The shrimp in your salad or tuna on your plate may have been caught illegally in areas threatened by overfishing. But tracing suspect seafood is a tricky task, given that many boats operate in unseen swaths of the ocean.

Global Fishing Watch, a new project from Oceana, SkyTruth and Google, aims to crack down on illegal fishing by training the watchful eye of surveillance satellites on the world's approximately 35,000 commercial fishing vessels.

The online technology platform collects more than 22 million data points per day from hundreds of thousands of ships. The free tool, still in its beta phase, lets anybody monitor and track activities of large commercial fishing vessels in near real time.

Leonardo DiCaprio, the actor/activist, unveiled Global Fishing Watch last week at the third annual Our Ocean Conference in Washington, D.C.

"This platform will empower citizens across the globe to become powerful advocates for our oceans," he said on Sept. 15 at the two-day summit.

More than 85 percent of the world's fisheries are reaching their biological limits due to overfishing, the World Wildlife Fund has estimated. Several popular commercial fish species, like the Atlantic bluefin tuna, have declined so much that their survival is threatened.

"Warming waters, acidification, plastic pollution, methane release, drilling, overfishing, and the destruction of marine ecosystems like coral reefs are pushing our oceans to the very brink," DiCaprio said.

"The only way we can avert this disaster is by ... scaling up innovative actions and solutions to these problems as quickly as possible," he said.

Global Fishing Watch gathers data from vessels' Automatic Identification System (AIS), which boat captains use to broadcast their position, course and speed to nearby ships, base stations and satellites.

The surveillance platform uses cloud computing and machine learning to process satellite AIS data and identify which vessels are fishing boats. It then logs when and where those vessels are fishing.

The tracker is regularly updated to show vessel tracks and fishing activity from Jan. 1, 2012 through the present, although it operates on a three-day delay.

"It will allow governments to track suspicious vessels, enforce rules and reduce seafood fraud," Jacqueline Savitz, vice president for U.S. and Global Fishing Watch at Oceana, a global ocean advocacy group, said in a statement.

"Journalists and everyday citizens will be able to identify behavior that may be related to illegal fishing or overfishing," she added.

U.S. Secretary of State John Kerry hosted the Our Oceans Conference, which joined diplomats, scientists and conservation groups from around the world to discuss steps to protect oceans from threats such as human-caused climate change, pollution and overfishing.

During the summit, countries announced plans to create more than 40 significant new or expanded Marine Protected Areas -- including the first U.S. marine national monument in the Atlantic Ocean

President Barack Obama last week designated over 4,900 square miles off the coast of New England as the Northeast Canyons and Seamounts Marine National Monument.

The action comes just weeks after Obama quadrupled the size of the Papahānaumokuākea marine monument near Hawaii. The area now encompasses nearly 583,000 square miles -- twice the size of Texas.

"Our conservation efforts and our obligations to combat climate change in fact go hand in hand, because marine areas already have enough to worry about, with overfishing and ship traffic and pollution," Obama said Sept. 15 in a special address at the summit.

"A healthier ocean and a healthier planet are about more than just our environment," the president added. "They are also vital to our foreign policy and to our national security."

Conservationists say Marine Protected Areas are needed to spare the oceans from further destruction and keep ecosystems healthy enough to adapt to warming and acidifying waters caused by climate change.

The movement took a significant step forward earlier this month when governments and global organizations adopted a measure to protect 30 percent of the world's oceans by 2030. As of now, only about 4 percent of oceans are protected, even including the latest additions announced in Washington.

Global foundations and conservation groups last week pledged a combined $5.3 billion to help protect marine ecosystems, prevent pollution and combat climate change.

The Wildlife Conservation Society, Waitt Foundation, blue moon fund and Global Environment Facility together committed $48 million specifically for expanding and managing Marine Protected Areas.

"The oceans are our future, and this new fund represents a commitment to safeguarding this invaluable resource," Cristián Samper, president and CEO of the Wildlife Conservation Society, said in a statement.