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Project LeaderLondon Wildlife TrustProject PartnersGreen Corridor Funding SourcesThames WaterProject Budget£13,734Project Timescale2016

Assessment of Barriers to Fish Passage in the Crane Catchment

Migration barriers have had a detrimental impact on The Crane’s ability to naturally recover from pollution events, such as those recorded in 2011 and 2013. It is believed that the high density of barriers on the lower half of the river is responsible for preventing the ingress of fish to the River Crane from the River Thames. Where fish stocking has been an effective interim mitigation measure for kick starting a new population of fish, barrier removal would provide a sustainable solution to ensuring the viability of the Crane’s fish stocks in years to come.

Migration barriers on the upper river prevent the distribution of fish species to areas where good habitat is available. This limits the diversity of fish species found on the Upper Crane and Yeading Brook. Migration barriers also prevent migratory species of fish, such as European Eels (Anguilla anguilla ), from reaching critical habitats required to complete their lifecycles. Eel monitoring surveys from the Zoological Society of London (ZSL) show that juvenile eels are unable to reach the upper river, with no eels ever recorded at the Crane Park Island monitoring station (Pecorelli, 2014). The River Crane could provide a valuable corridor for eel passage throughout West London and to other catchments, such as the Colne.

The Crane Valley Partnership Fisheries Group highlighted the need for a Barrier Passability Assessment report in order to deduce which barriers were passable by cyprinids and European eels. The study is a necessary piece of work before any barrier removal or fish easement projects take place. The report will enable the Crane Valley Partnership (CVP) to deduce which barriers are having the greatest impact on fish populations and which of these would be the most valuable to remove.

The report is available to download. Please note that the document has been optimised for web viewing, therefore the quality of the imagery has been reduced. As part of the project, a story map application is being developed from which you can view and interogate the data in more detail.

The map below depicts the top 10 barriers identified to improve fish passage in the Crane catchment.

Priority fish migration barriers
Priority barriers preventing fish migration