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Australia’s vast coastline is littered with marine debris. From burst balloons and countless straws to plastic drink bottles, styrofoam, and fishing lines, all sorts of trash ends up on the country’s beaches, and Heidi Tait, cofounder of the nonprofit Tangaroa Blue, has combed through it all. But as the old adage says, some trash is actually treasure—provided you look at it from the right perspective. In this case, Tait and the Tangaroa Blue volunteers working to clean up Australia’s beaches unexpectedly accumulated a trove of strange tire-shaped capsules scattered along the Cape York coast, near Australia’s northeastern tip.

When Tait and her teammates started finding the capsules washed ashore, they weren’t quite sure what they were looking at. But by busting one open, looking at the company names listed inside, and making a few calls, Tait eventually connected with Satlink—a Spanish satellite communications company. Satlink’s GPS-enabled buoys, the ones the beach cleaners kept finding, help commercial fishers track their nets, lines, and other gear.

Tait’s partner, Brett Tait, Tangaroa Blue’s circular economy developer, had a brainwave that would see the buoys not just recycled but reused.

For more than a decade, boat crews working farther west, in Australia’s Gulf of Carpentaria, had been telling the Taits about how abandoned fishing nets were circling the gulf, ensnaring and strangling sea turtles and dugong. These so-called ghost nets had either broken free from commercial fishing vessels and gotten lost, or were cut loose by fishers after getting snagged on rocks. Weighing a few tonnes each, the nets that boat crews had chanced upon in the gulf were often too big for them to heave out of the water. They’d typically report the finds to the authorities, but by the time anyone with an appropriately equipped vessel could head out to retrieve one, the mass of tangled rope had often vanished from sight.

Perhaps, Brett thought, Tangaroa Blue could solve the problem using their newfound GPS buoys. The trackers are “such a high-tech piece of equipment,” Tait says. They’re obviously not cheap, and for them to go to a landfill “seemed like such a waste.”

So, in December 2022, Tangaroa Blue started handing the buoys out to its flotilla of local partner crews: boat charter operators, commercial fishers, Indigenous rangers, and national park service members who had agreed to carry the repurposed buoys. When these teams come across a ghost net they can’t haul in, they hook one of the GPS-enabled floats onto it. Once attached, the tracker pings its location every few hours. A web portal lets Tangaroa Blue monitor the nets’ movements and alerts the organization if one is drifting dangerously close to a coral reef or shipping lane.

But finding and tagging the nets is only the first step; coordinating their recovery is the real challenge. The trackers can measure the weight of the rope dangling beneath the float, so Tangaroa Blue’s staff know how big of a boat they need to charter to retrieve it. But “we don’t have an unending supply of money to hire vessels,” says Tait.

So far, crews from around 100 commercial fishing vessels representing 22 international companies have gotten on board with Tangaroa Blue’s project; they’ve given Satlink permission to reassign any of their lost buoys that Tangaroa Blue finds for the nonprofit’s use. Eventually, Tait hopes to encourage fishing companies to chip in to a recovery fund that would pay for charter boats to retrieve nets without delay.

So far, the repurposed GPS trackers have helped Tangaroa Blue recover three ghost nets from Australian waters—including one particularly pesky net that had been spotted in the Gulf of Carpentaria multiple times by local boaters and evaded recovery for about a year. The net weighed three tonnes, and just three weeks after being tagged, it was hauled in on the gulf’s eastern flank, near the town of Weipa.

Tangaroa Blue’s idea to tag and track ghost nets isn’t entirely new; researchers with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s national science agency, suggested it a decade ago. Taking the idea on board, Australian maritime authorities tried using battery-powered tags to monitor a few ghost nets. Tangaroa Blue’s approach differs in that its recycled buoys are solar powered and require less upkeep. The nonprofit’s assembly of volunteer ghost-net spotters also greatly expands its reach.

From an environmental perspective, the GPS-fitted floats themselves are a massive plastic pollution problem. Researchers estimate that commercial fishers deploy between 46,000 and 65,000 GPS trackers in the Pacific Ocean each year. When the devices are lost or discarded, ocean currents and prevailing winds push many of them around Papua New Guinea and toward Australia’s northern coast. The Gulf of Carpentaria, in particular, is a magnet for both ghost gear and lost buoys. Its two long outstretched arms, shallow water, and clockwise gyre all work together to create a vortex that drags in junk fishing gear from all over.

In 2013, Denise Hardesty, a CSIRO marine scientist who had been tracking ghost net numbers in Australian waters, identified a narrow area where ghost gear seems to get sucked into the gulf. If Tangaroa Blue focuses efforts on that spot, her work suggests, it could intercept some nets before they ever get a chance to impact the wildlife that dwells in the gulf’s shallow water.

As supportive as he is of Tangaroa Blue’s approach, Erik van Sebille, an oceanographer at Utrecht University in the Netherlands, says there may be limits to the technique’s transferability to other countries similarly swamped by ghost gear. Many Pacific island nations, for example, might lack access to big vessels that could recover tagged ghost nets quickly. Ultimately, he adds, rather than looking for new ways to clean up lost nets, “it would be much better to prevent ghost nets from being in the ocean in the first place.”