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Restoring river connectivity: Prioritizing passage improvements for diadromous fishes and lampreys

Cowx, I. G.; Nunn, A. D.


I. G. Cowx


Physical obstructions are becoming increasingly recognized as major factors influencing the migrations, population structures, spawning success and recruitment of freshwater organisms. This paper presents a simple but effective method, intended for use by environmental managers, government agencies and conservation bodies, of rapidly assessing and prioritizing barriers to the migrations of diadromous fishes and lampreys for passage improvements. A prioritization matrix was developed using information on fish stock status, the passage efficiency of fishes at individual structures, the distance from the tidal limit and the passability of downstream barriers, and the quantity and quality of habitat upstream of each structure. Importantly, the 'Likelihood of access' was incorporated into the matrix to account for passage efficiency at downstream barriers. Barriers ranked as the highest priority for passage improvements were those characterized by poor fish stocks upstream, low passage efficiency, easy passage from downstream, and a large quantity and high quality of habitat upstream. Prioritization of migration barriers should ensure that access improvements are targeted to achieve optimum benefits. © Royal Swedish Academy of Sciences 2012.


Cowx, I. G., & Nunn, A. D. (2012). Restoring river connectivity: Prioritizing passage improvements for diadromous fishes and lampreys. AMBIO: A Journal of the Human Environment, 41(4), 402-409.

Journal Article Type Article
Acceptance Date Feb 1, 2011
Online Publication Date Mar 20, 2012
Publication Date Jun 1, 2012
Deposit Date Nov 13, 2014
Journal Ambio
Print ISSN 0044-7447
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 41
Issue 4
Pages 402-409
Keywords REF 2014 submission!
Public URL