Dates: March 24 – April 9, 2008
Vessel: NOAA ship OSCAR ELTON SETTE
Location: Northeast Pacific Ocean, Subtropical Convergence Zone
NOAA Marine Debris Program Staff: Kris McElwee
Project: At-Sea Detection and Removal of Derelict Fishing Gear in the North Pacific Subtropical Convergence Zone
Marine Debris in Hawaii
The Hawaiian Archipelago, extending from the southernmost island of Hawaii, 1,500 miles northwest to Kure Atoll, is among the longest and most remote island chains in the world. Because of their location in the current gyres of the North Pacific Ocean, the Hawaiian Islands are prone to accumulating floating debris, such as derelict fishing nets. Each year, approximately 52 metric tons of marine debris from domestic and foreign sources wash ashore and snag on reefs in the Northwestern Hawaiian Islands alone. In Hawaii, marine debris continues to present a hazard to marine habitat, safe navigation, and wildlife, including the endangered Hawaiian monk seal (Monachus schauinslandi) and various species of sea turtles, seabirds, and whales.
Movement and Accumulation of Marine Debris
It has been well documented that marine debris tends to accumulate in an area north of the Hawaiian Archipelago due to ocean and atmosphere interactions. Oceanic currents together with atmospheric winds provide the mechanism for movement and accumulation of marine debris north of Hawaii. Accumulation in Hawaii, especially in the Northwestern Hawaiian Islands (NWHI), is likely due to the location of the Subtropical Convergence Zone (STCZ). During winter months the STCZ shifts southward over the area 30–35 deg. N latitude, shifting further south during El Nino events.
Addressing the Issue
Debris removal efforts in the main and Northwestern Hawaiian Islands have been ongoing for several years. Additional efforts are needed to not only keep pace with the deposition of debris, but to prevent and lessen its impacts in these nearshore and shoreline areas.
High Seas GhostNet Project
For the last several years, the NOAA Environmental Technology Laboratory (now part of the Physical Sciences Division of the Earth System Research Laboratory), the NOAA Oceanic Research and Applications Division, the NOAA Pacific Fisheries Environmental Laboratory, and Airborne Technologies, Inc. have been developing a technique to efficiently locate ghostnets (lost or abandoned fishing nets) in the open ocean, focusing on the Pacific. Convergence zones are identified using data from satellites, and aircraft are directed to these zones to search for debris using remote sensors (high-speed cameras and video) on the aircraft and with spotters (people), also on the aircraft. Field tests of this technique, using satellite data to direct instrumented aircraft searches, have demonstrated that debris could be successfully located in convergence regions along the coast of Alaska and in the large STCZ north of Hawaii.
The High Seas GhostNet Detection Project is developing a method to efficiently locate ghostnets in the open ocean for at-sea removal.
Blogs from the field will follow.