Despite deals, plans and bans, the Mediterranean is awash in plastic

  • The Mediterranean is considered to be one of the world’s most polluted bodies of water due to waste disposal problems in many countries bordering the sea, as well as the intensity of marine activity in the region.
  • There are several existing policies and treaties in place aimed at regulating plastics and reducing plastic pollution in the Mediterranean, but experts say more international cooperation is needed to tackle the problem.
  • Citizen science organization OceanEye has been collecting water samples to measure the amount of microplastics present in the surface waters of the Mediterranean.

MARSEILLE, France — Pascal Hagmann lowered a manta trawl — a ray-shaped, metal device with a wide mouth and a fine-meshed net — off the side of his sailboat and into the blue waters off the coast of Marseille, France. Then he motored around at 3 knots. The manta trawl skimmed along the surface, taking in gulps of seawater and catching whatever was floating inside it.

“Maybe there will be [plastic], maybe not, you never know,” Hagmann, founder and CEO of the Swiss citizen science NGO OceanEye, told me in September as he steered his 40-foot (12-meter) sailboat, Daisy. “It depends on the surface currents and also on the weather forecast.”

Pascal Hagmann, founder and CEO of the Swiss citizen science NGO OceanEye, deploying a manta trawl off the coast of Marseille, France. Image by Elizabeth Claire Alberts for Mongabay.

After 30 minutes, Hagmann and Laurianne Trimoulla, OceanEye’s communication manager, tugged the manta trawl back on board. They took it apart and inspected the net.

“This blue here definitely is one,” said Trimoulla, pointing with the end of a screwdriver at a small piece of plastic. “And then there is a film — packaging wrap.”

Back at harbor, Hagmann went below deck to look at the sample under a microscope. He gestured to the eyepiece. “Have a look,” he said.

I squinted through the lens. There was a collage of plankton, blue threads of plastic fishing line, and white and green plastic particles. Some of these were nurdles, raw plastic pellets used as feedstock to manufacture an array of plastic products, from drink bottles to plastic bags to car parts.

“This is the point that I think is really frightening,” Hagmann said. “This pollution is just everywhere.”

The Mediterranean is considered to be one of the most polluted bodies of water in the world, with hundreds of tons of plastic blowing into the sea, mainly from land, every single year. One study published in 2015 in PLOS ONE put the amount of plastic pollution in the surface waters of the Mediterranean on par with what’s found in the accumulation zones of the five subtropical ocean gyres, including a collection of debris in the North Pacific gyre that’s known as the Great Pacific Garbage Patch.

A number of governments and intergovernmental organizations are trying to address this issue with policies and treaties that would hold companies and nations responsible for the plastic they use, transport and discard. But as of yet, none of these efforts seem to be stemming the tide of plastic steadily pouring into the Mediterranean.

A manta trawl deployed off the side of OceanEye’s sailboat, Daisy, in September 2021. Image by Elizabeth Claire Alberts for Mongabay.

‘Plastic trap’

About 20% of the plastic swirling around the Mediterranean comes from the vessels that crisscross the sea year-round, as well as from fishing and aquaculture activities, according to a 2018 WWF report. The other 80% comes from the land, the report says. Mercedes Muñoz, who manages activities related to plastic pollution at the IUCN, a global conservation authority, said the land-based plastic pollution is largely due to inconsistent waste management schemes.

“The collection of municipal solid waste is still a significant issue in most south Mediterranean countries,” Muñoz told Mongabay in an interview via phone and email. “Only a few countries have reached full waste collection coverage.”

For instance, one study found that Lebanon, which has 225 kilometers (140 miles) of Mediterranean coastline, only properly disposes of 48% of its waste. The rest is dumped outside landfills or burned, and as a result, much ends up in the sea. A 2018 NPR report even found that developers in Lebanon have been deliberately dumping thousands of tons of trash into the sea as a way to reclaim land from the ocean.

Turkey is known to be the biggest contributor to plastic pollution in the Mediterranean, allowing about 144 metric tons to enter the sea every day, according to the WWF report.

