Scallops and oysters are farmed in large numbers, and while sentience evidence is weaker than for fish, welfare considerations remain under genuine scientific debate.
Bivalve aquaculture occupies a unique position in animal welfare ethics. The biological evidence for sentience is weak — bivalves lack the neural architecture considered necessary for conscious experience by most neuroscientists. Yet the precautionary approach to sentience uncertainty means that complete dismissal is intellectually premature. Practically, bivalve farming has genuinely low welfare concerns relative to all other farmed animal systems: no pain medication is needed, no slaughter welfare concern that clearly applies, and no enrichment requirement is obvious. For those seeking to reduce animal welfare impact in diet, bivalves represent one of the most defensible animal-sourced food choices.