Coordinated migration ensuring sexual parasitism in fish species: Extreme weather conditions induce atypically large fish dispersal movements

Abstract

This study reports, for the first time, a previously undocumented large and coordinated upstream migration of Squalius pyrenaicus (Günther, 1868) and Squalius alburnoides (Steindachner, 1866) in the Vascão River (Mediterranean temporary river) (Portugal), covering distances of at least 1687 metres and up to 4540 metres. These species were considered resident, but this migration happened after a dry year followed by an extremely wet winter and spring. These findings suggest that these species possess stronger dispersal capacities than previously thought, and could coordinate migrations to ensure interspecific relationships, specifically the sperm parasitism of S. pyrenaicus by S. alburnoides.