Although not much is known about whether shrimp experience pain or not, we have a duty of care for the animals that are under our watch. To understand more about how our handling practices affect shrimp and how to minimise stress at slaughter, we teamed up with Professor Robin Cooper from the Department of Biology of Kentucky University, USA. With prof. Cooper, we travelled to our shrimp farm in Belize to study how we can minimise stress for shrimp at post-harvest through to slaughter. This assessment was previously carried out by looking at shrimp’s behaviour and movements but we found that these were inconsistent and some behaviours were difficult to interpret. We looked for other indicators to help us interpret behaviour and decided that measuring heart beating could have been helpful. Prof. Cooper has a wealth of knowledge and published research papers on the physiology of insects and crustaceans, and he could teach us how to measure the heart rate in shrimp as an indicator of reaction to external stimuli. We set up several experiments that looked at what happens to shrimp when they are placed in iced water and when they are electrically stunned to understand if these techniques could reduce exposure to stressful conditions.
We found out that measuring heart rate in shrimp is a very useful bio index to understand what shrimp are experiencing. The conclusions of the experiments showed that immersing shrimp in iced water is a method that rapidly achieves loss of consciousness. Exposure to cold reduces heartbeat which in turns reduces the ability of the nervous system to process external stimuli and therefore stress. The results from electric stunning were promising but more work is needed to fully understand how it works and what effects it has on shrimp.