• ICIMOD publication


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Re-establishment of fish passage for conserving threatened migratory species of West-Indian Himalayas

  • Shailendra Raut
  • Nishikant Gupta
  • Prakash Nautiyal
  • Mark Everard
  • Summary

Fish passes are structures (natural or manmade) bypassing barriers (e.g., dams), enabling satisfactory movement of migratory fish species. Reestablishment of fish passage, including facilitating overcoming barriers presented by impoundments or restoration of defunct structures, is attracting interest among scientists and policymakers as a mechanism to enable recovery of target fish species or fish communities. However, it is also important to note that fish passes may also act as ecological traps in some large neotropical rivers. A diversity of multispecies fish passage designs have been implemented in North and South America, Europe, and Australia, with varying efficacy for different species. However, field surveys between 2010 and 2018 supported by a review of published literature (N = 217) using Google Scholar search engine using six key terms reveal that few fish passes have been constructed in dams in the Indian Himalayan region, and their efficacy is largely unproven. Major problems associated with fish pass designs include uneven success across a range of species and largely untested effectiveness at the large scale of many major dams. The objective of this paper is to stress upon the requirement of a new approach to understand the operational drawbacks of different types of fish pass and to take an adaptive approach to both design and operation using field data to improve fish pass efficiency. These measures could contribute significantly to the conservation of threatened migratory fish in the increasingly impounded rivers of the Indian Himalayan region. © 2019 John Wiley & Sons Ltd