What’s bottom trawling, the new flashpoint between India-Sri Lanka, and why it’s still rampant in India

While India has seasonal bans on trawling and adheres to international guidelines that prohibit ‘destructive fishing activities’, it is still rampantly practised by Indian fishermen.

Representational image of fishermen preparing to set sail on the east coast of Tamil Nadu | ANI

New Delhi: Since the start of this year, the Sri Lankan Navy has arrested 69 Indian fishermen for trespassing in the waters of Palk Bay, the stretch of ocean between the island country and Tamil Nadu. It also impounded 10 mechanised boats used by the fishermen for bottom trawling, a commonly used method of fishing in the Bay of Bengal and India in general. 

According to an analysis by the Central Marine Research Fisheries Institute, in 2021, 52 percent of India’s total fishing catch came from trawl nets, but countries like Sri Lanka, Indonesia and Madagascar have banned the practice altogether for environmental reasons. 

“Bottom trawling disrupts the seabed, impacts ocean biodiversity, and leads to overfishing of non-target species,” Abhilasha Sharma, senior programme associate of the Sustainable Fisheries programme at Dakshin Foundation, told ThePrint. 

While India has, since 2014, issued certain conditions such as seasonal bans on trawling and adheres to international guidelines that prohibit ‘destructive fishing activities’, trawling is still rampantly practised by Indian fishermen. This isn’t the first time Indian fishermen have been apprehended for fishing in Sri Lanka’s Exclusive Economic Zone (EEZ), with 240 of them having been arrested last year.

ThePrint explains what bottom trawling is, how it’s ecologically harmful, the alternatives for it, and the reasons it still persists in India. 

What is bottom trawling and why is it harmful

Bottom trawling entails a fishing net being dragged across the bottom of the seabed, thus capturing marine animals inhabiting the bottom of the ocean like shrimp, octopus, and halibut. These animals are called demersal species, as they live and feed at the ocean’s bed. Most mechanical trawlers have conical nets attached to them, dragging at the speed of 1-7 kilometres per hour. 

“While in other forms of fishing, you can see the fish and target which ones you want to catch, bottom trawlers are intensive and don’t differentiate between the target species and others,” explained Sharma, quoted earlier. 

The extra species that get caught in the nets are known as bycatch and are either thrown back into the ocean or used to make fertiliser or fish meal. According to Sharma, bycatch makes up 40% of the total marine catch in the world annually. “In some places, depending on the size of the vessel and the area, bycatch is around 80 percent of the total catch,” she added.

Trawling also results in the uprooting of marine flora from the ocean bed. A 2017 study published in the Proceedings of the National Academy of Sciences Journal shows that mechanical trawlers, depending on their size, can deplete between 6-41 percent of the biota in the ocean every time they pass. As compared to parts of the ocean where trawling is rampant, other parts have more biodiversity, more organic matter content, and more species diversity, shows another study published in the same journal in 2014. 

Another major consequence of the nature of bottom trawlers is that because they ‘desuspend’ the bottom layer of sediments and flora on the ocean floor, they deprive certain fish of their food. The rampant overfishing and excessive bycatch also ensures the lack of availability of prey for carnivorous fish. Studies have shown how continuous trawling in an area results in poor food quality for fish, rendering them weak. 

“Marine animals often stay in different depths of the ocean depending on their life cycle — juveniles might stay deeper in the ocean and travel higher as they get older. If they are trawled in their juvenile stage or during the breeding season, it depletes their numbers,” said Sharma. 

Aside from the disruptions to the ocean bed, another ecological problem caused by bottom trawling is the release of carbon dioxide from the ocean floor. A seminal study published in Nature in 2021 found that bottom trawling is responsible for 1 gigaton of CO2 emissions annually — more than the entire aviation industry released in the year 2019, which is 918 million tonnes. 

Why do fishermen continue trawling?

In India, one of the reasons bottom-trawling continues to persist is because of the historic push for this form of fishing. The central government has offered subsidies for mechanised trawlers, engines and fuel to fishermen since the first five-year plan in 1951. Aside from the Indian government, organisations like the Food and Agriculture Organization (FAO) of the United Nations also provided training programmes for fishermen in Odisha to learn new forms of bottom trawling. 

