Offshore & deep-water aquaculture

Offshore and deep-water aquaculture moves fish production away from sheltered coastal sites into exposed, high-energy waters where stronger currents, higher winds and larger waves both disperse nutrient waste and stress equipment. The engineering answer is the submersible steel or HDPE cage that can sink below the storm-affected surface layer: SalMar’s Ocean Farm 1, the world’s first offshore fish farm, packs roughly 1.5 million salmon into a 110-metre-diameter semi-submersible structure rated for open-sea conditions. China has pushed a parallel mobile concept, the deep-sea aquaculture vessel — Qingdao Conson Blue Ocean’s Conson No. 1 ship-farm netted its first harvest of about 12 tons of Atlantic salmon while sailing to cooler water and away from typhoons. The cages are instrumented: real-time acoustic telemetry, AI feeders such as Innovasea’s FlowFeeder, and oxygen and current sensors keep growth on track 20-50 metres down. Two forces define the economics: storm survivability, designed against the Norwegian NS 9415 standard through tank and numerical hydrodynamics, and environmental load, increasingly managed with integrated multi-trophic aquaculture (IMTA) where seaweed and shellfish recycle the nitrogen the fish excrete. India entered the field in 2026, harvesting 4 tonnes of Indian pompano from a 12-metre open-sea cage off Andhra Pradesh and launching its first Andaman open-sea project.

The key directions of offshore & deep-water aquaculture are:

1. Submersible cage farms (storm-proof structures): SalMar’s Ocean Farm 1 and Innovasea’s SeaProtean fully submersible pens lower stock below the wave zone; Innovasea grew and harvested greater amberjack in the Red Sea in 2026 under NEOM’s Topian programme.
2. Autonomous vessel-farms (mobile mariculture): China’s Conson No. 1 farms fish inside a self-propelled hull that sails to optimal temperatures and dodges typhoons, harvesting 12 tons of Atlantic salmon on its first run.
3. Exposed-site engineering & standards (de-risking): SINTEF Ocean validates numerical models of wave, current and mooring loads for exposed-water cages, underpinning the NS 9415 cage standard that governs structural integrity and fish welfare.
4. Integrated multi-trophic aquaculture (IMTA): YSFRI develops trophic IMTA structures that use seaweed to capture nitrogen in the open sea, turning effluent into harvestable extractive biomass.

Sectoral value chain#

[site selection] ──> [cage build] ──> [stocking + IMTA] ──> [grow-out]
                                            │
                                    (submersion + AI feeding)
                                            │
                                            ▼
[market] <─── [multi-species harvest] <─────┘

Value chain levels#

Cross-cutting technologies of the sector:

• Submersible net pens (below-surface culture): cages that sink stock below storms and warm surface water to protect health and growth in exposed sites.
• Offshore cage hydrodynamics (NS 9415): numerical and tank modelling of wave, current and mooring loads that de-risks structural integrity and fish welfare.
• Integrated multi-trophic aquaculture (IMTA): co-culture of fed fish with seaweed and shellfish that recycle nitrogen and organic waste into biomass.

The stack pairs marine structural engineering with sensing and biological remediation to keep fish alive, fed and clean in hostile water.

1. Submersible cage structures (storm survivability):
   • Steel or HDPE cages submerge 20-50 metres to escape wave energy; SalMar’s 110-metre Ocean Farm 1 holds roughly 1.5 million salmon offshore.
   • Mobile hulls such as Conson No. 1 relocate the whole farm to optimal temperature and away from typhoons.
2. Hydrodynamic design and standards (NS 9415):
   • SINTEF Ocean validates numerical wave, current and mooring models against tank tests to certify structural integrity in exposed waters.
   • The Norwegian NS 9415 standard sets the load and inspection requirements adopted internationally for offshore cages.
3. Smart feeding, sensing and IMTA (welfare + environment):
   • AI feeders (FlowFeeder) and acoustic telemetry maintain feed conversion and welfare below the surface, while oxygen and current sensors stream real-time data.
   • IMTA co-culture with seaweed and shellfish recaptures excreted nitrogen, turning effluent into a second harvestable crop.