Abstract
Managing reproduction is the most effective approach to sustain
population or control invasion of species. Flow velocity is recognized
to affect the reproduction of fishes spawning drifting eggs in rivers.
Despite plenty of studies on this aspect, quantitative relations between
flow velocity and fish reproduction, including spawning, fertilizing,
hatching and surviving, has not yet been established. Here we for the
first time quantified the relationship between flow velocity and
reproduction of Chinese carps through lab experiments as well as field
surveys. The results showed that a minimum velocity was required to
trigger Hypophthalmichthys molitrix (H. molitrix) releasing eggs, and a
velocity range was preferential to sustain spawning activity. However,
the embryo incubation and larvae development of H. molitrix were found
to be inhibited with the increase in flow velocity. Considering the
requirements of spawning and hatching as well as larvae development, a
compromised optimal flow velocity was identified for reproduction of H.
molitrix in rivers. The findings were of great significance to guide the
operation of cascade dams to create suitable flow velocities during
reproduction season for either improving population or impeding invasion
of carps.