740,000 km of fishing lines and 14 billion hooks are lost every year
Two percent of all fishing gear used worldwide ends up polluting the oceans, according to our new research. To put that into perspective, the amount of longline fishing gear that litters the ocean each year can circle the Earth more than 18 times.
We surveyed 450 anglers from seven of the world’s biggest fishing nations, including Peru, Indonesia, Morocco and the United States, to find out how much gear is entering the world’s ocean. We found that at current loss rates, 65 years from now there would be enough fishing nets littering the sea to cover the entire planet.
This lost fishing gear, called ghost gear, can cause serious social, economic and environmental damage. It is estimated that hundreds of thousands of animals die every year from unintentional captures in fishing nets. Abandoned nets can continue to fish indiscriminately for decades.
The results of our research help highlight where to focus efforts to stem the tide of fishing pollution. It can also help inform fisheries management and policy interventions from local to global scales.
14 billion longline hooks litter the sea every year
The data we collected came directly from the fishermen themselves. They face this problem directly and are in the best position to inform our understanding of fishing gear losses.
We surveyed fishers using five main gear types: gillnets, longlines, purse seines, trawls, and traps and pots.
We asked them how much fishing gear they used and lost each year, and what gear and vessel characteristics could make the problem worse. This included the size of the vessel and gear, whether the gear contacts the seabed and the total amount of gear used by the vessel.
We coupled these surveys with information on global fishing effort data from commercial fisheries.
Anglers use different types of nets to catch different types of fish. Our research has revealed that the amount of nets that litter the ocean each year include:
- 740,000 kilometers of main longline lines
- nearly 3,000 square kilometers of gillnets
- 218 square kilometers of trawls
- 75,000 square kilometers of purse seines
In addition, fishermen lose more than 25 million pots and traps and almost 14 billion longline hooks every year.
These estimates only cover commercial fishing and do not include the amount of fishing line and other gear lost by recreational anglers.
We also estimate that between 1.7% and 4.6% of all plastic waste on land ends up in the sea. This amount likely exceeds lost fishing gear.
However, fishing gear is designed to catch animals and is therefore generally considered to be the most environmentally damaging type of plastic pollution in research to date.
Harm fishermen and marine life
Nearly 700 marine species are known to interact with marine debris, many of which are Near Threatened. Research from Australia and the United States in 2016 found that fishing gear posed the greatest entanglement threats to marine wildlife, such as sea turtles, marine mammals, seabirds and whales.
Other marine animals, including sawfish, dugongs, hammerhead sharks and crocodiles, have also been known to become entangled in fishing gear. Other problematic items include balloons and plastic bags.
The loss of fishing gear is not only an environmental risk, but it also has an economic impact for the fishermen themselves. Each meter of net or line lost represents a cost to the fisherman, not only to replace the gear, but also to his potential catch.
In addition, many fisheries have already undergone significant reforms to reduce their impact on the environment and improve the sustainability of their operations.
Some losses are attributable to the way the gear is used. For example, bottom trawls – which can snag on reefs – get lost more often than nets that do not come into contact with the seabed.
Ocean conditions can also make a significant difference. For example, fishermen have often reported that bad weather and overcrowding contribute to gear losses. Conflicts between contacting gears can also lead to gear losses, for example when towed nets cross drifting longlines or gillnets.
When fish are depleted, anglers have to work harder, operate in worse conditions or locations, and are more likely to come into contact with other people’s gear. All of these features increase casualties.
What do we do about it?
We actually found lower levels of fishing gear loss in our current study than in a previous review of the historical literature on the subject. Technological improvements, such as better weather forecasts and better marking and tracking of fishing gear can reduce loss rates.
Incentives can further reduce losses from phantom equipment. This could include buy-back programs for end-of-life fishing gear, low-cost loans for replacement nets, and port bins to encourage fishers to return used fishing gear.
Technological improvements and management interventions could also make a difference, such as gear marking and tracking requirements, as well as regular gear maintenance and repairs.
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Developing effective fisheries management systems can improve food security, leave us with a healthier environment, and create more profitable businesses for the fishers who operate there.
This article is republished from The Conversation under a Creative Commons license. Read the original article.