Invasive species and over-exploitation of water resources are the greatest threats facing freshwater fish in the Mediterranean basin.
An international team of scientists, led by the Forest Technology Centre of Catalonia, carried out the first large-scale study of the threats facing freshwater fish in the Mediterranean basin.
Miguel Clavero, lead author of the study and a researcher from the Landscape Ecology Group said: "The continental fish of the Mediterranean basin are one of the most threatened biological groups in the world."
The study examined the geographical pressures that had a negative impact on 232 endemic freshwater fish species and their distribution range – such as the Mediterranean barbel (Barbus meridionalis) and Bagre (Squalius laietanus) pictured above. The scientists calculated the number of fish species affected by each type of pressure in 10 square kilometre areas throughout the Mediterranean basin. The most severe pressures were pollution, water extraction, invasive species, reservoirs, agriculture and over-fishing.
By evaluating the conservation status of endemic continental fish species in the Mediterranean basin using International Union for the Conservation of Nature (IUCN) Centre for Mediterranean categories of threat, it was found that the Iberian Peninsula was one of the areas in which invasive species had the greatest impact on native fish.
Clavero says " are the leading causes of biodiversity loss among continental fish in the Mediterranean region." The results duplicate smaller studies carried out in various parts of the Mediterranean.
"We also have notorious examples in Spain of the negative effects of the over-exploitation of water resources, as is the case in the upper basin of the Guadiana (including the Tablas de Daimiel wetlands)," the scientist adds.
For more information see: Miguel Clavero, Virgilio Hermoso, Noam Levin, Salit Kark. Geographical linkages between threats and imperilment in freshwater fish in the Mediterranean Basin. Diversity and Distributions, 2010; 16 (5): 744 DOI: 10.1111/j.1472-4642.2010.00680.x