A groundbreaking study published in Scientific Reports sheds light on the often-overlooked issue of fish suffering during slaughter—especially focusing on rainbow trout. The research introduces a powerful new tool, the Welfare Footprint Framework (WFF), to scientifically quantify pain levels and evaluate the cost-effectiveness of humane slaughter methods.
⚠️ Fish Pain During Slaughter: What the Study Reveals
Each year, up to 2.2 trillion wild fish and 171 billion farmed fish are slaughtered globally. However, the welfare of these aquatic animals has largely been ignored—until now.
The study focuses on one of the most commonly farmed fish species, rainbow trout, and uncovers distressing data about air asphyxia, a widely used but inhumane slaughter method. Key findings include:
- Fish endure 2 to 22 minutes of intense pain during air asphyxia.
- On average, rainbow trout experience 10 minutes of suffering—amounting to 24 minutes of pain per kilogram of fish.
- Pain duration is influenced by factors like fish size and water temperature.
✅ Humane Alternatives: Electrical and Percussive Stunning
Thankfully, the study also offers hope. It evaluates cost-effective, humane slaughter interventions:
- Electrical stunning can prevent 60 to 1,200 minutes of moderate to extreme pain per U.S. dollar invested.
- Percussive stunning, though harder to standardize, is also a high-welfare alternative.
- Importantly, pre-slaughter practices such as crowding and transport may cause even greater cumulative suffering than the slaughter itself and must be addressed.
📊 Introducing the Welfare Footprint Framework (WFF)
At the core of the research is the Welfare Footprint Framework, a new scientific model created by the Center for Welfare Metrics. The WFF:
- Measures total time animals spend in states of suffering or well-being.
- Allows for clear comparisons between welfare interventions, similar to how carbon footprints are used in environmental science.
- Helps policymakers, certification bodies, and aquaculture investors make data-driven decisions to improve animal welfare.
As Dr. Wladimir Alonso, the method’s creator, explains:
“The Welfare Footprint Framework offers a transparent, evidence-based approach to measuring animal welfare, guiding resource allocation for maximum impact.”
🧭 What This Means for Aquaculture Policy and Fish Welfare
These findings could revolutionize how we think about fish harvesting, aquaculture policies, and animal welfare certifications. With concrete numbers and economic evaluations, stakeholders now have the tools to:
- Advocate for humane fish slaughter methods.
- Improve certification standards in aquaculture.
- Invest in welfare reforms that offer the most benefit per dollar.
📚 Reference
Cynthia Schuck-Paim et al. (2025)
Quantifying the welfare impact of air asphyxia in rainbow trout slaughter for policy and practice.
Published in: Scientific Reports
DOI: 10.1038/s41598-025-04272-1
Provided by: Welfare Footprint Institute