Open sea cage aquaculture dominates global salmon and sea bass production, with welfare implications from stocking density, sea lice, storm damage, and environmental conditions.
Open sea cage welfare involves accepting environmental variability as a defining constraint — weather, tides, temperature, and disease pressure all fluctuate with conditions outside farm control. Storm welfare events can be severe: structural cage failures cause acute injury and death in massive numbers of fish. Sea lice amplification at sites with high wild salmon and sea trout migrations is an ongoing welfare problem driving repeated treatment cycles. Stocking density decisions that determine competition and space availability are the primary management lever within the constraints of environmental variability.