Underwater ghost-busting to save Indian coral reefs
Every day, hundreds of thousands of pieces of lost or abandoned fishing equipment haunt the world’s oceans, killing indiscriminately and endangering marine life and livelihoods.
As it drifts, this ghost fishing gear takes on a life of its own; trapping fish, entangling all kinds of animals from seabirds and turtles to dolphins and whales, and snagging or smothering coral reefs.
Kanniah Marimuthu is one of many fishers living in the Gulf of Mannar in southeast India who is concerned about the community killing more than it catches, and the impacts of ghost gear on future business.
“Coral reefs are important for our livelihood. While we are fishing near the reef area, unknowingly the nets fall on reefs and damage the corals,” said Marimuthu, who comes from a village near the coastal town of Tuticorin.
“If there is no live coral, fish will also move away from that area,” he said.
More than 640,000 tonnes of discarded ghost gear are added to the sea each year, according to a UN Environment and FAO report.
Nets without borders
“Ghost nets are another side of the marine litter problem,” said Gabriel Grimsditch, an expert in marine ecosystems at UN Environment.
“They are killing megafauna in the Indian Ocean and are a transboundary problem, because nets from India find their way to other countries in the region such as the Maldives and kill many iconic species such as turtles, rays and sharks,” he said.
The Gulf of Mannar, a 560 km/sq area of islands and surrounding shallow coastal waters, was declared a marine park in 1986 and had coral reefs covering 110 sq/km.
Today, the area of live corals has shrunk to around 80 km/sq. This is mainly due to destructive fishing practices and climate change-induced coral bleaching events such as the one in 2016 that caused 16 per cent of corals in the Gulf of Mannar to die, reducing coral cover by 23 per cent.
With corals already struggling from global stressors, removing local threats such as ghost nets in this reef-rich area is crucial for saving reefs, marine life and a healthy local economy.
“We know by experience that we can catch more fish only if there are live corals, so it is important to save the corals from such damage to get good catches and better our livelihoods,” said Marimuthu.
Ghost nets have already affected up to 12 per cent of branching corals in the area and damaged around a quarter of a 7.2-hectare site where intensive coral rehabilitation had taken place.
Members of Suganthi Devadason Marine Research Institute manually remove discarded and lost fishing nets entangled with coral both in the natural reefs and the rehabilitated coral reef sites. Photo by Suganthi Devadason Marine Research Institute (SDMRI)
Ghostbusters of the seas
But since 2018, a dedicated team from the Suganthi Devadason Marine Research Institute (SDMRI) have turned ghost-net ‘busters’ by policing the reefs for lost fishing gear.
“Through removal of ghost nets, we hope not only to help conserve corals but also to support the small-scale fishermen who depend mainly on the reef-associated fishery resources for their livelihoods,” said Patterson Edward, Director of the Suganthi Devadason Marine Research Institute.
“By helping local reefs, we also hope to make life better for all peoples who live along the coast and who rely on coral reefs to protect them from erosion,” he said.
As part of the Community of Ocean Action formed after the UN Ocean Conference in 2017 and more than 1,400 voluntary commitments made to save life below water, the Suganthi Devadason Marine Research Institute pledged to remove torn fishing nets from the reefs of the Gulf of Mannar.
“We are excited to be delivering this voluntary commitment under the Coral Reef Community of Ocean Action,” said Edward.
He is part of a team of nine marine scientists and three support staff in association with the Tamil Nadu Forest Department that has made great progress towards reaching its goal.
The team has carried out surveying, monitoring and restoration work in the Gulf of Mannar, including looking for ghost nets in around seven island areas in the southern part near Tuticorin.
Ghost nets can keep causing problems for years or even decades after they are lost or discarded by fishers. If not removed, this net would have killed this young coral, struggling to recolonize an area damaged by coral bleaching. Photo by Suganthi Devadason Marine Research Institute (SDMRI)
Net goals and losses
Of the 5.2 km2 reef area surveyed so far, the team has found 565 m2 affected by ghost gear, including nylon fishing nets (gill nets, pelagic nets and bottom set nets), lines and ropes, and plastics.
Torn nets from destructive fishing operations like shore seine, push nets and gill nets cause physical damage and mortality to corals by breaking the coral branches and destabilizing the community structure.
They also endanger the associated fish life and can kill the coral if they get caught on the reef or inhibit natural recovery processes by over time, attracting deposits of sediment and other debris that cause algae to spread.
“It’s not just plastic bags and bottles negatively impacting marine life and the blue economy; it’s estimated that by weight, ghost gear makes up between 46 to 70 per cent of all macro plastics in our ocean,” said Grimsditch.
Members of the Suganthi Devadason Marine Research Institute team are still carrying out surveys in the remaining reef areas and marking those affected with GPS coordinates. Once the surveys are complete, they will remove all the ghost nets from the reef areas.