The River Dolphin and Gharial (a crocodile species) in the Ganges river and the Mekong catfish, Irrawaddy dolphin and the Eastern Imperial Eagle in Mekong River in Asia are at a higher risk of plastic litter with the rivers contributing an estimated 2,00,000 tons of plastic pollution to the Indian Ocean and the Pacific Ocean every year.
The findings are highlighted in a new report “Risk assessment of plastic pollution to migratory species in the Mekong and Ganga River Basins”, prepared under the UN’s Convention on the Conservation of Migratory Species of Wild Animals (CMS). In the report, the authors state that both river basins are home to 605 species protected under CMS including freshwater species, land animals, and birds. Many of them are listed as threatened or endangered by the IUCN, it added.
RISK
The report concludes that in the Asia-Pacific region discarded fishing gear is a particular threat to migratory species.
Ganges: The Ganges River Dolphin is at high risk of entanglement in fishing lines, especially in gillnets. Ingestion of micro plastic is an additional threat. The Gharial, a crocodile species, is likely to become entangled in fishing nets where fisheries overlap with its habitat. It is Critically Endangered.
Mekong: It is estimated that the critically Endangered Mekong Catfish and the Mekong River subpopulation of the Irrawaddy Dolphin face lethal threats from entanglement and ingestion of plastic. Drowning because of entanglement in nets is the key threat to Irrawaddy Dolphins that are estimated to number less than 100 individuals. The Mekong Catfish is considered a flagship species for the conservation of the lower Mekong ecosystem. It is long-lived, matures late, and is a long-distance migrant. This makes it even more vulnerable to human disturbances such as plastics and dams.
RAPTORS AT THE HIGHEST RISK AMONG BIRDS
In the Ganges, the Greater Spotted Eagle is threatened and may die from ingesting litter and by entanglement. The report pointed out that the Eastern Imperial Eagle in Mekong may suffer lethal injuries upon ingestion and entanglement in plastic. Water birds such as the Greylag Goose, Common Shelduck, Gadwall, Northern Pintail, Common Teal, Red-crested Pochard and Tufted Duck may interact with plastic in the environment. In some cases, waterbirds ingested plastics including micro plastic, the report noted.
Waders such as the Black-tailed Godwit, Eurasian Curlew, Marsh Sandpiper, Common Greenshank, Green Sandpiper and Temminck’s Stint can become entangled where line fishing occurs.
Among terrestrial species, Asian Elephants have been observed ingesting plastic while raiding dump sites for food. The impacts of ingestion by elephants, however, largely remain unknown.
RECOMMENDATION
- Upstream reduction of plastics in the commerce stream through industry and government regulations, incentives, and practices.
- More effective product design, waste management and recycling.
- Include the reduction of plastic pollution in conservation measures for migratory species.
- Need for more research on the impacts of plastics on terrestrial and freshwater species
- Education campaigns and programs to raise awareness among citizens.
PLASTIC LITTER IN THE MEKONG RIVER BASIN
A study projected that about 221,700 tons of plastic entered Tonle Sap basin between 2000 and 2020. The study projected that 282,300 + 8700 tons will enter the basin between 2021 and 2030.
PLASTIC LITTER IN THE GANGA RIVER BASIN
There are few published studies, which focus on plastic pollution within the Ganga River. However, it is estimated that Brahmaputra and Meghna rivers collectively (GBM), could release up to 1-3 billion micro plastics into the Bay of Bengal every day. Ganga basin, with an area of 860,000 sq. km, is sprawling across 11 states of India. The major cities such as Delhi, Kolkata, Kanpur, Lucknow, Patna, Agra, Meerut, Varanasi and Allahabad are situated in the basin which is expanding rapidly. The amount of mismanaged waste from these urban areas into this river system is extensive.
THE REPORT
Convention on the Conservation of Migratory Species of Wild Animals Executive Secretary Amy Fraenkel in the foreword said that the report examined the health risk posed by plastic pollution in the Ganges and Mekong River basins to twenty-three fresh water, terrestrial and avian species protected under CMS.
“It also presents a framework for estimating the risk of plastic pollution to species within freshwater and terrestrial ecosystems. It currently relies on the best available data from the Asia-Pacific region but can be improved on as additional research is conducted,” she said.
Fraenkel said: “This study confirms that plastic pollution is adversely impacting migratory species in fresh water and terrestrial settings. It provides an important tool to assess potential risk on such species that can be used globally.”
On the threats, she said that Mekong Giant Catfish and Irrawaddy Dolphin in the Mekong River basin are at high risk from entanglement with plastic, and the Irrawaddy Dolphin is also at moderate risk from plastic ingestion. In the Ganges River basin, the report concludes that the Ganges River Dolphin and Gharial are at high risk from entanglement with plastic, and the Ganges River Dolphin is also at medium risk from plastic ingestion. It further found that in the Asia-Pacific region, discarded fishing gear in freshwater ecosystems is a particular threat to migratory species, she said.
The report maps plastic hotspots and assesses the risk of plastic pollution on migratory species in the Ganges and Mekong River basins which are protected under CMS. It focuses on the impacts of plastic pollution on freshwater and terrestrial species – which has been significantly understudied.
