The quality of statistics about West African fisheries has often been criticised, mainly because the data about catches, biomass estimates and other key features assessed by national research institutes and sector administrations are frequently incomplete and not up-to-date.That means few stocks can be confidently assessed with conventional data-intensive methods. This is where a new algorithm (CMSY) based on only catch and resilience estimates comes to the rescue of robust management in such data poor conditions.

The Secretariat of the Sub-Regional Fisheries Commission (SRFC) composed of the following seven countries - Mauritania, Senegal, Gambia, Cape Verde, Guinea Bissau, Guinea and Sierra Leone - thus convened a training workshop for fisheries and data scientists of its member countries to be introduced to the new methodology. The training between 23 and 27 September 2019 was ensured by a team of the Sea Around Us project led by Prof. Daniel Pauly and Dr. Maria Lourdes (Deng) Palomares of the University of British Columbia in Vancouver, Canada, with the assistance of two PhD students, Myriam Khalfallah and Jessika Woroniak.

The major advantage of CMSY is that it requires only catch data, but not biomass estimates, which are difficult to derive. For good results, the following needs to be ascertained:

  • stocks are defined by ecosystem rather than by fishing area
  • continuous time series of catches are available, ideally of at least 10 years
  • setting up length-frequency data sets based on commercial catches from non-selective gears
  • estimates of resilience of the species caught can be obtained from FishBase (for fish) or SeaLifeBase (for other marine organisms)
  • indications of abundance, if available, can be derived from time series of catch per unit of effort (cpue) of at least three years or estimates of standing stock.

Dr. Mika Diop of the SRFC had invited Aliou Sall, Vice President of Mundus maris, to join as an observer.

The first day the analysis software was uploaded on the computers of all participants followed by an introductory lecture by Prof. Pauly. Then it was time to delve into the data sets participants had brought from their countries and prepare them for the analysis.

Mini-groups by country worked on the data from their own country supported by the UBC team to start the analyses. All difficulties or processing errors were discussed with the trainers to enable participants to not only grasp the method in principle, but become confident in its use. They were also invited to deliver oral presentations of their preliminary results in plenary in order lay the foundation for publications shortly after the training workshop. The workshop is a boost of capacities within the region to do its own analyses.

Publications of these assessments in peer-reviewed journals will increase the confidence of stock assessments and contribute to strengthening much needed fisheries management. More information is available here.