Aerial Survey Finds Marine Debris

Contact: James Churnside

A recent survey along the Pacific coast of Alaska demonstrated that a nested search was effective in locating marine debris. Sources of debris in the ocean include fishing, logging, shipping, and intentional dumping. Some of this debris can cause serious problems, including certain types of lost and abandoned fishing gear that entraps endangered marine mammals, sea birds, and turtles. It also causes significant damage to coral reefs, and removal from the reefs is a very laborious and expensive task. Removal of these nets from the open ocean is fairly straightforward, but finding them in the expanse of the ocean is difficult.

A collaboration consisting of NOAA/ETL, Airborne Technologies, Inc. (ATI), NOAA/NMFS, NOAA/NESDIS, NASA, and other university and industry partners was assembled by ATI to develop a nested-search technique to search the oceans for marine debris. Ocean circulation models were run to identify regions and periods of convergence, where debris would be likely to concentrate. These areas were examined using space-based instruments to locate actual convergence zones more precisely. These instruments included Synthetic Aperture Radar (SAR), radar altimeter, sea-surface temperature radiometer, and ocean color radiometer. An aircraft was equipped with sea-surface temperature (ETL) and ocean color (ATI) radiometers to locate the features identified in the satellite data. It was also equipped with visible and thermal imagers (ATI) and the ETL imaging Fish Lidar to detect objects floating in the water.

ETL participated in the testing of this system for three weeks in July of this year. The model identified several locations along the coast of Alaska and along the Alaskan continental shelf where eddies and convergences are common. The satellite data located a number of specific areas, both near the shore and farther off shore. Aircraft searches in these areas found concentrations of debris in about half of these areas. By contrast, almost no debris was seen in areas that were not identified as search areas from the satellite data, even though most of the flight time was spent in the areas between the identified areas.