Even as late as 1980, when countries like Indonesia enforced a ban on bottom trawling along its Malacca Straits, the Indian government was working on the Bay of Bengal Programme to encourage fishermen to adopt a new form of trawling called ‘high-opening bottom trawling’. 

Phasing out bottom trawling would require time and effort. “The government sees it as a question of livelihood, how can you suddenly ask fishermen to abandon their main source of income and disrupt the local economy?” says Aditya Shivamurthy, associate fellow at the Observer Research Foundation (India and South Asia). 

According to the Central Marine Research Fisheries Institute census of 2016, there are 30,772 mechanised trawlers in India. One such vessel can cost between Rs 25 lakh to Rs 1 crore, apart from maintenance and diesel costs. “Fishermen often find themselves stuck in a position where they can’t get out of trawling even if they want to. They have loans, and economic obligations that force them to continue,” said Dakshin Foundation’s Sharma.

A 2023 report by the Institute of Oceans and Fisheries, University of British Columbia, Canada, looks at the various reasons why Indian fishermen took up and continued bottom trawling. From economic debts to increasing demand for shrimp and other demersal species, the study explains why some fishermen are unable to give it up, while others choose it for profits. 

Trawling prohibitions in India and the world

The United Nations Convention on Biological Diversity (UNCBD) mentions in Article 10 that all parties must ensure sustainable use of their biological resources. The United Nations Convention on the Law of the Sea states that while States can utilise their marine resources, they should keep in mind sustainable yield and conservation measures. Neither of these documents explicitly mentions bottom trawling. 

In India, there are temporary bans on fishing in the Exclusive Economic Zone (EEZ) for a few months during the monsoon, to let the fish breed. In 2014, the ‘Guidelines for Fishing Operations in Indian Exclusive Economic Zone’ passed by the Department of Animal Husbandry, Dairying, and Fisheries expressly prohibited deep-sea vehicles in the EEZs from practising ‘bottom-trawling, bull-trawling or pair trawling’. 

“There also needs to be proper implementation of the existing laws to be able to control bottom trawling. Surveillance mechanisms and monitoring of trawling vessels should be carried out,” said Venu, programme manager for the International Collective in Support of Fishworkers, a non-profit. 

Unlike India, Sri Lanka’s ban on bottom trawling extends across its waters and doesn’t just cover EEZs. One of the main reasons cited by Sri Lanka for capturing Indian fishermen is trawling, which is illegal, on their waters. 

“The official reason might be trespassing, but Sri Lanka has stressed that Indian fishermen use trawlers on their waters, which both impacts their catch and also has a much larger environmental impact on their ecosystem,” said ORF’s Shivamurthy. 

Alternatives to bottom trawling

There are ways to mitigate the ecological impact of bottom trawling that don’t necessarily involve outright bans. Some organisations and governments have been working to innovate less harmful ways of bottom trawling, by changing aspects such as the nets’ mesh size. A 2023 study published in the Marine Policy journal suggests the ways in which alternative gear and alternative catch stimuli or bait can help reduce the carbon footprint of trawling. 

“Since the trawl nets carry so much bycatch, some modifications like increasing the mesh size might help some of the juvenile fish and non-target species to escape,” said Sharma. 

In recent years, the government too has started to implement measures to take people away from this extractive form of fishing. The Blue Revolution Scheme by the Department of Fisheries (2015) and the Pradhan Mantri Matsya Sampada Yojana (2020) are two schemes that aim to replace trawling boats of Indian fishermen with deep-sea fishing boats. Deep-sea fishing involves techniques like gill nets and tuna longlining which are both targeted methods of fishing and don’t touch the seabed. As of 2022, 800 such deep-sea boats have been given to fishermen in Tamil Nadu, according to a Lok Sabha reply in 2022. 

According to Dakshin Foundation’s Abhilasha Sharma, efforts to introduce sustainable fishing in India should include multiple stakeholders. “Any form of fishing, if overdone, is exploitative on the environment. The problem isn’t entirely with the fishermen either — the processors, consumers, and government are all liable to develop a system that isn’t intensive and still productive enough to match demand.” 

(Edited by Gitanjali Das)