A just-completed research cruise more than 900 miles due north of O'ahu may have brought wildlife managers a step closer to protecting the Northwestern Hawaiian Islands from one of its worst enemies: marine debris.

The March 24-April 9 voyage on the NOAA ship Oscar Elton Sette included testing the use of small, unmanned aircraft to find floating trash.

The prototype crafts built for the National Oceanic and Atmospheric Administration have wingspans of 7 feet and weigh just 10 pounds each. They carry video cameras that send real-time images back to the ship.

Alaska-based Airborne Technologies Inc. designed its Resolution class of aircraft specifically for this job.

In keeping with their deployment location, they've been named Malolo 1 and Malolo 2 — the Hawaiian word for flying fish.

Even the Resolution moniker refers to the ship Capt. James Cook sailed from Alaska to Hawai'i, said ATI President Tim Veenstra, who headed a three-man company team.

ATI has worked with NOAA for years on other high-tech ways to study the problem of marine debris. Past projects include hooking its "GhostNet" buoys to clumps of debris and tracking them by satellite to see where currents and wind concentrate the stuff.

Information from those buoys was among the data used to determine where the Sette would go to test-fly the Malolos.

The cruise destination was the North Pacific Subtropical Convergence Zone — the mixing zone between warm tropical waters and cooler northern seas. The area is usually several miles wide and thousands of miles long.

The zone stretches from 130 degrees West longitude to 160 degrees East and "was observed as a diffuse line across the Pacific during one of the first space shuttle flights," according to the Papahanaumokuakea Marine National Monument Web site.

The monument encompasses the 1,200-mile-long Northwestern Hawaiian Islands and is managed jointly by NOAA, the U.S. Fish & Wildlife Service and the state Department of Land and Natural Resources.

The critically endangered monk seals, threatened green sea turtles and delicate coral reef ecosystems of the monument would be the direct beneficiaries if marine debris found in the convergence zone can be removed before it gets there.

"Since 1996, about 627 tons of nets have been removed from the Northwestern Hawaiian Islands," monument resources manager Russell Reardon said by e-mail. Much of it was painstakingly cut from coral reefs by divers.

"This joint Papahanaumokuakea Marine National Monument-Pacific Islands Fisheries Science Center project was the first NOAA mission geared toward the at-sea detection and removal of marine debris in the North Pacific Subtropical Convergence Zone," Reardon said.

High winds and rough seas limited the flights the aircraft could make, but the team was able to get in nine trips, four by Malolo 1 and five by Malolo 2. Each one was a learning process, as described by team blog postings.

On March 31, the first day of launching, Malolo 1 made two flights, each cut short when the motor stopped. Supposing that aircraft had a battery problem, the team launched Malolo 2 for its first at-sea flight. But after 7 minutes in the air it, too, stalled out. The crew later determined that the motor speed controllers were overheating, Veenstar said.

The crew attached GhostNet tracking buoys to two pieces of marine debris — a hawser (barge-towing) line and a long-line fishing buoy with no line attached — since they weren't very large or threatening to wildlife.

"Tracking the movement of debris is very valuable information to help researchers determine how debris moves about the ocean," Veenstra said.

"From our perspective we are very pleased with the flights we were able to make," he said. "There is a large learning curve as we try and make UAS (unmanned aerial systems) flights from a ship at sea a safe and effective research tool."