Exotic species are, by definition, non-originating species that have never been recorded as occurring naturally in a particular location. Also known as alien species, currently in our rivers there are numerous fish species that were introduced by man and that there they found the conditions to survive and to proliferate with success..
In the Guadiana river basin, there are already 14 exotic fish species compared to the 11 naturally occurring ones. In addition to direct competiton for space, food and oxygen, these species predate native eggs, juveniles and adult fish, undemining their survival.
In addition to populating rivers and streams, exotic fish occur in abundance in dams, as they are more adapted to standing waters. However, when there are discharges from these systems, these species pass into the natural watercourses that are the preferred habitat of native fish and compete with them and may lead to their extinction.
Thus, one way of trying to protect the native fish populations in rivers is to reduce the quantity of exotic fish in the waterways, especially in the lotic sections, trying to restrict them to the masses of still water. With the objective of demonstrating that it is possible to reduce the flow of exotic species from artificial lentic systems, such as dams, to the natural water lines, a demonstration device was built in the Tasnal dam (Loulé county).
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Considering that dams are one of the main points of promotion of exotic species and that the proliferation of these species is one of the threats to native fish fauna, this is one of the measures implemented by the LIFE Saramugo Project with a view to safeguarding and protecting the native ichthyofauna, where the saramugo is inserted. In turn, given the experimental character and depending on the success of this measure, it may in the future be replicated in other places, becoming a good practice implemented by other entities in controlling the dissemination of exotic predatory and competing species in natural habitats.
