Aquaculture Net Pen Technology Is Being Redesigned Because the Ocean Conditions Are Getting Harder

The Coastal Crowding That Pushed Farming Offshore

Marine aquaculture, principally Atlantic salmon farming in Norway, Chile, Canada, and Scotland, has been conducted in sheltered coastal fjords and inshore bays whose protected waters provide the calm conditions that conventional surface net pens were designed for. The circular or rectangular net pen floating at the surface, whose nets hang below a rigid or flexible surface collar that maintains the pen's shape against tidal and wave forces, is the dominant commercial aquaculture structure whose design has remained fundamentally unchanged for several decades. The commercial productivity of salmon farming has increased dramatically during this period through improvements in feed conversion, disease management, genetics, and husbandry practice, but the net pen structure that houses the fish has evolved more slowly because the sheltered water conditions of the inshore fjord sites where most Norwegian and Chilean salmon farming is conducted have not demanded the structural performance that more exposed sites would require.

The commercial pressure to expand aquaculture production beyond the inshore fjord sites that have historically provided the majority of salmon farming capacity is creating the demand for net pen technology that can operate in the more exposed offshore conditions whose wave heights, current velocities, and weather severity exceed the design parameters of conventional inshore net pens. The inshore sites whose sheltered conditions support conventional net pen operation are limited in number and are increasingly under regulatory and environmental pressure from the salmon lice infestations, sea floor benthic impact, and waste nutrient discharge that intensive fish farming in limited water volumes creates. The regulatory frameworks in Norway, Scotland, and other major salmon producing nations are restricting the further intensification of inshore farming and in some cases requiring the fallowing of sites that have been under continuous production for extended periods. The commercial response from the salmon farming industry is the development of aquaculture structures capable of operating at offshore or semi-exposed sites where the greater water depth, stronger currents, and better water exchange reduce the environmental impact of farming while accessing the larger production volumes that site expansion at these locations could support.

Submersible Net Pens and Their Technical Challenges

Submersible net pens, which can be lowered below the surface to escape the most severe wave action and the sea surface conditions that surface pen structural integrity cannot withstand, represent the primary structural technology being developed for exposed and offshore aquaculture sites. A submersible pen whose buoyancy can be adjusted to lower it to a depth where wave orbital velocities are attenuated below the structural loading threshold of the pen and net system provides the operational flexibility to maintain production during weather events that would damage surface pens and require either emergency harvest or fish loss. The engineering challenges of submersible aquaculture pen design are substantially more demanding than those of conventional surface pens. The pen structure must maintain the volume and shape of the fish habitat at depth without the surface buoyancy ring that surface pens use for structural support. The feed delivery, monitoring, and fish management systems that maintain the biological performance of the fish population must operate effectively at depth rather than from the surface access that conventional pen husbandry assumes. And the mooring system must maintain the pen's position under the combined current and wave loading of exposed sites where anchor forces substantially exceed those of sheltered inshore locations.

The Norwegian offshore aquaculture development programme, which has established a licensing framework for offshore fish farming at exposed sites through its development licence scheme, has created the commercial context for investment in offshore aquaculture structures whose design must meet the structural requirements of the Norwegian Petroleum Directorate's offshore installation standards rather than the less demanding aquaculture equipment standards that govern inshore net pen design. The application of offshore oil and gas engineering standards to aquaculture structure design reflects the genuine severity of the offshore Norwegian marine environment and creates the structural safety requirements whose engineering cost adds to the investment required for offshore aquaculture development.

