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Bay of Biscay case study - Mapping exposure risk of marine megafauna to concomitant pressures


This case study seeks to explore tools, methods and data to assess environmental effects of maritime uses in the context of MSP and transboundary issues. The maps displayed in the report and the map collection illustrate transboundary issues for conservation of marine biodiversity. The report could thereby serve as a basis for developing cumulative effect assessment methods which could help implement MSFD and MSP with common tools and approaches.

Application in MSP:
Type of Issue:
Type of practice:
Stage of MSP cycle:
Cross-border / trans-national aspect:
Coherence with other processes:
Key words:

Questions this practice may help answer:

  • What are the main exposure risks to concomitant pressures of little delphinae and the great grey gulls in the border area of France and Spain?
  • What kind of methods and datasets can be used to analyse the cumulative pressures on marine mammals in the French and Spanish border area?
  • What are the main challenges and issues regarding the analysis of cumulative pressures on marine mammals?

Implementation Context:

The SIMNORAT project included this case study dedicated to the cumulative effects assessment of anthropogenic pressures on the marine environment. This case study seeks to explore tools, methods and data to assess environmental effects of maritime uses in the context of MSP and transboundary issues. In this context it was chosen to work on marine mammals and seabirds and on the most relevant anthropogenic pressures in terms of the likely effects on these communities and spatial planning issues.

Aspects / Objectives:

  • To share datasets focusing on similar/ equivalent themes between partners
  • To facilitate the comparison of these datasets using a common grid, while also integrating them in a cumulative pressures assessment tool in order highlight the exposure risk of marine megafauna to concomitant pressures and to compare the results depending on the datasets used.


  1. Produce maps of human activities and major pressures affecting marine mammals and seabirds.
  2. Produce maps of the potential exposure risk to human pressures for marine mammals and seabirds, in order to locate and rank the areas of probable overlapping between anthropogenic pressures and the marine communities studied.
  3. Assess the risk of exposure of marine mammals and seabirds to individual pressures
  4. Assess the risk of exposure of marine mammals and seabirds to cumulative pressures:

The focus has been on two simulations:

  1. Summer and winter exposure risk to concomitant pressures of little delphinae (French datasets)
  2. Summer and winter exposure risk to concomitant pressures of great grey gulls (Spanish and French datasets)

Main Outputs / Results:

The report consists of a large number of maps on the pressures of the little dephinae and the great grey gulls. An example can be seen in the map below which shows the intensity of multi-pressures that can interact with great grey gulls (simulation with Spanish and French datasets).

Three main lessons have been learned from the exercise/case study:

  1. The networking of partners from the two countries involved in the project is an important and needed first step for a better assessment of transboundary stakes. The discussion between them addressed many topics in order to lay the foundations for a mutual understanding. After the end of the project, this network should be supported, politically and technically, to continue to work and to progress on these issues.
  2. A very important part of the work concerned the development of a coherent and operational dataset to implement and illustrate the method. Many constraints and limitations were encountered and required an adaptation of the desired ambition for the results.
  3. The consideration of mobile stakes in Cumulative Effect Assessment is not as well developed as for the habitats. This approach, new for the partners, has led to very interesting developments in the methodologies, and improved the knowledges of issues to take into account in the processes.

Main conclusion:

The maps displayed in this report and the map collection are good illustrations of transboundary issues for conservation of marine biodiversity, particularly in the context of MSP. For example, the distribution map of little delphininae and grey gulls, in summer or winter, shows the need to develop a coherent and coordinated management approach on both sides of the maritime boundaries. In the same way, the example maps showing the multi-activity index, multi-pressure index and risk of exposure show that the pressures on these species are distributed on both sides of the border and that it is necessary to develop a coordinated management of these activities. These maps also show significant challenges in building common interoperable datasets that are necessary to have a comprehensive and shared view of the issues. All of these issues are well known in the context of implementation of MSFD and MSP.

The main challenge faced by this case study was the collection and production of coherent datasets from both France and Spain. The other challenges were the methodological and technical development for the assessment of the risk of exposure and the number of variation factors to consider on ecological components like marine mammals and seabirds as a model relevant for the MSP.


The analysis of cumulative pressures using complex data sets and mapping is becoming one of the key components of MSP in many countries. Several EU funded projects have been discussion these tools, such as SIMCELT and SIMNORAT. The methods used in plan developments and these projects can be of interests of other project and countries wanting to do a similar exercise of understanding and mapping cumulative pressures.


French Biodiversity Agency




Neil Alloncle

French Biodiversity Agency (neil[dot]alloncle[at]afbiodiversite[dot]fr)