Freshwater and marine mussels are among the most environmentally sustainable aquaculture products. Their welfare status is genuinely uncertain, raising questions about the precautionary principle.
Mussels represent a useful test case for welfare ethics under uncertainty. The evidence for their sentience is genuinely weak — weaker than for fish, crustaceans, or insects. Yet "weak evidence" is not "no evidence," and the precautionary principle would suggest some consideration. For most animal welfare advocates and researchers, the environmental credentials of mussel farming, combined with low sentience probability, make mussels one of the more defensible animal protein choices available. The welfare questions that do exist relate primarily to bivalve handling and harvesting conditions, where the precautionary approach is simply to avoid unnecessarily slow or distressing processes on the reasonable assumption that some capacity for aversive states may exist.