ANSE and WWF release 70 eels into the Mar Menor

The eels were tagged before release and will now be monitored as part of a long-term conservation project

The idea of eels being released into the Mar Menor might not sound especially appealing, but it is an important step in protecting the species. They were returned to the lagoon by environmental group ANSE, working alongside WWF and the San Pedro del Pinatar Fishermen’s Guild.

The Mar Menor has always been home to European eels, but their numbers have dropped dramatically over the years, which is why fishing is tightly controlled. The eel fishing season only runs from December 1 to January 15 and from March 1 to 31, with a maximum catch of 25 tonnes. This is enough to allow fishing, but still gives the eels a chance to survive and migrate. 

Once the first fishing period ended on January 15, ANSE and WWF added 70 carefully tagged eels back into the lagoon. The idea is to help the species grow, give them a safe start on their long journey to the Atlantic, and track them along the way as part of a long-term conservation project.

The European eel is now listed as Critically Endangered by the International Union for Conservation of Nature. Not so long ago, just a century or so, it was common in rivers and irrigation channels across Europe. Today, it has disappeared from many waterways in south-east Spain. Over the years, dams and canals have broken up its habitats, wetlands have been degraded, overfishing has taken its toll, invasive species have moved in, and climate change is adding another layer of pressure. All of this makes it harder and harder for eels to move freely and complete their life cycle.

Coastal lagoons like the Mar Menor are important for the European eels. Calm waters like the Mar Menor give them a safe place to feed and grow.

The situation has gotten so serious that experts are now recommending zero eel catches in 2026, for every stage of their life. Recreational fishing is already banned, and professional fishing in the Mediterranean faces extended closures.

The GePescArt-2 project, backed by Spain’s Biodiversity Foundation and co-funded by the EU, started this phase in 2024 but continues work ANSE began back in 2017.

Over the years, researchers have been tracking eels to see where they still survive and where populations have disappeared. Using tags and small acoustic transmitters, they can follow the eels’ movements within the lagoon and sometimes even further. In some cases, this tracking has confirmed adult eels leaving the Mar Menor to begin an incredible 6,000-kilometre journey back to the Sargasso Sea, in the middle of the North Atlantic near the Caribbean.

European eels play an important role in keeping rivers and lagoons healthy. They feed on insects, small fish, and other creatures, and in turn provide food for birds and larger fish. If they disappeared, it would upset the whole balance of these wetlands, affecting plants, fish, and wildlife that depend on them.

Images: ANSE