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Manipulating flow velocity to manage fish reproductions in dammed rivers
  • +4
  • Qiuwen Chen,
  • Lei Tang,
  • Jun Wang,
  • Kangle Mo,
  • Yuchen Chen,
  • Yuqing Lin,
  • Yong Gao
Qiuwen Chen
Nanjing Hydraulic Research Institute
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Lei Tang
Nanjing Hydraulic Research Institute
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Jun Wang
Nanjing Hydraulic Research Institute
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Kangle Mo
Nanjing Hydraulic Research Institute
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Yuchen Chen
Nanjing Hydraulic Research Institute
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Yuqing Lin
Nanjing Hydraulic Research Institute
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Yong Gao
China Three Gorges Corporation
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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.