Marine biologists diving in the Gulf of Thailand were thrilled in 2023 to rediscover several colonies of a rare type of ocean sponge once thought to be extinct in the wild. But their excitement quickly gave way to concern when they realized many of the Neptune’s cup sponges (Cliona patera) were entangled in discarded fishing gear.

“We rediscovered it conclusively in the Gulf of Thailand, but we’re losing them at a rate that means this could just be a blip in the entire story of this species,” Rahul Mehrotra, research director at the Aow Thai Marine Ecology Center, told Mongabay.

Spurred by the sponge’s plight, Mehrotra recently led a study that assessed the scale of the impacts of discarded or “ghost” fishing gear on Thailand’s marine species. The study, published in the journal Marine Pollution Bulletin, compiled data from more than 100 underwater surveys conducted between 2021 and 2023 at sites across the Gulf of Thailand and Andaman Sea, to the country’s east and west, respectively.

The teams of marine researchers and citizen scientists found 606 pieces of ghost gear across all the dive sites, amounting to more than 1,200 square meters (about 13,000 square feet) of netting and hundreds of meters of rope and fishing line. A wide range of species, from the hard corals that build crucial reef habitats, to crabs, marine snails and schooling and predatory fish, had perished in the abandoned equipment.

Among the victims were barracuda, groupers, batfish and porcupinefish, as well as branching corals and large predatory sea snails with ornate shells that readily got caught in netting. Although no sharks, rays or turtles were documented in the surveys, Mehrotra said an abundance of social media posts indicate such animals, including whale sharks, get entangled in Thai waters.

The magnitude of the impacts on invertebrates, a group often overlooked in studies in favor of economically valuable fish, was particularly eye-opening for Mehrotra. “The impact on the invertebrate community was drastic in terms of just the quantity of wasted marine life,” he said. Ultimately, he added, “an extinction is an extinction.”

Just as worrisome, the researchers regularly observed how the ghost gear creates a never-ending loop of entanglement, whereby trapped animals attract predators, which are in turn caught, only to attract more scavengers and predators, which are also caught. “We saw this regularly when we were there at a net. Imagine how often that happens when we’re not there,” Mehrotra said.

Isolated offshore sites, such as seamounts, shipwrecks or submerged pinnacles, tended to have more fishing debris than sites closer to shore, according to the findings. The authors say this indicates these sites urgently need better fisheries management to protect them from illegal fishing as well as from nets that drift in currents and accumulate there.

Abandoned or lost nets, traps, pots and fishing lines are often made of durable plastics that can persist for years or even decades, passively killing all manner of marine species. They not only pose a direct threat to biodiversity, but also jeopardize the sustainability of fisheries by needlessly killing commercially viable species. What’s more, as they break down over time, they contribute to the ocean’s growing burden of microplastic pollution.

Urgent measures needed

The findings are the most complete evidence to date of the massive extent of ghost fishing gear in Thailand’s waters, Mehrotra said. He urged rapid measures at both the grassroots and policy levels to address the problem. “We’ve shown this issue is more than site-specific. We can’t continue to ignore it.”

Mehrotra and his colleagues designed a simplified survey methodology that allowed them to train recreational divers to take part in the survey effort. This allowed for a large amount of data and sites to be sampled. “We were able to investigate the issue at a much greater scale [than before],” he said, adding that he hopes this efficient approach will be adopted by government agencies, such as Thailand’s Department of Marine and Coastal Resources, to ramp up their efforts to address the issue.

“Discarded fishing gear is one of the most critical threats to marine habitats and species in Thailand,” according to Thamasak Yeemin, a marine scientist at Ramkhamhaeng University in Bangkok, who wasn’t involved in the study. Thamasak welcomed the new findings as yet more evidence of the devastating toll of ghost gear, citing prior studies that found smothered corals suffering “tissue loss, diseases, fragmentation and bleaching.”

Mehrotra’s teams disentangled 98% of the discarded gear they encountered and brought it ashore. However, their efforts were a drop in the ocean compared to the global scale of the issue. The total volume of gear they retrieved across all 100 surveys amounted to far less than even the most conservative estimates of annual gear losses from a single fishing vessel.

