When you picture a marine protected area, you might think of a diverse ecosystem where fish, sharks and corals thrive in a healthy, protected habitat. You probably don’t imagine industrial fishing operations scraping the depths of the ocean with large trawling nets.
But using data from Global Fishing Watch and the World Database of Protected Areas, we found that in 2016, the three most trawled marine protected areas (MPAs) in the world were in the European Union. Fishing vessels spent over 930,000 hours trawling MPAs off the coasts of the Netherlands, Italy and Spain.
The practice of trawling, one of the most damaging types of fishing, uses large cone-shaped nets to catch fish at the bottom or mid-water of the ocean. These methods are notorious for unintentionally catching turtles, marine mammals and other species besides fish. When trawling nets scrape the bottom of the ocean, they also destroy critical marine habitats and corals. Yet while the practice is destructive, it’s not illegal: We found only 14 percent of the world’s 3,900 MPAs prevent fishing and drilling.
A recent paper published in Science and led by Manuel Dureuil, a Ph.D. student at Dalhousie University, used Global Fishing Watch data and found that 60 percent of the EU’s MPAs are being industrially fished with trawlers. Dureuil’s team found that on average, the 700 MPAs they looked at in the EU are being trawled even more than unprotected areas.
Trawling fishing methods are notorious for unintended bycatch.
Which MPAs Were Trawled the Most?
Global Fishing Watch tracks ships and fishing methods (e.g. trawling, longline) using automatic identification systems from GPS-like trackers onboard fishing vessels. Using the Global Fishing Watch data hosted on Resource Watch and the World Database of Protected Areas, we saw how much time countries spent trawling in MPAs.
Here are the MPAs where countries spent the most time trawling in 2016:
Wadden Sea & North Sea Coast
Two MPAs on the northern coast of Netherlands, Wadden Sea and the North Sea Coast, were heavily trawled in 2016. The two areas make up a large coastal wetland home to 2,700 marine species, including grey seals, herring, harbor seals and harbor porpoises. Wadden Sea is such a unique environment that it has been listed as a UNESCO World Heritage Site since 2009.
Using Global Fishing Watch data, we found that ships spent more than 547,000 hours trawling these areas in 2016.
Pelagos Sanctuary for the Conservation of Marine Mammals is located off Italy’s western coastline. The marine sanctuary was trawled for 230,000 hours in 2016. Established in 2001 and jointly managed by Italy, Monaco and France, the Sanctuary is intended to protect several species of marine mammals, such as whales and dolphins. Two such species, fin whales and striped dolphins, are the most commonly observed.
The delta of the Ebro River forms a large wetland area in the western Mediterranean. According to the Atlas of Marine Protected Areas, this region is “one of the most important feeding areas for seabirds in the Mediterranean.” Fin whales and bottlenose dolphins reside there, as well as several species of fish. Ships trawled the area for more than 152,000 hours in 2016.
The Impact of Unrestricted Trawling
Trawling produces negative impacts on the very species MPAs are supposed to protect. Dureuil and colleagues found that populations of sharks, rays and skates decreased by 69 percent in heavily trawled areas.
Research published in 2016 points out that some MPAs have trawling bans, but many don’t restrict it and don’t have the management plans and enforcement needed to prevent trawling. Led by Italian researchers, the paper points out that a lack of enforcement is why the Pelagos Sanctuary is not effective at protecting whales and dolphins in the Mediterranean.
MPAs are still an important tool for conservation, but in order to be successful, they need to have the right policies in place as well as enough staffing and funds.
The world’s $190 billion seafood industry depends on healthy fish habitats, but damaging fishing practices and over-exploitation threatens the sustainability of the industry and marine ecosystems. The transparency provided by Global Fishing Watch and open data on Resource Watch can help provide the information needed for better decision making.
Explore Global Fishing Watch data, including trawling data, on Resource Watch.
Methods note: This analysis only looked at protected area polygons where all of the area is within the marine environment, as defined by the WDPA. The analysis used Global Fishing Watch data for 2016 and only included protected areas established before 2016. View the Google Earth Engine Code to see how we did the analysis.