pens, which avoid surface waves, sea lice, algae blooms, and warm surface waters. Examples include SubFlex in the Mediterranean and SeaStation in Hawaii.

The Blue Economy CRC developed a novel submersible offshore fish pen named SeaFisher. It has a modular 2 × n array of cubic pens (20 m per side) built from HDPE pipes with diagrid GFRP rods for stiffness. HDPE was chosen for its resistance to rotting and weathering, ease in construction, and antifouling performance. Key features include pyramidal top and bottom nets for air access and mort collection, a bow shield, adjustable ballast for depth control, and a single-point mooring system that allows the pen to weathervane and disperse wastes. The design has received Bureau Veritas Approval in Principle (Level 1).

Development follows a 3-phase strategy: (1) conceptual design, (2) validation through scale testing, simulations, and component trials, and (3) offshore prototype deployment. This process advanced the SeaFisher from TRL 3 to TRL 4–5, providing a validated framework for industry adoption. Key lessons include the value of combining physical and digital modelling early, involving industry partners to ensure practical design, and testing construction methods alongside hydrodynamic performance.

This innovative design empowers fish farms to meet the rising global demand for seafood while ensuring affordability and sustainability. BV’s involvement reflects our commitment to addressing global challenges and fostering local innovation in Australia.

Eric Radford,
Pacific Business Director, Bureau Veritas Marine & Offshore

The impact

The project has strengthened the productivity and sustainability of Australian aquaculture by enabling safe, cost-effective expansion into offshore environments. Offshore farming opens access to larger, higher-quality marine sites, easing pressures on nearshore ecosystems while increasing production capacity.

By developing and validating the novel SeaFisher submersible pen through experiments, simulations, and prototype testing, the project has de-risked offshore adoption and given industry confidence to invest. Collaboration among researchers, industry, and classification bodies accelerated technology readiness from TRL 3 to 5, reducing uncertainty, costs, and time to commercial deployment.

WHAT’S NEXT?

This project marks the first stage of a broader strategy to establish offshore aquaculture as a viable and scalable industry in Australia. Building on the SeaFisher design, the next phase will pilot the system in real offshore conditions to assess performance, maintenance, and long-term durability. These sea trials will generate critical data to refine standards, operational protocols and risk management, ensuring the technology can be scaled with confidence.

Beyond finfish, the Blue Economy CRC is exploring wider applications of the SeaFisher concept, including farming oysters, lobsters and seaweed, as well as integrating renewable energy systems such as PV panels. Looking ahead, the Blue Economy CRC will collaborate with classification societies, regulators, and industry to streamline approvals, establish best-practice guidelines and accelerate adoption.

Future initiatives include modular systems for flexible deployment, real-time monitoring and predictive maintenance and international partnerships in equipment development and skill transfer. Together, these efforts will position Australia as a global leader in sustainable offshore aquaculture, uniting innovation, environmental stewardship and commercial scalability.

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