Sea cage design affects water flow, oxygen distribution, stocking density experience, and behavioral opportunities for farmed Atlantic salmon. Design choices have significant welfare implications.
Sea cage design choices made primarily for production efficiency have significant welfare consequences that are not always recognized during design decisions. Water flow through cages is perhaps the most important design variable — adequate current provides oxygen-rich water to the entire fish population, removes waste, and creates swimming conditions that allow exercise. Feeding system design affects food access equity — systems that distribute feed uniformly across the cage surface reduce the competitive exclusion that causes subordinate fish to receive inadequate nutrition. Lighting management for photoperiod manipulation to control growth and maturation must balance production objectives with the welfare consequences of disrupting natural light-driven behavior and physiology. Welfare assessment should be incorporated into cage design decisions alongside engineering and production efficiency considerations.