(Editors Note: This article originally appeared on the National Geographic website http://news.nationalgeographic.com/2015/06/150615-skytruth-pirate-fishing-illegal-big-data-ocean-conservation/)

Working late into the night in land-locked West Virginia, Bjorn Bergman helped authorities stop a fishing boat from illegally harvesting tuna and sharks thousands of miles away, off the Pacific island nation of Palau.

In late January, Bergman analyzed swiggles on his screen that represented the movements of the Taiwan-flagged fishing boat ShinJyi Chyuu 33. A records search told Bergman that the boat did not have a permit to fish in Palau’s waters, but the zig-zag patterns playing across his monitor suggested that’s exactly what the crew was doing.

Thinking he was seeing pirate fishing in action, Bergman notified Palau’s authorities, who intercepted the boat just 10 miles (16 kilometers) from the outer border of the country’s territory. Officials found a hold full of shark fins and tuna, which they suspected had been illegally caught. (Learn about Palau’s other dramatic efforts to fight pirate fishing.)

Bergman is an analyst with SkyTruth, a small nonprofit that is trying to solve some of the ocean’s most pressing problems by crunching big data.

An aha moment came in 2012, says David Manthos, communications director of Shepherdstown-based SkyTruth, when the team used publically available radar and satellite data to track down the ship responsible for a spill that spread oil across 90 miles (145 kilometers) off Angola.

“We found a black slick and a bright white point at the end of it,” says Manthos, indicating the responsible vessel.

Gradually, the team learned to turn mapping technology toward one of the ocean’s biggest problems: illegal or “pirate” fishing, which a recent studyfound is responsible for 20 to 32 percent of wild-caught seafood imported into the U.S. Pirate fishers thwart government quotas, avoid fees, and pillage sanctuaries. (See how the White House plans to fight illegal fishing.)

To detect such rule-breaking, SkyTruth partnered with the Pew Charitable Trusts to conduct systematic monitoring in large swaths of the Pacific. That experience led to a new partnership between SkyTruth, Google, and the nonprofit Oceana to develop a platform to allow fisheries officials, governments, companies, and advocacy groups to better track fishing vessels. The result is a website called Global Fishing Watch, launched last November.

How the Technology Works

Global Fishing Watch tracks about 40,000 fishing vessels, only a small percentage of the estimated four million that ply the seas. But it’s a start, says Manthos. (Learn how drones can also fight illegal fishing.)

At the core of the platform is data from the Automatic Identification System (AIS) network, which broadcasts ships’ GPS locations. AIS was originally developed so ships could better avoid running into each other and more easily locate those who might need help, but SkyTruth and others discovered that the data tell a lot about what a ship is up to. If it rakes back and forth across a stretch of water, for example, there’s a good chance it’s trawling for fish.

In the future anyone will be able to go on the Global Fishing Watch website and track ships, but the data open to the public will probably be a few days old and might not name each ship. Those that pay access fees charged by the satellite providers (such as fisheries enforcement officials) should be able to track individual ships in real time.

Manthos says one goal of the program is to “narrow down the number of vessels in what we call the dark fleet,” or those that opt not to use AIS transmitters.

No Easy Task

The system isn’t foolproof. Some pirate fishers avoid AIS transmitters, says Ami Daniel, co-founder and CEO of the Tel Aviv-based data company Windward. Ships also change their AIS broadcast signals mid-voyage, or secretly transfer illegally caught fish to a second vessel in the middle of the ocean.

Such activities mean tools like Global Fishing Watch are “hopelessly hobbled by inaccurate data,” says Daniel.

Instead, his company is working on an “even bigger” data approach that would combine more types of information into a single “vessel story,” including public and private data from government agencies, intelligence services, and shipping companies. This approach would be harder to cheat.

“Think of it like your own credit card,” says Ami. “If I have your credit card logs, I know where you shop, what you eat, where you go, and so on. Similarly, we are creating the story of a vessel, which provides new visibility.”

To Manthos, the ocean is a resource that belongs to everyone, even though it is often out of sight and out of mind for most people.

“But understanding what fishermen are doing out there, and where our food comes from, is extremely important,” he says.

This story was updated on June 16 at 10 am ET with more information about SkyTruth’s programs and to correct the error that there are four million fishing boats in the world, not 400,000.