Trash piled on a beach in Algeria. Image by Belgueblimohammed2013 / Wikimedia Commons (CC BY-SA 4.0).

Once plastic has entered the Mediterranean Sea, it tends to stay there because of the sea’s semi-enclosed shape and the currents that only move water out via a deep-water layers. It’s a “plastic trap,” as the WWF report puts it.

Plastic will also change shape, breaking into smaller and smaller pieces. Any fragment smaller than 5 millimeters, about three-sixteenths of an inch, is considered a microplastic. Some of these microplastics will remain in the surface waters, while others will drift through the water column, travel with the currents and settle on the seafloor.

“The concentration [of plastic pollution] in the Med is pretty bad,” Lucile Courtial, executive director of Monaco-based NGO Beyond Plastic Med, told Mongabay in a phone interview. “If we don’t act on it, it will [become] much worse.”

A 2020 report released by the IUCN, to which OceanEye contributed data, suggests that the Mediterranean has already accumulated nearly ​​1.2 million metric tons of plastic. A recent United Nations report says that 730 metric tons of plastic waste end up in the Mediterranean Sea every single day, and that plastic could outweigh fish stocks in the near future. However, some experts say there is an ongoing need for more data to understand if plastic pollution in the Mediterranean is increasing or decreasing.

The WWF report also suggests that plastic pollution is costing the EU fishing fleet about 61.7 million euros ($70.7 million) every year because of a “reduction in fish catch, damage to vessels or reduced seafood demand due to concern about fish quality.”

Trash piled on a beach in Rhodes, Greece. Image by Pxfuel (CC0 license).

‘Gaps in the whole chain’

One of the most rigorous agreements in place to address the global issue of plastic pollution is the Basel Convention, the U.N. treaty formulated in 1989 to regulate the international shipment of hazardous waste. In 2019, an amendment to the Basel Convention added plastic to the other kinds of waste the convention regulates, with changes scheduled to take effect in 2021.

Rolph Payet, executive secretary of the Basel, Rotterdam and Stockholm conventions, said the amendment allows countries to holds companies accountable for any plastic they transport or trade through the enactment of national laws and norms.

“We identify gaps in the whole chain because some people are saying, ‘Yes, we are disposing, we are doing very well,’” Payet told Mongabay in September at the IUCN Congress in Marseille. “But then we find the bottles in the ocean, right? So this will help to narrow down where the problems are and help … companies be more accountable in terms of their waste.”

However, a major gap in the effectiveness of the Basel Convention is the fact that the United States has not yet joined the Basel Convention, despite being a major exporter of hazardous waste, including plastic, worldwide. Right now, the U.S. is the only major nation that has not implemented the Basel Convention.

Payet said that the U.N. plans to use OceanEye’s data, as well as other global data sets, to help establish a baseline for the amount of plastic in the Mediterranean that can be used in the future to determine if the Basel Convention is having a positive impact on the regulation of plastic. However, he added that it may take a few years before these effects can be seen since countries are still working to implement the new rules.

Another policy aiming to address the issue of plastic pollution in the Mediterranean is the Regional Plan on Marine Litter Management (RPML), which was adopted by contracting parties to the Barcelona Convention, including the European Union, in 2013. In short, the plan legally requires parties to “prevent and reduce marine litter and plastic pollution in the Mediterranean” and to remove as much existing marine litter as possible.

Microplastics mixed with organic matter in the net of a manta trawl. Image by OceanEye.

Then there’s the European Union’s recent ban on many kinds of single-use plastics, including cotton bud sticks, cutlery and beverage stirrers, as part of the EU’s transition to a “circular economy.” When EU member states cannot ban these items, they need to implement an “ambitious and sustained reduction,” according to the directive.

But are countries abiding by these policies and enforcing them? Courtial said these are tricky questions to answer.

“In general, we need regulations and guidelines and these kinds of treaties so that countries actually try to [achieve] the goals that are there,” she said. “The main problem … is that there is no real way of enforcing the countries to actually respect it, and implement the different actions or activities.”

