Proposed deep-sea mining operations threaten to destroy some of Earth's most pristine ecosystems and the animals within them. The welfare implications for deep-sea organisms are profound and poorly understood.
The welfare implications of deep-sea mining are difficult to quantify because deep-sea animal sentience is largely unstudied. However, the precautionary principle demands serious consideration. Many deep-sea animals including octopuses, fish, crustaceans, and echinoderms are likely sentient to varying degrees. Sediment plume smothering would cause slow suffocation of sessile organisms. Mining noise and vibration would stress mobile animals. The permanent destruction of unique, irreplaceable ecosystems would eliminate entire communities of animals that have evolved over millions of years. Given our profound ignorance of deep-sea animal welfare and the irreversibility of mining impacts, a moratorium is the only welfare-consistent position.