The objective of this activity is to test and compare the different calculation methods of abundance indices based on scientific surveys data and commercial data. The first method consists of the calculation of the abundance index from a series of scientific observations or catches per unit of effort (CPUE) adjusted to a generalised linear model (GLM) with one or more explicative variables. The second approach, which is most adapted to scientific survey data (geostatistic approach), consists of calculating an average abundance index, which variance of estimation is estimated from adjusted models of the experimental (observed) variogram or covariogram. A test of combination of data (scientific and commercial data) will also be tested.

Persons involved in the case studies

Didier Gascuel, Fisheries scientist	Nicolas Bez, Geostatistics science
Emmanuel Chassot , Fisheries scientist	Aboubacar Sidibe, Biology
Didier Jouffre , Biology	Francis Laloë , Statistics
Cheik Abdallahi Inejih , Biology	Modou Thiaw, Biology
Abdelmalek Faraj , Biology

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