LAUSR

Abstract It is not known how high age-0 Silver Carp ( Hypophthalmichthys molitrix ) can jump and whether they can jump voluntarily to cross waterfalls, a question that is potentially related to fishway design or prohibitions on distribution. Age-0 Silver Carp were observed to jump to a height (mean ± SD) of 20.53 ± 5.26 cm (1.90 ± 0.48 times of total length) when startled by a jet of water, exhibiting a jumping speed of 23.88 ± 4.42 cm/s. The number of leaps, entry rate, and success rate were significantly affected by waterfall height (5, 10, or 15 cm) but not by discharge rate (0.002, 0.004, or 0.006 m 3 /s). The success rate (fish crossing the waterfall) was low for all waterfalls, with the median success rate being the highest (10%) for the 5-cm drop. When overcoming the 5-cm drop, fish used standing, swim-in, and leaping behaviors, whereas only leaping behavior was used for higher drops. These results suggest that age-0 Silver Carp are capable of leaping, but they have a poor ability to voluntarily cross waterfalls and appear to avoid the downstream turbulence produced by waterfall conditions.