Environmental Enrichment for Farmed Salmon: What Works and Why It Matters

Salmon in net pen aquaculture show welfare improvements with environmental enrichment including objects, structures, and lighting modifications. Evidence is growing that enrichment reduces stress and improves fish welfare at commercial scale.

Key Facts

Farmed Atlantic salmon are held in barren circular net pens with no environmental complexity beyond the pen structure itself
Wild salmon inhabit complex river and marine environments with substrate, cover, currents, and conspecific social structure
Research shows salmon provided with submerged objects or structures show reduced stress indicators and more natural behaviour
Lighting manipulation — providing photoperiod variation — reduces abnormal circling behaviour in salmon net pens
Feeding enrichment using varied feeding locations and reduced predictability may engage natural foraging motivation
Norwegian regulatory guidance on salmon welfare is beginning to incorporate environmental enrichment recommendations

Welfare Considerations

Salmon enrichment research is at an earlier stage than enrichment science for terrestrial farm animals, but evidence is accumulating that barren net pen environments cause welfare-relevant deprivation. Salmon in barren pens show abnormal repetitive circling behaviour, elevated cortisol in baseline measurements, and reduced positive behavioural indicators compared to fish with environmental complexity. Simple interventions — submerged objects, varied lighting regimes, and unpredictable feeding schedules — reduce stereotypic behaviour and cortisol levels in experimental settings. Scaling these interventions to commercial net pens (each holding 200,000+ fish) requires feasibility research that is ongoing. The welfare significance of environmental complexity for salmon is theoretically supported by their wild ecology — complex riverine environments during smolting and freshwater phases shape salmon behavioural repertoires. Norwegian welfare regulations, which are the world's most advanced for farmed salmon, are developing enrichment criteria as part of operational welfare indicators.

What You Can Do

Support research organisations studying practical salmon enrichment interventions at commercial scale
Choose salmon from Norwegian or Icelandic producers with documented operational welfare indicator programmes
Advocate for inclusion of enrichment requirements in international farmed salmon welfare certification standards
Reduce farmed salmon consumption or choose land-based RAS-farmed salmon with greater environmental control