Tracking Tuna On The Blockchain To Prevent Slavery And Overfishing

Where does your fish come from? With the Provenance system, now you will know.


If you buy a can of tuna in a grocery store–or sashimi at a restaurant–it’s likely that it was unsustainably fished, and there’s even a good chance that it was caught by slaves in Southeast Asia. Even a certification on the label isn’t definite proof that a product is okay, since certifications can sometimes be duplicated and faked.


In a recent pilot project, a U.K.-based startup called Provenance traveled to Indonesia and tested tracking tuna on the blockchain, the same ultra-secure technology used to track Bitcoins.

In the pilot, traditional fisherman sent simple text messages to register a catch, and that created a new “asset” on the blockchain. Every time a batch of fish was sold–to traders, and processors, brands, and supermarkets–the blockchain ID was sold with it. That digital identity also tracks the audit information that proves that fish were caught legally and sustainably.

“When you sell the physical fish, you transfer the digital fish,” says Jessi Baker, founder of Provenance. “What that allows is to prevent the double-spending of those claims. Because otherwise, you could sell two fish that both make the claims of sustainability and social responsibility. In our system, that becomes impossible, because you can’t double-spend a digital version of the fish.”

With larger fish, like the yellowfin tuna, which can weigh as much as 400 pounds, the startup tested using physical tags and even tracking DNA. But they say it’s less important to track specific fish–especially for tiny skipjack tuna, which would be impractical and expensive to tag–than to track the certifications that go with the fish.

“It doesn’t technically matter if the fish get swapped,” says Baker. “The key thing is that their claims don’t get duplicated. A large problem at the moment with certification is that you start on a farm with 30 tons of organic tomatoes, and all of the sudden those 30 tons of organic tomatoes, along the chain, turn into 300 tons of tomatoes inside pasta sauces. Along the chain of custody, the claims get multiplied and duplicated and faked, which then means you’re drastically reducing the effectiveness of those claims to support a sustainable ecosystem.”

While various non-profits and government agencies are working on tracking fish through the supply chain, the different tracking systems can’t easily share data. For security reasons, they often can’t be accessed by anyone else. Because the blockchain can provide a secure public ledger, it’s a way to ensure real transparency.


When a blockchain-tracked fish gets to a supermarket, it’s also something that consumers could more easily trust. And by choosing responsibly-caught fish, consumers can also help to shift demand away from the suppliers using the worst practices.

Globally, 10-15% of commercial fisherman are estimated to work in slave-like conditions. In Southeast Asia, where three-quarters of the world’s fishing fleets operate, hundreds of thousands of people have been tricked into slavery on fishing boats–sometimes forced to work for years–and in processing plants.

In February 2016, the U.S. finally closed a loophole in a law that allowed imports of slave-produced goods if there wasn’t enough American supply of the product. The government also proposed a new traceability program. The blockchain could be a useful tool to make sure that program actually works. Along with forced labor, it can also track other serious issues in seafood, like overfishing.

In the U.K., Provenance is beginning a new partnership with Coop, a major supermarket chain, to track fish and other types of food. The startup has had the most interest from manufacturers of high-value products, such as wine and olive oil. But it’s equally committed to products that come at the highest social costs, like fish. Their ultimate goal: an open-source platform that anyone can use to customize the system for any industry.

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About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley, and contributed to the second edition of the bestselling book "Worldchanging: A User's Guide for the 21st Century."