See Shell App and the Illegal Tortoiseshell Trade

The ability to recognize tortoiseshell jewelry will help travelers avoid purchasing these items. (Hal Brindley /

BEAUTIFUL NECKLACES, BRACELETS, EARRINGS, and other items with elaborate brown and amber patterns adorn the shelves of shops and tourist markets worldwide. They might seem like the perfect souvenirs of your latest dive trip.

These items, often called tortoiseshell, may be made from the colorful plates, called scutes, covering the shells of hawksbill sea turtles (Eretmochelys imbricata). The International Union for the Conservation of Nature (IUCN) Red List includes this species as critically endangered, and the U.S. Endangered Species Act considers them endangered, so buying such souvenirs contributes to a global trade that represents a major threat to its survival.

Fortunately, other options exist, including products made from acceptable alternatives such as resin, horn, bone, or coconut shells. But unfortunately, most people cannot tell the difference between the real thing and the alternatives.

A new app called See Shell can. The conservation nonprofit SEE Turtles developed it to use deep machine learning and photographic image recognition.

“One of the major roadblocks to eliminating the illegal tortoiseshell trade has been how difficult it is to distinguish real from fake products,” said Brad Nahill, president of SEE Turtles. Consumers, sellers, law enforcement, and even wildlife officials struggle to tell the difference. That means, while there is an intentional black market, some sellers and buyers may unwittingly contribute to the trade — including divers who would rather see these iconic marine animals in the ocean than on a shelf.

Now would-be souvenir buyers can simply take a photo of a product and upload it to the app. The technology compares the item with a data library of more than 4,000 real and artificial tortoiseshell products, discerning which the item is with 94 percent accuracy.

“We already had a guide on our website to help people identify illegal tortoiseshell products, and we got a good response to that,” Nahill said. “But people aren’t going to print the guide out or pull it up online when walking around a market. Now they’ll have the app.”

International laws prohibit the sale of tortoiseshell goods, but there is an active, mostly illegal trade in at least 40 countries, according to a 2020 report from SEE Turtles titled “Global Tortoiseshell Trade.” The report identified Nicaragua, Costa Rica, and Cuba as hot spots for this trade.

Conservationists estimate that only about 15,000 to 25,000 adult female hawksbills remain in the wild (females come ashore to nest and can be counted, while males remain at sea their entire adult lives). These sea turtles live in tropical waters around the world, hanging out near coral reefs, mangroves, and shallow coastal areas. They weigh between 100 and 200 pounds and reach 2 to 3 feet in length when fully grown. Hawksbills use the sharp, bird-like beak from which they get their name to eat sponges, which have physical and chemical defenses that cause most marine animals to avoid them. Sponges compete aggressively and can dominate reef communities. A single hawksbill can consume an estimated 1,000 pounds or more of sponges a year, keeping them in check and helping to provide space for other species.

Hawksbills and other sea turtle species also contribute to beach ecosystems. When they nest on sandy beaches, their eggs and hatchlings provide food for many predators, and unhatched eggs contribute high-density nutrients for beach vegetation that stabilizes shorelines and provides food for various animals. Adult sea turtles are a food source for predators on shore and at sea. Further decreases in their numbers have wide-ranging effects on marine ecosystems.

The app can not only steer tourists in the right direction, but it could also support police and customs officials’ worldwide efforts to stop the illegal trade. They aren’t experts on identifying items made from real shells and those made from alternatives either, Nahill points out. SEE Turtles and partners in Indonesia and Latin American have field-tested the app and are providing law enforcement with training on using it to document tortoiseshell trade occurring in their areas. Those organizations include the Turtle Foundation in Indonesia, Fundación Tortugas del Mar in Colombia, Costa Rica’s Latin American Sea Turtles, The Leatherback Project in Panama, and Sos Nicaragua. The app is part of Too Rare to Wear, a larger SEE Turtles educational campaign to combat the illegal trade.

As more people upload images from around the globe into the app, it will create a clearer picture of the size and location of the illegal tortoiseshell trade, helping direct trade enforcement and hawksbill conservation efforts where they are most needed.

Nahill hopes online retailers and shoppers will also use the tool to avoid selling illegal products, as the app can also recognize real shells and alternatives from online photos. He stresses that people should not confront shop owners or sellers if the app identifies something made of a hawksbill shell. The See Shell app provides SEE Turtles with a notice when it identifies an illegal product, and Nahill said his team is considering how best to use that information.

“We encourage people to avoid shopping at places selling illegal products, to go elsewhere, and to tell their friends,” he said. “We want to be deliberate about that process, though. We don’t want to put tourists into awkward situations. But the app could help us find hotspots, for example, and we could alert local law enforcement about those.”

Alexander Robillard, a computer vision engineer with SEE Turtles and a pre-doctoral fellow with the Smithsonian OCIO Data Science Lab and National Zoo, helped develop the app. The World Wildlife Fund for Nature provided financial and technical support to help advance the application’s data collection and documentation and promote its use by government agencies and online retailers. 

Download the app from the Apple store or Google Play or at Find the How to Recognize Hawksbill Turtle Shell guide at AD


Hawksbill turtle
A hawksbill turtle swims along the colorful reef at the Tatawa Besar dive site in Komodo National Park, Indonesia.

“One of the major roadblocks to eliminating the illegal tortoiseshell trade has been how difficult it is to distinguish real from fake products,” said Brad Nahill, president of SEE Turtles.

A new app called See Shell can.

Now would-be souvenir buyers can simply take a photo of a product and upload it to the app.

© Alert Diver — Q3 2022