Prioritising culvert removals to restore habitat for at-risk salmonids in the boreal forest

In the boreal forests of Canada, industrial development has resulted in the installation of thousands of culverted road crossings that act as barriers to fish movement and degrade habitat for native freshwater fishes. In view of culvert removals being expensive, prioritisation methods have been developed, but the efficacy of such methods has not been thoroughly investigated nor have they been tested on low‐gradient boreal forest watersheds containing at‐risk salmonids. The management utility of a novel GIS‐based optimisation‐planning tool to prioritise fish barrier remediation was tested in two highly developed watersheds. Region‐specific parameter estimates of monetary variables (e.g. budget, individual barrier remediation costs), barrier passability and biologically relevant information for species on conservation concern (e.g. habitat suitability, dispersal ability) were incorporated. Results indicate that for Arctic grayling, Thymallus arcticus Pallas, and bull trout, Salvelinus confluentus Suckley, a large proportion (~61–83%) of currently isolated habitat can be reconnected with low investment (~$200–$500 K). This study demonstrates the management utility of barrier optimisation methods for use in boreal watersheds, particularly as it significantly reduces the technical expertise needed to perform relatively complex optimisation analyses.