Ghost fishing gear threatening aquatic life in the Ganges
by Sahana Ghosh
December 24,2020
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The endangered Ganges river dolphin and species of threatened freshwater turtle and otter are wildlife “most at risk” from getting tangled up in waste fishing gear adrift in the transboundary Ganges river system, research has said.
Scientists associated with the Sea to Source expedition carried out a biodiversity threat assessment of Gangetic wildlife species most at risk from entanglement in abandoned, lost, or otherwise discarded fishing gear in nine sampling sites along the river in Bangladesh coast in the Bay of Bengal to upstream in the Himalayas in Rishikesh.
“Waste and active fishing gear impact aquatic wildlife in similar ways, but what we know about them differs quite significantly. Generally, we know more about how entanglement in active gear (called “by-catch”) affects species because fishers encounter the animals more frequently while checking their nets, etc,” study author Sarah Nelms, University of Exeter, Cornwall, told Mongabay-India.
Although ingestion of debris can pose a risk to fauna, the threat assessment focused on entanglement because entanglement in plastic pollution, such as waste fishing gear, is known to cause mortality and injury in various aquatic vertebrate species. “This has clear welfare implications for the individual animals but may also cause declines in populations of species that are of conservation concern,” observed Nelms.
Twenty-one species of conservation concern, as identified by the Wildlife Institute of India, with ranges that overlap with the sampling locations, were investigated during river bank surveys in Bhola, Chandpur, Rajbari (in Bangladesh) and Sahibganj, Patna, Varanasi, Kannau, Anupshahr, Rishikesh (in India).
Three-striped roofed turtle (Batagur dhongoka), Ganges river dolphin (Platanista gangetica ), black-spotted turtle (Geoclemys hamiltonii), northern river terrapin (Batagur baska) and smooth-coated otter (Lutrogale perspicilata) were found to be most vulnerable to entanglement with, and impacts from, waste fishing gear.
Nelms underscored that since waste gear is not monitored and can move over large distances, humans don’t necessarily observe how it interacts with wildlife. This could lead us to underestimate the harm it causes, she said.
The Ganges river system (known as the Ganga in India and Padma and Meghna in Bangladesh) has been identified as one of the 14 continental rivers in the world into which over a quarter of global waste is discarded. It is considered the second-largest plastic pollution-contributing catchment in the world (0.12 million tonnes of plastic discharged per year).
The expedition researchers recorded the abundance, distribution and characteristics of waste fishing gear such as nets, ropes, string, floats and line along the river, complementing their surveys by speaking to fishers to understand the behavioural drivers that lead to waste fishing gear entering the environment.
Led by women scientists, this expedition is the world’s first ground-truthing effort to verify the quantum of plastic load that a freshwater body carries to the sea and substantiate theory as well as models proposed in research.
They found higher levels of waste fishing gear in sampling sites near the sea: likely due to the high prevalence of fishing activity at these sites combined with the downstream accumulation of waste gear from further up the river.
The study comes amid an increasing awareness on understanding what impacts plastic is having on species living in and around rivers. The United Nations Environment Programme Regional Office for Asia and the Pacific is implementing the Promotion of Action against Marine Plastic Litter in Asia and the Pacific (Counter MEASURE II) project that aims to generate, share and disseminate scientific knowledge on plastic pollution in the Mekong, Ganges and selected rivers in Sri Lanka and Myanmar to inform policy and decision-making processes at the local, national, regional and global level.
Parties to the Convention on Migratory Species adopted Decisions 13.122 – 13.125 and called for further research on this issue at COP13 of the Convention on Migratory Species, held in earlier this year in India, according to the Convention on Migratory Species.
The 2,525 km-long Ganga binds five Indian states along its main stem and 11 in her entire basin that is home to 625 million people. Despite its cultural and religious importance, the river has rapidly degraded since the 20th century due to human activities.
The Ganges River catchment supports some of the world’s largest inland fisheries but no research has yet been conducted to examine the input of debris from this industry.
Additionally, no studies have investigated the potential movement of abandoned, lost, or otherwise discarded fishing gear from rivers into the sea. By highlighting the most at-risk species, focused interventions, such as monitoring programs, can be developed to better understand the impacts and potential solutions, the authors emphasize.
Theme(s): Fishing Craft, Gear and Fishing Methods.
