The ocean is increasingly dominated by anthropogenic noise from shipping, seismic surveys, and military sonar, with profound welfare consequences for cetaceans and other marine mammals that depend on acoustic environments for navigation, communication, and foraging.
Chronic acoustic stress in cetaceans caused by shipping noise represents a welfare harm that is invisible but measurable through stress hormone analysis. Elevated glucocorticoids indicate chronic negative physiological states. The masking of communication affects social bonding, mate finding, and mother-calf contact. Military sonar causes acute acoustic trauma - hemorrhage around acoustic organs, disorientation, and in severe cases death through stranding. The cumulative acoustic load on marine ecosystems has increased dramatically with shipping growth. Noise mitigation measures - ship speed reductions, routing changes, and quieter vessel designs - reduce welfare harm while also benefiting navigation safety.