Distribution of Marine Litter
Despite actions taken nationally and internationally, the situation with regard to marine litter is continuously getting worse.
Globally: There are no recent and certain figures on the amounts of marine litter worldwide. Nor are there any such global figures on the annual input of marine litter to the marine and coastal environment. In 1997, the US Academy of Sciences estimated the total input of marine litter into the oceans, worldwide, at approximately 6.4 million tonnes per year. According to other calculations, some 8 million items of marine litter have been estimated to enter oceans and seas every day, about 5 million of which are thrown overboard or lost from ships. Furthermore, it has been estimated that over 13,000 pieces of plastic litter are floating on every square kilometre of ocean surface.
In 2009, 498,818 volunteers picked up 7.4 million pounds of marine debris in 108 countries around the world. They removed marine litter from more than 21,000 kilometres of coastline and waterways collecting more than 6.2 million pieces of marine litter, weighing over 4,000 tonnes. Almost 58 per cent of the marine litter found could be attributed to shoreline and recreational activities, such as beach-picnicking and general littering. Many other such cleanup operations are carried out every year by thousands of school children, volunteers and local authorities in a large number of countries in all parts of the world.
Regionally: In contrast, various regional figures on quantities and distribution of marine litter are available.
In a 1998 survey, 89 per cent of the litter observed floating on ocean surface in the North Pacific was plastic. The Algalita Marine Research Foundation (AMRF) has conducted surveys to compare the quantities of plastic fragments floating on the ocean surface to the availability of food with which they are mixed. In the central Pacific gyre, the AMRF in 2002 found 6 kilos of plastic for every kilo of plankton near the surface.
About 3,500 plastic resin pellets per km2 have been reported floating on the surface in the Sargasso Sea. Near industrial centres in New Zealand, concentrations of up to 100,000 pellets were observed in one km2 of beach. In 1990, American scientists reported a 200–400 per cent increase from 1972 to 1987 in the number of pellets present in the North Atlantic Ocean.
During one decade (1992–2002), over 73,000 m3 of marine litter have been gathered on some 300 kilometres of rocky beach on the Swedish west coasts (including thousands of islands, islets and skerries), which is the easternmost part of the North Sea. The average annual amount of litter cleaned up on those beaches is 6,000–8,000 m3.
According to figures from the North Sea, as well as from the water around Australia, it has been estimated that up to 70 per cent of the marine litter that enters the sea ends up on the seabed, whereas half of the remaining amount is found on beaches and half floating on the water surface.
In 2002, the United States National Oceanic and Atmospheric Administration (NOAA) collected 107 tonnes of nets and lines and other fishing gear on the Pearl and Hermes Atoll (northern Hawaiian Islands) alone. In 2003, another 90 tonnes were found near the Pearl and Hermes, and Midway Islands. Heavy fishing gear litters the beaches, but probably much more serious is the fact that the gear gets snagged in the coral reefs, tearing the corals apart. It also traps endangered monk seals and threatens green sea turtles.
There are strong indications from many regions, e.g., the North Sea, that the quantities of marine litter are increasing. Consequently, the resulting environmental and socio-economic problems are worsening.
Despite international and national efforts made during the last two decades, there are no clear indications that the quantities and distribution of marine litter are decreasing, either globally or regionally.
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