Nearly 300 Chinese vessels are pillaging the waters in the Galapagos Marine Reserve primarily for squid, which are essential to the diet of local Galapagos species such as hammerhead sharks, as well as for many commercial and recreational fish species, including tuna, according to an analysis by the NGO Oceana.

Using the Global Fishing Watch mapping tool, Oceana analyzed data from fishing vessels operating near the Galapagos Islands from July 13 to August 13. During this period, the NGO documented estimates the Chinese fleet logged more than 73,000 hours of apparent fishing. In fact, 99% of the visible fishing activity off the Galapagos during this period was by Chinese vessels

“For a month, the world watched and wondered what China’s enormous fishing fleet was doing off the Galapagos Islands, but now we know,” said Dr. Marla Valentine, Oceana’s illegal fishing and transparency analyst, in a statement. “This massive and ongoing fishing effort of China’s fleet threatens the Galapagos Islands, the rare species that only call it home and everyone that depends on it for food and livelihoods.”

The Galapagos Islands are a remote area nearly 900 kilometers off the coast of Ecuador and was once a “living laboratory” that inspired Charles Darwin’s theory of evolution. The area is an oasis for ocean wildlife with more than 20% of its marine species found nowhere else on Earth. The Galapagos Marine Reserve covers more than 133,000 square kilometers surrounding the Galapagos Islands.

There are more than 30 species of sharks living in Galapagos, some of which are threatened with extinction, such as the Endangered whale shark (Rhincodon typus) or the Critically Endangered hammerhead (Sphyrna lewini). Many of them constantly move between the islands and the mainland.

As part of its analysis, Oceana also documented Chinese vessels apparently disabling their public tracking devices, providing conflicting vessel identification information and engaging in potentially suspect transshipment practices, all of which can enable illicit activities. China has the largest fleet of distant-water vessels in the world, estimated at more than 17,000.

“The governments of the world must work together to ensure that all seafood is safe, legally caught, responsibly sourced and honestly labeled to protect the oceans and the people who depend upon them,” said Beth Lowell, Oceana’s deputy vice president for U.S. campaigns, in a statement

China is the leading nation when it comes to illegal, unreported and unregulated fishing, and its fleets have been routinely implicated in violations related to overfishing, targeting endangered shark species, illegal intrusion of jurisdiction, false licensing and catch documentation, and forced labor.

The high seas, also called international waters, cover 41% of the planet and 60% of all the oceans on Earth. However, there is almost no law that sets rules about how much, how, what and when to fish there. That’s why environmentalists are asking for a global treaty that sets a framework for conserving biodiversity in the high seas.