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On 22 February 2022, a resident of the Scottish isle of Islay found a yellow plastic disk—a “drifter”—that had been released off the Arctic coast of Alaska nearly 40 years before by USGS scientists studying currents.

Photo of a yellow plastic disk sitting on a counter.
Drifter discovered on the wee strand at the head of Loch Indaal, Scotland, on 22 February 2022. The disk is about 7 inches across. Photograph by the drifter’s discoverer, Kate Hannett. Used with permission.

“We were walking along the shore at the end of our workday—amidst hail showers and after some big storms—to see what had blown in,” wrote Kate Hannett, discoverer of the disk. “The drifter was face down but looked interesting. To my surprise I saw wording on the back. I looked up the address online, was pleased to see it was the USGS and so contacted the team from there.”

Hannett found the drifter on a beach called “the wee strand” at the head of Loch Indaal. Her find was the second USGS drifter to reach Scotland. In 2010, a couple vacationing on the Isle of Coll found one of its release-mates on Cliad beach.

“It is amazing that one, let alone two of our drifters traveled to Scotland,” said Peter Barnes, the retired USGS scientist whose name and USGS address were printed on the disks.

Photo looks out at an ocean bay from a stony beach with grasses growing.
The wee strand at the head of Loch Indaal, Scotland. Photograph by Kate Hannett. Used with permission.

Barnes and his colleagues released 2,000 drifters in August 1983 from a boat and a low-flying aircraft near Barter Island in the Beaufort Sea. Half were designed to float with surface currents and half to move with bottom currents. The scientists wanted to investigate how water and ice might transport sediment and pollutants in the area, which was undergoing development and offshore drilling by oil companies. They relied on chance recovery of the drifters by residents and offered a $1 reward in exchange for the date and location of each find. By summer 1984, dozens of the yellow drifters had been recovered, nearly all of them having traveled eastward from their release points, in a few cases by a couple hundred miles.

The scientists wrapped up their study at that point, but over the years, the drifters have continued to wash up on beaches and make their way back to the USGS, albeit at very long intervals.

Map of the Arctic Circle with arrows drawn in the ocean to indicate the direction of currents and gyres.
Arctic region currents. Blue currents are cold, relatively fresh water. Red currents are warm salty water. In the Arctic Ocean, the salt content of the warm currents makes them denser, so they flow below the fresher cold currents. © Woods Hole Oceanographic Institution, J. Cook. Used with permission.

In the 2000s, USGS scientists began using drifters equipped with GPS units that record their routes. USGS oceanographer Curt Storlazzi and his colleagues have used GPS drifters to study coral larval dispersal in Maui, Oahu, and Guam, and to look at general water circulation in American Samoa and Kauai (for example, see

The plastic disks released in 1983 had no such instrumentation. Even if they had, GPS units would have recorded their whereabouts only for as long as the batteries worked—typically from hours to weeks. Scientists can only speculate on the paths the long-traveled drifters took.

Barnes wrote, “It’s likely that this drifter got caught up in the ice and could have spent several years traveling in the Beaufort Gyre,” a current that moves clockwise around the Arctic Ocean. “The Transpolar Drift might have carried it down the east side of Greenland, where it could eventually turn east in the northern edge of the Gulf Stream. A short hop in the North Atlantic Current would move it toward Scotland, where it decided to stop.”

Barnes added: “Recent warming and thinning of sea ice in the Arctic Ocean would help release any debris from the ice for ongoing transport by ocean currents.” That debris could include some of the old drifters, which might finally make their way to a distant shore, having done their tour of duty for science.

A map of islands in the ocean with labels on the island to show locations.
Scottish islands where USGS drifters were discovered in 2010 (Coll) and 2022 (Islay). Yellow arrow points to the approximate location of the 2022 drifter discovery. Base map data from The National Map.
Map of an island and surrounding water, labeled to show locations.
Yellow arrow points to the spot where Kate Hannett found a USGS drifter on 22 February 2022 on the wee strand. Base map data from The National Map.

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