EA - What matters to shrimps? Factors affecting shrimp welfare in aquaculture by Lucas Lewit-Mendes

Link to original articleWelcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: What matters to shrimps? Factors affecting shrimp welfare in aquaculture, published by Lucas Lewit-Mendes on November 3, 2022 on The Effective Altruism Forum.Shrimp Welfare Project (SWP) produced this report to guide our decision making on funding for further research into shrimp welfare and on which interventions to allocate our resources. We are cross-posting this on the forum because we think it may be useful to share the complexity of understanding the needs of beneficiaries who cannot communicate with us. We also hope it will be useful for other organisations working on shrimp welfare, and it’s also hopefully an interesting read!The report was written by Lucas Lewit-Mendes, with detailed feedback provided by Sasha Saugh and Aaron Boddy. We are thankful for and build on the work and feedback of other NGOs, including Charity Entrepreneurship, Rethink Priorities, Aquatic Life Institute, Fish Welfare Initiative, Compassion in World Farming and Crustacean Compassion. All errors and shortcomings are our own.Executive SummaryWhile many environmental conditions and farming practices could plausibly affect the welfare of shrimps, little research has been done to assess which factors most affect shrimp welfare.This report aims to assess the importance of various factors for the welfare of farmed shrimps, with a particular focus on Litopenaeus vannamei (also known as Penaeus vannamei, or whiteleg shrimp), due to the scale and intensity of farming (~171-405 billion globally per annum) (Mood and Brooke, 2019). Where evidence is scarce, we extend our research to other shrimps, other decapods, or even other aquatic animals. Further research into the most significant factors and practices affecting farmed shrimp welfare is needed.Conclusions from our review are summarised below:Eyestalk Ablation: Shrimps demonstrate aversive behavioural responses to eyestalk ablation, and applying anaesthesia before ablation has therapeutic effects. We believe this is strongly indicative that eyestalk ablation is a welfare concern.Disease: Infectious diseases cause significant mortality events. This is likely to both cause suffering prior to death and increase the total number of shrimps who are farmed and experience suffering.Stunning and Slaughter: Current slaughter practices (asphyxiation or immersion in ice slurry) are likely to be inhumane. While evidence on the optimal slaughter method for shrimps is limited, electrical stunning appears to be the most promising method to effectively stun and kill shrimps.Stocking Density: There is strong experimental evidence to suggest that reductions in stocking density indirectly improve welfare by improving water quality, reducing disease, and increasing survival. There is also some tentative evidence that stocking density directly impacts shrimp behaviour and measurable stress biomarkers (e.g. serotonin).Environmental Enrichment (EE): Environmental enrichments (e.g. feeding methods that mimic natural behaviours, hiding sites, different tank shapes and colours, plants, substrates, and sediments) probably improve shrimp survival, but there is little evidence on their impact on shrimp stress or behaviour. There is moderately strong evidence that physical enrichment (such as physical structure, plant, and substrate) improves welfare for aquatic animals, including crustaceans.Transport and Handling: Poor transport and handling practices are likely to lead to physical injury and stress, although research is limited on the welfare effects of current shrimp farming practices.Food: While some decapods appear resilient to lack of food, inadequate nutrition leads to risk of non-infectious disease and may lead to aggressive and abnormal behaviour.Water QualityDissolved Oxygen (DO): Several studies indicate that insufficient DO levels increase mort...