Fish-Passage Facilities as Ecological Traps in Large Neotropical Rivers

Abstract:  At present most of the large rivers of South America are impounded. Management plans historically have relied on the construction of fish passages, specifically ladders, to mitigate the impact of these waterway blockages on fisheries and biodiversity. Nevertheless, the design of these facilities is not ecologically sound and they are not monitored continually. Consequently, the real role of South American fish passages in fisheries and biodiversity management is unclear and the results of some studies suggest that ladders are problematic in fish conservation. We examined the characteristics and negative aspects of fish passages within a larger context and considered the notion that these facilities are ecological traps in some Brazilian impoundments. Four conditions are required to characterize a fish passage as an ecological trap: (1) attractive forces leading fish to ascend the passage; (2) unidirectional migratory movements (upstream); (3) the environment above the passage has poor conditions for fish recruitment (e.g., the absence of spawning grounds and nursery areas); and (4) the environment below the passage has a proper structure for recruitment. When these conditions exist individuals move to poor-quality habitats, fitness is reduced, and populations are threatened. To exemplify this situation we analyzed two case studies in the upper Paraná River basin, Brazil, in which the four conditions were met and migratory fish populations were declining. If passages work as ecological traps, regional fisheries will be in danger of collapse and conservation policies toward biodiversity will become more difficult and ineffective. The situation demands the closing of the passage in conjunction with alternative management actions to preserve system functionality, especially the conservation of critical habitats downstream and the restoration of damaged habitats in the region.     

Brazilian Experience in the Joint Development of Energy Resources

On the basis of the Brazilian experience, the author reviews the relevant aspects of negotiation between countries for the development of joint energy projects, as well as forms of organization and distribution of their respective costs and benefits. The factors which lead to a successful agreement between the parties were harmonious relations between the countries involved, willingness to negotiate, the ability to make concessions, a real interest in the project, whether for local consumption or for export, and the availability of technical and financial resources on the part of at least one of the partners. En se basant sur l'expérience faite par le Brésil, l'auteur passe en revue les aspects significatifs des négotiations entre pays pour la mise en valeur de projets énergétiques conjoints. Il etudie également les modes d'organisation et de distribution des coûts et avantages respectifs de ces projets. L'auteur cite les facteurs suivants qui dans le passé ont conduit à un accord satisfaisant entre les parties: relations harmonieuses entre pays concernés, désir de négocier, pouvoir de faire des concessions, intérêt réel porté au projet (qu'il soit conçu pour la consommation domestique ou l'exportation), moyens techniques et financiers de la part, au moins, d'un des partenaires. Basado en la experiencia brasileña, el autor pasa revista a los aspectos importantes en la negociación entre países para el desarrollo conjunto de proyectos de energía, así como sobre las formas de organización y distribución de los costos y beneficios. Los factores que condujeron a una negociación fructífera fuerion la relación armoniosa entre los países, deseo de negociar, disposición a hacer concesiones, interés real en el proyecto y la disponibilidad de tecnología y capacidad financiera en por lo menos uno de las partes.