River Esva

The river Esva rises in the Sierra de Tineo, and when it reaches the town of Brieves it is joined by its main tributary, the Llourín, which flows into the Cantabrian Sea, between Cantón and L'Arena.

It is rich in fish (trout and salmon), is home to the largest population of otters in Europe and is surrounded by the Esva Gorges, a natural area declared a European Special Protection Area and of great natural beauty.

Plant life

The climax forests of this river basin are mainly oligotrophic coalfields. There is still some small woodland in the headwaters of some tributaries and in the area of the Esva gorges. However, the landscape is dominated by eucalyptus and pine plantations, as well as heathland and gorse. There are also good examples of chestnut groves, many of which are made up of old fruiting chestnut trees that have now been abandoned, and most of which are wood plantations. The rest of the landscape is made up of extensive mowed meadows and excellent farmland located on the riverbanks of the basin and on the less steep slopes.

The riparian forests, almost all of which are western alder groves, are relatively well preserved and good examples remain, such as at the mouth of the river.

Also of great value are the small extensions of strawberry groves that still survive on the rocky crests facing south, such as those located around Merás.

Wildlife

From the faunistic point of view, the loss of habitats due to the strong human transformation of the territory has led to the disappearance by regression of many vertebrate species.

Among the most significant, only the wolf maintains a certain presence in the basin, while populations of some wild artiodactyls persist, such as wild boar and roe deer.

The otter is in better conditions due to the refuges found on the riverbanks, which are in an acceptable degree of conservation, and due to the good availability of food resources present. This area is among the best for this species in the region as a whole.

In relation to the above, the good conditions of the river and tributaries of this basin are also evident in the excellent densities of trout, especially in its lateral streams, and in the acceptable situation of salmon in the basin. In the case of the latter species, it should also be noted that this situation has been achieved after a process of recovery and reconstruction of the population in recent decades, a unique phenomenon within the region's salmon rivers as a whole, where the trend has been towards a gradual decline in this species.