Endangered Nude-bream, Gymnocharacinus bergii.

The Nude-bream (Gymnocharacinus bergii) is a strictly endemic fish of Patagonia-Argentina. Distributional range of this fish is restricted to the Valcheta stream, an 80 km watercourse.

However, the Nude-bream only live at the beginning´s of this watercourse, because geothermal conditions of these sites. This stream is placed at the Somuncurá plateau in Río Negro Province. The beginning of the Valcheta stream has higher temperatures than other watercourses in the region. The Nude-bream is an habitat specialist with a strait range of thermal requirements for their life cycle, and for this reason these fishes only occur isolated, at some places of this stream. Several factors such as habitat fragmentation and the construction of irrigation channels for human activities are contributing to the degradation of the habitat for this species. However, one of the most important threats are the presence of two introduced fishes that predates on this bream, the rainbow trout (Oncorhynchus mykiss) and the brook trout (Salvelinus frontalis). Because their critical status, the Nude-bream was declared as endangered species by IUCN. However, at present moment, some population parameters remain unknown and management actions are needed in order to assure the long lasting viability of its populations.

This project attempts to protect Nude-bream populations by: a) the study of some ecological features (habitat requirements, occupancy, abundance and population structure) and effects of main threats in order to assess the viability of its populations, b) educational activities, in order to promote the conservation of this species and its habitat by local community and, c) the use of the information gathered during this project to give advice and to promote a conservation action plan for Nude-bream and Valcheta stream.