Moreover, just 1% of the retrieved gear was suitable for recycling by Net Free Seas, the only fishing gear recycling initiative in Thailand. The remaining gear was deemed too heavily soiled with encrusting materials for automated recycling machines and was sent to municipal authorities for traditional waste disposal — most likely landfill or incineration.

Although the Net Free Seas program, led by the U.K.-based Environmental Justice Foundation (EJF), has to date recycled roughly 130 metric tons of old fishing equipment into new products like electronic components and vehicle parts, it’s rarely possible to recycle gear salvaged from the sea.

The stark recycling limitations and sheer mass of gear in the oceans underscore the need for solutions beyond cleanups, Mehrotra said. Preventing gear from entering the ocean in the first place is paramount. As he puts it: “Cleanups are always going to be a band aid on a gunshot wound.”

Momentum for policy change

Salisa Traipipitsiriwat, Southeast Asia plastic manager at the EJF and a co-author of the study, said surveys like these are the first step in understanding where the problem areas are so that solutions can be developed alongside fishing communities. At a higher level, she said, policymakers must create a sustainable framework for managing all plastics in Thailand, not just discarded fishing gear.

The World Bank’s 2024 policy guidelines for Thailand’s climate change resilience recommended the government boost its circular economy efforts, focusing on recycling and resource recovery. Momentum is also building around several pieces of legislation moving through parliament, including the Circular Economy Act and the Packaging Act, as well as global dialogue on the establishment of a new treaty to stop plastic pollution.

According to Salisa, a major hurdle is that Thailand’s current legislation is overly focused on downstream waste management. Authorities only have a mandate to collect and dispose of plastic waste, limiting the public’s influence on how plastics, including fishing gear, are made and limiting efforts to improve their sustainability.

“The laws don’t cover the full life cycle of plastics from production to disposal,” Salisa said, noting that Thailand would benefit from a framework similar to the extended producer responsibility regulations in Europe, which would hold manufacturers accountable for the entire life cycle of their products.

Another bottleneck, Salisa said, is the lack of incentives for recycling. Disposing of waste via landfill or incinerators is often cheaper in Thailand, she said: “Doing something greener and better for the planet is more expensive than just throwing waste away.” Management of fishing gear also falls across the jurisdiction of several government agencies, leading to a lack of coordinated action, Salisa added.

Overcoming these governance challenges will be a key part of the solution to addressing the tide of discarded fishing gear. In the meantime, the Global Ghost Gear Initiative (GGGI), an international alliance of fishing industry, NGOs, academics and government stakeholders united around the issue, recommend several measures. These include restricting the use of high-risk gear in certain areas or at certain times of year; marking and tagging fishing gear so it’s clearly visible and can be retrieved; establishing clear systems for monitoring and reporting used and discarded fishing gear; and improving disposal infrastructure.

“We need to have that foundation of policies and laws that give stakeholders and government agencies the power to regulate plastics within their mandates,” Salisa said. “Only then we can properly address the fishing gear issues.”

Banner image: A red emperor bream caught in a fishing net smothering a shipwreck off Thailand’s Rayong province. This fish was subsequently rescued by the survey team. Image courtesy of Aow Thai Marine Ecology Center (ATMEC).

Carolyn Cowan is a staff writer for Mongabay.

Citations:

Mehrotra, R., Monchanin, C., Desmolles, M., Traipipitsiriwat, S., Chakrabongse, D., Patel, A., … Jualaong, S. (2024). Assessing the scale and ecological impact of derelict and discarded fishing gear across Thailand via the MARsCI citizen science protocol. Marine Pollution Bulletin, 205, 116577. doi:10.1016/j.marpolbul.2024.116577

Richardson, K., Hardesty, B. D., Vince, J., & Wilcox, C. (2022). Global estimates of fishing gear lost to the ocean each year. Science Advances, 8(41). doi:10.1126/sciadv.abq0135

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