The document provides an overview of the consolidated knowledge about fisheries catching black marlin (Istiompax indica) in the Indian Ocean since the early 1950s based on a range of data sets collected by Contracting Parties and Cooperating Non-Contracting Parties (CPCs) of the IOTC and curated by the IOTC Secretariat. The available fisheries statistics indicate that black marlins are mostly caught in artisanal fisheries which represented more than 70% of the total catch of black marlin in 2020. Total catches of black marlin with gillnets and small longlines in the coastal waters of I.R. Iran, India, Sri Lanka, Indonesia, Pakistan, and Oman have shown a major increasing trend over the last decade with catches from large-scale longline fisheries experiencing a major decline since 2008. Information available on discarding practices of black marlin in industrial fisheries indicates that discard levels are small in longline fisheries while black marlins are more often discarded in large-scale purse seine fisheries, although in small quantities. Discarding in coastal fisheries interacting with the species is poorly known but considered to be negligible. Information available on the spatial distribution of catch and effort has substantially improved over the last decade and shows that black marlins are mostly caught in the north west part of the Indian Ocean, with important catches reported along the coasts of the Arabian Sea, India, and Sri Lanka. The reporting of size-frequency data has slightly improved over the last decade but remains very limited for most artisanal and industrial fisheries.