PIFSC Marine Debris Team Conducts Aerial Surveys for Derelict Fishing Gear in the Main Hawaiian Islands

Derelict fishing gear in coastal marine habitats presents a potentially lethal entanglement hazard to various marine animals, most notably the critically endangered Hawaiian monk seal, the green sea turtle, and the humpback whale. This type of marine debris may also damage or smother sensitive reef habitat and has been known to act as a vector for the introduction of non-native species.

While past marine debris survey and removal efforts have focused on the Northwestern Hawaiian Islands, the NOAA Fisheries' Pacific Islands Fisheries Science Center Marine Debris Program has recently initiated a large-scale campaign to address the problem in the main Hawaiian Islands. In February 2006, the Marine Debris Program began a series of helicopter surveys to assess the distribution patterns, abundance, and effects of marine debris in the main Hawaiian Islands. Completed aerial surveys of the Big Island and Kauai have proved the helicopter survey technique effective, with the documentation of 250 individual debris sites. The Marine Debris Program plans to conduct additional surveys in the main Hawaiian Islands and lead a cooperative program to clean up the debris in the summer or fall of 2006.

The Big Island aerial survey team consisted of three marine ecosystem specialists trained in marine debris survey techniques, aviation safety, and helicopter emergency egress. Survey flights were conducted using a Hughes 500 helicopter owned and operated by Maui-based Windward Aviation Inc. A January 13 calibration flight on Maui facilitated the refinement of aerial survey protocols that were developed as follows:

Two NOAA observers onboard each flight
A team member on ground follows the flight via computer with a real-time satellite tracking system
Two flights per day, about 2 hours per flight
Average survey speed: 15-20 knots
Average distance covered per flight: 30-40 miles
Cruising survey altitude: 1100 feet
Range of distance from shore: 500-1300 ft (400 meters), depending on reef extension

Each observer onboard the helicopter has a specific set of duties. The aft observer is responsible for scanning the coastline and near-shore waters with a pair of image-stabilizing binoculars and collecting photographic data on debris sites. The forward observer is tasked with unaided scanning of the coastline, recording descriptive data on debris sites, and obtaining GPS waypoints for specific sites. Descriptive data collected include information on the type, size, location, and accessibility of debris.

Debris Points and Aerial Tracks of the main Hawaiian Islands
(Click the image for the higher resolution)

Hawaii

Maui

Oahu

Lanai

Molokai

When debris is spotted, the observers inform the pilot of its location. If conditions allow, the pilot moves the helicopter closer to the debris for further observation. The observers and pilot first scan the surrounding area for humpback whales and Hawaiian monk seals. If no whales or seals are present, the pilot drops the helicopter to an altitude of not less than 300 feet above the debris site. After observers collect further data, the pilot ascends back to an altitude of 1100 feet to continue along the survey path.

The team surveyed the entire coastline of the Big Island from February 13 -17 in a series of 10 flights. Most of the flights were based out of Hilo, while the last two departed from Kona. The first flight on the Big Island began on a southerly route from Hilo, progressing clockwise around the coastline. Successive flights headed around South Point and up to Milolii on the west side. Another Hilo-based flight was conducted to survey the Hamakua Coast. Finally, two more Kona-based flights were needed to survey the remainder of the leeward coast.

Derelict fishing gear was observed on all sides of the island, with the highest concentration of the Big Island's 79 specific debris sights located near South Point. Additional debris zones included the Waikoloa area southwest of Puako, the Kawaihae Harbor area, and the region between Upolu Point and Waimea Valley.

On February 17, in response to a report from the Hawaiian Islands Humpback Whale National Marine Sanctuary of a whale entangled in derelict fishing gear, the aerial survey team set out from Kona Airport in an unanticipated search effort. The search covered the Big Island's leeward waters. Although the whale was not located, the flight allowed for the unexpected documentation of 12 large accumulations of free-floating derelict fishing gear. In the future, the Marine Debris Program hopes to attach tracking buoys to such floating debris accumulations to provide more information on the paths of free-floating marine debris in the Hawaiian Islands. Knowledge of the movement patterns of marine debris could allow for specially concentrated efforts to mitigate the threats of derelict fishing gear.

The aerial survey team also completed marine debris surveys around Kauai. Based out of Lihue Airport, four helicopter surveys were conducted clockwise around the entire coastline of Kauai on February 24 and 25. A total of 171 marine debris waypoints were recorded. More than 150 debris sites were observed in 50 kilometers of Kauai's eastern coastline. The highest densities of debris were recorded between Kepuhi Point and Nawiliwili Bay. During the surveys, nine monk seal haul-out sites were recorded around the island, some in close proximity to debris accumulations.

The aerial survey team of the Marine Debris Program hopes to continue aerial surveys of the main Hawaiian Islands over the next several weeks. Surveys are planned for Maui, Lanai, Molokai, and Oahu. Research into the known locations of marine debris accumulation and monk seal haul out sites has been conducted in preparation for the surveys.

The Marine Debris Program is developing plans to remove the derelict fishing gear located during the aerial surveys, using small boats, starting in summer or fall of 2006. PIFSC Marine Debris Program staff will coordinate with state and local agencies and businesses, and focus the boat-based removal effort on regions of coastline that are particularly prone to debris accumulation. In addition to removing known debris accumulations onshore, the marine debris team plans to conduct underwater towed-diver surveys on adjacent reefs to assess and remove underwater entanglement hazards.