Anguillicolosis among silver eels: A 2-year survey in 4 habitats from Camargue (Rhône delta, south of France)

• Main Authors: Lefebvre, F., Acou, Anthony, Poizat, G., Crivelli, A.
• Other Authors: Institut de biochimie et génétique cellulaires (IBGC), Université Bordeaux Segalen - Bordeaux 2-Centre National de la Recherche Scientifique (CNRS), Pôle OFB-INRAE-Institut Agro-UPPA pour la gestion des migrateurs amphihalins dans leur environnement (MIAME), Université de Pau et des Pays de l'Adour (UPPA)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Office français de la biodiversité (OFB)-Institut Agro Rennes Angers, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Patrimoine naturel (PatriNat), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Office français de la biodiversité (OFB), Station Biologique de la Tour du Valat
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: Anguilla anguilla; Anguillicola crassus; swimbladder; Infection; parasite pressure; Pathology; Spawning migration; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere
• Online Access: https://hal.science/hal-04611082; https://doi.org/10.1051/kmae:2003039

International audience We have investigated the spread of the infection by Anguillicola crassus among the silver phase of the European eel Anguilla anguilla in the Rhône delta. We reported values of prevalence, mean intensity and abundance in 4 habitats and we revealed negative relationships between these parasitic parameters and values of salinity (prevalence from 52 % in brackish waters to 77 % in fresh waters). We have also assessed the health state of the infected organ, i.e. the swimbladder. This may be a way to check the parasitic history of individuals throughout their continental phase. In silver eels free from parasites, the proportion of past infected individuals was ranged between 40 % and 78 %. When adding individuals showing worms at the autopsy with those showing signs of past infection(s), we highlighted a great proportion of silver eels really affected by anguillicolosis (from 71 % to 95 %, with a negative relationship in respect to salinity values). So, considering the spread of the infection, and its potential impairments on body condition, gas exchanges, hydrostatic abilities, etc., one may legitimately question about the proportion of silver eels that may get back to the Sargasso sea and reproduce.