Résumé
The time series of EU purse seine fleet catches per unit effort (CPUE) of small (=10kg) yellowfin tuna (YFT) from the Indian Ocean were standardized using an extension of the Delta-lognormal GLMM to three components. These components are: (i) the detection rate of schools per unit of searching time, (ii) the proportion of sets for which the targeted size category is present and (iii) the biomass of the targeted size category in the fish school. The aim was to use the commercial size categories as a proxy to depict the trend in abundance for adult and juvenile YFT observed in free schools (FSC), as well as for juveniles caught under floating objects (FOB).