The bluefin tuna is one of the biggest, fastest fishes in the ocean. Its streamlined body can sprint at up to 45 miles per hour in pursuit of its prey. Reaching some 500 pounds, this giant once dominated the Atlantic, Pacific and Indian oceans. But humans have hunted the bluefin for thousands of years. In the last century stocks have been decimated. The Pacific population is now just 2.6 percent of its original size.

Many other species that live in the high seas—the two thirds of Earth’s oceans that lie beyond national waters—are suffering a similar fate. There is no universal law protecting biodiversity. “This is a massive gap, a literal hole in the middle of the ocean,” says Lance Morgan, president of the Marine Conservation Institute, a U.S. nonprofit focused on ocean protection.

That is about to change. The United Nations is pushing to protect marine life on the high seas with a legally binding treaty by 2020. Delegates from 193 nations are working on it at U.N. headquarters in New York City, through September 17. Yet tension is already in the air. Russia, for example, is vocalizing its opposition to global governance of international waters, a position that could delay or even scuttle the process. And certain nations, from Africa and South America in particular, have made it clear any benefits reaped from international waters should be shared with countries worldwide.

The high seas are home to some of the planet’s most charismatic creatures, such as dolphins, sharks, whales and turtles. They contain valuable fisheries and support ecosystems found nowhere else. Yet until last year there was not a single, large marine protected area in international waters. Today, just 1 percent of the high seas is off-limits to industry.

Mounting pressure for protection is stemming in part from a new wave of exploitation about to hit the high seas. The International Seabed Authority (ISA) has granted licenses to 29 contractors representing 19 countries—from Japan and the U.K. to Kiribati—to explore for minerals at ecologically important sites. These include the Clarion-Clipperton Fracture Zone—a region of seamounts in the central Pacific—and the Lost City, a hydrothermal field in the Atlantic scientists say could hold clues to the evolution of life on Earth. Meanwhile chemical manufacturers are scouring the deep sea for organisms whose genomes could lead to new cosmetics, foods or pharmaceuticals.

By the end of the U.N. meeting, delegates expect to have thrashed out the bones of an agreement, which will then be drafted and circulated to nations for review before the next summit in April 2019. The treaty is likely to be an extension of the U.N. Convention on the Law of the Sea (UNCLOS), which was agreed to in 1982 and came into force in 1994 to set limits on ocean activities. That agreement does not cover biodiversity, however.

Despite being the only major nation not to ratify UNCLOS, the U.S. may play an important role in shaping this latest pact. In 1995 the U.S. was key to developing the U.N. Fish Stocks Agreement (pdf), an add-on to UNCLOS that was a historic step in protecting migratory fish stocks. The U.S. has a huge delegation here, and is particularly interested in patenting, trade law and fisheries, according to Kristina Gjerde, who is representing the International Union for Conservation of Nature at the talks.

Another issue that could derail the negotiations is how to share the benefits of discoveries. Under existing UNCLOS law, anything discovered on or beneath the seabed in international waters—including minerals and marine genomes—is the “common heritage of mankind,” and should benefit all nations. Right now, a single corporation—the German chemical company BASF—owns nearly half (pdf) of all globally registered patents for marine genetic sequences, and has the right to commercialize patents from the high seas without sharing the profits or other benefits. In national waters that is no longer possible, owing to a 2010 U.N. resolution called the Nagoya Protocol; a person, company or nation using genetic resources from a different country’s waters must work out some mutually beneficial terms with the “host” country.

Developing countries would like to extend this principle to international waters. But developed nations such as the U.K., the U.S. and Japan are largely opposed to compensating other nations for patents acquired from the high seas. Still, “there’s goodwill at the talks to find common ground,” Gjerde says. “This is about more than monetary compensation. It’s also about issues like access to data.”

Delegates want the new treaty to clean up well-established industries such as fishing, too. Here, the task could be harder. Some 20 organizations manage discrete or regional activities on the high seas, including the ISA, and the International Maritime Organization, which oversees shipping. And there is little communication between sectors.

Fearing a global deal will lead to more regulation, pushback is likely from industry as well as from major high seas fishing nations such as China, Japan, South Korea and Spain. But 90 percent of the world’s fish stocks are fully or over-exploited, and several independent studies have shown closing the high seas to fishing would not hurt either global catches or profits. “We’ve done a very good job of managing resources to the brink,” says Liz Karan, a high seas expert with The Pew Charitable Trusts who is attending the meeting. “Now we’re finally waking up to the fact that we can’t just rely on the oceans to be resilient.”

The impetus for high seas protection is timely. Scientists have warned that the world should place at least 30 percent of global ocean space within marine protected areas by 2030 if it wants to avoid a mass extinction of marine life. Only around 2 percent of the oceans are within marine protected areas, and the U.N. has set a target of 10 percent by 2020. Over the past 20 years scientists have identified numerous places teeming with life such as the White Shark Café, an area between Baja California and Hawaii where hundreds of great whites congregate each year, and the Sargasso Sea, a massive gyre in the North Atlantic that entrains nutritious seaweed, which feeds a huge diversity of marine life, from eels to turtles to seabirds. “This is an opportunity to try to preserve ocean resources for all of us before it’s too late,” Karan says.