Genetic status of pure Mediterranean Brown trout populations
The Mediterranean trout is an emblematic fish of Mediterranean regions that is seriously threatened due to hybridization with Atlantic trout introduced for fishing, the advance of climate change, and the degradation of river ecosystems.
In this study, we reveal that in the rivers of the Catalan Pyrenees, only 10.4% of its populations remain genetically pure, while the rest show varying levels of hybridization. The historical range of territories inhabited by trout populations has decreased by more than 60% in recent years, but even more concerning is that the area occupied by native populations has shrunk by nearly 90%. To halt this decline, we propose identifying and protecting the populations that still retain their original genetics, actively managing river sections by removing hybrid trout and reintroducing pure individuals, and better regulating human activities to ensure adequate flow levels. We also emphasize the importance of recognizing the Mediterranean trout as a distinct species and classifying it as “Endangered” on the IUCN Red List, since under current Spanish legislation these populations are included within Salmo trutta, a species considered of “Least Concern,” which limits their protection. Overall, these actions are essential to safeguard the evolutionary uniqueness of the Mediterranean trout and preserve the biodiversity of Mediterranean rivers.
Access to the journal: https://onlinelibrary.wiley.com/toc/10990755/2025/35/12
Open access to the full study: https://doi.org/10.1002/aqc.70269
