Fishing is one of the most common and ancient of human practices — and it has grown by leaps and bounds over the past 40,000 years into a massive industrialized business.

Now, thanks to satellite feeds, machine learning and ship-tracking technology, we know just how massive it is.

Outlined in a study published in Science, researchers found that more than 55 percent of the world's oceans are covered by industrial fishing vessels, that the Earth's fleet of fishing ships trek more than 285 million miles (460 million kilometers) a year and that five countries — China, Spain, Taiwan, Japan and South Korea — account for 85 percent of the world's fishing on the high seas.

The data the scientists gathered are available for anyone to use and view through an interactive map and website hosted by Global Fishing Watch.

"By making this data public, we are providing governments, management bodies and researchers with the information needed to make transparent and well-informed decisions to better regulate fishing activities and reach conservation and sustainability goals," co-author Juan Mayorga, a project scientist in the Sustainable Fisheries Group at the University of California Santa Barbara (UCSB) and National Geographic's Pristine Seas Project, said in a statement issued by the university.

Searching for the fishers

Fishermen in orange jackets pull in a trawl of fish Tracking fishing vessels has been a difficult task for researchers. (Photo: DoublePHOTO studio/Shutterstock)

Figuring out just how large the industrialized fishing business has never been easy. Researchers have had to rely on ships' logs and observations to track them, and such methods have led to spotty results. Monitoring information of the ships' movements were rarely provided, so researchers had to look elsewhere to collect their data. And that elsewhere was outer space.

From 2012 to 2016, researchers tracked the 22 billion blips of ships' automatic identification systems (AIS). The AIS sends a signal to a satellite every few seconds as a way to avoid collisions. The information in those signals included the ship's position, speed and turning angle. With this information, researchers were able to track the movement of industrial vessels measuring from six to 146 meters that are required to have AIS monitoring on them.

The upside of the AIS signals? They're available to everyone.

"Those AIS messages that are broadcasted are publicly available via satellite," Mayorga explained to National Geographic. "We then combed through [the signals] with sophisticated computing capabilities provided by Google and machine learning algorithms."

Based purely on the movement of the ships, the researchers were able to identify more than 70,000 individual vessels, their sizes, engine power, what type of fish they caught, how they caught it and where they fished, and all with a great deal of accuracy. Indeed, when the researchers compared the AIS data with log books, they matched.

Fishing habits

Tuna fish in container on fishing boat dawn Cairns Australia Tuna is a prized item for the fishing industry. (Photo: sirtravelalot/Shutterstock)

So apart from the sheer scope of fishing activities happening in oceans around the world, the researchers picked up on a few fishing trends as well.

For instance, things like holidays and fuel costs played a larger role than environmental conditions when it came to determining when to fish. Chinese vessels, which accounted for 17 million of the 40 million hours tracked in 2016, saw massive dips in activity around the Chinese New Year. The dip is about on par with activity observed during government-mandated seasonal bans.

Christmas and New Year holidays similarly impacted fishing schedules around the world.

Most countries stick to their own exclusive economic zones when it came to fishing, but those previously mentioned five countries went out to bigger waters to fish. The high seas are less closely monitored than the economic zones and are also areas where vessels are more likely to catch tuna and sharks. The data backed this up as ships fishing in the high seas were more likely to use long-line fishing, a method that generally catches more tuna and sharks.

The majority of vessels followed laws regarding no-fishing zones and the like, but they tended to hover near the protected areas, skirting the edges of the law.

Fuel prices didn't factor into fishing routines, however. Researchers told National Geographic that fishing subsidies are likely making up the difference, which in turn is contributing to overfishing.

Conservation aid

Given the study's impressive view of the fishing industry, researcher believe their findings will only aid governments and conservation agencies in developing better legislation and ocean protections.

With the information publicly available, Global Fishing Watch contends that low-cost marine reserves can be easily implemented that in turn will allow fish populations to thrive again. Additionally, since we now know which regions are prone the most fishing, groups and governments can focus on providing those areas more protection.

"This [global dataset] makes any decision making or negotiating transparent," Mayorga told National Geographic.

Global Fishing Watch, UCSB and National Geographic's Pristine Seas Project collaborated with Google, SkyTruth, Dalhousie University and Stanford University on the project.