Abstract
The last remaining population of European sturgeon (Acipenser sturio) lives in the Gironde-Garonne-Dordogne (France) catchment (GGD). Captive young individuals are released into the GGD hydrosystem each year, as part of a restocking programme. This study aims to assess the health status of juveniles A. sturio to current conditions in the GGD hydrosystem, to evaluate their capacity to survive and grow in a moderately anthropized ecosystems. 3-month-old farmed sturgeons were exposed for one month in experimental conditions that mimic the environmental conditions in the Garonne and Dordogne rivers, followed by five months of depuration. After one month of exposure, fish exposed to Dordogne and Garonne waters bioaccumulated higher levels of metals and persistent organic pollutants, displayed a reduced hepato-somatic index, and had depleted levels of lipids and glycogen content in their liver, when compared with the Reference group. However, metabolic and swimming performance, as well as the costs of swimming were not impaired. After the 5 months depuration, a significant decrease of K was observed for all exposure conditions. HSI also decreased with time. The overall health status and adaptive capacity of juvenile A. sturio appeared to be maintained over the experimental 6 months’ period. Juveniles of A. sturio seem to have the adaptive capacity to survive and grow in the GGD hydrosystem, after being released as part of a restocking programme.
Highlights
The European sturgeon (Acipenser sturio) is the most threatened migratory diadromous fish in Europe (IUCN, 2016)
Organic contaminants In all sediments, the sum of polycyclic aromatic hydrocarbons (PAHs) concentrations was higher than those of PCBs and organochlorine pesticides (OCPs) in which the concentrations were close to 0 ng. g− 1 (Table 1)
Regarding the pollutant accumulation in tissues and their physio logical and histological responses, it can be assumed that current contamination in the Gironde Garonne Dordogne (GGD) catchment is not likely to adversely affect European sturgeon juveniles in current water temperature and oxygen conditions
Summary
The European sturgeon (Acipenser sturio) is the most threatened migratory diadromous fish in Europe (IUCN, 2016). The last natural reproduction of the species was observed in 1994 (Rochard et al, 2001). 3 months old individuals becoming mature are released and ex pected to re-enter the GGD basin for reproduction in the decade. To protect and manage this species, it is essential to have more precise information on the risks and the environmental conditions faced by these released juveniles sturgeons in the GGD basin. PAHs (Vignet et al, 2014a; Marit and Weber, 2012; Claireaux and Lefranç ois, 2007), organochlorines (Bussolaro et al, 2012) and metals (Javed and Usmani, 2019; Turan et al, 2020) are known to induce oxidative stress, genotoxicity and histopathology changes which can result in develop mental defects, reduce aerobic metabolism and growth, as well as impairing reproduction
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