Site icon Conservation news

Illegal bottom trawling widespread inside Mediterranean marine protected areas

Trawlers lined up in the port of Termoli, on the east coast of mainland Italy. Over the last three years, some trawlers based at Termoli fished in the Tremiti Biological Protection Zone, about 25 miles to the east, Global Fishing Watch data shows. Image ©Francesco Cabras / MedReAct.

  • A new “atlas” reveals widespread illegal bottom trawling inside Mediterranean marine protected areas.
  • The atlas, an interactive online map, shows thousands of days of apparent bottom-trawling activity in areas where it is banned, in 2020 and 2021.
  • Bottom trawlers can damage the seabed, destroy coral and sponge habitats, and catch unintended species at a high rate.
  • The findings demonstrate “the lack of enforcement and transparency in the Med, which is the most overfished sea in the world,” an atlas coordinator told Mongabay.

The Mediterranean Sea isn’t the source of plenty it once was. It now contains some of the most ecologically degraded marine areas in the world, and has been the site of dead zones and fish stock collapses in recent decades. Populations of countless species are in decline, including sharks, seagrasses and marine mammals. The sea is “on the verge of ‘burn out,’” WWF has declared.

Overfishing and destructive fishing practices, including bottom trawling, are part of the problem. Bottom trawlers drag fishing nets weighted down with heavy “doors,” and they often damage the seabed, destroying coral and sponge habitats, and catch unintended species at a high rate. Conservationists have pushed the creation of marine protected areas (MPAs) and no-trawl zones, but these are only effective if managed and regulated well, and reports in recent years have indicated that, in the Mediterranean, this isn’t the case.

Now the Med Sea Alliance (MSA), an umbrella group of NGOs and environmental advocates, has launched an “atlas” showing widespread illegal bottom trawling in the Mediterranean. The atlas, an interactive online map, shows thousands of days of apparent bottom-trawling activity in areas where it is banned, in 2020 and 2021. The atlas uses data from transponders that fishing vessels carry, as well as 169 confirmed infractions based on coast guard records and media reports.

“It’s the first time such an atlas [has been] released,” Anne Rémy, MSA’s movement coordinator, told Mongabay. “It can appear like a very scientific map, but behind this map, you have a very interesting story about the lack of enforcement and transparency in the Med, which is the most overfished sea in the world.”

Rémy stressed that the marine areas in question were especially ecologically sensitive.

“We are seeing the worst cases that could happen. Because it’s not bottom trawling [just] anywhere, it’s bottom trawling in areas which should really be protected,” she said.

Coralligenous habitat in the Mediterranean Sea. Such habitats are typically found at depths between 40 and 250 meters (roughly 130 to 820 feet). Image © Thodoris Tsimpidis / Archipelagos Institute of Marine Conservation.

The findings

The atlas, which MSA released in a soft launch in June before the official launch in early November, comprises two interactive sections: one for “presumed” cases of bottom trawling inside closed areas, and the other for “confirmed” cases.

The “presumed” cases section shows that, during 2020 and 2021, 305 different vessels likely trawled in 35 of the 350 areas closed to trawling that MSA studied. Collectively, the vessels conducted 9,518 days of presumed trawling activity in those areas during the two-year period.

These figures might not reveal the full scale of the problem. The atlas is built on geolocation data from automatic identification systems (AIS) that many vessels don’t use consistently, Tony Long, the CEO of Global Fishing Watch (GFW), a nonprofit that publicly tracks fishing activity, said in a press release. GFW, an MSA member organization, collected the AIS data used in the atlas.

While only 10% (35 out of 350) of studied areas had apparent violations, these tended to be larger areas more suitable for trawling, according to Luca Marsaglia, a GFW fisheries analyst.

To try to ensure that only bottom trawling activity appeared in the atlas, GFW cross-checked the AIS data against EU fleet registration data that shows vessels’ primary fishing gear. However, this data-filtering method was not foolproof, Marsaglia said: some of the included vessels also have registered secondary gear, which may be what they used in some cases inside the protected areas. (GFW has highlighted the vessels with secondary gear in the atlas’s tables.)

