Spawning areas and migration patterns in the early life history of <i>Squalius cephalus</i> (Linnaeus, 1758): Use of otolith microchemistry for conservation and sustainable management

In the context of River Rhône restoration programme, objective this study was to assess dispersal and population connectivity European chub, Squalius cephalus (Linnaeus, 1758) in a section natural, free-flowing part lower Rhône. The elemental water signatures for Sr:Ca Ba:Ca were measured at seven stations within river section, including its tributaries backwaters, determine whether they could be differentiated by microchemistry. From August October differed among three sectors reach: Rhône; Ardèche; backwaters. otoliths 178 young-of-the-year (YOY) chub from spawning areas identify early migratory life histories. Analyses otolith microchemistry identified natal origin 95% fish. showed downstream migration 30.4% YOY chub; however, 70% fish recruited relatively close their suggesting potential inshore retention results (i) non-negligible contribution backwaters recruitment into main channel; (ii) ability migrate over several kilometres during first few months life. This shows that combination analyses growth increases understanding history. Moreover, revealed half came other reproduction (despite high anthropization). These methods offer promising future applications management ecological rehabilitation, especially effectiveness measures applied floodplain riverine conservation.