European purse seiners CPUE standardization of Big Eye tuna caught under dFADs

Abundance index for Big Eye tuna (BET) in the Indian Ocean was derived from the European purse seiner CPUEs series (2010-2021) for fishing operations made on drifting FADs (Fishing aggregating Devices). By classifying sets to non-followed dFADs (i.e., dFADs randomly encounter for which the purse seiner has no previous information) and followed-dFADs (dFADs from which purse seiner has previous information and therefore it is not randomly encounter) we take into account the difference between them. The VAST methodology was used to standardized the BET CPUE. A GLMM approach has been also applied to compare the outputs when using an alternative modelling approach