An optimized whole-body corticosteroid hormones quantification method by LC-MS/MS for assessing stress levels in European glass eels (Anguilla anguilla).

The European eel (Anguilla anguilla) juvenile stage exhibits facultative estuarine migration. The causes of this behavior are yet unknown but it may have an impact on the population's fate by altering the sex ratio of the population. Recent studies have highlighted potential stress-related issues in glass eels settling in estuaries but studying stress response in small organisms requires sensitive, accurate and precise analytical methods.

A psychiatric drug found in waste-water plant effluents alters the migratory behavior of critically endangered Anguilla anguilla juveniles.

Migratory fishes cross or settle in several environments potentially polluted. Psychiatric drugs, which represent one growing pollution and are found in discharges from waste-water treatment plants, may alter individual behaviors. Here, we assessed behavioral alterations in the upstream migratory behavior of Anguilla anguilla caused by diazepam, an anxiolytic.

Realistic variations in substrate composition affect spawning preference and egg retention in river lamprey (Lampetra fluviatilis).

Egg drift from the nest is clearly an important cause of mortality in lithophilic species, but the effect of substrate composition on this process has been overlooked. Here, we investigated the role of substrate on the spawning preference and egg retention of river lamprey (Lampetra fluviatilis) during a whole breeding season in a two-option experimental setting. Despite no initial preference, the lamprey eventually favoured the most efficient substrate for egg retention.

Individual and group characteristics affecting nest building in sea lamprey (Petromyzon marinus L. 1758).

Nest building relates to reproductive effort, sexual selection, intersexual conflict and cooperation and may be linked to individual phenotype and interindividual interactions. In particular, larger individuals having more energy reserves are expected to build more, larger nests, without having to trade intrasexual competition for cooperative nest building. Capture-mark-recapture and nest survey of sea lamprey (Petromyzon marinus L.