The effort to build the atlas revealed a lack of transparency regarding trawling infractions. MSA member organization MedReAct, a Rome-based NGO, had to trawl through media archives in five languages to discover the 169 “confirmed” infractions in the atlas. MedReAct requested information from national control authorities, such as coast guards, but only those in France and Italy complied. Even then, the data from France were aggregated and not usable for this iteration of the atlas.

And so, as with the “presumed” cases, the 169 “confirmed” cases represent only “the tip of the iceberg,” Eleonora Panella, who contributed to the atlas as a senior adviser at MedReAct and has since left the organization, told Mongabay.

Unlike the “presumed” cases, the exact locations of the “confirmed” cases aren’t visible on the map, because many of the media reports used by MedReAct failed to provide exact locations.

According to a statement provided to Mongabay by a spokesperson for the European Commission, the executive branch of the European Union, the number of “confirmed” cases in the atlas “demonstrates that the EU Member States take their control responsibilities very seriously.” The EC has proposed strengthening controls and geopositioning rules for vessels, the statement said. Recently, the European Fisheries Control Agency, which performs enforcement and inspections, has “beefed up” operations, deploying a patrol vessel in the Mediterranean, the statement said. The spokesperson declined to be named, citing EC policy.

The stern of a trawler at port in southern Spain in 2019, showing a pair of heavy metal “doors,” which bottom trawlers drag along the seabed. Image © Enrique Talledo / Oceana.

Paper parks, real consequences

To coincide with the atlas launch, MedReAct published a report on bottom trawling activities in two protected areas in the Italian Adriatic Sea. MedReAct cites these as two examples of Italy’s “paper parks”: MPAs and no-trawl zones where authorities don’t enforce the rules on the books.

In the Tremiti Biological Protection Zone (ZTB), roughly 24 kilometers (15 miles) off the east coast of mainland Italy, trawling is banned for seven months out of the year; but this is only “on paper,” the report says. GFW data show significant presumed bottom trawling activity during the closed periods over the last three years: more than 200 days of trawling in total, covering the entirety of the ZTB. (This activity does not appear in the atlas, which includes only trawling activity in areas where it’s banned year-round.)

In an accompanying video, small-scale fishers confirm the trawling activity in the Tremiti ZTB, where juvenile hake and other species aggregate, and discuss its impact.

“We’re collapsing, not just suffering — we’re in intensive care,” Luigi Attanasio, a local small-scale fisher, says in the MedReAct video. “In this biological protection zone, there is a lot of trawling. Fishing boats go in one after the other.

“This biological protection zone exists only on paper, like many other Italian laws,” Attanasio says. “This is just one more to add to the pile.”

Hake (nasello in Italian), used in this baby food product, is one of the targets of trawlers in the Tremiti Biological Protection Zone. Image by kiliweb via Open Food Facts (CC BY-SA 3.0).

As bad as the situation may be in Tremiti, the report shows the level of illegal trawling is even higher some 240 km (150 mi) to the northwest, in the Barbare ZTB. Twenty-five vessels apparently trawled in the Barbare ZTB in 2020 and 2021, for a total of 507 fishing days. (This data does appear in the atlas, in the “presumed” section, because the Barbare ZTB is permanently closed to trawling.)

The 25 vessels are relatively small — mostly between 20 and 30 meters (about 65 to 100 feet) — which is common for trawlers in the Mediterranean, including those identified in the atlas. These types of vessels have limited storage space and usually take fishing trips of only one to two days, though there’s a growing contingent of larger shrimp trawlers, mostly from non-EU Mediterranean countries, that stay out for weeks at a time, according to Domitilla Senni, president of MedReAct.

Neither the Italian Coast Guard nor a spokesperson for a new industry group, European Bottom Fishing Alliance, responded to a request for comment for this article.

Annalisa Lisci, a small-scale fisher in the Tremiti Islands, on her fishing boat. “This is an area that should support the spawning of some species, but in reality, it is not controlled as much as it should be,” she says in a video released by MedReAct. Image ©Francesco Cabras / MedReAct.

A lack of control

The atlas builds upon a recent series of reports and studies showing that the Mediterranean’s MPAs, and Europe’s more broadly, are not restricting trawling as intended.

