Mining noise would ensonify 5.5 million km2 above whale behavior thresholds

Deep-sea mining generates continuous industrial noise from three simultaneous sources distributed vertically through the entire water column: collector vehicles scraping the seabed (4,000-6,000m), riser pipe pumps at mid-depth, and surface support vessels. Unlike shipping noise which is concentrated at the surface, this full-column noise propagation is uniquely disruptive to deep-diving cetaceans like beaked whales and sperm whales that forage at depth. Acoustic modeling published in Marine Pollution Bulletin (2025) shows that if each ISA contractor operated just one mining system, a radius of 4-6 km around each mine site would exceed 120 dB re 1 uPa -- the U.S. NMFS threshold for behavioral disturbance to marine mammals. Cumulatively across all contracted areas, approximately 5.5 million km2 of ocean would be ensonified above gentle-weather ambient conditions. The CCZ is a migratory corridor for multiple whale species, yet the ISA's draft mining code contains no noise emission limits, no requirement for marine mammal observers, and no seasonal restrictions to protect breeding or migration periods. This gap exists because the ISA's environmental working group only recently began developing noise thresholds, and deep-sea mining equipment designs are still proprietary, so published noise source characteristics are unavailable for independent assessment.