Environmental signal in skipjack recruitment in the Indian Ocean: An updated analysis using the SS3-assessment outputs of 2023

A study presented at the WPTT25-Data Preparatory meeting investigated the link between interannual changes in ocean productivity and skipjack recruitment in the Indian Ocean fishery, using the then available recruitment index series produced by the 2020 skipjack stock assessment, with recruitment data up to 2018. With a new recruitment time series produced by the 2023 assessment (until 2021), we redid the analysis both in the western region of the Indian Ocean, and in a large equatorial region stretching from 40°E to 100°E. This new study using the updated recruitment index confirms the main outcome of the previous study i.e. 1) a positive response in recruitment with positive anomalies of sea surface chlorophyll (SSC) which are associated to negative Indian Ocean Dipoles; 2) a less marked response, though towards slightly reduced recruitment, in situations of negative SSC associated to positive Indian Ocean Dipoles. Such responses in recruitment can make a valuable ancillary information in the setting of a management advice for skipjack at the IOTC