A 2018 study in the journal Science found that most of the 700 EU MPAs it analyzed were industrially trawled — indeed, that trawling activity was higher inside MPAs than in unprotected waters. In a 2019 report, WWF found that while 9.68% of the Mediterranean had been designated as MPAs, only 1.27% was covered by effectively managed MPAs, and only 0.03% was fully protected from commercial fishing. In 2020, the European Court of Auditors found that the EU’s protected areas “provide limited protection in practice.”

In 2022, a study in Frontiers in Marine Science found that “high-risk” fishing, primarily bottom trawling, was “widespread” in EU and U.K. MPAs, and that “without systematic restrictions on damaging fishing gears, MPAs are unlikely to help reverse the ongoing declines of European marine habitats.”

In October, BLOOM, a Paris-based marine conservation NGO, issued a report showing that almost half of the industrial fishing in French waters, including in the Mediterranean, occurs within MPAs. Behind the “idyllic” image of marine conservation put forth by the French government, MPAs are systematically exploited by industrial fishing, the reports says.

“The result of our investigation is unequivocal … so-called ‘protected’ marine areas have no impact on industrial fishing,” the BLOOM report says.

BLOOM has been part of a campaign for stricter trawling laws in the North Atlantic that made progress in September when some deep-water trawling was banned there. In the Mediterranean, similar campaigns are underway. Environmental advocates say they’re encouraged by the “30×30” target — to protect 30% of the sea with effectively managed MPAs by 2030, and 10% from all commercial fishing — that Mediterranean countries set at a meeting in December 2021.

If compliance and transparency problems are severe in European waters, they are even more pronounced elsewhere in the Mediterranean.

The EU requires vessels longer than 15 m (about 50 ft) to use AIS transponders, but non-EU countries on the Mediterranean don’t, so most of the presumed cases in the atlas are in the northern and western sections of the sea. (Another reason most of the activity in the atlas is in the north and west: The southern and eastern Mediterranean also has fewer areas permanently closed to trawling.)

Not only do some trawlers working in the non-EU Mediterranean not use AIS, but some fail even to use the vessel monitoring system (VMS), according to Senni of MedReAct. VMS is a geolocation monitoring system used by national fisheries authorities that’s already required for all vessels larger than 15 m long in the Mediterranean, per a General Fisheries Commission for the Mediterranean (GFCM) regulation. VMS data is not publicly available, and is therefore considered less useful than AIS for international accountability and transparency purposes, but is an important compliance tool for national authorities.

In its press release, MSA called for all Mediterranean countries to adopt a 15-m AIS rule and measures to improve VMS tracking at a GFCM meeting in Albania in November. However, no AIS or VMS measures that apply to the entire Mediterranean were formally considered. Delegates to the meeting did pass tighter VMS regulations for certain fishing vessels in three particular areas of the Mediterranean, according to Vanya Vulperhorst, a campaign director at the global marine conservation NGO Oceana.

A trawler off of Malta in 2009. Image by KNOW MALTA by Peter Grima via Flickr (CC BY-SA 2.0).

Banner image: Trawlers lined up in the port of Termoli, on the east coast of mainland Italy. Over the last three years, some trawlers based at Termoli fished in the Tremiti Biological Protection Zone, about 25 miles to the east, Global Fishing Watch data shows. Image ©Francesco Cabras / MedReAct.

Correction 11/30/22: The original version of this story described Eleonora Panella as a senior adviser at MedReAct. We have updated the story to reflect that fact that she has since left that position.


Dureuil, M., Boerder, K., Burnett, K. A., Froese, R., & Worm, B. (2018). Elevated trawling inside protected areas undermines conservation outcomes in a global fishing hot spot. Science, 362(6421), 1403-1407. doi:10.1126/science.aau0561

Gomei, M., Abdulla, A., Schröder, C., Yadav, S., Sánchez, A., Rodríguez, D., & Abdul Malak, D. (2021) [original 2019]. Towards 2020: How Mediterranean countries are performing to protect their sea. WWF. Retrieved from

Perry, A. L., Blanco, J., García, S., & Fournier, N. (2022). Extensive use of habitat-damaging fishing gears inside habitat-protecting marine protected areas. Frontiers in Marine Science, 9, 811926. doi:10.3389/fmars.2022.811926

Listen to Claire Nouvian of BLOOM discuss the effects of bottom trawling:

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