Assessing jumping ability in three endemic leuciscid (Cypriniformes) fish species

Abstract

The ability of fish to move within river networks supports population connectivity and persistence, though anthropogenic low-head barriers pose a widespread threat. Jumping ability is a key determinant of whether species can negotiate vertical drops, yet data for non-salmonid fishes remain scarce. We conducted a systematic review of jumping performance data for Cypriniformes and assessed the jumping performance of endemic rheophilic leuciscids: Italian chub (Squalius squalus), Italian riffle dace (Telestes muticellus), and South European nase (Protochondrostoma genei), under laboratory conditions across vertical drop heights (Δh = 10, 20, 30, 40 cm). All species negotiated the 10 cm drop (42–74% success), but success declined sharply to 28–38% at 20 cm. Performance diverged at higher drops: P. genei failed entirely at 30 and 40 cm, and only one S. squalus passed at 40 cm. Drop height was the only significant predictor of success; body length had no significant effect within the tested range. Maximum Δh/BL ratios of 3.3 (S. squalus, T. muticellus) are among the highest reported for Cypriniformes. Results demonstrate low-head barriers of 20–40 cm can severely restrict upstream passage in rheophilic leuciscids, underscoring the conservation relevance of small vertical drops and the need to account for jumping performance in barrier assessment and passage design for non-salmonid species.

The authors' abstract, as published at the source. Journal of Ecohydraulics, 2026 · DOI ↗