Associative Behavior-Based abundance Index (ABBI) for western Indian Ocean bigeye tuna (Thunnus obesus) obtained from echosounder buoys data.

This paper presents the estimates of bigeye tuna (Thunnus obesus) abundance assessed from the associative behavior-based abundance index (ABBI). Taking advantage of the associative behavior of species around floating objects (FOBs) and acoustic data collected by echosounder buoys used in the tropical tuna purse seine fishery, the ABBI approach index allows for direct and effort-independent abundance estimates of tropical tuna species. Its implementation in the western Indian Ocean on small bigeye tuna (individual less than 10 kg) has shown a decline in abundance of this species since 2018, relative to the reference levels of 2013.