Greenpeace’s Tavish Campbell attaches a GPS tracker to the ghost fishing gear in October 2018. © Justin Hofman / Greenpeace.

The massive tangle of discarded fishing nets and ropes, weighing about 1500lbs, was first located by Greenpeace in the North Pacific Gyre. The crew of the Greenpeace ship MV Arctic Sunrise were there to document plastics and other marine debris, and attached a GPS tracker to the drifting net to learn more about how and where plastic migrates across the oceans. The device is one of more than a dozen used by Mary Crowley of the Ocean Voyages Institute to study the dynamics of marine debris and colonizing species. The trackers have been attached to nets and other objects with help of many volunteers and partners, sailing to and from Hawaiian Islands, which will allow them to be intercepted.

At the same time, a team at the University of Hawaii are using the trackers to study physical and biological processes controlling the miniature marine ecosystems that develop around floating debris. As part of the NASA-funded study, the trajectories of the trackers are synthesized with satellite remote sensing and numerical modeling help to better understand ocean dynamics and changes in the ecosystem over time.

The 10ft ghost net conglomerate tagged by Greenpeace in October 2018 was located some 700 nautical miles northeast of Hawaii. After wandering in the gyre and multiple interactions with ocean eddies and storms, its trajectory turned towards Hawaii. At that point, the researchers called local environmental partner organizations including Parley, asking for their attention and possible help.

“For the first time, we have opportunity to follow in near-real time movement of large marine debris as it approaches our islands,” explained Dr. Nikolai Maximenko, researcher at the University of Hawaii’s International Pacific Research Center at the time. “Should this happen, it could become an excellent example of interaction between the open and coastal ocean.”

By March, there was a chance the net would make landfall on the Hawaiian coastline – crashing onto rocks or reefs in the rough surf and becoming entangled. The future trajectory of the ghost net at that point was hard to predict – it was caught in a current leading towards an unstable 'bifurcation' point that would push it either towards the Hawaiian islands, squeeze it between them or turn it northeastward away from from the islands. On April 16, the data showed the tracker coming ashore, and Parley Hawaii’s Kahi Pacarro headed out to a remote stretch of coastline to locate it.

“This interception could be the start of something much bigger that reduces the impact these giant conglomerates are having on our reefs, wildlife, and coastlines,” says Kahi. “Although we want to focus on the source, we also need to deal with the realities of the present. Too many conglomerates are damaging our near shore resources. Intercepting them before making landfall and knowing where they tend to land will help us minimize the damage.”

The ghost net and tracker (white buoy with blue stripe) were finally located by Parley and Love the Sea off the north shore of Maui.

A search across treacherous rocks turned up a few smaller ropes, but not the large net conglomerate and tracker. The next day, GPS data showed it had bounced off the coastline and was floating just offshore. Kahi joined Love the Sea’s Campbell Farrell on a boat and finally spotted the ghost net offshore on April 17. The team towed the tangled mess of ropes and netting ashore for further study and disposal. Samples were taken, and the tracker was retrieved after its epic voyage, ready to head back out to sea on future studies.

”There are still many unanswered question in relation with marine debris in the ocean and their fate and transportation across different biogeographical oceanic regions,” explains oceanographer and Parley Science Advisor Dr. Sarah-Jeanne Royer. “To help answer scientific questions in relation to the trajectory of marine debris we need to work with organisations that are in the field and in close connection with the ocean. This project is a great example of how collaboration work is a key to the success of such a mission with the involvement of many citizen scientists and researchers! Thanks to everyone for being part of this one-of-a-kind project.”