Author(s): Filipe Romao; Ana L. Quaresma; Francisco J. Bravo-Cordoba; Amaral Susana; Francisco J. Sanz-Ronda; Jose M. Santos And Antonio N. Pinheiro
Linked Author(s): José Maria Santos, António Pinheiro, Ana Quaresma
Keywords: Invasive alien species Cyprinids Fish passage Vertical slot fishway Selective fishways
Abstract: Invasive alien fish species threaten freshwater ecosystems globally by disrupting native biodiversity and ecosystem balance. In fragmented rivers, where barriers block natural water flow and fish movements, fishways can assist fish in bypassing these obstructions. However, these structures can unintentionally contribute to spreading invasive species, worsening ecological damage. To address this issue, a full-scale experiment was conducted using a vertical slot fishway (VSF) to assess the passage performance of two cyprinid species: the invasive common carp (Cyprinus carpio) and the native Iberian barbel (Luciobarbus bocagei). Two fishway configurations (VSF_hm1 and VSF_hm2), differing in water depth (hm1 = 0.55 m and hm2 = 0.80 m), were tested under steep slopes (15.2%), significant head drops between pools (Δh = 0.28 m), and high volumetric dissipation power (Pv > 150 W/m3) that exceeded design guidelines for cyprinids. The time-to-event analysis revealed that VSF_hm1 selectively favoured the native barbel. Carp showed significantly lower motivation to pass both configurations, with only one successful ascent in VSF_hm2, compared to 9 and 17 barbel ascents in VSF_hm2 and VSF_hm1, respectively. Overall, the selective design (VSF_hm1) shows promise in managing the non-native invasive carp in regulated rivers.
Year: 2025