The encyclopedia · Software & IT · Technical decision · 2018–2022
Dentsu taught AI the eyes of Japan's master tuna graders
Japan's master tuna graders are dying out — Dentsu paired tail-photo cross-sections with masters' ratings and taught an AI to grade tuna anywhere instantly.
Sojitz Corporation · Dentsu Inc.
The solution
Tuna quality examination is a tacit skill that takes at least ten years to master, and Japan's master graders judge fish by eye alone. Their numbers have fallen to less than half of the industry's golden age, and it is feared there will be no successors to carry on the craft.
Dentsu and Sojitz built TUNA SCOPE: at Yaizu port they photographed the cross-sections of tuna tails and recorded them with five-level quality ratings given by master examiners with 35 years' experience. Deep learning taught the AI 'the unexplainable nuances and secrets' of the examination craft. Tested against real master examiners in Dalian, China, roughly 90% of the app's results were consistent with its human counterparts.
The system grades tuna from a tail cross-section instantly, anywhere, around the clock. In 2019 the highest-rated AI tuna became its own brand, 'AI Tuna', served at sushi-train restaurants in Tokyo; in February 2020 the TUNA SCOPE Certification Mark launched with AI-certified tuna sold in New York, Singapore and Tokyo. The work won the Creative Data Grand Prix at Spikes Asia 2022.
Why it worked
- The bottleneck was not money or demand but a vanishing, untransferable human skill — the training dataset made the expertise replicable and location-independent.
- Scaling is free: once the AI masters the craft, marginal grading costs nothing, unlike training apprentices one by one.
- The product itself (AI-certified tuna) is the proof of the AI's worth, creating a market that adopts the technology because it benefits from it.
What can be applied
When the bottleneck is a vanishing, untransferable human skill, convert the expert's judgment into a training dataset — the scarce craft then scales with zero marginal expertise.
Aftermath
TUNA SCOPE has expanded beyond tuna: an AI bluefin tuna brand launched in 2023, a Southeast Asia SDGs fisheries project using TUNA SCOPE was adopted by JICA's SME & SDGs Business Support Program in 2025, and Dentsu frames the approach as transferable to any artisan skill.
Sources
- Spikes Asia Grands Prix and Special Award Winners Announced
- TUNA SCOPE — Inheriting the Disappearing Legacy of Tuna Examiners
- 'Tuna Scope' Uses AI Tech to Judge Tuna Quality as Human Practitioners Numbers Fall
spotted an error? The archive wants to know.