PROJECT DESCRIPTION
BACKGROUND
The giant European pearl mussel (Margaritifera auricularia), also known as grande mulette and Spengler’s freshwater mussel, was once a common species in Western Europe, where it thrived in large, slow-flowing rivers from England, Germany and Spain, in the watersheds of the Adour, the Rhône and the Po. However, today only a few populations remain in some French rivers and the Ebro basin in Spain. The causes of this decline include the morphological degradation of rivers, habitat destruction, water pollution, overfishing, water extraction activities, fragmentation of populations and the near-extinction of its main host-fish European sturgeon (Acipenser sturio); parasitic larvae must develop on the gills or fins of host-fish until becoming free-swimming juveniles.
OBJECTIVES
The goal of the LIFE Giant Pearl Mussel project was the conservation of the critically endangered giant pearl mussel (Margaritifera auricularia) in France, specifically in the Charente, Vienne and Creuse rivers where up to 98% of the world’s giant pearl mussel population can be found. The project aimed to use artificial breeding and restocking of rivers as the basis for the species’ long-term conservation in Western Europe. It would thus help implement French and Spanish National Action Plans for this species. Project actions would also form part of the EU biodiversity strategy for 2020.
RESULTS
The LIFE_Giant_Pearl_Mussel projectconstructed a provisory and a mobile rearing station for the target species that were well conceived and proved to be easy to operate. It also helped improve knowledge of the historical range and the current occurrences of the species in France. For example, a previously unknown population in the Adour catchment area, along with two other unknown sub-populations on other rivers, were identified. The project also increased knowledge on the ecological requirements of the species. Greater understanding of the giant pearl mussel will benefit future conservation efforts.
The results of the project were documented on the homepage https://life.univ-tours.fr/ and in a 20 min video (https://www.youtube.com/watch?v=Fk0lADZ-XjM), which has won the award as the best academic documentary in France in 2018. A two-volume “The Giant Freshwater Pearl Mussel (Margaritifera auricularia) Handbook” has been edited on the biology and on the artificial rearing techniques and several scientific articles and brochures provide details about the results and make them freely accessible to scientists and conservationists. In summary, the rearing technique has been advanced and several efficient host fish species (other than sturgeon) were identified. Two mobile labs were built for fish inoculation and juvenile mussel rearing. 4000 juveniles were released into the Vienne River. Due to lack of timely cofinancing by the partner, the project was shut down by the end of 2018, interrupting the successful rearing and release of juveniles.
The French National Plan for the Conservation of the Giant Freshwater Pearl Mussel (now: Pseudunio auricularia) has been elaborated (https://www.consultations-publiques.developpement-durable.gouv.fr/IMG/pdf/pna2_grande_mulette_2022_2031_17_01_2022.pdf). The dredging of the mud that was menacing the largest extant population in the Charente has taken place in 2019. A project to re-use the mobile laboratory units for artificial rearing has been submitted. A monograph on the species, seniored by Keiko Nakamura, will be published in 2023.
