Efforts to protect the critically endangered European eel are intensifying across Europe and the UK, with conservationists prioritizing the removal of river barriers and the implementation of large-scale monitoring projects. Once a common sight in rivers, the European eel population has faced a dramatic decline since the 1980s, with reports citing population drops ranging from 70% to 97% over the last several decades.
Restoring Migration Routes Through Weir Removal
A primary obstacle to eel survival is the presence of physical barriers in river systems. In West Cumbria, the West Cumbria Rivers Trust has initiated a £50,000 project to dismantle a redundant weir at Glinger Burn near Longtown. According to the Trust, the weir has posed a significant risk to eels, which often struggle to leap over such structures, particularly when water levels are low. The project, funded by the Environment Agency, involves the use of heavy machinery to remove the obstruction, allowing fish to migrate up and down the river more easily. This focus on connectivity is mirrored in broader international efforts. In Italy’s Po River Basin, researchers participating in the LIFEEL project are constructing fish passages to defragment riverways. These interventions are designed to address the habitat loss caused by fragmented rivers, which, alongside drought, pollution, and climate change, continues to threaten the species’ survival.
Citizen Science and Monitoring Initiatives
To better understand and aid local populations, conservation groups are turning to citizen science. In the Kennet and Pang catchments, the Action for the River Kennet (ARK) is leading a project to monitor eel presence using passive habitat trapping. Such data-gathering is essential for the Thames Catchment Community Eels Project (TCCEP), which works with partners like the Zoological Society of London to coordinate action plans for the species. In Italy, researchers are similarly monitoring baby “glass eels” as they enter the Po River from the sea, noting that recruitment levels have seen a drastic decrease compared to previous years.
The Complex Life Cycle of the European Eel
Conservationists emphasize that the eel’s unique life cycle makes them particularly vulnerable to environmental pressures. All European eels are believed to hatch in the Sargasso Sea in the western Atlantic Ocean. Newly hatched larvae, known as leptocephali, drift on ocean currents for one to three years before reaching the continental shelf of Europe. The species’ reliance on both freshwater and saltwater habitats means they are exposed to varied threats throughout their lives, including illegal trafficking.
Challenges to Long-Term Recovery
Despite these conservation measures, the European eel remains classified as critically endangered
on the IUCN Red List. Beyond physical barriers and illegal fishing, researchers are still working to solve fundamental biological mysteries, such as how eels determine their sex and what specific triggers initiate their return migration. Because scientists cannot yet artificially breed freshwater eels, current efforts remain focused on habitat restoration, reducing anthropogenic threats, and protecting existing populations as they navigate their epic journey between European rivers and the Sargasso Sea.
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