Standardized purse seine CPUE of Yellowfin tuna in the Indian Ocean for the European fleet

The time series of EU purse seine fleet catches per unit effort (CPUE) of small (<10kg) and large
(>=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).