Aquaculture

Farmed Salmon Sea Pen Design

The physical design of sea cages for salmon farming affects water flow, fish behaviour, disease transmission and welfare outcomes, and innovation in cage design can improve welfare at scale.

Key Facts

Standard net pen cages provide limited vertical dimension relative to fish swimming behaviour
Semi-closed containment systems (SCS) allow freshwater flushing that treats AGD without chemical baths
Offshore exposed site salmon farming faces welfare challenges from wave exposure and storm damage
Current depth of standard cages (15-30m) restricts the salmon's ability to escape surface temperatures

Welfare Considerations

Salmon in standard sea cages cannot access cool, dark deep water that they naturally use to regulate temperature and avoid sea lice in the wild. Surface-level crowding increases sea lice transmission. Sea lice aggregating in surface waters infest fish that cannot escape to depth. Innovative cage designs including deeper pens and semi-closed systems address these welfare problems but require significant investment.

What You Can Do

Support research into innovative sea cage design that improves salmon welfare
Advocate for welfare-based cage design standards in aquaculture licensing
Choose salmon from producers investing in sea pen welfare improvements
Back funding for semi-closed containment system development and pilot testing