Closed Containment and the Land-Based Alternative

The offshore net pen development track is not the only commercial response to the constraints of inshore salmon farming. Land-based recirculating aquaculture systems, which grow salmon in tanks on land using water filtration and biological treatment to maintain water quality without the natural water exchange that coastal sites provide, offer the complete environmental isolation from wild fish populations that sea lice transmission and disease management in net pens cannot fully achieve. The commercial challenge of land-based RAS salmon farming is its energy intensity, which reflects the pumping, aeration, and biological treatment that the artificial water environment requires and which creates an operating cost structure that the inshore net pen's use of natural water exchange avoids. The commercial development of land-based RAS salmon farming at the scale required for commercial viability has attracted substantial capital investment in Norway, the United States, and China, with the highest-profile projects including Atlantic Sapphire's Bluehouse facility in Florida representing the commercial test of whether land-based salmon farming can compete with net pen production on economic terms that the market can support.

Top 10 Companies in Aquaculture Net Pen and Offshore Aquaculture Technology Globally

1. Kongsberg: Norwegian technology company with aquaculture sensor systems, underwater cameras, and feed monitoring technology; its FishTalk feeding control system and its AquaHub digital platform create the operational technology infrastructure for net pen management that offshore aquaculture's remote location and complex environment requires beyond the physical structure of the pen itself.
2. Botngaard: Norwegian aquaculture technology company developing the Salmonor submersible net pen system for exposed sites; its steel-framed submersible pen design and its deployment experience in Norwegian offshore development licence sites create the commercial reference for submersible pen technology whose operational performance determines the investment case for offshore salmon farming.
3. Mowi: World's largest Atlantic salmon farming company whose investment in offshore aquaculture development licences and its R&D into offshore pen technology create the commercial demand that offshore aquaculture equipment manufacturers are developing their products to meet; its operational scale means that its equipment procurement decisions shape the technology development priorities of the entire aquaculture equipment supply chain.
4. SFK Group: Norwegian net pen and mooring system manufacturer with conventional and semi-exposed site net pen products; its flexible collar pen designs for semi-exposed sites and its mooring system engineering create the structural technology that bridges conventional inshore pen operation and the full offshore submersible pen capability that the most exposed sites require.
5. AKVA Group: Norwegian aquaculture technology company with net pen equipment, feeding systems, and digital aquaculture management platforms; its global distribution across salmon farming markets in Norway, Chile, Scotland, and Canada and its integrated equipment and software offering create the commercial scale that smaller specialist aquaculture technology companies cannot match.
6. SalMar (Ocean Farm): Norwegian salmon farmer whose Ocean Farm 1 offshore aquaculture structure is the world's first semi-offshore aquaculture installation at exposed site; its steel-framed circular structure capable of housing one and a half million salmon in open sea conditions represents the most commercially ambitious offshore aquaculture demonstration project and its operational data is informing the next generation of offshore aquaculture design.
7. Seafarm Invest: Aquaculture investment company developing offshore aquaculture structures in partnership with engineering and salmon farming companies; its capital deployment into offshore aquaculture technology development reflects the investment community's assessment that regulatory constraints on inshore expansion will make offshore aquaculture commercially necessary for the salmon industry's continued growth.
8. HAV Design: Norwegian offshore and aquaculture engineering company developing aquaculture vessel and offshore structure designs; its naval architecture and offshore engineering heritage applied to aquaculture creates the structural engineering expertise that offshore fish farming structures require from designers whose experience spans marine environments that inshore aquaculture engineers have not previously addressed.
9. Nordlaks (Havfarm): Norwegian salmon farmer whose Havfarm offshore aquaculture vessel is the world's largest aquaculture vessel operating in exposed Norwegian coastal waters; its ship-shaped aquaculture structure that can change position in response to weather and biological management needs represents the most radical departure from fixed-location net pen aquaculture and the commercial test of aquaculture mobility as an alternative to fixed offshore structures.
10. Atlantic Sapphire: Norwegian-US land-based RAS salmon farming company whose Bluehouse facility in Miami represents the largest land-based salmon farming investment; its commercial production challenges and its energy cost experience are creating the real-world data on land-based RAS salmon farming economics that the investment community needs to assess the commercial viability of the land-based alternative to offshore net pen expansion.