Shrimp welfare research at Rethink Priorities
Rethink Priorities’ Shrimp Welfare Sequence is a series that addresses whether and how best to protect the welfare of shrimp. At any time, more shrimp are alive on farms than any other group of farmed animals. This is the fourth report in the sequence. Previous reports estimated shrimp pre-slaughter mortality rates and overviewed the welfare threats shrimp face. This report quantifies the pain caused to shrimp by 18 welfare threats, using the Welfare Footprint Project’s framework.
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Executive summary
This is the fourth report in the Rethink Priorities Shrimp Welfare Sequence. In this report, we quantify the suffering caused to shrimp by 18 welfare threats to assess which welfare issues cause the most harm.
See a complete description of the methodology here. We focused on penaeid shrimp in ongrowing farms and broodstock facilities. Incorporating uncertainty at each step of the model, we estimated the prevalence, intensity, and duration of pain caused by each welfare issue. The intensity was based on the Welfare Footprint Project’s Pain-Track categories, and ‘pain’ refers to their definition of pain, encapsulating both physical and mental negative experiences (Alonso & Schuck-Paim, 2024a). We collapse different pain type estimates into a single metric: ‘Disabling-equivalent pain’. See the results in Figure 1.
Figure 1: Estimated hours of shrimp pain caused by 18 welfare threats, by pain intensity. Circles are means, lines are 90% Subjective Credible Intervals.
The average farmed shrimp spends 157 hours in disabling-equivalent pain (90% Subjective Credible (equal-tailed) Interval (SCI): [28, 356]). If we assume that 608 billion penaeid shrimp die on ongrowing farms annually (i.e., including those that die pre-slaughter; Waldhorn & Autric, 2023) then mean values imply that they experience 95 trillion hours of disabling-equivalent pain a year (90% SCI: [17 trillion, 216 trillion]).
The highest-ranking threats are chronic issues that affect most farmed shrimp. The top three are high stocking density, high un-ionized ammonia, and low dissolved oxygen. Threats ranked lower are broadly acute, one-off events affecting only a subpopulation (e.g., eyestalk ablation, which affects only broodstock). However, the credible intervals are too wide to determine the rank order of most welfare issues confidently.
Acknowledgments
This report is a project of Rethink Priorities—a think tank dedicated to informing decisions made by high-impact organizations and funders across various cause areas. The authors are Hannah McKay and William McAuliffe. Thanks to Daniela R. Waldhorn for generating the initial idea and framework for the method used here. Thanks to Laura Duffy and Cynthia Schuck-Paim for helpful feedback on drafts of the report.
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