A decade of ecological recovery
This summer marks a significant date: ten years ago a hidden camera in the Tenes river captured a historic image, the first to show the presence of an otter in the Besòs-Tordera basins. That snapshot, recorded in 2014, symbolized a victory for biodiversity, after years of absence of these mammals in the metropolitan region, where they had disappeared in the mid-1980s due to indiscriminate hunting.
A past marked by persecution
The historical context reveals that a Franco law, the Ley de Alimañas, allowed the hunting of animals considered harmful, including the otter. Sònia Sánchez, a technician at the Rivus Foundation, recalls that the last specimen captured was displayed as a trophy in a bar in Breda. The reintroduction of these animals began in the early 2000s, and was not a spontaneous process, but required a conscious effort to restore river populations.
A controlled expansion
After the first reintroductions in the Muga and Fluvià basins during the 1990s, otters began to explore new territories. Researchers recorded footprints in the Congost and Tordera rivers as early as 2004, but it was in 2014 that photographic evidence was documented in the Tenes. Based on a research project started in 2018, the habitats and diet of this mammal have been analyzed, revealing its adaptability in humanized environments.
Indicators of ecological health
The presence of the otter is a signal that indicates the quality of aquatic ecosystems. Experts point out that this species, considered a bioindicator, is a reflection of the health of fish communities. Its diet includes fish, amphibians and birds, and it has been observed to make significant nocturnal movements in search of food and shelter, often in quieter areas of rivers.
A promising future
Currently, the estimate of the number of otters in the Besòs basin varies between 10 and 15, while in Tordera they are close to 25 individuals. The Rivus Foundation continues to work throughout the year to monitor the behavior of this mammal and identify the necessary conditions to ensure its permanence in Catalan waters. Sònia Sánchez emphasizes the importance of providing the right spaces to guarantee not only the survival of the otter, but also that of many other species.
A challenge for the environment
The task of conserving the otter and its habitats does not end here. It is essential to maintain water quality and improve the conditions of river ecosystems. The presence of this mammal is a positive indicator, but work must continue to ensure that these waters remain a refuge for biodiversity. The future of the otter and, by extension, many other animals depends on the collective effort to preserve our rivers.
