Skipjack tuna (Katsuwonus pelamis) is a cosmopolitan species found in the tropical and subtropical waters of the Indian, Pacific and Atlantic Oceans. It is considered a highly migratory species that generally forms large schools, often in association with other tunas of similar size such as juveniles of yellowfin tuna and bigeye tuna (IOTC 2017). The evidence of rapid and large-scale movements of skipjack tuna in the Indian Ocean reported by the Regional Tuna Tagging Project-Indian Ocean (RTTP-IO) supports the assumption of a single stock of skipjack tuna population within the Indian Ocean (Murua et al. 2015)(IOTC 2017)(Artetxe-Arrate et al. 2021).

The structure of skipjack populations in the Indian Ocean is thought to consist of two different stocks, namely between the western waters of Sumatra and the southern waters of Java to Nusa Tenggara. The genetic diversity of skipjack populations in the Indian Ocean is relatively high so that the population status is likely not to be depressed by fishing activities (LRPT 2017). The ecological characteristics of skipjack tuna associated with FADs in the Indian Ocean are indicated by the main interactions with hook and line, and purse seine fishing gear, measuring between 8 - 67 cm FL, average 34 cm FL or aged around 1.7 years (LRPT 2016).