Two threatened species of fish that inhabit the Odelouca river in Silves have received a welcome boost to their numbers, courtesy of environmental organisation Quercus as part of the ‘in situ’ project.
About 600 young fish have been set free after being reared in captivity and now are swimming freely along the Odelouca river in the Alferce area of Monchique.
Quercus said that the fish belong to the critically endangered species of ‘Boga do sudoeste’, more correctly known as Iberochondrostoma almacai and the Escalo-do-Arade, or Squalius aradensis.
The fish rescue project has been underway since 2008 and aims to reproduce and maintain populations of some of the most threatened freshwater fish species in Portugal.
Reproduction of captured fish is carried out at the Vasco da Gama Aquarium in Oeiras, and at the Campelo Aquaculture Station in Figueiró dos Vinhos, managed by Quercus.
At the end of the breeding cycle, the restocking of baby fish is carried out in those sections of home rivers where the breeding stock was captured to increase the chances of a favourable environment and survival for the tiddlers.
The project is led by Quercus, Vasco da Gama Aquarium, Marine Biology Research Center (MARE-ISPA) and Faculty of Veterinary Medicine, with partners such as Câmara de Figueiró dos Vinhos and the region’s water company, Águas do Algarve
How to spot these rare fish:
The Boga-do-sudoeste’ has an elongated, narrow body of a light brown color with a grayish hue. It has large eyes, a small head, arched mouth, and the same sized dorsal and anal fins, with the dorsal rounded. It can reach 15 cm in length.
The Escalo-do-Arade is small with an elongated but tall body, small but wide head with round profile. The mouth is subterminal. The dorsal fin profile is straight and the anal fin profile is convex, with 8 branched rays on the dorsal fin and 7 on the anal fin.
The in situ project is a response to the fact that Portugal’s waterways are under severe pressure with many subject to extreme degradation. The combined effects of industrial discharge, excess nutrients and long dry periods, has been devastating for many river organisms.
At the same time, invasion of weeds is putting some species at risk, contributing to the threat of extinction.
Emergency measures have been set in motion for five fish species including the two listed above plus the Western Ruivaco (Achondrostoma occidentale), the Portuguese Boga (Iberochondrostoma lusitanicum), and the Escalo-do-Mira (Squalius torgalensis) along with three plants: the Algarvian narcissus (Narcissus willkommi), the four-leaf clover (Marsilea quadrifolia) and the small, flowerless fern, Pilularia minuta.
In 2008, a partnership was set up between the Vasco da Gama Aquarium, the Higher Institute of Applied Psychology, the Faculty of Veterinary Medicine of the Technical University of Lisbon, Quercus, Energias de Portugal and the Figueiró dos Vinhos Municipal Council in order to carry out ex situ conservation to preserve these species.
The breeding programme is managing successfully to maintain and reproduce specimens and in this second phase, the rivers are being repopulated with endangered fish and plants.
Boga do sudoeste (Iberochondrostoma almacai)
Escalo-do-Arade (Squalius aradensis)