Courtial added that it’s difficult to coordinate an effort between the 22 countries bordering the Mediterranean Sea, especially as the countries are in different stages of economic development.

“Some of the countries have more problems trying to feed their people, so dealing with plastic waste is really not a priority,” she said. “That’s what makes it really difficult.”

Experts are placing a lot of hope in a possible U.N. treaty that would legally require parties to address the entire life cycle of plastics, from production to disposal.

Muñoz says this treaty would be a “great step forward and very needed” since there needs to be more international cooperation on the issue.

“We always say that the Earth is just one big ocean,” she said. “What happens on one side will probably have some impact on another part. So we need international commitments that are aligned and they’re working together to reduce the problem.”

But the U.N. treaty has yet to come to fruition — and it is also not clear how effective it would be at stopping plastic from spilling into the Mediterranean.

Hagmann looking at a microplastic sample through a microscope. Image by Elizabeth Claire Alberts for Mongabay.

‘That’s why we carry on’

While research shows that the Mediterranean holds a considerable amount of plastic, some experts say more data is needed to fully understand the complexities of the issue. For instance, Hagmann said there’s still not enough data to understand how plastic pollution is dispersed across the Mediterranean and how the levels of pollution might change over time.

The need for this data is what motivated Hagmann to repurpose his recreational sailboat to become a citizen science vessel 10 years ago, and start cruising through the Mediterranean with a manta trawl to collect samples from the water’s surface. He also recruited a network of volunteers operating 10 other vessels to gather additional plastic pollution data, not only in the Mediterranean, but also in the Arctic and Atlantic.

Hagmann, who has an engineering background, says OceanEye’s mission is to contribute data to intergovernmental organizations that are monitoring plastic pollution and actively working on solutions. Already, OceanEye’s data have been used by the European Commission, United Nations and the IUCN in their databases and reports.

Hagmann and his volunteers focus on surface trawls, using the sampling protocol formulated by environmental scientist Marcus Eriksen, co-founder of the California-based plastic pollution research institute 5 Gyres.

Microplastic samples ready to be processed at OceanEye’s lab in Geneva. Image by OceanEye.

In June and July, Hagmann and a small crew sailed Daisy around the Adriatic Sea, taking some data samples near coastlines and others in open water, depending on weather conditions and cargo routes. Then, in September, immediately following the IUCN Congress in Marseille, the OceanEye crew sailed through the central Mediterranean to collect additional samples. So far, only the samples from the Adriatic expedition have been processed at OceanEye’s lab in Geneva.

Hagmann said the processed samples contain “particularly high concentrations of plastic” of more than a million particles weighing 1,000 grams per square kilometer, or about 91 ounces per square mile. But the final results, he said, still need further interpretation and analysis by outside experts.

“We provide the data … and then it’s [out of] our hands,” said Trimoulla of OceanEye. But she said she’s optimistic that the organization’s work will have a positive effect, arguing that the more data they provide to various bodies, the bigger the impact these bodies can muster.

“That’s why we carry on,” she said. “We have to.”


Alessi, E., & Di Carlo, G. (2018). Out of the plastic trap: saving the Mediterranean from plastic pollution. Retrieved from WWF Mediterranean Marine Initiative website:

Boucher, J., & Billard, G. (2020). The Mediterranean: Mare plasticum. Retrieved from IUCN website:

Cózar, A., Sanz-Martín, M., Martí, E., González-Gordillo, J. I., Ubeda, B., Gálvez, J. Á., … Duarte, C. M. (2015). Plastic accumulation in the Mediterranean Sea. PLOS ONE, 10(4), e0121762. doi:10.1371/journal.pone.0121762

Mediterranean Action Plan and Plan Bleu. (2020). Retrieved from United Nations Environment Programme website:

Banner image caption: Trash-filled plastic bags in the ocean. Image by SMR / Pixahive (CC0 License)

Elizabeth Claire Alberts is a staff writer for Mongabay. Follow her on Twitter @ECAlberts.

FEEDBACK: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.