Blue mussels are farmed extensively in the UK in rope and bed systems, with welfare science increasingly examining their capacity for nociception and stress responses.
The welfare status of mussels is genuinely uncertain from a scientific standpoint. While they possess simple nervous systems and respond to harmful stimuli, the capacity for subjective suffering is unclear. Harvest mortality through air exposure and mechanical damage may cause some form of distress if they have any capacity for negative states. Their farming in clean water with access to natural phytoplankton represents relatively low-impact production.