Free floating fishing nets kill marine mammals, turtles and sea birds
NOAA scientists battle ocean 'ghostnets' using remote sensing technology
May 4, 2005
Concentrated in relatively small areas of ocean by winds and currents, ghostnets present a hazard to wildlife, entangling marine mammals, turtles and sea birds and a largely unseen form of environmental pollution.
Because the synthetic materials currently used in fishing nets decay extremely slowly, they can continue to drift for years. Many end up trapped on the coral reefs, where entanglement rates are even higher than in the open ocean and where they damage the fragile coral.
The nets not only damage the reefs, but are extremely costly and time-consuming to remove.
Sea turtle found dead in fishing net in the Bay of Antongil, Madagascar.
Sea turtles are highly threatened by ghostnets and other commercial fishing activities.
NOAA scientists are using satellite and other technologies to predict area where current and winds combine to funnel and accumulate debris into what are called convergence zones. However, a recent field deployment to confirm that the satellites accurately predicted the existence of a possible convergence zone off Hawaii gave a first substantive look into the severity of the ghostnet problem in the open ocean.
According to James Churnside, a researcher with the NOAA Environmental Technology Laboratory in Boulder, Colo., the bottom line is that, "There is a lot more trash out there than I expected."
Using data from several satellites, scientists from the NOAA Satellite and Information Service and the NOAA Fisheries Service tracked the Pacific convergence zone through the winter. The data they collected were combined with more recent satellite data to determine the most likely areas to find aggregations of debris.
Coral reef of the Yucatan peninsula in Mexico.
Coral reefs are damaged by ghostnets.
Over three days, the plane overflew the convergence zone to allow scientists to make visual observations and to use an electronic imaging system with automated pattern recognition to determine how much and what kinds of debris had accumulated.
Churnside said that about 2,000 individual pieces of debris were seen. These included at least 100 that were identified as nets or pieces of net. A number were balls of net up to 10 meters (30 feet) across.
"One piece of driftnet that was still stretched out, and presumably still fishing, was 200-300 meters long," Churnside said.
Although surprised by just how much material was found in the convergence zone, Churnside said that a lot of analysis will need to be done to sort out whether convergence zones are more efficient at trapping debris than predicted or whether there simply is much more material floating free and available for capture than suspected.
This year, NOAA has also undertaken efforts to re-establish a centralized marine debris capability within the agency. The NOAA Office of Response and Restoration is coordinating these efforts by working with Churnside and other NOAA scientists to bring together, strengthen and increase the visibility of activities related to the prevention, reduction and mitigation of debris in the marine environment. One area of focus will be coordinating activities that identify and reduce the impacts of sea-based sources of marine debris (i.e. fishing nets and derelict gear) on endangered, threatened or protected species, and sensitive habitats in United States waters.
NOAA, an agency of the U.S. Department of Commerce, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation's coastal and marine resources.
This article is a release from NOAA: Original Release
Relevant Web Sites
NOAA Environmental Technology Laboratory
How to save sea turtles
Peter West, NOAA Research, (301) 713-2483 ext. 181