PROJECT DESCRIPTION
BACKGROUND
The asper (Zingel asper) is a fish species, listed on Annex II of the Habitats Directive, which only occurs in the Rhone catchment. It is about 15 to 20 cm long and lives in clear, oxygen-rich waters with gravel bottoms. Because of its secretive nature, scientific knowledge about the asper is still poor. The fish is sedentary and territorial and hides at the bottom of the water during the daytime, where it is almost invisible thanks to its excellent camouflage. At the beginning of the century the asper occurred throughout the entire Rhone catchment, i.e. over a length of 1,700 km. Currently its distribution is only over 380 km at most and the total population is estimated at between 2,000 and 4,000 individuals, divided between various genetically isolated subpopulations. The reasons for this decline are connected to hydraulic engineering works like dams, which are impassable barriers to the asper and isolate populations from each other. The pollution of rivers and changes to their flow dynamics as a result of pumping out water for agricultural purposes have also led to severe degradation of the asper's habitat.
OBJECTIVES
This project sought to boost populations of aspers at 6 sites and to facilitate the colonisation of former sites. Besides improving knowledge about the biology and ecology of the species, the project was to establish emergency procedures in the event of a threat to asper habitat. It was also planned to:
make modifications to hydraulic engineering works to allow the fish to pass through ; set up a centre to breed the species in captivity to permit the feasibility of captive breeding and to permit, if relevant, to re-introduce fish by releasing such captive-bred specimens in the main appropriate site to augment naturally-occurring populations ; produce a technical manual for the management of aspers and their habitats to integrate the conservation of these fish into watercourse management schemes ; organise an international symposium at the end of the project on the asper family, which includes three other species endangered in Europe.
RESULTS
The overall aim of the project was to stop the decline of the asper, an endemic species of the Rhone catchment. Despite the good results of the project, the species situation did not improve during the project but there was a significant progress regarding scientific knowledge and species management. Moreover, captive breeding and reproduction is now well mastered, allowing for future population reinforcement or reintroduction in the wild. The main results are:
The knowledge improvement of the species: before the project, causes for the species decline were almost unknown. The main threats and needs of the species have now been identified, allowing the future implementation of concrete actions on the field. The census of Asper populations have been made to estimate the size of the various population nuclei and to eventually confirm the presence of the species on project sites. The Beaume site population has been particularly studied. It enabled to understand the mechanism of seasonal survival, recruitment and spatial distribution of the species. Interconnections between the different population nuclei appeared to be crucial for the species' survival. A genetic characterisation of the population has also been carried out, based on 187 fishes from 11 nuclei and 6 different rivers. This study revealed differences between the various sub-populations studied and they should thus be considered as distinct conservation units. Some works have also permitted to characterise the preference of the species in terms of habitat according to the different phases of its life cycle. The most suitable habitat corresponds to a 20-40 cm water level on stony or sandy river bottom, and a stream flow >0,2 m/s. Several sites present such characteristics in the old Rhone, the Donzère and the Drôme river. The publication of a guide for the management of the species and its habitat. This guide was intended to managers and administrators with the objective of integrating Asper issues in all projects or plans relating to rivers. 600 copies have been distributed. The guide gathers the knowledge acquired on the species and provides tools for the conservation and management of the species. The success of the captive breeding and reproduction of the species: At the end of the project, 200 aspers were bred in a centre and used for various studies. The project did not foresee any reintroduction in the wild but the feasibility of such an operation has been studied and the main parameters to take into account have been identified (reintroduction sites, origin and age of reintroduced individuals…). The awareness campaign that was carried out, using various media such as the TV, videos, the press, the Internet, seminars, exhibitions, booklets… Thanks to the project, the species is not unknown anymore.
