From non-tidal to tidal environments: movement behaviour of Chinese mitten crabs on downstream spawning migration

During their spawning migration, adult mitten crabs reveal movement behaviour that maximises their fitness. In shallow non-tidal rivers, migrating at night likely reduces predation risk. In tidal rivers, this behaviour largely disappears, which could be linked to increased depth and turbidity, or the prevalence of the tidal migration cue. Based on detection and acceleration data, this study provides the first evidence that adult mitten crabs use selective tidal stream transport during their migration. As a slow-moving species, this behaviour helps to preserve energy for spawning during the challenging final phase of their life cycle.