Assessing Humane Stunning Methods for Shrimp

Decapod crustaceans such as crabs, lobsters, crayfish, and shrimp are increasingly recognised as capable of experiencing pain, prompting growing scrutiny of stunning and slaughter practices used at scale. Identifying humane practices is therefore a pressing welfare challenge. This report synthesises behavioural, physiological, and electrophysiological evidence on two stunning practices of particular relevance: chilling, due to its widespread use, and electrical stunning, due to its growing prevalence as a potentially more humane alternative.

Both chilling and electrical stunning can suppress behaviour and disrupt cardiac activity, and neither shows consistent biochemical changes indicative of an acute stress response. However, they differ in their neural effects. Chilling produces transient, species-dependent behavioural quiescence, but electrophysiological studies show that neural activity and sensory responsiveness persist even when animals appear immobile. Behavioural during chilling therefore cannot be treated as a proxy for insensibility.

Electrical stunning produces rapid behavioural and cardiac suppression across all decapod species studied and can abolish neural activity in central and peripheral pathways for extended periods in several species, suggesting that insensibility is achievable in principle. However, neural outcomes are not uniform across species or parameters, indicating the need for further validation.

Overall, the evidence indicates that electrical stunning has greater potential than chilling to induce insensibility, while chilling may suppress behaviour without eliminating sensory processing. Crucial uncertainty remains regarding defining species-appropriate electrical stunning parameters and translating neural evidence into reliable operational standards. On this basis, the report outlines implications for research priorities, regulatory standards, and industry practices aimed at ensuring that humane stunning practices reliably induce insensibility.