Fish Obstacles Porosity

Trialling of the methodology for quantifying the impacts of obstacles to fish passage


The overall objective of the Fish Obstacles Porosity project was to:

  • allow the authorities with responsibility for implementing the Water Framework Directive to classify water bodies according to the potential impacts of obstacles to fish migration on fish populations using a consistent methodology; and
  • provide a methodology to allow agencies and fishery managers to identify the obstacles that have the greatest impact upon fish migration, both upstream and downstream. This will allow obstacles to be prioritised for removal or to have passage facilities (which may include changes to the water flow regime) installed, thus maximising the ratio of ecological benefit to capital expenditure.


Phase 1 of this project was undertaken during the first half of 2008 by Dr. Paul Kemp of Southampton University.

The aim of this project (Phase 2a) was to organise and manage the trialling of the methodology developed to assess the porosity of obstacles to fish migration and, on the basis of the trialling experience, to propose revisions to the methodology. The project was undertaken by Dr Colin Bull of University of Stirling.

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